Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2922 insertions, 0 deletions

diff --git a/intl/icu/source/common/ucnv.cpp b/intl/icu/source/common/ucnv.cpp
new file mode 100644
index 0000000000..a7a07d65d6
--- /dev/null
+++ b/intl/icu/source/common/ucnv.cpp
@@ -0,0 +1,2922 @@
+// © 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+/*
+******************************************************************************
+*
+*   Copyright (C) 1998-2016, International Business Machines
+*   Corporation and others.  All Rights Reserved.
+*
+******************************************************************************
+*
+*  ucnv.c:
+*  Implements APIs for the ICU's codeset conversion library;
+*  mostly calls through internal functions;
+*  created by Bertrand A. Damiba
+*
+* Modification History:
+*
+*   Date        Name        Description
+*   04/04/99    helena      Fixed internal header inclusion.
+*   05/09/00    helena      Added implementation to handle fallback mappings.
+*   06/20/2000  helena      OS/400 port changes; mostly typecast.
+*/
+
+#include "unicode/utypes.h"
+
+#if !UCONFIG_NO_CONVERSION
+
+#include <memory>
+
+#include "unicode/ustring.h"
+#include "unicode/ucnv.h"
+#include "unicode/ucnv_err.h"
+#include "unicode/uset.h"
+#include "unicode/utf.h"
+#include "unicode/utf16.h"
+#include "putilimp.h"
+#include "cmemory.h"
+#include "cstring.h"
+#include "uassert.h"
+#include "utracimp.h"
+#include "ustr_imp.h"
+#include "ucnv_imp.h"
+#include "ucnv_cnv.h"
+#include "ucnv_bld.h"
+
+/* size of intermediate and preflighting buffers in ucnv_convert() */
+#define CHUNK_SIZE 1024
+
+typedef struct UAmbiguousConverter {
+    const char *name;
+    const char16_t variant5c;
+} UAmbiguousConverter;
+
+static const UAmbiguousConverter ambiguousConverters[]={
+    { "ibm-897_P100-1995", 0xa5 },
+    { "ibm-942_P120-1999", 0xa5 },
+    { "ibm-943_P130-1999", 0xa5 },
+    { "ibm-946_P100-1995", 0xa5 },
+    { "ibm-33722_P120-1999", 0xa5 },
+    { "ibm-1041_P100-1995", 0xa5 },
+    /*{ "ibm-54191_P100-2006", 0xa5 },*/
+    /*{ "ibm-62383_P100-2007", 0xa5 },*/
+    /*{ "ibm-891_P100-1995", 0x20a9 },*/
+    { "ibm-944_P100-1995", 0x20a9 },
+    { "ibm-949_P110-1999", 0x20a9 },
+    { "ibm-1363_P110-1997", 0x20a9 },
+    { "ISO_2022,locale=ko,version=0", 0x20a9 },
+    { "ibm-1088_P100-1995", 0x20a9 }
+};
+
+/*Calls through createConverter */
+U_CAPI UConverter* U_EXPORT2
+ucnv_open (const char *name,
+                       UErrorCode * err)
+{
+    UConverter *r;
+
+    if (err == nullptr || U_FAILURE (*err)) {
+        return nullptr;
+    }
+
+    r =  ucnv_createConverter(nullptr, name, err);
+    return r;
+}
+
+U_CAPI UConverter* U_EXPORT2 
+ucnv_openPackage   (const char *packageName, const char *converterName, UErrorCode * err)
+{
+    return ucnv_createConverterFromPackage(packageName, converterName,  err);
+}
+
+/*Extracts the char16_t* to a char* and calls through createConverter */
+U_CAPI UConverter*   U_EXPORT2
+ucnv_openU (const char16_t * name,
+                         UErrorCode * err)
+{
+    char asciiName[UCNV_MAX_CONVERTER_NAME_LENGTH];
+
+    if (err == nullptr || U_FAILURE(*err))
+        return nullptr;
+    if (name == nullptr)
+        return ucnv_open (nullptr, err);
+    if (u_strlen(name) >= UCNV_MAX_CONVERTER_NAME_LENGTH)
+    {
+        *err = U_ILLEGAL_ARGUMENT_ERROR;
+        return nullptr;
+    }
+    return ucnv_open(u_austrcpy(asciiName, name), err);
+}
+
+/* Copy the string that is represented by the UConverterPlatform enum
+ * @param platformString An output buffer
+ * @param platform An enum representing a platform
+ * @return the length of the copied string.
+ */
+static int32_t
+ucnv_copyPlatformString(char *platformString, UConverterPlatform pltfrm)
+{
+    switch (pltfrm)
+    {
+    case UCNV_IBM:
+        uprv_strcpy(platformString, "ibm-");
+        return 4;
+    case UCNV_UNKNOWN:
+        break;
+    }
+
+    /* default to empty string */
+    *platformString = 0;
+    return 0;
+}
+
+/*Assumes a $platform-#codepage.$CONVERTER_FILE_EXTENSION scheme and calls
+ *through createConverter*/
+U_CAPI UConverter*   U_EXPORT2
+ucnv_openCCSID (int32_t codepage,
+                UConverterPlatform platform,
+                UErrorCode * err)
+{
+    char myName[UCNV_MAX_CONVERTER_NAME_LENGTH];
+    int32_t myNameLen;
+
+    if (err == nullptr || U_FAILURE (*err))
+        return nullptr;
+
+    /* ucnv_copyPlatformString could return "ibm-" or "cp" */
+    myNameLen = ucnv_copyPlatformString(myName, platform);
+    T_CString_integerToString(myName + myNameLen, codepage, 10);
+
+    return ucnv_createConverter(nullptr, myName, err);
+}
+
+/* Creating a temporary stack-based object that can be used in one thread, 
+and created from a converter that is shared across threads.
+*/
+
+U_CAPI UConverter* U_EXPORT2
+ucnv_safeClone(const UConverter* cnv, void *stackBuffer, int32_t *pBufferSize, UErrorCode *status)
+{
+    UConverter *localConverter, *allocatedConverter;
+    int32_t stackBufferSize;
+    int32_t bufferSizeNeeded;
+    UErrorCode cbErr;
+    UConverterToUnicodeArgs toUArgs = {
+        sizeof(UConverterToUnicodeArgs),
+            true,
+            nullptr,
+            nullptr,
+            nullptr,
+            nullptr,
+            nullptr,
+            nullptr
+    };
+    UConverterFromUnicodeArgs fromUArgs = {
+        sizeof(UConverterFromUnicodeArgs),
+            true,
+            nullptr,
+            nullptr,
+            nullptr,
+            nullptr,
+            nullptr,
+            nullptr
+    };
+
+    UTRACE_ENTRY_OC(UTRACE_UCNV_CLONE);
+
+    if (status == nullptr || U_FAILURE(*status)){
+        UTRACE_EXIT_STATUS(status? *status: U_ILLEGAL_ARGUMENT_ERROR);
+        return nullptr;
+    }
+
+    if (cnv == nullptr) {
+        *status = U_ILLEGAL_ARGUMENT_ERROR;
+        UTRACE_EXIT_STATUS(*status);
+        return nullptr;
+    }
+
+    UTRACE_DATA3(UTRACE_OPEN_CLOSE, "clone converter %s at %p into stackBuffer %p",
+                                    ucnv_getName(cnv, status), cnv, stackBuffer);
+
+    if (cnv->sharedData->impl->safeClone != nullptr) {
+        /* call the custom safeClone function for sizing */
+        bufferSizeNeeded = 0;
+        cnv->sharedData->impl->safeClone(cnv, nullptr, &bufferSizeNeeded, status);
+        if (U_FAILURE(*status)) {
+            UTRACE_EXIT_STATUS(*status);
+            return nullptr;
+        }
+    }
+    else
+    {
+        /* inherent sizing */
+        bufferSizeNeeded = sizeof(UConverter);
+    }
+
+    if (pBufferSize == nullptr) {
+        stackBufferSize = 1;
+        pBufferSize = &stackBufferSize;
+    } else {
+        stackBufferSize = *pBufferSize;
+        if (stackBufferSize <= 0){ /* 'preflighting' request - set needed size into *pBufferSize */
+            *pBufferSize = bufferSizeNeeded;
+            UTRACE_EXIT_VALUE(bufferSizeNeeded);
+            return nullptr;
+        }
+    }
+
+    /* Adjust (if necessary) the stackBuffer pointer to be aligned correctly for a UConverter.
+     * TODO(Jira ICU-20736) Redo this using std::align() once g++4.9 compatibility is no longer needed.
+     */
+    if (stackBuffer) {
+        uintptr_t p = reinterpret_cast<uintptr_t>(stackBuffer);
+        uintptr_t aligned_p = (p + alignof(UConverter) - 1) & ~(alignof(UConverter) - 1);
+        ptrdiff_t pointerAdjustment = aligned_p - p;
+        if (bufferSizeNeeded + pointerAdjustment <= stackBufferSize) {
+            stackBuffer = reinterpret_cast<void *>(aligned_p);
+            stackBufferSize -= static_cast<int32_t>(pointerAdjustment);
+        } else {
+            /* prevent using the stack buffer but keep the size > 0 so that we do not just preflight */
+            stackBufferSize = 1;
+        }
+    }
+
+    /* Now, see if we must allocate any memory */
+    if (stackBufferSize < bufferSizeNeeded || stackBuffer == nullptr)
+    {
+        /* allocate one here...*/
+        localConverter = allocatedConverter = (UConverter *) uprv_malloc (bufferSizeNeeded);
+
+        if(localConverter == nullptr) {
+            *status = U_MEMORY_ALLOCATION_ERROR;
+            UTRACE_EXIT_STATUS(*status);
+            return nullptr;
+        }
+        // If pBufferSize was nullptr as the input, pBufferSize is set to &stackBufferSize in this function.
+        if (pBufferSize != &stackBufferSize) {
+            *status = U_SAFECLONE_ALLOCATED_WARNING;
+        }
+
+        /* record the fact that memory was allocated */
+        *pBufferSize = bufferSizeNeeded;
+    } else {
+        /* just use the stack buffer */
+        localConverter = (UConverter*) stackBuffer;
+        allocatedConverter = nullptr;
+    }
+
+    uprv_memset(localConverter, 0, bufferSizeNeeded);
+
+    /* Copy initial state */
+    uprv_memcpy(localConverter, cnv, sizeof(UConverter));
+    localConverter->isCopyLocal = localConverter->isExtraLocal = false;
+
+    /* copy the substitution string */
+    if (cnv->subChars == (uint8_t *)cnv->subUChars) {
+        localConverter->subChars = (uint8_t *)localConverter->subUChars;
+    } else {
+        localConverter->subChars = (uint8_t *)uprv_malloc(UCNV_ERROR_BUFFER_LENGTH * U_SIZEOF_UCHAR);
+        if (localConverter->subChars == nullptr) {
+            uprv_free(allocatedConverter);
+            UTRACE_EXIT_STATUS(*status);
+            return nullptr;
+        }
+        uprv_memcpy(localConverter->subChars, cnv->subChars, UCNV_ERROR_BUFFER_LENGTH * U_SIZEOF_UCHAR);
+    }
+
+    /* now either call the safeclone fcn or not */
+    if (cnv->sharedData->impl->safeClone != nullptr) {
+        /* call the custom safeClone function */
+        localConverter = cnv->sharedData->impl->safeClone(cnv, localConverter, pBufferSize, status);
+    }
+
+    if(localConverter==nullptr || U_FAILURE(*status)) {
+        if (allocatedConverter != nullptr && allocatedConverter->subChars != (uint8_t *)allocatedConverter->subUChars) {
+            uprv_free(allocatedConverter->subChars);
+        }
+        uprv_free(allocatedConverter);
+        UTRACE_EXIT_STATUS(*status);
+        return nullptr;
+    }
+
+    /* increment refcount of shared data if needed */
+    if (cnv->sharedData->isReferenceCounted) {
+        ucnv_incrementRefCount(cnv->sharedData);
+    }
+
+    if(localConverter == (UConverter*)stackBuffer) {
+        /* we're using user provided data - set to not destroy */
+        localConverter->isCopyLocal = true;
+    }
+
+    /* allow callback functions to handle any memory allocation */
+    toUArgs.converter = fromUArgs.converter = localConverter;
+    cbErr = U_ZERO_ERROR;
+    cnv->fromCharErrorBehaviour(cnv->toUContext, &toUArgs, nullptr, 0, UCNV_CLONE, &cbErr);
+    cbErr = U_ZERO_ERROR;
+    cnv->fromUCharErrorBehaviour(cnv->fromUContext, &fromUArgs, nullptr, 0, 0, UCNV_CLONE, &cbErr);
+
+    UTRACE_EXIT_PTR_STATUS(localConverter, *status);
+    return localConverter;
+}
+
+U_CAPI UConverter* U_EXPORT2
+ucnv_clone(const UConverter* cnv, UErrorCode *status)
+{
+    return ucnv_safeClone(cnv, nullptr, nullptr, status);
+}
+
+/*Decreases the reference counter in the shared immutable section of the object
+ *and frees the mutable part*/
+
+U_CAPI void  U_EXPORT2
+ucnv_close (UConverter * converter)
+{
+    UErrorCode errorCode = U_ZERO_ERROR;
+
+    UTRACE_ENTRY_OC(UTRACE_UCNV_CLOSE);
+
+    if (converter == nullptr)
+    {
+        UTRACE_EXIT();
+        return;
+    }
+
+    UTRACE_DATA3(UTRACE_OPEN_CLOSE, "close converter %s at %p, isCopyLocal=%b",
+        ucnv_getName(converter, &errorCode), converter, converter->isCopyLocal);
+
+    /* In order to speed up the close, only call the callbacks when they have been changed.
