Adding upstream version 124.0.1.upstream/124.0.1

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

1 files changed, 2045 insertions, 0 deletions

diff --git a/intl/icu/source/common/ucnvscsu.cpp b/intl/icu/source/common/ucnvscsu.cpp
new file mode 100644
index 0000000000..2138e289ca
--- /dev/null
+++ b/intl/icu/source/common/ucnvscsu.cpp
@@ -0,0 +1,2045 @@
+// © 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+/*
+******************************************************************************
+*
+*   Copyright (C) 2000-2016, International Business Machines
+*   Corporation and others.  All Rights Reserved.
+*
+******************************************************************************
+*   file name:  ucnvscsu.c
+*   encoding:   UTF-8
+*   tab size:   8 (not used)
+*   indentation:4
+*
+*   created on: 2000nov18
+*   created by: Markus W. Scherer
+*
+*   This is an implementation of the Standard Compression Scheme for Unicode
+*   as defined in https://www.unicode.org/reports/tr6/ .
+*   Reserved commands and window settings are treated as illegal sequences and
+*   will result in callback calls.
+*/
+
+#include "unicode/utypes.h"
+
+#if !UCONFIG_NO_CONVERSION && !UCONFIG_ONLY_HTML_CONVERSION
+
+#include "unicode/ucnv.h"
+#include "unicode/ucnv_cb.h"
+#include "unicode/utf16.h"
+#include "ucnv_bld.h"
+#include "ucnv_cnv.h"
+#include "cmemory.h"
+
+/* SCSU definitions --------------------------------------------------------- */
+
+/* SCSU command byte values */
+enum {
+    SQ0=0x01, /* Quote from window pair 0 */
+    SQ7=0x08, /* Quote from window pair 7 */
+    SDX=0x0B, /* Define a window as extended */
+    Srs=0x0C, /* reserved */
+    SQU=0x0E, /* Quote a single Unicode character */
+    SCU=0x0F, /* Change to Unicode mode */
+    SC0=0x10, /* Select window 0 */
+    SC7=0x17, /* Select window 7 */
+    SD0=0x18, /* Define and select window 0 */
+    SD7=0x1F, /* Define and select window 7 */
+
+    UC0=0xE0, /* Select window 0 */
+    UC7=0xE7, /* Select window 7 */
+    UD0=0xE8, /* Define and select window 0 */
+    UD7=0xEF, /* Define and select window 7 */
+    UQU=0xF0, /* Quote a single Unicode character */
+    UDX=0xF1, /* Define a Window as extended */
+    Urs=0xF2  /* reserved */
+};
+
+enum {
+    /*
+     * Unicode code points from 3400 to E000 are not adressible by
+     * dynamic window, since in these areas no short run alphabets are
+     * found. Therefore add gapOffset to all values from gapThreshold.
+     */
+    gapThreshold=0x68,
+    gapOffset=0xAC00,
+
+    /* values between reservedStart and fixedThreshold are reserved */
+    reservedStart=0xA8,
+
+    /* use table of predefined fixed offsets for values from fixedThreshold */
+    fixedThreshold=0xF9
+};
+
+/* constant offsets for the 8 static windows */
+static const uint32_t staticOffsets[8]={
+    0x0000, /* ASCII for quoted tags */
+    0x0080, /* Latin - 1 Supplement (for access to punctuation) */
+    0x0100, /* Latin Extended-A */
+    0x0300, /* Combining Diacritical Marks */
+    0x2000, /* General Punctuation */
+    0x2080, /* Currency Symbols */
+    0x2100, /* Letterlike Symbols and Number Forms */