+    This performance check will only work when the callbacks are set within a shared library
+    or from user code that statically links this code. */
+    /* first, notify the callback functions that the converter is closed */
+    if (converter->fromCharErrorBehaviour != UCNV_TO_U_DEFAULT_CALLBACK) {
+        UConverterToUnicodeArgs toUArgs = {
+            sizeof(UConverterToUnicodeArgs),
+                true,
+                nullptr,
+                nullptr,
+                nullptr,
+                nullptr,
+                nullptr,
+                nullptr
+        };
+
+        toUArgs.converter = converter;
+        errorCode = U_ZERO_ERROR;
+        converter->fromCharErrorBehaviour(converter->toUContext, &toUArgs, nullptr, 0, UCNV_CLOSE, &errorCode);
+    }
+    if (converter->fromUCharErrorBehaviour != UCNV_FROM_U_DEFAULT_CALLBACK) {
+        UConverterFromUnicodeArgs fromUArgs = {
+            sizeof(UConverterFromUnicodeArgs),
+                true,
+                nullptr,
+                nullptr,
+                nullptr,
+                nullptr,
+                nullptr,
+                nullptr
+        };
+        fromUArgs.converter = converter;
+        errorCode = U_ZERO_ERROR;
+        converter->fromUCharErrorBehaviour(converter->fromUContext, &fromUArgs, nullptr, 0, 0, UCNV_CLOSE, &errorCode);
+    }
+
+    if (converter->sharedData->impl->close != nullptr) {
+        converter->sharedData->impl->close(converter);
+    }
+
+    if (converter->subChars != (uint8_t *)converter->subUChars) {
+        uprv_free(converter->subChars);
+    }
+
+    if (converter->sharedData->isReferenceCounted) {
+        ucnv_unloadSharedDataIfReady(converter->sharedData);
+    }
+
+    if(!converter->isCopyLocal){
+        uprv_free(converter);
+    }
+
+    UTRACE_EXIT();
+}
+
+/*returns a single Name from the list, will return nullptr if out of bounds
+ */
+U_CAPI const char*   U_EXPORT2
+ucnv_getAvailableName (int32_t n)
+{
+    if (0 <= n && n <= 0xffff) {
+        UErrorCode err = U_ZERO_ERROR;
+        const char *name = ucnv_bld_getAvailableConverter((uint16_t)n, &err);
+        if (U_SUCCESS(err)) {
+            return name;
+        }
+    }
+    return nullptr;
+}
+
+U_CAPI int32_t   U_EXPORT2
+ucnv_countAvailable ()
+{
+    UErrorCode err = U_ZERO_ERROR;
+    return ucnv_bld_countAvailableConverters(&err);
+}
+
+U_CAPI void    U_EXPORT2
+ucnv_getSubstChars (const UConverter * converter,
+                    char *mySubChar,
+                    int8_t * len,
+                    UErrorCode * err)
+{
+    if (U_FAILURE (*err))
+        return;
+
+    if (converter->subCharLen <= 0) {
+        /* Unicode string or empty string from ucnv_setSubstString(). */
+        *len = 0;
+        return;
+    }
+
+    if (*len < converter->subCharLen) /*not enough space in subChars */
+    {
+        *err = U_INDEX_OUTOFBOUNDS_ERROR;
+        return;
+    }
+
+    uprv_memcpy (mySubChar, converter->subChars, converter->subCharLen);   /*fills in the subchars */
+    *len = converter->subCharLen; /*store # of bytes copied to buffer */
+}
+
+U_CAPI void    U_EXPORT2
+ucnv_setSubstChars (UConverter * converter,
+                    const char *mySubChar,
+                    int8_t len,
+                    UErrorCode * err)
+{
+    if (U_FAILURE (*err))
+        return;
+    
+    /*Makes sure that the subChar is within the codepages char length boundaries */
+    if ((len > converter->sharedData->staticData->maxBytesPerChar)
+     || (len < converter->sharedData->staticData->minBytesPerChar))
+    {
+        *err = U_ILLEGAL_ARGUMENT_ERROR;
+        return;
+    }
+    
+    uprv_memcpy (converter->subChars, mySubChar, len); /*copies the subchars */
+    converter->subCharLen = len;  /*sets the new len */
+
+    /*
+    * There is currently (2001Feb) no separate API to set/get subChar1.
+    * In order to always have subChar written after it is explicitly set,
+    * we set subChar1 to 0.
+    */
+    converter->subChar1 = 0;
+    
+    return;
+}
+
+U_CAPI void U_EXPORT2
+ucnv_setSubstString(UConverter *cnv,
+                    const char16_t *s,
+                    int32_t length,
+                    UErrorCode *err) {
+    alignas(UConverter) char cloneBuffer[U_CNV_SAFECLONE_BUFFERSIZE];
+    char chars[UCNV_ERROR_BUFFER_LENGTH];
+
+    UConverter *clone;
+    uint8_t *subChars;
+    int32_t cloneSize, length8;
+
+    /* Let the following functions check all arguments. */
+    cloneSize = sizeof(cloneBuffer);
+    clone = ucnv_safeClone(cnv, cloneBuffer, &cloneSize, err);
+    ucnv_setFromUCallBack(clone, UCNV_FROM_U_CALLBACK_STOP, nullptr, nullptr, nullptr, err);
+    length8 = ucnv_fromUChars(clone, chars, (int32_t)sizeof(chars), s, length, err);
+    ucnv_close(clone);
+    if (U_FAILURE(*err)) {
+        return;
+    }
+
+    if (cnv->sharedData->impl->writeSub == nullptr
+#if !UCONFIG_NO_LEGACY_CONVERSION
+        || (cnv->sharedData->staticData->conversionType == UCNV_MBCS &&
+         ucnv_MBCSGetType(cnv) != UCNV_EBCDIC_STATEFUL)
+#endif
+    ) {
+        /* The converter is not stateful. Store the charset bytes as a fixed string. */
+        subChars = (uint8_t *)chars;
+    } else {
+        /*
+         * The converter has a non-default writeSub() function, indicating
+         * that it is stateful.
+         * Store the Unicode string for on-the-fly conversion for correct
+         * state handling.
+         */
+        if (length > UCNV_ERROR_BUFFER_LENGTH) {
+            /*
+             * Should not occur. The converter should output at least one byte
+             * per char16_t, which means that ucnv_fromUChars() should catch all
+             * overflows.
+             */
+            *err = U_BUFFER_OVERFLOW_ERROR;
+            return;
+        }
+        subChars = (uint8_t *)s;
+        if (length < 0) {
+            length = u_strlen(s);
+        }
+        length8 = length * U_SIZEOF_UCHAR;
+    }
+
+    /*
+     * For storing the substitution string, select either the small buffer inside
+     * UConverter or allocate a subChars buffer.
+     */
+    if (length8 > UCNV_MAX_SUBCHAR_LEN) {
+        /* Use a separate buffer for the string. Outside UConverter to not make it too large. */
+        if (cnv->subChars == (uint8_t *)cnv->subUChars) {
+            /* Allocate a new buffer for the string. */
+            cnv->subChars = (uint8_t *)uprv_malloc(UCNV_ERROR_BUFFER_LENGTH * U_SIZEOF_UCHAR);
+            if (cnv->subChars == nullptr) {
+                cnv->subChars = (uint8_t *)cnv->subUChars;
+                *err = U_MEMORY_ALLOCATION_ERROR;
+                return;
+            }
+            uprv_memset(cnv->subChars, 0, UCNV_ERROR_BUFFER_LENGTH * U_SIZEOF_UCHAR);
+        }
+    }
+
+    /* Copy the substitution string into the UConverter or its subChars buffer. */
+    if (length8 == 0) {
+        cnv->subCharLen = 0;
+    } else {
+        uprv_memcpy(cnv->subChars, subChars, length8);
+        if (subChars == (uint8_t *)chars) {
+            cnv->subCharLen = (int8_t)length8;
+        } else /* subChars == s */ {
+            cnv->subCharLen = (int8_t)-length;
+        }
+    }
+
+    /* See comment in ucnv_setSubstChars(). */
+    cnv->subChar1 = 0;
+}
+
+/*resets the internal states of a converter
+ *goal : have the same behaviour than a freshly created converter
+ */
+static void _reset(UConverter *converter, UConverterResetChoice choice,
+                   UBool callCallback) {
+    if(converter == nullptr) {
+        return;
+    }
+
+    if(callCallback) {
+        /* first, notify the callback functions that the converter is reset */
+        UErrorCode errorCode;
+
+        if(choice<=UCNV_RESET_TO_UNICODE && converter->fromCharErrorBehaviour != UCNV_TO_U_DEFAULT_CALLBACK) {
+            UConverterToUnicodeArgs toUArgs = {
+                sizeof(UConverterToUnicodeArgs),
+                true,
+                nullptr,
+                nullptr,
+                nullptr,
+                nullptr,
+                nullptr,
+                nullptr
+            };
+            toUArgs.converter = converter;
+            errorCode = U_ZERO_ERROR;
+            converter->fromCharErrorBehaviour(converter->toUContext, &toUArgs, nullptr, 0, UCNV_RESET, &errorCode);
+        }
+        if(choice!=UCNV_RESET_TO_UNICODE && converter->fromUCharErrorBehaviour != UCNV_FROM_U_DEFAULT_CALLBACK) {
+            UConverterFromUnicodeArgs fromUArgs = {
+                sizeof(UConverterFromUnicodeArgs),
+                true,
+                nullptr,
+                nullptr,
+                nullptr,
+                nullptr,
+                nullptr,
+                nullptr
+            };
+            fromUArgs.converter = converter;
+            errorCode = U_ZERO_ERROR;
+            converter->fromUCharErrorBehaviour(converter->fromUContext, &fromUArgs, nullptr, 0, 0, UCNV_RESET, &errorCode);
+        }
+    }
+
+    /* now reset the converter itself */
+    if(choice<=UCNV_RESET_TO_UNICODE) {
+        converter->toUnicodeStatus = converter->sharedData->toUnicodeStatus;
+        converter->mode = 0;
+        converter->toULength = 0;
+        converter->invalidCharLength = converter->UCharErrorBufferLength = 0;
+        converter->preToULength = 0;
+    }
+    if(choice!=UCNV_RESET_TO_UNICODE) {
+        converter->fromUnicodeStatus = 0;
+        converter->fromUChar32 = 0;
+        converter->invalidUCharLength = converter->charErrorBufferLength = 0;
+        converter->preFromUFirstCP = U_SENTINEL;
+        converter->preFromULength = 0;
+    }
+
+    if (converter->sharedData->impl->reset != nullptr) {
+        /* call the custom reset function */
+        converter->sharedData->impl->reset(converter, choice);
+    }
+}
+
+U_CAPI void  U_EXPORT2
+ucnv_reset(UConverter *converter)
+{
+    _reset(converter, UCNV_RESET_BOTH, true);
+}
+
+U_CAPI void  U_EXPORT2
+ucnv_resetToUnicode(UConverter *converter)
+{
+    _reset(converter, UCNV_RESET_TO_UNICODE, true);
+}
+
+U_CAPI void  U_EXPORT2
+ucnv_resetFromUnicode(UConverter *converter)
+{
+    _reset(converter, UCNV_RESET_FROM_UNICODE, true);
+}
+
+U_CAPI int8_t   U_EXPORT2
+ucnv_getMaxCharSize (const UConverter * converter)
+{
+    return converter->maxBytesPerUChar;
+}
+
+
+U_CAPI int8_t   U_EXPORT2
+ucnv_getMinCharSize (const UConverter * converter)
+{
+    return converter->sharedData->staticData->minBytesPerChar;
+}
+
+U_CAPI const char*   U_EXPORT2
+ucnv_getName (const UConverter * converter, UErrorCode * err)
+     
+{
+    if (U_FAILURE (*err))
+        return nullptr;
+    if(converter->sharedData->impl->getName){
+        const char* temp= converter->sharedData->impl->getName(converter);
+        if(temp)
+            return temp;
+    }
+    return converter->sharedData->staticData->name;
+}
+
+U_CAPI int32_t U_EXPORT2
+ucnv_getCCSID(const UConverter * converter,
+              UErrorCode * err)
+{
+    int32_t ccsid;
+    if (U_FAILURE (*err))
+        return -1;
+
+    ccsid = converter->sharedData->staticData->codepage;
+    if (ccsid == 0) {
+        /* Rare case. This is for cases like gb18030,
+        which doesn't have an IBM canonical name, but does have an IBM alias. */
+        const char *standardName = ucnv_getStandardName(ucnv_getName(converter, err), "IBM", err);
+        if (U_SUCCESS(*err) && standardName) {
+            const char *ccsidStr = uprv_strchr(standardName, '-');
+            if (ccsidStr) {
+                ccsid = (int32_t)atol(ccsidStr+1);  /* +1 to skip '-' */
+            }
+        }
+    }
+    return ccsid;
+}
+
+
+U_CAPI UConverterPlatform   U_EXPORT2
+ucnv_getPlatform (const UConverter * converter,
+                                      UErrorCode * err)
+{
+    if (U_FAILURE (*err))
+        return UCNV_UNKNOWN;
+
+    return (UConverterPlatform)converter->sharedData->staticData->platform;
+}
+
+U_CAPI void U_EXPORT2
+    ucnv_getToUCallBack (const UConverter * converter,
+                         UConverterToUCallback *action,
+                         const void **context)
+{
+    *action = converter->fromCharErrorBehaviour;
+    *context = converter->toUContext;
+}
+
+U_CAPI void U_EXPORT2
+    ucnv_getFromUCallBack (const UConverter * converter,
+                           UConverterFromUCallback *action,
+                           const void **context)
+{
+    *action = converter->fromUCharErrorBehaviour;
+    *context = converter->fromUContext;
+}
+
+U_CAPI void    U_EXPORT2
+ucnv_setToUCallBack (UConverter * converter,
+                            UConverterToUCallback newAction,
+                            const void* newContext,
+                            UConverterToUCallback *oldAction,
+                            const void** oldContext,
+                            UErrorCode * err)
+{
+    if (U_FAILURE (*err))
+        return;
+    if (oldAction) *oldAction = converter->fromCharErrorBehaviour;
+    converter->fromCharErrorBehaviour = newAction;
+    if (oldContext) *oldContext = converter->toUContext;
+    converter->toUContext = newContext;
+}
+
+U_CAPI void  U_EXPORT2
+ucnv_setFromUCallBack (UConverter * converter,
+                            UConverterFromUCallback newAction,
+                            const void* newContext,
+                            UConverterFromUCallback *oldAction,
+                            const void** oldContext,
+                            UErrorCode * err)
+{
+    if (U_FAILURE (*err))
+        return;
+    if (oldAction) *oldAction = converter->fromUCharErrorBehaviour;
+    converter->fromUCharErrorBehaviour = newAction;
+    if (oldContext) *oldContext = converter->fromUContext;
+    converter->fromUContext = newContext;
+}
+
+static void
+_updateOffsets(int32_t *offsets, int32_t length,
+               int32_t sourceIndex, int32_t errorInputLength) {
+    int32_t *limit;
+    int32_t delta, offset;
+
+    if(sourceIndex>=0) {
+        /*
+         * adjust each offset by adding the previous sourceIndex
+         * minus the length of the input sequence that caused an
+         * error, if any
+         */
+        delta=sourceIndex-errorInputLength;
+    } else {
+        /*
+         * set each offset to -1 because this conversion function
+         * does not handle offsets
+         */
+        delta=-1;
+    }
+
+    limit=offsets+length;
+    if(delta==0) {
+        /* most common case, nothing to do */
+    } else if(delta>0) {
+        /* add the delta to each offset (but not if the offset is <0) */
+        while(offsets<limit) {
+            offset=*offsets;
+            if(offset>=0) {
+                *offsets=offset+delta;
+            }
+            ++offsets;
+        }
+    } else /* delta<0 */ {
+        /*
+         * set each offset to -1 because this conversion function
+         * does not handle offsets
+         * or the error input sequence started in a previous buffer
+         */
+        while(offsets<limit) {
+            *offsets++=-1;
+        }
+    }
+}
+
+/* ucnv_fromUnicode --------------------------------------------------------- */
+
+/*
+ * Implementation note for m:n conversions
+ *
+ * While collecting source units to find the longest match for m:n conversion,
+ * some source units may need to be stored for a partial match.
+ * When a second buffer does not yield a match on all of the previously stored
+ * source units, then they must be "replayed", i.e., fed back into the converter.
+ *
+ * The code relies on the fact that replaying will not nest -
+ * converting a replay buffer will not result in a replay.
+ * This is because a replay is necessary only after the _continuation_ of a
+ * partial match failed, but a replay buffer is converted as a whole.
+ * It may result in some of its units being stored again for a partial match,
+ * but there will not be a continuation _during_ the replay which could fail.
+ *
+ * It is conceivable that a callback function could call the converter
+ * recursively in a way that causes another replay to be stored, but that
+ * would be an error in the callback function.
+ * Such violations will cause assertion failures in a debug build,
+ * and wrong output, but they will not cause a crash.
+ */
+
+static void
+_fromUnicodeWithCallback(UConverterFromUnicodeArgs *pArgs, UErrorCode *err) {
+    UConverterFromUnicode fromUnicode;
+    UConverter *cnv;
+    const char16_t *s;
+    char *t;
+    int32_t *offsets;
+    int32_t sourceIndex;
+    int32_t errorInputLength;
+    UBool converterSawEndOfInput, calledCallback;
+
+    /* variables for m:n conversion */
+    char16_t replay[UCNV_EXT_MAX_UCHARS];
+    const char16_t *realSource, *realSourceLimit;
+    int32_t realSourceIndex;
+    UBool realFlush;
+
+    cnv=pArgs->converter;
+    s=pArgs->source;
+    t=pArgs->target;
+    offsets=pArgs->offsets;
+
+    /* get the converter implementation function */
+    sourceIndex=0;
+    if(offsets==nullptr) {
+        fromUnicode=cnv->sharedData->impl->fromUnicode;
+    } else {
+        fromUnicode=cnv->sharedData->impl->fromUnicodeWithOffsets;
+        if(fromUnicode==nullptr) {
+            /* there is no WithOffsets implementation */
+            fromUnicode=cnv->sharedData->impl->fromUnicode;
+            /* we will write -1 for each offset */
+            sourceIndex=-1;
+        }
+    }
+
+    if(cnv->preFromULength>=0) {
+        /* normal mode */
+        realSource=nullptr;
+
+        /* avoid compiler warnings - not otherwise necessary, and the values do not matter */
+        realSourceLimit=nullptr;
+        realFlush=false;
+        realSourceIndex=0;
+    } else {
+        /*
+         * Previous m:n conversion stored source units from a partial match
+         * and failed to consume all of them.
+         * We need to "replay" them from a temporary buffer and convert them first.
+         */
+        realSource=pArgs->source;
+        realSourceLimit=pArgs->sourceLimit;
+        realFlush=pArgs->flush;
+        realSourceIndex=sourceIndex;
+
+        uprv_memcpy(replay, cnv->preFromU, -cnv->preFromULength*U_SIZEOF_UCHAR);
+        pArgs->source=replay;
+        pArgs->sourceLimit=replay-cnv->preFromULength;
+        pArgs->flush=false;
+        sourceIndex=-1;
+
+        cnv->preFromULength=0;
+    }
+
+    /*
+     * loop for conversion and error handling
+     *
+     * loop {
+     *   convert
+     *   loop {
+     *     update offsets
+     *     handle end of input
+     *     handle errors/call callback
+     *   }
+     * }
+     */
+    for(;;) {
+        if(U_SUCCESS(*err)) {
+            /* convert */
+            fromUnicode(pArgs, err);
+
+            /*
+             * set a flag for whether the converter
+             * successfully processed the end of the input
+             *
+             * need not check cnv->preFromULength==0 because a replay (<0) will cause
+             * s<sourceLimit before converterSawEndOfInput is checked
+             */
+            converterSawEndOfInput=
+                (UBool)(U_SUCCESS(*err) &&
+                        pArgs->flush && pArgs->source==pArgs->sourceLimit &&
+                        cnv->fromUChar32==0);
+        } else {
+            /* handle error from ucnv_convertEx() */
+            converterSawEndOfInput=false;
+        }
+
+        /* no callback called yet for this iteration */
+        calledCallback=false;
+
+        /* no sourceIndex adjustment for conversion, only for callback output */
+        errorInputLength=0;
+
+        /*
+         * loop for offsets and error handling
+         *
+         * iterates at most 3 times:
+         * 1. to clean up after the conversion function
+         * 2. after the callback
+         * 3. after the callback again if there was truncated input
+         */
+        for(;;) {
+            /* update offsets if we write any */
+            if(offsets!=nullptr) {
+                int32_t length=(int32_t)(pArgs->target-t);
+                if(length>0) {
+                    _updateOffsets(offsets, length, sourceIndex, errorInputLength);
+
+                    /*
+                     * if a converter handles offsets and updates the offsets
+                     * pointer at the end, then pArgs->offset should not change
+                     * here;
+                     * however, some converters do not handle offsets at all
+                     * (sourceIndex<0) or may not update the offsets pointer
+                     */
+                    pArgs->offsets=offsets+=length;
+                }
+
+                if(sourceIndex>=0) {
+                    sourceIndex+=(int32_t)(pArgs->source-s);
+                }
+            }
+
+            if(cnv->preFromULength<0) {
+                /*
+                 * switch the source to new replay units (cannot occur while replaying)
+                 * after offset handling and before end-of-input and callback handling
+                 */
+                if(realSource==nullptr) {
+                    realSource=pArgs->source;
+                    realSourceLimit=pArgs->sourceLimit;
+                    realFlush=pArgs->flush;
+                    realSourceIndex=sourceIndex;
+
+                    uprv_memcpy(replay, cnv->preFromU, -cnv->preFromULength*U_SIZEOF_UCHAR);
+                    pArgs->source=replay;
+                    pArgs->sourceLimit=replay-cnv->preFromULength;
+                    pArgs->flush=false;
+                    if((sourceIndex+=cnv->preFromULength)<0) {
+                        sourceIndex=-1;
+                    }
+
+                    cnv->preFromULength=0;
+                } else {
+                    /* see implementation note before _fromUnicodeWithCallback() */
+                    U_ASSERT(realSource==nullptr);
+                    *err=U_INTERNAL_PROGRAM_ERROR;
+                }
+            }
+
+            /* update pointers */
+            s=pArgs->source;
+            t=pArgs->target;
+
+            if(U_SUCCESS(*err)) {
+                if(s<pArgs->sourceLimit) {
+                    /*
+                     * continue with the conversion loop while there is still input left
+                     * (continue converting by breaking out of only the inner loop)
+                     */
+                    break;
+                } else if(realSource!=nullptr) {
+                    /* switch back from replaying to the real source and continue */
+                    pArgs->source=realSource;
+                    pArgs->sourceLimit=realSourceLimit;
+                    pArgs->flush=realFlush;
+                    sourceIndex=realSourceIndex;
+
+                    realSource=nullptr;
+                    break;
+                } else if(pArgs->flush && cnv->fromUChar32!=0) {
+                    /*
+                     * the entire input stream is consumed
+                     * and there is a partial, truncated input sequence left
+                     */
+
+                    /* inject an error and continue with callback handling */
+                    *err=U_TRUNCATED_CHAR_FOUND;
+                    calledCallback=false; /* new error condition */
+                } else {
+                    /* input consumed */
+                    if(pArgs->flush) {
+                        /*
+                         * return to the conversion loop once more if the flush
+                         * flag is set and the conversion function has not
+                         * successfully processed the end of the input yet
+                         *
+                         * (continue converting by breaking out of only the inner loop)
+                         */
+                        if(!converterSawEndOfInput) {
+                            break;
+                        }
+
+                        /* reset the converter without calling the callback function */
+                        _reset(cnv, UCNV_RESET_FROM_UNICODE, false);
+                    }
+
+                    /* done successfully */
+                    return;
+                }
+            }
+
+            /* U_FAILURE(*err) */
+            {
+                UErrorCode e;
+
+                if( calledCallback ||
+                    (e=*err)==U_BUFFER_OVERFLOW_ERROR ||
+                    (e!=U_INVALID_CHAR_FOUND &&
+                     e!=U_ILLEGAL_CHAR_FOUND &&
+                     e!=U_TRUNCATED_CHAR_FOUND)
+                ) {
+                    /*
+                     * the callback did not or cannot resolve the error:
+                     * set output pointers and return
+                     *
+                     * the check for buffer overflow is redundant but it is
+                     * a high-runner case and hopefully documents the intent
+                     * well
+                     *
+                     * if we were replaying, then the replay buffer must be
+                     * copied back into the UConverter
+                     * and the real arguments must be restored
+                     */
+                    if(realSource!=nullptr) {
+                        int32_t length;
+
+                        U_ASSERT(cnv->preFromULength==0);
+
+                        length=(int32_t)(pArgs->sourceLimit-pArgs->source);
+                        if(length>0) {
+                            u_memcpy(cnv->preFromU, pArgs->source, length);
+                            cnv->preFromULength=(int8_t)-length;
+                        }
+
+                        pArgs->source=realSource;
+                        pArgs->sourceLimit=realSourceLimit;
+                        pArgs->flush=realFlush;
+                    }
+
+                    return;
+                }
+            }
+
+            /* callback handling */
+            {
+                UChar32 codePoint;
+
+                /* get and write the code point */
+                codePoint=cnv->fromUChar32;
+                errorInputLength=0;
+                U16_APPEND_UNSAFE(cnv->invalidUCharBuffer, errorInputLength, codePoint);
+                cnv->invalidUCharLength=(int8_t)errorInputLength;
+
+                /* set the converter state to deal with the next character */
+                cnv->fromUChar32=0;
+
+                /* call the callback function */
+                cnv->fromUCharErrorBehaviour(cnv->fromUContext, pArgs,
+                    cnv->invalidUCharBuffer, errorInputLength, codePoint,
+                    *err==U_INVALID_CHAR_FOUND ? UCNV_UNASSIGNED : UCNV_ILLEGAL,
+                    err);
+            }
+
+            /*
+             * loop back to the offset handling
+             *
+             * this flag will indicate after offset handling
+             * that a callback was called;
+             * if the callback did not resolve the error, then we return
+             */
+            calledCallback=true;
+        }
+    }
+}
+
+/*
+ * Output the fromUnicode overflow buffer.