+    0x3000  /* CJK Symbols and punctuation */
+};
+
+/* initial offsets for the 8 dynamic (sliding) windows */
+static const uint32_t initialDynamicOffsets[8]={
+    0x0080, /* Latin-1 */
+    0x00C0, /* Latin Extended A */
+    0x0400, /* Cyrillic */
+    0x0600, /* Arabic */
+    0x0900, /* Devanagari */
+    0x3040, /* Hiragana */
+    0x30A0, /* Katakana */
+    0xFF00  /* Fullwidth ASCII */
+};
+
+/* Table of fixed predefined Offsets */
+static const uint32_t fixedOffsets[]={
+    /* 0xF9 */ 0x00C0, /* Latin-1 Letters + half of Latin Extended A */
+    /* 0xFA */ 0x0250, /* IPA extensions */
+    /* 0xFB */ 0x0370, /* Greek */
+    /* 0xFC */ 0x0530, /* Armenian */
+    /* 0xFD */ 0x3040, /* Hiragana */
+    /* 0xFE */ 0x30A0, /* Katakana */
+    /* 0xFF */ 0xFF60  /* Halfwidth Katakana */
+};
+
+/* state values */
+enum {
+    readCommand,
+    quotePairOne,
+    quotePairTwo,
+    quoteOne,
+    definePairOne,
+    definePairTwo,
+    defineOne
+};
+
+typedef struct SCSUData {
+    /* dynamic window offsets, initialize to default values from initialDynamicOffsets */
+    uint32_t toUDynamicOffsets[8];
+    uint32_t fromUDynamicOffsets[8];
+
+    /* state machine state - toUnicode */
+    UBool toUIsSingleByteMode;
+    uint8_t toUState;
+    int8_t toUQuoteWindow, toUDynamicWindow;
+    uint8_t toUByteOne;
+    uint8_t toUPadding[3];
+
+    /* state machine state - fromUnicode */
+    UBool fromUIsSingleByteMode;
+    int8_t fromUDynamicWindow;
+
+    /*
+     * windowUse[] keeps track of the use of the dynamic windows:
+     * At nextWindowUseIndex there is the least recently used window,
+     * and the following windows (in a wrapping manner) are more and more
+     * recently used.
+     * At nextWindowUseIndex-1 there is the most recently used window.
+     */
+    uint8_t locale;
+    int8_t nextWindowUseIndex;
+    int8_t windowUse[8];
+} SCSUData;
+
+static const int8_t initialWindowUse[8]={ 7, 0, 3, 2, 4, 5, 6, 1 };
+static const int8_t initialWindowUse_ja[8]={ 3, 2, 4, 1, 0, 7, 5, 6 };
+
+enum {
+    lGeneric, l_ja
+};
+
+/* SCSU setup functions ----------------------------------------------------- */
+U_CDECL_BEGIN
+static void U_CALLCONV
+_SCSUReset(UConverter *cnv, UConverterResetChoice choice) {
+    SCSUData *scsu=(SCSUData *)cnv->extraInfo;
+
+    if(choice<=UCNV_RESET_TO_UNICODE) {
+        /* reset toUnicode */
+        uprv_memcpy(scsu->toUDynamicOffsets, initialDynamicOffsets, 32);
+
+        scsu->toUIsSingleByteMode=true;
+        scsu->toUState=readCommand;
+        scsu->toUQuoteWindow=scsu->toUDynamicWindow=0;
+        scsu->toUByteOne=0;
+
+        cnv->toULength=0;
+    }
+    if(choice!=UCNV_RESET_TO_UNICODE) {
+        /* reset fromUnicode */
+        uprv_memcpy(scsu->fromUDynamicOffsets, initialDynamicOffsets, 32);
+
+        scsu->fromUIsSingleByteMode=true;
+        scsu->fromUDynamicWindow=0;
+
+        scsu->nextWindowUseIndex=0;
+        switch(scsu->locale) {
+        case l_ja:
+            uprv_memcpy(scsu->windowUse, initialWindowUse_ja, 8);
+            break;
+        default:
+            uprv_memcpy(scsu->windowUse, initialWindowUse, 8);
+            break;
+        }
+
+        cnv->fromUChar32=0;
+    }
+}
+
+static void U_CALLCONV
+_SCSUOpen(UConverter *cnv,
+          UConverterLoadArgs *pArgs,
+          UErrorCode *pErrorCode) {
+    const char *locale=pArgs->locale;
+    if(pArgs->onlyTestIsLoadable) {
+        return;
+    }
+    cnv->extraInfo=uprv_malloc(sizeof(SCSUData));
+    if(cnv->extraInfo!=nullptr) {
+        if(locale!=nullptr && locale[0]=='j' && locale[1]=='a' && (locale[2]==0 || locale[2]=='_')) {
+            ((SCSUData *)cnv->extraInfo)->locale=l_ja;
+        } else {
+            ((SCSUData *)cnv->extraInfo)->locale=lGeneric;
+        }
+        _SCSUReset(cnv, UCNV_RESET_BOTH);
+    } else {
+        *pErrorCode=U_MEMORY_ALLOCATION_ERROR;
+    }
+
+    /* Set the substitution character U+fffd as a Unicode string. */
+    cnv->subUChars[0]=0xfffd;
+    cnv->subCharLen=-1;
+}
+
+static void U_CALLCONV
+_SCSUClose(UConverter *cnv) {
+    if(cnv->extraInfo!=nullptr) {
+        if(!cnv->isExtraLocal) {
+            uprv_free(cnv->extraInfo);
+        }
+        cnv->extraInfo=nullptr;
+    }
+}
+
+/* SCSU-to-Unicode conversion functions ------------------------------------- */
+
+static void U_CALLCONV
+_SCSUToUnicodeWithOffsets(UConverterToUnicodeArgs *pArgs,
+                          UErrorCode *pErrorCode) {
+    UConverter *cnv;
+    SCSUData *scsu;
+    const uint8_t *source, *sourceLimit;
+    char16_t *target;
+    const char16_t *targetLimit;
+    int32_t *offsets;
+    UBool isSingleByteMode;
+    uint8_t state, byteOne;
+    int8_t quoteWindow, dynamicWindow;
+
+    int32_t sourceIndex, nextSourceIndex;
+
+    uint8_t b;
+
+    /* set up the local pointers */
+    cnv=pArgs->converter;
+    scsu=(SCSUData *)cnv->extraInfo;
+
+    source=(const uint8_t *)pArgs->source;
+    sourceLimit=(const uint8_t *)pArgs->sourceLimit;
+    target=pArgs->target;
+    targetLimit=pArgs->targetLimit;
+    offsets=pArgs->offsets;
+
+    /* get the state machine state */
+    isSingleByteMode=scsu->toUIsSingleByteMode;
+    state=scsu->toUState;
+    quoteWindow=scsu->toUQuoteWindow;
+    dynamicWindow=scsu->toUDynamicWindow;
+    byteOne=scsu->toUByteOne;
+
+    /* sourceIndex=-1 if the current character began in the previous buffer */
+    sourceIndex=state==readCommand ? 0 : -1;
+    nextSourceIndex=0;
+
+    /*
+     * conversion "loop"
+     *
+     * For performance, this is not a normal C loop.
+     * Instead, there are two code blocks for the two SCSU modes.
+     * The function branches to either one, and a change of the mode is done with a goto to
+     * the other branch.
+     *
+     * Each branch has two conventional loops:
+     * - a fast-path loop for the most common codes in the mode
+     * - a loop for all other codes in the mode
+     * When the fast-path runs into a code that it cannot handle, its loop ends and it
+     * runs into the following loop to handle the other codes.
+     * The end of the input or output buffer is also handled by the slower loop.
+     * The slow loop jumps (goto) to the fast-path loop again as soon as possible.
+     *
+     * The callback handling is done by returning with an error code.
+     * The conversion framework actually calls the callback function.