+ * Call this function if(cnv->charErrorBufferLength>0).
+ * @return true if overflow
+ */
+static UBool
+ucnv_outputOverflowFromUnicode(UConverter *cnv,
+                               char **target, const char *targetLimit,
+                               int32_t **pOffsets,
+                               UErrorCode *err) {
+    int32_t *offsets;
+    char *overflow, *t;
+    int32_t i, length;
+
+    t=*target;
+    if(pOffsets!=nullptr) {
+        offsets=*pOffsets;
+    } else {
+        offsets=nullptr;
+    }
+
+    overflow=(char *)cnv->charErrorBuffer;
+    length=cnv->charErrorBufferLength;
+    i=0;
+    while(i<length) {
+        if(t==targetLimit) {
+            /* the overflow buffer contains too much, keep the rest */
+            int32_t j=0;
+
+            do {
+                overflow[j++]=overflow[i++];
+            } while(i<length);
+
+            cnv->charErrorBufferLength=(int8_t)j;
+            *target=t;
+            if(offsets!=nullptr) {
+                *pOffsets=offsets;
+            }
+            *err=U_BUFFER_OVERFLOW_ERROR;
+            return true;
+        }
+
+        /* copy the overflow contents to the target */
+        *t++=overflow[i++];
+        if(offsets!=nullptr) {
+            *offsets++=-1; /* no source index available for old output */
+        }
+    }
+
+    /* the overflow buffer is completely copied to the target */
+    cnv->charErrorBufferLength=0;
+    *target=t;
+    if(offsets!=nullptr) {
+        *pOffsets=offsets;
+    }
+    return false;
+}
+
+U_CAPI void U_EXPORT2
+ucnv_fromUnicode(UConverter *cnv,
+                 char **target, const char *targetLimit,
+                 const char16_t **source, const char16_t *sourceLimit,
+                 int32_t *offsets,
+                 UBool flush,
+                 UErrorCode *err) {
+    UConverterFromUnicodeArgs args;
+    const char16_t *s;
+    char *t;
+
+    /* check parameters */
+    if(err==nullptr || U_FAILURE(*err)) {
+        return;
+    }
+
+    if(cnv==nullptr || target==nullptr || source==nullptr) {
+        *err=U_ILLEGAL_ARGUMENT_ERROR;
+        return;
+    }
+
+    s=*source;
+    t=*target;
+
+    if ((const void *)U_MAX_PTR(sourceLimit) == (const void *)sourceLimit) {
+        /*
+        Prevent code from going into an infinite loop in case we do hit this
+        limit. The limit pointer is expected to be on a char16_t * boundary.
+        This also prevents the next argument check from failing.
+        */
+        sourceLimit = (const char16_t *)(((const char *)sourceLimit) - 1);
+    }
+
+    /*
+     * All these conditions should never happen.
+     *
+     * 1) Make sure that the limits are >= to the address source or target
+     *
+     * 2) Make sure that the buffer sizes do not exceed the number range for
+     * int32_t because some functions use the size (in units or bytes)
+     * rather than comparing pointers, and because offsets are int32_t values.
+     *
+     * size_t is guaranteed to be unsigned and large enough for the job.
+     *
+     * Return with an error instead of adjusting the limits because we would
+     * not be able to maintain the semantics that either the source must be
+     * consumed or the target filled (unless an error occurs).
+     * An adjustment would be targetLimit=t+0x7fffffff; for example.
+     *
+     * 3) Make sure that the user didn't incorrectly cast a char16_t * pointer
+     * to a char * pointer and provide an incomplete char16_t code unit.
+     */
+    if (sourceLimit<s || targetLimit<t ||
+        ((size_t)(sourceLimit-s)>(size_t)0x3fffffff && sourceLimit>s) ||
+        ((size_t)(targetLimit-t)>(size_t)0x7fffffff && targetLimit>t) ||
+        (((const char *)sourceLimit-(const char *)s) & 1) != 0)
+    {
+        *err=U_ILLEGAL_ARGUMENT_ERROR;
+        return;
+    }
+    
+    /* output the target overflow buffer */
+    if( cnv->charErrorBufferLength>0 &&
+        ucnv_outputOverflowFromUnicode(cnv, target, targetLimit, &offsets, err)
+    ) {
+        /* U_BUFFER_OVERFLOW_ERROR */
+        return;
+    }
+    /* *target may have moved, therefore stop using t */
+
+    if(!flush && s==sourceLimit && cnv->preFromULength>=0) {
+        /* the overflow buffer is emptied and there is no new input: we are done */
+        return;
+    }
+
+    /*
+     * Do not simply return with a buffer overflow error if
+     * !flush && t==targetLimit
+     * because it is possible that the source will not generate any output.
+     * For example, the skip callback may be called;
+     * it does not output anything.
+     */
+
+    /* prepare the converter arguments */
+    args.converter=cnv;
+    args.flush=flush;
+    args.offsets=offsets;
+    args.source=s;
+    args.sourceLimit=sourceLimit;
+    args.target=*target;
+    args.targetLimit=targetLimit;
+    args.size=sizeof(args);
+
+    _fromUnicodeWithCallback(&args, err);
+
+    *source=args.source;
+    *target=args.target;
+}
+
+/* ucnv_toUnicode() --------------------------------------------------------- */
+
+static void
+_toUnicodeWithCallback(UConverterToUnicodeArgs *pArgs, UErrorCode *err) {
+    UConverterToUnicode toUnicode;
+    UConverter *cnv;
+    const char *s;
+    char16_t *t;
+    int32_t *offsets;
+    int32_t sourceIndex;
+    int32_t errorInputLength;
+    UBool converterSawEndOfInput, calledCallback;
+
+    /* variables for m:n conversion */
+    char replay[UCNV_EXT_MAX_BYTES];
+    const char *realSource, *realSourceLimit;
+    int32_t realSourceIndex;
+    UBool realFlush;
+
+    cnv=pArgs->converter;
+    s=pArgs->source;
+    t=pArgs->target;
+    offsets=pArgs->offsets;
+
+    /* get the converter implementation function */
+    sourceIndex=0;
+    if(offsets==nullptr) {
+        toUnicode=cnv->sharedData->impl->toUnicode;
+    } else {
+        toUnicode=cnv->sharedData->impl->toUnicodeWithOffsets;
+        if(toUnicode==nullptr) {
+            /* there is no WithOffsets implementation */
+            toUnicode=cnv->sharedData->impl->toUnicode;
+            /* we will write -1 for each offset */
+            sourceIndex=-1;
+        }
+    }
+
+    if(cnv->preToULength>=0) {
+        /* normal mode */
+        realSource=nullptr;
+
+        /* avoid compiler warnings - not otherwise necessary, and the values do not matter */
+        realSourceLimit=nullptr;
+        realFlush=false;
+        realSourceIndex=0;
+    } else {
+        /*
+         * Previous m:n conversion stored source units from a partial match
+         * and failed to consume all of them.
+         * We need to "replay" them from a temporary buffer and convert them first.
+         */
+        realSource=pArgs->source;
+        realSourceLimit=pArgs->sourceLimit;
+        realFlush=pArgs->flush;
+        realSourceIndex=sourceIndex;
+
+        uprv_memcpy(replay, cnv->preToU, -cnv->preToULength);
+        pArgs->source=replay;
+        pArgs->sourceLimit=replay-cnv->preToULength;
+        pArgs->flush=false;
+        sourceIndex=-1;
+
+        cnv->preToULength=0;
+    }
+
+    /*
+     * loop for conversion and error handling
+     *
+     * loop {
+     *   convert
+     *   loop {
+     *     update offsets
+     *     handle end of input
+     *     handle errors/call callback
+     *   }
+     * }
+     */
+    for(;;) {
+        if(U_SUCCESS(*err)) {
+            /* convert */
+            toUnicode(pArgs, err);
+
+            /*
+             * set a flag for whether the converter
+             * successfully processed the end of the input
+             *
+             * need not check cnv->preToULength==0 because a replay (<0) will cause
+             * s<sourceLimit before converterSawEndOfInput is checked
+             */
+            converterSawEndOfInput=
+                (UBool)(U_SUCCESS(*err) &&
+                        pArgs->flush && pArgs->source==pArgs->sourceLimit &&
+                        cnv->toULength==0);
+        } else {
+            /* handle error from getNextUChar() or ucnv_convertEx() */
+            converterSawEndOfInput=false;
+        }
+
+        /* no callback called yet for this iteration */
+        calledCallback=false;
+
+        /* no sourceIndex adjustment for conversion, only for callback output */
+        errorInputLength=0;
+
+        /*
+         * loop for offsets and error handling
+         *
+         * iterates at most 3 times:
+         * 1. to clean up after the conversion function
+         * 2. after the callback
+         * 3. after the callback again if there was truncated input
+         */
+        for(;;) {
+            /* update offsets if we write any */
+            if(offsets!=nullptr) {
+                int32_t length=(int32_t)(pArgs->target-t);
+                if(length>0) {
+                    _updateOffsets(offsets, length, sourceIndex, errorInputLength);
+
+                    /*
+                     * if a converter handles offsets and updates the offsets
+                     * pointer at the end, then pArgs->offset should not change
+                     * here;
+                     * however, some converters do not handle offsets at all
+                     * (sourceIndex<0) or may not update the offsets pointer
+                     */
+                    pArgs->offsets=offsets+=length;
+                }
+
+                if(sourceIndex>=0) {
+                    sourceIndex+=(int32_t)(pArgs->source-s);
+                }
+            }
+
+            if(cnv->preToULength<0) {
+                /*
+                 * switch the source to new replay units (cannot occur while replaying)
+                 * after offset handling and before end-of-input and callback handling
+                 */
+                if(realSource==nullptr) {
+                    realSource=pArgs->source;
+                    realSourceLimit=pArgs->sourceLimit;
+                    realFlush=pArgs->flush;
+                    realSourceIndex=sourceIndex;
+
+                    uprv_memcpy(replay, cnv->preToU, -cnv->preToULength);
+                    pArgs->source=replay;
+                    pArgs->sourceLimit=replay-cnv->preToULength;
+                    pArgs->flush=false;
+                    if((sourceIndex+=cnv->preToULength)<0) {
+                        sourceIndex=-1;
+                    }
+
+                    cnv->preToULength=0;
+                } else {
+                    /* see implementation note before _fromUnicodeWithCallback() */
+                    U_ASSERT(realSource==nullptr);
+                    *err=U_INTERNAL_PROGRAM_ERROR;
+                }
+            }
+
+            /* update pointers */
+            s=pArgs->source;
+            t=pArgs->target;
+
+            if(U_SUCCESS(*err)) {
+                if(s<pArgs->sourceLimit) {
+                    /*
+                     * continue with the conversion loop while there is still input left
+                     * (continue converting by breaking out of only the inner loop)
+                     */
+                    break;
+                } else if(realSource!=nullptr) {
+                    /* switch back from replaying to the real source and continue */
+                    pArgs->source=realSource;
+                    pArgs->sourceLimit=realSourceLimit;
+                    pArgs->flush=realFlush;
+                    sourceIndex=realSourceIndex;
+
+                    realSource=nullptr;
+                    break;
+                } else if(pArgs->flush && cnv->toULength>0) {
+                    /*
+                     * the entire input stream is consumed
+                     * and there is a partial, truncated input sequence left
+                     */
+
+                    /* inject an error and continue with callback handling */
+                    *err=U_TRUNCATED_CHAR_FOUND;
+                    calledCallback=false; /* new error condition */
+                } else {
+                    /* input consumed */
+                    if(pArgs->flush) {
+                        /*
+                         * return to the conversion loop once more if the flush
+                         * flag is set and the conversion function has not
+                         * successfully processed the end of the input yet
+                         *
+                         * (continue converting by breaking out of only the inner loop)
+                         */
+                        if(!converterSawEndOfInput) {
+                            break;
+                        }
+
+                        /* reset the converter without calling the callback function */
+                        _reset(cnv, UCNV_RESET_TO_UNICODE, false);
+                    }
+
+                    /* done successfully */
+                    return;
+                }
+            }
+
+            /* U_FAILURE(*err) */
+            {
+                UErrorCode e;
+
+                if( calledCallback ||
+                    (e=*err)==U_BUFFER_OVERFLOW_ERROR ||
+                    (e!=U_INVALID_CHAR_FOUND &&
+                     e!=U_ILLEGAL_CHAR_FOUND &&
+                     e!=U_TRUNCATED_CHAR_FOUND &&
+                     e!=U_ILLEGAL_ESCAPE_SEQUENCE &&
+                     e!=U_UNSUPPORTED_ESCAPE_SEQUENCE)
+                ) {
+                    /*
+                     * the callback did not or cannot resolve the error:
+                     * set output pointers and return
+                     *
+                     * the check for buffer overflow is redundant but it is
+                     * a high-runner case and hopefully documents the intent
+                     * well
+                     *
+                     * if we were replaying, then the replay buffer must be
+                     * copied back into the UConverter
+                     * and the real arguments must be restored
+                     */
+                    if(realSource!=nullptr) {
+                        int32_t length;
+
+                        U_ASSERT(cnv->preToULength==0);
+
+                        length=(int32_t)(pArgs->sourceLimit-pArgs->source);
+                        if(length>0) {
+                            uprv_memcpy(cnv->preToU, pArgs->source, length);
+                            cnv->preToULength=(int8_t)-length;
+                        }
+
+                        pArgs->source=realSource;
+                        pArgs->sourceLimit=realSourceLimit;
+                        pArgs->flush=realFlush;
+                    }
+
+                    return;
+                }
+            }
+
+            /* copy toUBytes[] to invalidCharBuffer[] */
+            errorInputLength=cnv->invalidCharLength=cnv->toULength;
+            if(errorInputLength>0) {
+                uprv_memcpy(cnv->invalidCharBuffer, cnv->toUBytes, errorInputLength);
+            }
+
+            /* set the converter state to deal with the next character */
+            cnv->toULength=0;
+
+            /* call the callback function */
+            if(cnv->toUCallbackReason==UCNV_ILLEGAL && *err==U_INVALID_CHAR_FOUND) {
+                cnv->toUCallbackReason = UCNV_UNASSIGNED;
+            }
+            cnv->fromCharErrorBehaviour(cnv->toUContext, pArgs,
+                cnv->invalidCharBuffer, errorInputLength,
+                cnv->toUCallbackReason,
+                err);
+            cnv->toUCallbackReason = UCNV_ILLEGAL; /* reset to default value */
+
+            /*
+             * loop back to the offset handling
+             *
+             * this flag will indicate after offset handling
+             * that a callback was called;
+             * if the callback did not resolve the error, then we return
+             */
+            calledCallback=true;
+        }
+    }
+}
+
+/*
+ * Output the toUnicode overflow buffer.