+     */
+    if(isSingleByteMode) {
+        /* fast path for single-byte mode */
+        if(state==readCommand) {
+fastSingle:
+            while(source<sourceLimit && target<targetLimit && (b=*source)>=0x20) {
+                ++source;
+                ++nextSourceIndex;
+                if(b<=0x7f) {
+                    /* write US-ASCII graphic character or DEL */
+                    *target++=(char16_t)b;
+                    if(offsets!=nullptr) {
+                        *offsets++=sourceIndex;
+                    }
+                } else {
+                    /* write from dynamic window */
+                    uint32_t c=scsu->toUDynamicOffsets[dynamicWindow]+(b&0x7f);
+                    if(c<=0xffff) {
+                        *target++=(char16_t)c;
+                        if(offsets!=nullptr) {
+                            *offsets++=sourceIndex;
+                        }
+                    } else {
+                        /* output surrogate pair */
+                        *target++=(char16_t)(0xd7c0+(c>>10));
+                        if(target<targetLimit) {
+                            *target++=(char16_t)(0xdc00|(c&0x3ff));
+                            if(offsets!=nullptr) {
+                                *offsets++=sourceIndex;
+                                *offsets++=sourceIndex;
+                            }
+                        } else {
+                            /* target overflow */
+                            if(offsets!=nullptr) {
+                                *offsets++=sourceIndex;
+                            }
+                            cnv->UCharErrorBuffer[0]=(char16_t)(0xdc00|(c&0x3ff));
+                            cnv->UCharErrorBufferLength=1;
+                            *pErrorCode=U_BUFFER_OVERFLOW_ERROR;
+                            goto endloop;
+                        }
+                    }
+                }
+                sourceIndex=nextSourceIndex;
+            }
+        }
+
+        /* normal state machine for single-byte mode, minus handling for what fastSingle covers */
+singleByteMode:
+        while(source<sourceLimit) {
+            if(target>=targetLimit) {
+                /* target is full */
+                *pErrorCode=U_BUFFER_OVERFLOW_ERROR;
+                break;
+            }
+            b=*source++;
+            ++nextSourceIndex;
+            switch(state) {
+            case readCommand:
+                /* redundant conditions are commented out */
+                /* here: b<0x20 because otherwise we would be in fastSingle */
+                if((1UL<<b)&0x2601 /* binary 0010 0110 0000 0001, check for b==0xd || b==0xa || b==9 || b==0 */) {
+                    /* CR/LF/TAB/NUL */
+                    *target++=(char16_t)b;
+                    if(offsets!=nullptr) {
+                        *offsets++=sourceIndex;
+                    }
+                    sourceIndex=nextSourceIndex;
+                    goto fastSingle;
+                } else if(SC0<=b) {
+                    if(b<=SC7) {
+                        dynamicWindow=(int8_t)(b-SC0);
+                        sourceIndex=nextSourceIndex;
+                        goto fastSingle;
+                    } else /* if(SD0<=b && b<=SD7) */ {
+                        dynamicWindow=(int8_t)(b-SD0);
+                        state=defineOne;
+                    }
+                } else if(/* SQ0<=b && */ b<=SQ7) {
+                    quoteWindow=(int8_t)(b-SQ0);
+                    state=quoteOne;
+                } else if(b==SDX) {
+                    state=definePairOne;
+                } else if(b==SQU) {
+                    state=quotePairOne;
+                } else if(b==SCU) {
+                    sourceIndex=nextSourceIndex;
+                    isSingleByteMode=false;
+                    goto fastUnicode;
+                } else /* Srs */ {
+                    /* callback(illegal) */
+                    *pErrorCode=U_ILLEGAL_CHAR_FOUND;
+                    cnv->toUBytes[0]=b;
+                    cnv->toULength=1;
+                    goto endloop;
+                }
+
+                /* store the first byte of a multibyte sequence in toUBytes[] */
+                cnv->toUBytes[0]=b;
+                cnv->toULength=1;
+                break;
+            case quotePairOne:
+                byteOne=b;
+                cnv->toUBytes[1]=b;
+                cnv->toULength=2;
+                state=quotePairTwo;
+                break;
+            case quotePairTwo:
+                *target++=(char16_t)((byteOne<<8)|b);
+                if(offsets!=nullptr) {
+                    *offsets++=sourceIndex;
+                }
+                sourceIndex=nextSourceIndex;
+                state=readCommand;
+                goto fastSingle;
+            case quoteOne:
+                if(b<0x80) {
+                    /* all static offsets are in the BMP */
+                    *target++=(char16_t)(staticOffsets[quoteWindow]+b);
+                    if(offsets!=nullptr) {
+                        *offsets++=sourceIndex;
+                    }
+                } else {
+                    /* write from dynamic window */
+                    uint32_t c=scsu->toUDynamicOffsets[quoteWindow]+(b&0x7f);
+                    if(c<=0xffff) {
+                        *target++=(char16_t)c;
+                        if(offsets!=nullptr) {
+                            *offsets++=sourceIndex;
+                        }
+                    } else {
+                        /* output surrogate pair */
+                        *target++=(char16_t)(0xd7c0+(c>>10));
+                        if(target<targetLimit) {
+                            *target++=(char16_t)(0xdc00|(c&0x3ff));
+                            if(offsets!=nullptr) {
+                                *offsets++=sourceIndex;
+                                *offsets++=sourceIndex;
+                            }
+                        } else {
+                            /* target overflow */
+                            if(offsets!=nullptr) {
+                                *offsets++=sourceIndex;
+                            }
+                            cnv->UCharErrorBuffer[0]=(char16_t)(0xdc00|(c&0x3ff));
+                            cnv->UCharErrorBufferLength=1;
+                            *pErrorCode=U_BUFFER_OVERFLOW_ERROR;
+                            goto endloop;
+                        }
+                    }
+                }
+                sourceIndex=nextSourceIndex;
+                state=readCommand;
+                goto fastSingle;
+            case definePairOne:
+                dynamicWindow=(int8_t)((b>>5)&7);
+                byteOne=(uint8_t)(b&0x1f);
+                cnv->toUBytes[1]=b;
+                cnv->toULength=2;
+                state=definePairTwo;
+                break;
+            case definePairTwo:
+                scsu->toUDynamicOffsets[dynamicWindow]=0x10000+(byteOne<<15UL | b<<7UL);
+                sourceIndex=nextSourceIndex;
+                state=readCommand;
+                goto fastSingle;
+            case defineOne:
+                if(b==0) {
+                    /* callback(illegal): Reserved window offset value 0 */
+                    cnv->toUBytes[1]=b;
+                    cnv->toULength=2;
+                    goto endloop;
+                } else if(b<gapThreshold) {
+                    scsu->toUDynamicOffsets[dynamicWindow]=b<<7UL;
+                } else if((uint8_t)(b-gapThreshold)<(reservedStart-gapThreshold)) {
+                    scsu->toUDynamicOffsets[dynamicWindow]=(b<<7UL)+gapOffset;
+                } else if(b>=fixedThreshold) {
+                    scsu->toUDynamicOffsets[dynamicWindow]=fixedOffsets[b-fixedThreshold];
+                } else {
+                    /* callback(illegal): Reserved window offset value 0xa8..0xf8 */
+                    cnv->toUBytes[1]=b;
+                    cnv->toULength=2;
+                    goto endloop;
+                }
+                sourceIndex=nextSourceIndex;
+                state=readCommand;
+                goto fastSingle;
+            }
+        }
+    } else {
+        /* fast path for Unicode mode */
+        if(state==readCommand) {
+fastUnicode:
+            while(source+1<sourceLimit && target<targetLimit && (uint8_t)((b=*source)-UC0)>(Urs-UC0)) {
+                *target++=(char16_t)((b<<8)|source[1]);
+                if(offsets!=nullptr) {
+                    *offsets++=sourceIndex;
+                }
+                sourceIndex=nextSourceIndex;
+                nextSourceIndex+=2;
+                source+=2;
+            }
+        }
+