+ * Call this function if(cnv->UCharErrorBufferLength>0).
+ * @return true if overflow
+ */
+static UBool
+ucnv_outputOverflowToUnicode(UConverter *cnv,
+                             char16_t **target, const char16_t *targetLimit,
+                             int32_t **pOffsets,
+                             UErrorCode *err) {
+    int32_t *offsets;
+    char16_t *overflow, *t;
+    int32_t i, length;
+
+    t=*target;
+    if(pOffsets!=nullptr) {
+        offsets=*pOffsets;
+    } else {
+        offsets=nullptr;
+    }
+
+    overflow=cnv->UCharErrorBuffer;
+    length=cnv->UCharErrorBufferLength;
+    i=0;
+    while(i<length) {
+        if(t==targetLimit) {
+            /* the overflow buffer contains too much, keep the rest */
+            int32_t j=0;
+
+            do {
+                overflow[j++]=overflow[i++];
+            } while(i<length);
+
+            cnv->UCharErrorBufferLength=(int8_t)j;
+            *target=t;
+            if(offsets!=nullptr) {
+                *pOffsets=offsets;
+            }
+            *err=U_BUFFER_OVERFLOW_ERROR;
+            return true;
+        }
+
+        /* copy the overflow contents to the target */
+        *t++=overflow[i++];
+        if(offsets!=nullptr) {
+            *offsets++=-1; /* no source index available for old output */
+        }
+    }
+
+    /* the overflow buffer is completely copied to the target */
+    cnv->UCharErrorBufferLength=0;
+    *target=t;
+    if(offsets!=nullptr) {
+        *pOffsets=offsets;
+    }
+    return false;
+}
+
+U_CAPI void U_EXPORT2
+ucnv_toUnicode(UConverter *cnv,
+               char16_t **target, const char16_t *targetLimit,
+               const char **source, const char *sourceLimit,
+               int32_t *offsets,
+               UBool flush,
+               UErrorCode *err) {
+    UConverterToUnicodeArgs args;
+    const char *s;
+    char16_t *t;
+
+    /* check parameters */
+    if(err==nullptr || U_FAILURE(*err)) {
+        return;
+    }
+
+    if(cnv==nullptr || target==nullptr || source==nullptr) {
+        *err=U_ILLEGAL_ARGUMENT_ERROR;
+        return;
+    }
+
+    s=*source;
+    t=*target;
+
+    if ((const void *)U_MAX_PTR(targetLimit) == (const void *)targetLimit) {
+        /*
+        Prevent code from going into an infinite loop in case we do hit this
+        limit. The limit pointer is expected to be on a char16_t * boundary.
+        This also prevents the next argument check from failing.
+        */
+        targetLimit = (const char16_t *)(((const char *)targetLimit) - 1);
+    }
+
+    /*
+     * All these conditions should never happen.
+     *
+     * 1) Make sure that the limits are >= to the address source or target
+     *
+     * 2) Make sure that the buffer sizes do not exceed the number range for
+     * int32_t because some functions use the size (in units or bytes)
+     * rather than comparing pointers, and because offsets are int32_t values.
+     *
+     * size_t is guaranteed to be unsigned and large enough for the job.
+     *
+     * Return with an error instead of adjusting the limits because we would
+     * not be able to maintain the semantics that either the source must be
+     * consumed or the target filled (unless an error occurs).
+     * An adjustment would be sourceLimit=t+0x7fffffff; for example.
+     *
+     * 3) Make sure that the user didn't incorrectly cast a char16_t * pointer
+     * to a char * pointer and provide an incomplete char16_t code unit.
+     */
+    if (sourceLimit<s || targetLimit<t ||
+        ((size_t)(sourceLimit-s)>(size_t)0x7fffffff && sourceLimit>s) ||
+        ((size_t)(targetLimit-t)>(size_t)0x3fffffff && targetLimit>t) ||
+        (((const char *)targetLimit-(const char *)t) & 1) != 0
+    ) {
+        *err=U_ILLEGAL_ARGUMENT_ERROR;
+        return;
+    }
+    
+    /* output the target overflow buffer */
+    if( cnv->UCharErrorBufferLength>0 &&
+        ucnv_outputOverflowToUnicode(cnv, target, targetLimit, &offsets, err)
+    ) {
+        /* U_BUFFER_OVERFLOW_ERROR */
+        return;
+    }
+    /* *target may have moved, therefore stop using t */
+
+    if(!flush && s==sourceLimit && cnv->preToULength>=0) {
+        /* the overflow buffer is emptied and there is no new input: we are done */
+        return;
+    }
+
+    /*
+     * Do not simply return with a buffer overflow error if
+     * !flush && t==targetLimit
+     * because it is possible that the source will not generate any output.
+     * For example, the skip callback may be called;
+     * it does not output anything.
+     */
+
+    /* prepare the converter arguments */
+    args.converter=cnv;
+    args.flush=flush;
+    args.offsets=offsets;
+    args.source=s;
+    args.sourceLimit=sourceLimit;
+    args.target=*target;
+    args.targetLimit=targetLimit;
+    args.size=sizeof(args);
+
+    _toUnicodeWithCallback(&args, err);
+
+    *source=args.source;
+    *target=args.target;
+}
+
+/* ucnv_to/fromUChars() ----------------------------------------------------- */
+
+U_CAPI int32_t U_EXPORT2
+ucnv_fromUChars(UConverter *cnv,
+                char *dest, int32_t destCapacity,
+                const char16_t *src, int32_t srcLength,
+                UErrorCode *pErrorCode) {
+    const char16_t *srcLimit;
+    char *originalDest, *destLimit;
+    int32_t destLength;
+
+    /* check arguments */
+    if(pErrorCode==nullptr || U_FAILURE(*pErrorCode)) {
+        return 0;
+    }
+
+    if( cnv==nullptr ||
+        destCapacity<0 || (destCapacity>0 && dest==nullptr) ||
+        srcLength<-1 || (srcLength!=0 && src==nullptr)
+    ) {
+        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
+        return 0;
+    }
+
+    /* initialize */
+    ucnv_resetFromUnicode(cnv);
+    originalDest=dest;
+    if(srcLength==-1) {
+        srcLength=u_strlen(src);
+    }
+    if(srcLength>0) {
+        srcLimit=src+srcLength;
+        destCapacity=pinCapacity(dest, destCapacity);
+        destLimit=dest+destCapacity;
+
+        /* perform the conversion */
+        ucnv_fromUnicode(cnv, &dest, destLimit, &src, srcLimit, 0, true, pErrorCode);
+        destLength=(int32_t)(dest-originalDest);
+
+        /* if an overflow occurs, then get the preflighting length */
+        if(*pErrorCode==U_BUFFER_OVERFLOW_ERROR) {
+            char buffer[1024];
+
+            destLimit=buffer+sizeof(buffer);
+            do {
+                dest=buffer;
+                *pErrorCode=U_ZERO_ERROR;
+                ucnv_fromUnicode(cnv, &dest, destLimit, &src, srcLimit, 0, true, pErrorCode);
+                destLength+=(int32_t)(dest-buffer);
+            } while(*pErrorCode==U_BUFFER_OVERFLOW_ERROR);
+        }
+    } else {
+        destLength=0;
+    }
+
+    return u_terminateChars(originalDest, destCapacity, destLength, pErrorCode);
+}
+
+U_CAPI int32_t U_EXPORT2
+ucnv_toUChars(UConverter *cnv,
+              char16_t *dest, int32_t destCapacity,
+              const char *src, int32_t srcLength,
+              UErrorCode *pErrorCode) {
+    const char *srcLimit;
+    char16_t *originalDest, *destLimit;
+    int32_t destLength;
+
+    /* check arguments */
+    if(pErrorCode==nullptr || U_FAILURE(*pErrorCode)) {
+        return 0;
+    }
+
+    if( cnv==nullptr ||
+        destCapacity<0 || (destCapacity>0 && dest==nullptr) ||
+        srcLength<-1 || (srcLength!=0 && src==nullptr))
+    {
+        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
+        return 0;
+    }
+
+    /* initialize */
+    ucnv_resetToUnicode(cnv);
+    originalDest=dest;
+    if(srcLength==-1) {
+        srcLength=(int32_t)uprv_strlen(src);
+    }
+    if(srcLength>0) {
+        srcLimit=src+srcLength;
+        destCapacity=pinCapacity(dest, destCapacity);
+        destLimit=dest+destCapacity;
+
+        /* perform the conversion */
+        ucnv_toUnicode(cnv, &dest, destLimit, &src, srcLimit, 0, true, pErrorCode);
+        destLength=(int32_t)(dest-originalDest);
+
+        /* if an overflow occurs, then get the preflighting length */
+        if(*pErrorCode==U_BUFFER_OVERFLOW_ERROR)
+        {
+            char16_t buffer[1024];
+
+            destLimit=buffer+UPRV_LENGTHOF(buffer);
+            do {
+                dest=buffer;
+                *pErrorCode=U_ZERO_ERROR;
+                ucnv_toUnicode(cnv, &dest, destLimit, &src, srcLimit, 0, true, pErrorCode);
+                destLength+=(int32_t)(dest-buffer);
+            }
+            while(*pErrorCode==U_BUFFER_OVERFLOW_ERROR);
+        }
+    } else {
+        destLength=0;
+    }
+
+    return u_terminateUChars(originalDest, destCapacity, destLength, pErrorCode);
+}
+
+/* ucnv_getNextUChar() ------------------------------------------------------ */
+
+U_CAPI UChar32 U_EXPORT2
+ucnv_getNextUChar(UConverter *cnv,
+                  const char **source, const char *sourceLimit,
+                  UErrorCode *err) {
+    UConverterToUnicodeArgs args;
+    char16_t buffer[U16_MAX_LENGTH];
+    const char *s;
+    UChar32 c;
+    int32_t i, length;
+
+    /* check parameters */
+    if(err==nullptr || U_FAILURE(*err)) {
+        return 0xffff;
+    }
+
+    if(cnv==nullptr || source==nullptr) {
+        *err=U_ILLEGAL_ARGUMENT_ERROR;
+        return 0xffff;
+    }
+
+    s=*source;
+    if(sourceLimit<s) {
+        *err=U_ILLEGAL_ARGUMENT_ERROR;
+        return 0xffff;
+    }
+
+    /*
+     * Make sure that the buffer sizes do not exceed the number range for
+     * int32_t because some functions use the size (in units or bytes)
+     * rather than comparing pointers, and because offsets are int32_t values.
+     *
+     * size_t is guaranteed to be unsigned and large enough for the job.
+     *
+     * Return with an error instead of adjusting the limits because we would
+     * not be able to maintain the semantics that either the source must be
+     * consumed or the target filled (unless an error occurs).
+     * An adjustment would be sourceLimit=t+0x7fffffff; for example.
+     */
+    if(((size_t)(sourceLimit-s)>(size_t)0x7fffffff && sourceLimit>s)) {
+        *err=U_ILLEGAL_ARGUMENT_ERROR;
+        return 0xffff;
+    }
+
+    c=U_SENTINEL;
+
+    /* flush the target overflow buffer */
+    if(cnv->UCharErrorBufferLength>0) {
+        char16_t *overflow;
+
+        overflow=cnv->UCharErrorBuffer;
+        i=0;
+        length=cnv->UCharErrorBufferLength;
+        U16_NEXT(overflow, i, length, c);
+
+        /* move the remaining overflow contents up to the beginning */
+        if((cnv->UCharErrorBufferLength=(int8_t)(length-i))>0) {
+            uprv_memmove(cnv->UCharErrorBuffer, cnv->UCharErrorBuffer+i,
+                         cnv->UCharErrorBufferLength*U_SIZEOF_UCHAR);
+        }
+
+        if(!U16_IS_LEAD(c) || i<length) {
+            return c;
+        }
+        /*
+         * Continue if the overflow buffer contained only a lead surrogate,
+         * in case the converter outputs single surrogates from complete
+         * input sequences.
+         */
+    }
+
+    /*
+     * flush==true is implied for ucnv_getNextUChar()
+     *
+     * do not simply return even if s==sourceLimit because the converter may
+     * not have seen flush==true before
+     */
+
+    /* prepare the converter arguments */
+    args.converter=cnv;
+    args.flush=true;
+    args.offsets=nullptr;
+    args.source=s;
+    args.sourceLimit=sourceLimit;
+    args.target=buffer;
+    args.targetLimit=buffer+1;
+    args.size=sizeof(args);
+
+    if(c<0) {
+        /*
+         * call the native getNextUChar() implementation if we are
+         * at a character boundary (toULength==0)
+         *
+         * unlike with _toUnicode(), getNextUChar() implementations must set
+         * U_TRUNCATED_CHAR_FOUND for truncated input,
+         * in addition to setting toULength/toUBytes[]
+         */
+        if(cnv->toULength==0 && cnv->sharedData->impl->getNextUChar!=nullptr) {
+            c=cnv->sharedData->impl->getNextUChar(&args, err);
+            *source=s=args.source;
+            if(*err==U_INDEX_OUTOFBOUNDS_ERROR) {
+                /* reset the converter without calling the callback function */
+                _reset(cnv, UCNV_RESET_TO_UNICODE, false);
+                return 0xffff; /* no output */
+            } else if(U_SUCCESS(*err) && c>=0) {
+                return c;
+            /*
+             * else fall through to use _toUnicode() because
+             *   UCNV_GET_NEXT_UCHAR_USE_TO_U: the native function did not want to handle it after all
+             *   U_FAILURE: call _toUnicode() for callback handling (do not output c)
+             */
+            }
+        }
+
+        /* convert to one char16_t in buffer[0], or handle getNextUChar() errors */
+        _toUnicodeWithCallback(&args, err);
+
+        if(*err==U_BUFFER_OVERFLOW_ERROR) {
+            *err=U_ZERO_ERROR;
+        }
+
+        i=0;
+        length=(int32_t)(args.target-buffer);
+    } else {
+        /* write the lead surrogate from the overflow buffer */
+        buffer[0]=(char16_t)c;
+        args.target=buffer+1;
+        i=0;
+        length=1;
+    }
+
+    /* buffer contents starts at i and ends before length */
+
+    if(U_FAILURE(*err)) {
+        c=0xffff; /* no output */
+    } else if(length==0) {
+        /* no input or only state changes */
+        *err=U_INDEX_OUTOFBOUNDS_ERROR;
+        /* no need to reset explicitly because _toUnicodeWithCallback() did it */
+        c=0xffff; /* no output */
+    } else {
+        c=buffer[0];
+        i=1;
+        if(!U16_IS_LEAD(c)) {
+            /* consume c=buffer[0], done */
+        } else {
+            /* got a lead surrogate, see if a trail surrogate follows */
+            char16_t c2;
+
+            if(cnv->UCharErrorBufferLength>0) {
+                /* got overflow output from the conversion */
+                if(U16_IS_TRAIL(c2=cnv->UCharErrorBuffer[0])) {
+                    /* got a trail surrogate, too */
+                    c=U16_GET_SUPPLEMENTARY(c, c2);
+
+                    /* move the remaining overflow contents up to the beginning */
+                    if((--cnv->UCharErrorBufferLength)>0) {
+                        uprv_memmove(cnv->UCharErrorBuffer, cnv->UCharErrorBuffer+1,
+                                     cnv->UCharErrorBufferLength*U_SIZEOF_UCHAR);
+                    }
+                } else {
+                    /* c is an unpaired lead surrogate, just return it */
+                }
+            } else if(args.source<sourceLimit) {
+                /* convert once more, to buffer[1] */
+                args.targetLimit=buffer+2;
+                _toUnicodeWithCallback(&args, err);
+                if(*err==U_BUFFER_OVERFLOW_ERROR) {
+                    *err=U_ZERO_ERROR;
+                }
+
+                length=(int32_t)(args.target-buffer);
+                if(U_SUCCESS(*err) && length==2 && U16_IS_TRAIL(c2=buffer[1])) {
+                    /* got a trail surrogate, too */
+                    c=U16_GET_SUPPLEMENTARY(c, c2);
+                    i=2;
+                }
+            }
+        }
+    }
+
+    /*
+     * move leftover output from buffer[i..length[
+     * into the beginning of the overflow buffer
+     */
+    if(i<length) {
+        /* move further overflow back */
+        int32_t delta=length-i;
+        if((length=cnv->UCharErrorBufferLength)>0) {
+            uprv_memmove(cnv->UCharErrorBuffer+delta, cnv->UCharErrorBuffer,
+                         length*U_SIZEOF_UCHAR);
+        }
+        cnv->UCharErrorBufferLength=(int8_t)(length+delta);
+
+        cnv->UCharErrorBuffer[0]=buffer[i++];
+        if(delta>1) {
+            cnv->UCharErrorBuffer[1]=buffer[i];
+        }
+    }
+
+    *source=args.source;
+    return c;
+}
+
+/* ucnv_convert() and siblings ---------------------------------------------- */
+
+U_CAPI void U_EXPORT2
+ucnv_convertEx(UConverter *targetCnv, UConverter *sourceCnv,
+               char **target, const char *targetLimit,
+               const char **source, const char *sourceLimit,
+               char16_t *pivotStart, char16_t **pivotSource,
+               char16_t **pivotTarget, const char16_t *pivotLimit,
+               UBool reset, UBool flush,
+               UErrorCode *pErrorCode) {
+    char16_t pivotBuffer[CHUNK_SIZE];
+    const char16_t *myPivotSource;
+    char16_t *myPivotTarget;
+    const char *s;
+    char *t;
+
+    UConverterToUnicodeArgs toUArgs;
+    UConverterFromUnicodeArgs fromUArgs;
+    UConverterConvert convert;
+
+    /* error checking */
+    if(pErrorCode==nullptr || U_FAILURE(*pErrorCode)) {
+        return;
+    }
+
+    if( targetCnv==nullptr || sourceCnv==nullptr ||
+        source==nullptr || *source==nullptr ||
+        target==nullptr || *target==nullptr || targetLimit==nullptr
+    ) {
+        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
+        return;
+    }
+
+    s=*source;
+    t=*target;
+    if((sourceLimit!=nullptr && sourceLimit<s) || targetLimit<t) {
+        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
+        return;
+    }
+
+    /*
+     * Make sure that the buffer sizes do not exceed the number range for
+     * int32_t. See ucnv_toUnicode() for a more detailed comment.
+     */
+    if(
+        (sourceLimit!=nullptr && ((size_t)(sourceLimit-s)>(size_t)0x7fffffff && sourceLimit>s)) ||
+        ((size_t)(targetLimit-t)>(size_t)0x7fffffff && targetLimit>t)
+    ) {
+        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
+        return;
+    }
+    
+    if(pivotStart==nullptr) {
+        if(!flush) {
+            /* streaming conversion requires an explicit pivot buffer */
+            *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
+            return;
+        }
+
+        /* use the stack pivot buffer */
+        myPivotSource=myPivotTarget=pivotStart=pivotBuffer;
+        pivotSource=(char16_t **)&myPivotSource;
+        pivotTarget=&myPivotTarget;
+        pivotLimit=pivotBuffer+CHUNK_SIZE;
+    } else if(  pivotStart>=pivotLimit ||
+                pivotSource==nullptr || *pivotSource==nullptr ||
+                pivotTarget==nullptr || *pivotTarget==nullptr ||
+                pivotLimit==nullptr
+    ) {
+        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
+        return;
+    }
+
+    if(sourceLimit==nullptr) {
+        /* get limit of single-byte-NUL-terminated source string */
+        sourceLimit=uprv_strchr(*source, 0);
+    }
+
+    if(reset) {
+        ucnv_resetToUnicode(sourceCnv);
+        ucnv_resetFromUnicode(targetCnv);
+        *pivotSource=*pivotTarget=pivotStart;
+    } else if(targetCnv->charErrorBufferLength>0) {
+        /* output the targetCnv overflow buffer */
+        if(ucnv_outputOverflowFromUnicode(targetCnv, target, targetLimit, nullptr, pErrorCode)) {
+            /* U_BUFFER_OVERFLOW_ERROR */
+            return;
+        }
+        /* *target has moved, therefore stop using t */
+
+        if( !flush &&
+            targetCnv->preFromULength>=0 && *pivotSource==*pivotTarget &&
+            sourceCnv->UCharErrorBufferLength==0 && sourceCnv->preToULength>=0 && s==sourceLimit
+        ) {
+            /* the fromUnicode overflow buffer is emptied and there is no new input: we are done */
+            return;
+        }
+    }
+
+    /* Is direct-UTF-8 conversion available? */
+    if( sourceCnv->sharedData->staticData->conversionType==UCNV_UTF8 &&
+        targetCnv->sharedData->impl->fromUTF8!=nullptr
+    ) {
+        convert=targetCnv->sharedData->impl->fromUTF8;
+    } else if( targetCnv->sharedData->staticData->conversionType==UCNV_UTF8 &&
+               sourceCnv->sharedData->impl->toUTF8!=nullptr
+    ) {
+        convert=sourceCnv->sharedData->impl->toUTF8;
+    } else {
+        convert=nullptr;
+    }
+
+    /*
+     * If direct-UTF-8 conversion is available, then we use a smaller
+     * pivot buffer for error handling and partial matches
+     * so that we quickly return to direct conversion.
+     *
+     * 32 is large enough for UCNV_EXT_MAX_UCHARS and UCNV_ERROR_BUFFER_LENGTH.
+     *
+     * We could reduce the pivot buffer size further, at the cost of
+     * buffer overflows from callbacks.
+     * The pivot buffer should not be smaller than the maximum number of
+     * fromUnicode extension table input UChars
+     * (for m:n conversion, see
+     * targetCnv->sharedData->mbcs.extIndexes[UCNV_EXT_COUNT_UCHARS])
+     * or 2 for surrogate pairs.
+     *
+     * Too small a buffer can cause thrashing between pivoting and direct
+     * conversion, with function call overhead outweighing the benefits
+     * of direct conversion.