+        /* normal state machine for Unicode mode */
+/* unicodeByteMode: */
+        while(source<sourceLimit) {
+            if(target>=targetLimit) {
+                /* target is full */
+                *pErrorCode=U_BUFFER_OVERFLOW_ERROR;
+                break;
+            }
+            b=*source++;
+            ++nextSourceIndex;
+            switch(state) {
+            case readCommand:
+                if((uint8_t)(b-UC0)>(Urs-UC0)) {
+                    byteOne=b;
+                    cnv->toUBytes[0]=b;
+                    cnv->toULength=1;
+                    state=quotePairTwo;
+                } else if(/* UC0<=b && */ b<=UC7) {
+                    dynamicWindow=(int8_t)(b-UC0);
+                    sourceIndex=nextSourceIndex;
+                    isSingleByteMode=true;
+                    goto fastSingle;
+                } else if(/* UD0<=b && */ b<=UD7) {
+                    dynamicWindow=(int8_t)(b-UD0);
+                    isSingleByteMode=true;
+                    cnv->toUBytes[0]=b;
+                    cnv->toULength=1;
+                    state=defineOne;
+                    goto singleByteMode;
+                } else if(b==UDX) {
+                    isSingleByteMode=true;
+                    cnv->toUBytes[0]=b;
+                    cnv->toULength=1;
+                    state=definePairOne;
+                    goto singleByteMode;
+                } else if(b==UQU) {
+                    cnv->toUBytes[0]=b;
+                    cnv->toULength=1;
+                    state=quotePairOne;
+                } else /* Urs */ {
+                    /* callback(illegal) */
+                    *pErrorCode=U_ILLEGAL_CHAR_FOUND;
+                    cnv->toUBytes[0]=b;
+                    cnv->toULength=1;
+                    goto endloop;
+                }
+                break;
+            case quotePairOne:
+                byteOne=b;
+                cnv->toUBytes[1]=b;
+                cnv->toULength=2;
+                state=quotePairTwo;
+                break;
+            case quotePairTwo:
+                *target++=(char16_t)((byteOne<<8)|b);
+                if(offsets!=nullptr) {
+                    *offsets++=sourceIndex;
+                }
+                sourceIndex=nextSourceIndex;
+                state=readCommand;
+                goto fastUnicode;
+            }
+        }
+    }
+endloop:
+
+    /* set the converter state back into UConverter */
+    if(U_FAILURE(*pErrorCode) && *pErrorCode!=U_BUFFER_OVERFLOW_ERROR) {
+        /* reset to deal with the next character */
+        state=readCommand;
+    } else if(state==readCommand) {
+        /* not in a multi-byte sequence, reset toULength */
+        cnv->toULength=0;
+    }
+    scsu->toUIsSingleByteMode=isSingleByteMode;
+    scsu->toUState=state;
+    scsu->toUQuoteWindow=quoteWindow;
+    scsu->toUDynamicWindow=dynamicWindow;
+    scsu->toUByteOne=byteOne;
+
+    /* write back the updated pointers */
+    pArgs->source=(const char *)source;
+    pArgs->target=target;
+    pArgs->offsets=offsets;
+    return;
+}
+
+/*
+ * Identical to _SCSUToUnicodeWithOffsets but without offset handling.
+ * If a change is made in the original function, then either
+ * change this function the same way or
+ * re-copy the original function and remove the variables
+ * offsets, sourceIndex, and nextSourceIndex.
+ */
+static void U_CALLCONV
+_SCSUToUnicode(UConverterToUnicodeArgs *pArgs,
+               UErrorCode *pErrorCode) {
+    UConverter *cnv;
+    SCSUData *scsu;
+    const uint8_t *source, *sourceLimit;
+    char16_t *target;
+    const char16_t *targetLimit;
+    UBool isSingleByteMode;
+    uint8_t state, byteOne;
+    int8_t quoteWindow, dynamicWindow;
+
+    uint8_t b;
+
+    /* set up the local pointers */
+    cnv=pArgs->converter;
+    scsu=(SCSUData *)cnv->extraInfo;
+
+    source=(const uint8_t *)pArgs->source;
+    sourceLimit=(const uint8_t *)pArgs->sourceLimit;
+    target=pArgs->target;
+    targetLimit=pArgs->targetLimit;
+
+    /* get the state machine state */
+    isSingleByteMode=scsu->toUIsSingleByteMode;
+    state=scsu->toUState;
+    quoteWindow=scsu->toUQuoteWindow;
+    dynamicWindow=scsu->toUDynamicWindow;
+    byteOne=scsu->toUByteOne;
+
+    /*
+     * conversion "loop"
+     *
+     * For performance, this is not a normal C loop.