+     */
+    if(convert!=nullptr && (pivotLimit-pivotStart)>32) {
+        pivotLimit=pivotStart+32;
+    }
+
+    /* prepare the converter arguments */
+    fromUArgs.converter=targetCnv;
+    fromUArgs.flush=false;
+    fromUArgs.offsets=nullptr;
+    fromUArgs.target=*target;
+    fromUArgs.targetLimit=targetLimit;
+    fromUArgs.size=sizeof(fromUArgs);
+
+    toUArgs.converter=sourceCnv;
+    toUArgs.flush=flush;
+    toUArgs.offsets=nullptr;
+    toUArgs.source=s;
+    toUArgs.sourceLimit=sourceLimit;
+    toUArgs.targetLimit=pivotLimit;
+    toUArgs.size=sizeof(toUArgs);
+
+    /*
+     * TODO: Consider separating this function into two functions,
+     * extracting exactly the conversion loop,
+     * for readability and to reduce the set of visible variables.
+     *
+     * Otherwise stop using s and t from here on.
+     */
+    s=t=nullptr;
+
+    /*
+     * conversion loop
+     *
+     * The sequence of steps in the loop may appear backward,
+     * but the principle is simple:
+     * In the chain of
+     *   source - sourceCnv overflow - pivot - targetCnv overflow - target
+     * empty out later buffers before refilling them from earlier ones.
+     *
+     * The targetCnv overflow buffer is flushed out only once before the loop.
+     */
+    for(;;) {
+        /*
+         * if(pivot not empty or error or replay or flush fromUnicode) {
+         *   fromUnicode(pivot -> target);
+         * }
+         *
+         * For pivoting conversion; and for direct conversion for
+         * error callback handling and flushing the replay buffer.
+         */
+        if( *pivotSource<*pivotTarget ||
+            U_FAILURE(*pErrorCode) ||
+            targetCnv->preFromULength<0 ||
+            fromUArgs.flush
+        ) {
+            fromUArgs.source=*pivotSource;
+            fromUArgs.sourceLimit=*pivotTarget;
+            _fromUnicodeWithCallback(&fromUArgs, pErrorCode);
+            if(U_FAILURE(*pErrorCode)) {
+                /* target overflow, or conversion error */
+                *pivotSource=(char16_t *)fromUArgs.source;
+                break;
+            }
+
+            /*
+             * _fromUnicodeWithCallback() must have consumed the pivot contents
+             * (*pivotSource==*pivotTarget) since it returned with U_SUCCESS()
+             */
+        }
+
+        /* The pivot buffer is empty; reset it so we start at pivotStart. */
+        *pivotSource=*pivotTarget=pivotStart;
+
+        /*
+         * if(sourceCnv overflow buffer not empty) {
+         *     move(sourceCnv overflow buffer -> pivot);
+         *     continue;
+         * }
+         */
+        /* output the sourceCnv overflow buffer */
+        if(sourceCnv->UCharErrorBufferLength>0) {
+            if(ucnv_outputOverflowToUnicode(sourceCnv, pivotTarget, pivotLimit, nullptr, pErrorCode)) {
+                /* U_BUFFER_OVERFLOW_ERROR */
+                *pErrorCode=U_ZERO_ERROR;
+            }
+            continue;
+        }
+
+        /*
+         * check for end of input and break if done
+         *
+         * Checking both flush and fromUArgs.flush ensures that the converters
+         * have been called with the flush flag set if the ucnv_convertEx()
+         * caller set it.
+         */
+        if( toUArgs.source==sourceLimit &&
+            sourceCnv->preToULength>=0 && sourceCnv->toULength==0 &&
+            (!flush || fromUArgs.flush)
+        ) {
+            /* done successfully */
+            break;
+        }
+
+        /*
+         * use direct conversion if available
+         * but not if continuing a partial match
+         * or flushing the toUnicode replay buffer
+         */
+        if(convert!=nullptr && targetCnv->preFromUFirstCP<0 && sourceCnv->preToULength==0) {
+            if(*pErrorCode==U_USING_DEFAULT_WARNING) {
+                /* remove a warning that may be set by this function */
+                *pErrorCode=U_ZERO_ERROR;
+            }
+            convert(&fromUArgs, &toUArgs, pErrorCode);
+            if(*pErrorCode==U_BUFFER_OVERFLOW_ERROR) {
+                break;
+            } else if(U_FAILURE(*pErrorCode)) {
+                if(sourceCnv->toULength>0) {
+                    /*
+                     * Fall through to calling _toUnicodeWithCallback()
+                     * for callback handling.
+                     *
+                     * The pivot buffer will be reset with
+                     *   *pivotSource=*pivotTarget=pivotStart;
+                     * which indicates a toUnicode error to the caller
+                     * (*pivotSource==pivotStart shows no pivot UChars consumed).
+                     */
+                } else {
+                    /*
+                     * Indicate a fromUnicode error to the caller
+                     * (*pivotSource>pivotStart shows some pivot UChars consumed).
+                     */
+                    *pivotSource=*pivotTarget=pivotStart+1;
+                    /*
+                     * Loop around to calling _fromUnicodeWithCallbacks()
+                     * for callback handling.
+                     */
+                    continue;
+                }
+            } else if(*pErrorCode==U_USING_DEFAULT_WARNING) {
+                /*
+                 * No error, but the implementation requested to temporarily
+                 * fall back to pivoting.
+                 */
+                *pErrorCode=U_ZERO_ERROR;
+            /*
+             * The following else branches are almost identical to the end-of-input
+             * handling in _toUnicodeWithCallback().
+             * Avoid calling it just for the end of input.
+             */
+            } else if(flush && sourceCnv->toULength>0) { /* flush==toUArgs.flush */
+                /*
+                 * the entire input stream is consumed
+                 * and there is a partial, truncated input sequence left
+                 */
+
+                /* inject an error and continue with callback handling */
+                *pErrorCode=U_TRUNCATED_CHAR_FOUND;
+            } else {
+                /* input consumed */
+                if(flush) {
+                    /* reset the converters without calling the callback functions */
+                    _reset(sourceCnv, UCNV_RESET_TO_UNICODE, false);
+                    _reset(targetCnv, UCNV_RESET_FROM_UNICODE, false);
+                }
+
+                /* done successfully */
+                break;
+            }
+        }
+        
+        /*
+         * toUnicode(source -> pivot);
+         *
+         * For pivoting conversion; and for direct conversion for
+         * error callback handling, continuing partial matches
+         * and flushing the replay buffer.
+         *
+         * The pivot buffer is empty and reset.
+         */
+        toUArgs.target=pivotStart; /* ==*pivotTarget */
+        /* toUArgs.targetLimit=pivotLimit; already set before the loop */
+        _toUnicodeWithCallback(&toUArgs, pErrorCode);
+        *pivotTarget=toUArgs.target;
+        if(*pErrorCode==U_BUFFER_OVERFLOW_ERROR) {
+            /* pivot overflow: continue with the conversion loop */
+            *pErrorCode=U_ZERO_ERROR;
+        } else if(U_FAILURE(*pErrorCode) || (!flush && *pivotTarget==pivotStart)) {
+            /* conversion error, or there was nothing left to convert */
+            break;
+        }
+        /*
+         * else:
+         * _toUnicodeWithCallback() wrote into the pivot buffer,
+         * continue with fromUnicode conversion.
+         *
+         * Set the fromUnicode flush flag if we flush and if toUnicode has
+         * processed the end of the input.
+         */
+        if( flush && toUArgs.source==sourceLimit &&
+            sourceCnv->preToULength>=0 &&
+            sourceCnv->UCharErrorBufferLength==0
+        ) {
+            fromUArgs.flush=true;
+        }
+    }
+
+    /*
+     * The conversion loop is exited when one of the following is true:
+     * - the entire source text has been converted successfully to the target buffer
+     * - a target buffer overflow occurred
+     * - a conversion error occurred
+     */
+
+    *source=toUArgs.source;
+    *target=fromUArgs.target;
+
+    /* terminate the target buffer if possible */
+    if(flush && U_SUCCESS(*pErrorCode)) {
+        if(*target!=targetLimit) {
+            **target=0;
+            if(*pErrorCode==U_STRING_NOT_TERMINATED_WARNING) {
+                *pErrorCode=U_ZERO_ERROR;
+            }
+        } else {
+            *pErrorCode=U_STRING_NOT_TERMINATED_WARNING;
+        }
+    }
+}
+
+/* internal implementation of ucnv_convert() etc. with preflighting */
+static int32_t
+ucnv_internalConvert(UConverter *outConverter, UConverter *inConverter,
+                     char *target, int32_t targetCapacity,
+                     const char *source, int32_t sourceLength,
+                     UErrorCode *pErrorCode) {
+    char16_t pivotBuffer[CHUNK_SIZE];
+    char16_t *pivot, *pivot2;
+
+    char *myTarget;
+    const char *sourceLimit;
+    const char *targetLimit;
+    int32_t targetLength=0;
+
+    /* set up */
+    if(sourceLength<0) {
+        sourceLimit=uprv_strchr(source, 0);
+    } else {
+        sourceLimit=source+sourceLength;
+    }
+
+    /* if there is no input data, we're done */
+    if(source==sourceLimit) {
+        return u_terminateChars(target, targetCapacity, 0, pErrorCode);
+    }
+
+    pivot=pivot2=pivotBuffer;
+    myTarget=target;
+    targetLength=0;
+
+    if(targetCapacity>0) {
+        /* perform real conversion */
+        targetLimit=target+targetCapacity;
+        ucnv_convertEx(outConverter, inConverter,
+                       &myTarget, targetLimit,
+                       &source, sourceLimit,
+                       pivotBuffer, &pivot, &pivot2, pivotBuffer+CHUNK_SIZE,
+                       false,
+                       true,
+                       pErrorCode);
+        targetLength=(int32_t)(myTarget-target);
+    }
+
+    /*
+     * If the output buffer is exhausted (or we are only "preflighting"), we need to stop writing
+     * to it but continue the conversion in order to store in targetCapacity
+     * the number of bytes that was required.