+     * Instead, there are two code blocks for the two SCSU modes.
+     * The function branches to either one, and a change of the mode is done with a goto to
+     * the other branch.
+     *
+     * Each branch has two conventional loops:
+     * - a fast-path loop for the most common codes in the mode
+     * - a loop for all other codes in the mode
+     * When the fast-path runs into a code that it cannot handle, its loop ends and it
+     * runs into the following loop to handle the other codes.
+     * The end of the input or output buffer is also handled by the slower loop.
+     * The slow loop jumps (goto) to the fast-path loop again as soon as possible.
+     *
+     * The callback handling is done by returning with an error code.
+     * The conversion framework actually calls the callback function.
+     */
+    if(isSingleByteMode) {
+        /* fast path for single-byte mode */
+        if(state==readCommand) {
+fastSingle:
+            while(source<sourceLimit && target<targetLimit && (b=*source)>=0x20) {
+                ++source;
+                if(b<=0x7f) {
+                    /* write US-ASCII graphic character or DEL */
+                    *target++=(char16_t)b;
+                } else {
+                    /* write from dynamic window */
+                    uint32_t c=scsu->toUDynamicOffsets[dynamicWindow]+(b&0x7f);
+                    if(c<=0xffff) {
+                        *target++=(char16_t)c;
+                    } else {
+                        /* output surrogate pair */
+                        *target++=(char16_t)(0xd7c0+(c>>10));
+                        if(target<targetLimit) {
+                            *target++=(char16_t)(0xdc00|(c&0x3ff));
+                        } else {
+                            /* target overflow */
+                            cnv->UCharErrorBuffer[0]=(char16_t)(0xdc00|(c&0x3ff));
+                            cnv->UCharErrorBufferLength=1;
+                            *pErrorCode=U_BUFFER_OVERFLOW_ERROR;
+                            goto endloop;
+                        }
+                    }
+                }
+            }
+        }
+
+        /* normal state machine for single-byte mode, minus handling for what fastSingle covers */
+singleByteMode:
+        while(source<sourceLimit) {
+            if(target>=targetLimit) {
+                /* target is full */
+                *pErrorCode=U_BUFFER_OVERFLOW_ERROR;
+                break;
+            }
+            b=*source++;
+            switch(state) {
+            case readCommand:
+                /* redundant conditions are commented out */
+                /* here: b<0x20 because otherwise we would be in fastSingle */
+                if((1UL<<b)&0x2601 /* binary 0010 0110 0000 0001, check for b==0xd || b==0xa || b==9 || b==0 */) {
+                    /* CR/LF/TAB/NUL */
+                    *target++=(char16_t)b;
+                    goto fastSingle;
+                } else if(SC0<=b) {
+                    if(b<=SC7) {
+                        dynamicWindow=(int8_t)(b-SC0);
+                        goto fastSingle;
+                    } else /* if(SD0<=b && b<=SD7) */ {
+                        dynamicWindow=(int8_t)(b-SD0);
+                        state=defineOne;
+                    }
+                } else if(/* SQ0<=b && */ b<=SQ7) {
+                    quoteWindow=(int8_t)(b-SQ0);
+                    state=quoteOne;
+                } else if(b==SDX) {
+                    state=definePairOne;
+                } else if(b==SQU) {
+                    state=quotePairOne;
+                } else if(b==SCU) {
+                    isSingleByteMode=false;
+                    goto fastUnicode;
+                } else /* Srs */ {
+                    /* callback(illegal) */
+                    *pErrorCode=U_ILLEGAL_CHAR_FOUND;
+                    cnv->toUBytes[0]=b;
+                    cnv->toULength=1;
+                    goto endloop;
+                }
+
+                /* store the first byte of a multibyte sequence in toUBytes[] */
+                cnv->toUBytes[0]=b;
+                cnv->toULength=1;
+                break;
+            case quotePairOne:
+                byteOne=b;
+                cnv->toUBytes[1]=b;