+     */
+    if(*pErrorCode==U_BUFFER_OVERFLOW_ERROR || targetCapacity==0)
+    {
+        char targetBuffer[CHUNK_SIZE];
+
+        targetLimit=targetBuffer+CHUNK_SIZE;
+        do {
+            *pErrorCode=U_ZERO_ERROR;
+            myTarget=targetBuffer;
+            ucnv_convertEx(outConverter, inConverter,
+                           &myTarget, targetLimit,
+                           &source, sourceLimit,
+                           pivotBuffer, &pivot, &pivot2, pivotBuffer+CHUNK_SIZE,
+                           false,
+                           true,
+                           pErrorCode);
+            targetLength+=(int32_t)(myTarget-targetBuffer);
+        } while(*pErrorCode==U_BUFFER_OVERFLOW_ERROR);
+
+        /* done with preflighting, set warnings and errors as appropriate */
+        return u_terminateChars(target, targetCapacity, targetLength, pErrorCode);
+    }
+
+    /* no need to call u_terminateChars() because ucnv_convertEx() took care of that */
+    return targetLength;
+}
+
+U_CAPI int32_t U_EXPORT2
+ucnv_convert(const char *toConverterName, const char *fromConverterName,
+             char *target, int32_t targetCapacity,
+             const char *source, int32_t sourceLength,
+             UErrorCode *pErrorCode) {
+    UConverter in, out; /* stack-allocated */
+    UConverter *inConverter, *outConverter;
+    int32_t targetLength;
+
+    if(pErrorCode==nullptr || U_FAILURE(*pErrorCode)) {
+        return 0;
+    }
+
+    if( source==nullptr || sourceLength<-1 ||
+        targetCapacity<0 || (targetCapacity>0 && target==nullptr)
+    ) {
+        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
+        return 0;
+    }
+
+    /* if there is no input data, we're done */
+    if(sourceLength==0 || (sourceLength<0 && *source==0)) {
+        return u_terminateChars(target, targetCapacity, 0, pErrorCode);
+    }
+
+    /* create the converters */
+    inConverter=ucnv_createConverter(&in, fromConverterName, pErrorCode);
+    if(U_FAILURE(*pErrorCode)) {
+        return 0;
+    }
+
+    outConverter=ucnv_createConverter(&out, toConverterName, pErrorCode);
+    if(U_FAILURE(*pErrorCode)) {
+        ucnv_close(inConverter);
+        return 0;
+    }
+
+    targetLength=ucnv_internalConvert(outConverter, inConverter,
+                                      target, targetCapacity,
+                                      source, sourceLength,
+                                      pErrorCode);
+
+    ucnv_close(inConverter);
+    ucnv_close(outConverter);
+
+    return targetLength;
+}
+
+/* @internal */
+static int32_t
+ucnv_convertAlgorithmic(UBool convertToAlgorithmic,
+                        UConverterType algorithmicType,
+                        UConverter *cnv,
+                        char *target, int32_t targetCapacity,
+                        const char *source, int32_t sourceLength,
+                        UErrorCode *pErrorCode) {
+    UConverter algoConverterStatic; /* stack-allocated */
+    UConverter *algoConverter, *to, *from;
+    int32_t targetLength;
+
+    if(pErrorCode==nullptr || U_FAILURE(*pErrorCode)) {
+        return 0;
+    }
+
+    if( cnv==nullptr || source==nullptr || sourceLength<-1 ||
+        targetCapacity<0 || (targetCapacity>0 && target==nullptr)
+    ) {
+        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
+        return 0;
+    }
+
+    /* if there is no input data, we're done */
+    if(sourceLength==0 || (sourceLength<0 && *source==0)) {
+        return u_terminateChars(target, targetCapacity, 0, pErrorCode);
+    }
+
+    /* create the algorithmic converter */
+    algoConverter=ucnv_createAlgorithmicConverter(&algoConverterStatic, algorithmicType,
+                                                  "", 0, pErrorCode);
+    if(U_FAILURE(*pErrorCode)) {
+        return 0;
+    }
+
+    /* reset the other converter */
+    if(convertToAlgorithmic) {
+        /* cnv->Unicode->algo */
+        ucnv_resetToUnicode(cnv);
+        to=algoConverter;
+        from=cnv;
+    } else {
+        /* algo->Unicode->cnv */
+        ucnv_resetFromUnicode(cnv);
+        from=algoConverter;
+        to=cnv;
+    }
+
+    targetLength=ucnv_internalConvert(to, from,
+                                      target, targetCapacity,
+                                      source, sourceLength,
+                                      pErrorCode);
+
+    ucnv_close(algoConverter);
+
+    return targetLength;
+}
+
+U_CAPI int32_t U_EXPORT2
+ucnv_toAlgorithmic(UConverterType algorithmicType,
+                   UConverter *cnv,
+                   char *target, int32_t targetCapacity,
+                   const char *source, int32_t sourceLength,
+                   UErrorCode *pErrorCode) {
+    return ucnv_convertAlgorithmic(true, algorithmicType, cnv,
+                                   target, targetCapacity,
+                                   source, sourceLength,
+                                   pErrorCode);
+}
+
+U_CAPI int32_t U_EXPORT2
+ucnv_fromAlgorithmic(UConverter *cnv,
+                     UConverterType algorithmicType,
+                     char *target, int32_t targetCapacity,
+                     const char *source, int32_t sourceLength,
+                     UErrorCode *pErrorCode) UPRV_NO_SANITIZE_UNDEFINED {
+
+    if(algorithmicType<0 || UCNV_NUMBER_OF_SUPPORTED_CONVERTER_TYPES<=algorithmicType) {
+        *pErrorCode = U_ILLEGAL_ARGUMENT_ERROR;
+        return 0;
+    }
+    return ucnv_convertAlgorithmic(false, algorithmicType, cnv,
+                                   target, targetCapacity,
+                                   source, sourceLength,
+                                   pErrorCode);
+}
+
+U_CAPI UConverterType  U_EXPORT2
+ucnv_getType(const UConverter* converter)
+{
+    int8_t type = converter->sharedData->staticData->conversionType;
+#if !UCONFIG_NO_LEGACY_CONVERSION
+    if(type == UCNV_MBCS) {
+        return ucnv_MBCSGetType(converter);
+    }
+#endif
+    return (UConverterType)type;
+}
+
+U_CAPI void  U_EXPORT2
+ucnv_getStarters(const UConverter* converter, 
+                 UBool starters[256],
+                 UErrorCode* err)
+{
+    if (err == nullptr || U_FAILURE(*err)) {
+        return;
+    }
+
+    if(converter->sharedData->impl->getStarters != nullptr) {
+        converter->sharedData->impl->getStarters(converter, starters, err);
+    } else {
+        *err = U_ILLEGAL_ARGUMENT_ERROR;
+    }
+}
+
+static const UAmbiguousConverter *ucnv_getAmbiguous(const UConverter *cnv)
+{
+    UErrorCode errorCode;
+    const char *name;
+    int32_t i;
+
+    if(cnv==nullptr) {
+        return nullptr;
+    }
+
+    errorCode=U_ZERO_ERROR;
+    name=ucnv_getName(cnv, &errorCode);
+    if(U_FAILURE(errorCode)) {
+        return nullptr;
+    }
+
+    for(i=0; i<UPRV_LENGTHOF(ambiguousConverters); ++i)
+    {
+        if(0==uprv_strcmp(name, ambiguousConverters[i].name))
+        {
+            return ambiguousConverters+i;
+        }
+    }
+
+    return nullptr;
+}
+
+U_CAPI void  U_EXPORT2
+ucnv_fixFileSeparator(const UConverter *cnv, 
+                      char16_t* source,
+                      int32_t sourceLength) {
+    const UAmbiguousConverter *a;
+    int32_t i;
+    char16_t variant5c;
+
+    if(cnv==nullptr || source==nullptr || sourceLength<=0 || (a=ucnv_getAmbiguous(cnv))==nullptr)
+    {
+        return;
+    }
+
+    variant5c=a->variant5c;
+    for(i=0; i<sourceLength; ++i) {
+        if(source[i]==variant5c) {
+            source[i]=0x5c;
+        }
+    }
+}
+
+U_CAPI UBool  U_EXPORT2
+ucnv_isAmbiguous(const UConverter *cnv) {
+    return (UBool)(ucnv_getAmbiguous(cnv)!=nullptr);
+}
+
+U_CAPI void  U_EXPORT2
+ucnv_setFallback(UConverter *cnv, UBool usesFallback)
+{
+    cnv->useFallback = usesFallback;
+}
+
+U_CAPI UBool  U_EXPORT2
+ucnv_usesFallback(const UConverter *cnv)
+{
+    return cnv->useFallback;
+}
+
+U_CAPI void  U_EXPORT2
+ucnv_getInvalidChars (const UConverter * converter,
+                      char *errBytes,
+                      int8_t * len,
+                      UErrorCode * err)
+{
+    if (err == nullptr || U_FAILURE(*err))
+    {
+        return;
+    }
+    if (len == nullptr || errBytes == nullptr || converter == nullptr)
+    {
+        *err = U_ILLEGAL_ARGUMENT_ERROR;
+        return;
+    }
+    if (*len < converter->invalidCharLength)
+    {
+        *err = U_INDEX_OUTOFBOUNDS_ERROR;
+        return;
+    }
+    if ((*len = converter->invalidCharLength) > 0)
+    {
+        uprv_memcpy (errBytes, converter->invalidCharBuffer, *len);
+    }
+}
+
+U_CAPI void  U_EXPORT2
+ucnv_getInvalidUChars (const UConverter * converter,
+                       char16_t *errChars,
+                       int8_t * len,
+                       UErrorCode * err)
+{
+    if (err == nullptr || U_FAILURE(*err))
+    {
+        return;
+    }
+    if (len == nullptr || errChars == nullptr || converter == nullptr)
+    {
+        *err = U_ILLEGAL_ARGUMENT_ERROR;
+        return;
+    }
+    if (*len < converter->invalidUCharLength)
+    {
+        *err = U_INDEX_OUTOFBOUNDS_ERROR;
+        return;
+    }
+    if ((*len = converter->invalidUCharLength) > 0)
+    {
+        u_memcpy (errChars, converter->invalidUCharBuffer, *len);
+    }
+}
+
+#define SIG_MAX_LEN 5
+
+U_CAPI const char* U_EXPORT2
+ucnv_detectUnicodeSignature( const char* source,
+                             int32_t sourceLength,
+                             int32_t* signatureLength,
+                             UErrorCode* pErrorCode) {
+    int32_t dummy;
+
+    /* initial 0xa5 bytes: make sure that if we read <SIG_MAX_LEN
+     * bytes we don't misdetect something 
+     */
+    char start[SIG_MAX_LEN]={ '\xa5', '\xa5', '\xa5', '\xa5', '\xa5' };
+    int i = 0;
+
+    if((pErrorCode==nullptr) || U_FAILURE(*pErrorCode)){
+        return nullptr;
+    }
+    
+    if(source == nullptr || sourceLength < -1){
+        *pErrorCode = U_ILLEGAL_ARGUMENT_ERROR;
+        return nullptr;
+    }
+
+    if(signatureLength == nullptr) {
+        signatureLength = &dummy;
+    }
+
+    if(sourceLength==-1){
+        sourceLength=(int32_t)uprv_strlen(source);
+    }
+
+    
+    while(i<sourceLength&& i<SIG_MAX_LEN){
+        start[i]=source[i];
+        i++;
+    }
+
+    if(start[0] == '\xFE' && start[1] == '\xFF') {
+        *signatureLength=2;
+        return  "UTF-16BE";
+    } else if(start[0] == '\xFF' && start[1] == '\xFE') {
+        if(start[2] == '\x00' && start[3] =='\x00') {
+            *signatureLength=4;
+            return "UTF-32LE";
+        } else {
+            *signatureLength=2;
+            return  "UTF-16LE";
+        }
+    } else if(start[0] == '\xEF' && start[1] == '\xBB' && start[2] == '\xBF') {
+        *signatureLength=3;
+        return  "UTF-8";
+    } else if(start[0] == '\x00' && start[1] == '\x00' && 
+              start[2] == '\xFE' && start[3]=='\xFF') {
+        *signatureLength=4;
+        return  "UTF-32BE";
+    } else if(start[0] == '\x0E' && start[1] == '\xFE' && start[2] == '\xFF') {
+        *signatureLength=3;
+        return "SCSU";
+    } else if(start[0] == '\xFB' && start[1] == '\xEE' && start[2] == '\x28') {
+        *signatureLength=3;
+        return "BOCU-1";
+    } else if(start[0] == '\x2B' && start[1] == '\x2F' && start[2] == '\x76') {
+        /*
+         * UTF-7: Initial U+FEFF is encoded as +/v8  or  +/v9  or  +/v+  or  +/v/
+         * depending on the second UTF-16 code unit.
+         * Detect the entire, closed Unicode mode sequence +/v8- for only U+FEFF
+         * if it occurs.
+         *
+         * So far we have +/v
+         */
+        if(start[3] == '\x38' && start[4] == '\x2D') {
+            /* 5 bytes +/v8- */
+            *signatureLength=5;
+            return "UTF-7";
+        } else if(start[3] == '\x38' || start[3] == '\x39' || start[3] == '\x2B' || start[3] == '\x2F') {
+            /* 4 bytes +/v8  or  +/v9  or  +/v+  or  +/v/ */
+            *signatureLength=4;
+            return "UTF-7";
+        }
+    }else if(start[0]=='\xDD' && start[1]== '\x73'&& start[2]=='\x66' && start[3]=='\x73'){
+        *signatureLength=4;
+        return "UTF-EBCDIC";
+    }
+
+
+    /* no known Unicode signature byte sequence recognized */
+    *signatureLength=0;
+    return nullptr;
+}
+
+U_CAPI int32_t U_EXPORT2
+ucnv_fromUCountPending(const UConverter* cnv, UErrorCode* status)
+{
+    if(status == nullptr || U_FAILURE(*status)){
+        return -1;
+    }
+    if(cnv == nullptr){
+        *status = U_ILLEGAL_ARGUMENT_ERROR;
+        return -1;
+    }
+
+    if(cnv->preFromUFirstCP >= 0){
+        return U16_LENGTH(cnv->preFromUFirstCP)+cnv->preFromULength ;
+    }else if(cnv->preFromULength < 0){
+        return -cnv->preFromULength ;
+    }else if(cnv->fromUChar32 > 0){
+        return 1;
+    }
+    return 0; 
+
+}
+
+U_CAPI int32_t U_EXPORT2
+ucnv_toUCountPending(const UConverter* cnv, UErrorCode* status){
+
+    if(status == nullptr || U_FAILURE(*status)){
+        return -1;
+    }
+    if(cnv == nullptr){
+        *status = U_ILLEGAL_ARGUMENT_ERROR;
+        return -1;
+    }
+
+    if(cnv->preToULength > 0){
+        return cnv->preToULength ;
+    }else if(cnv->preToULength < 0){
+        return -cnv->preToULength;
+    }else if(cnv->toULength > 0){
+        return cnv->toULength;
+    }
+    return 0;
+}
+
+U_CAPI UBool U_EXPORT2
+ucnv_isFixedWidth(UConverter *cnv, UErrorCode *status){
+    if (U_FAILURE(*status)) {
+        return false;
+    }
+
+    if (cnv == nullptr) {
+        *status = U_ILLEGAL_ARGUMENT_ERROR;
+        return false;
+    }
+
+    switch (ucnv_getType(cnv)) {
+        case UCNV_SBCS:
+        case UCNV_DBCS:
+        case UCNV_UTF32_BigEndian:
+        case UCNV_UTF32_LittleEndian:
+        case UCNV_UTF32:
+        case UCNV_US_ASCII:
+            return true;
+        default:
+            return false;
+    }
+}
+#endif
+
+/*
+ * Hey, Emacs, please set the following:
+ *
+ * Local Variables:
+ * indent-tabs-mode: nil
+ * End:
+ *
+ */