+                cnv->toULength=2;
+                state=quotePairTwo;
+                break;
+            case quotePairTwo:
+                *target++=(char16_t)((byteOne<<8)|b);
+                state=readCommand;
+                goto fastSingle;
+            case quoteOne:
+                if(b<0x80) {
+                    /* all static offsets are in the BMP */
+                    *target++=(char16_t)(staticOffsets[quoteWindow]+b);
+                } else {
+                    /* write from dynamic window */
+                    uint32_t c=scsu->toUDynamicOffsets[quoteWindow]+(b&0x7f);
+                    if(c<=0xffff) {
+                        *target++=(char16_t)c;
+                    } else {
+                        /* output surrogate pair */
+                        *target++=(char16_t)(0xd7c0+(c>>10));
+                        if(target<targetLimit) {
+                            *target++=(char16_t)(0xdc00|(c&0x3ff));
+                        } else {
+                            /* target overflow */
+                            cnv->UCharErrorBuffer[0]=(char16_t)(0xdc00|(c&0x3ff));
+                            cnv->UCharErrorBufferLength=1;
+                            *pErrorCode=U_BUFFER_OVERFLOW_ERROR;
+                            goto endloop;
+                        }
+                    }
+                }
+                state=readCommand;
+                goto fastSingle;
+            case definePairOne:
+                dynamicWindow=(int8_t)((b>>5)&7);
+                byteOne=(uint8_t)(b&0x1f);
+                cnv->toUBytes[1]=b;
+                cnv->toULength=2;
+                state=definePairTwo;
+                break;
+            case definePairTwo:
+                scsu->toUDynamicOffsets[dynamicWindow]=0x10000+(byteOne<<15UL | b<<7UL);
+                state=readCommand;
+                goto fastSingle;
+            case defineOne:
+                if(b==0) {
+                    /* callback(illegal): Reserved window offset value 0 */
+                    cnv->toUBytes[1]=b;
+                    cnv->toULength=2;
+                    goto endloop;
+                } else if(b<gapThreshold) {
+                    scsu->toUDynamicOffsets[dynamicWindow]=b<<7UL;
+                } else if((uint8_t)(b-gapThreshold)<(reservedStart-gapThreshold)) {
+                    scsu->toUDynamicOffsets[dynamicWindow]=(b<<7UL)+gapOffset;
+                } else if(b>=fixedThreshold) {
+                    scsu->toUDynamicOffsets[dynamicWindow]=fixedOffsets[b-fixedThreshold];
+                } else {
+                    /* callback(illegal): Reserved window offset value 0xa8..0xf8 */
+                    cnv->toUBytes[1]=b;
+                    cnv->toULength=2;
+                    goto endloop;
+                }
+                state=readCommand;
+                goto fastSingle;
+            }
+        }
+    } else {
+        /* fast path for Unicode mode */
+        if(state==readCommand) {
+fastUnicode:
+            while(source+1<sourceLimit && target<targetLimit && (uint8_t)((b=*source)-UC0)>(Urs-UC0)) {
+                *target++=(char16_t)((b<<8)|source[1]);
+                source+=2;
+            }
+        }
+
+        /* normal state machine for Unicode mode */
+/* unicodeByteMode: */
+        while(source<sourceLimit) {
+            if(target>=targetLimit) {
+                /* target is full */
+                *pErrorCode=U_BUFFER_OVERFLOW_ERROR;
+                break;
+            }
+            b=*source++;
+            switch(state) {
+            case readCommand:
+                if((uint8_t)(b-UC0)>(Urs-UC0)) {
+                    byteOne=b;
+                    cnv->toUBytes[0]=b;
+                    cnv->toULength=1;
+                    state=quotePairTwo;
+                } else if(/* UC0<=b && */ b<=UC7) {
+                    dynamicWindow=(int8_t)(b-UC0);
+                    isSingleByteMode=true;
+                    goto fastSingle;
+                } else if(/* UD0<=b && */ b<=UD7) {
+                    dynamicWindow=(int8_t)(b-UD0);
+                    isSingleByteMode=true;
+                    cnv->toUBytes[0]=b;
+                    cnv->toULength=1;
+                    state=defineOne;
+                    goto singleByteMode;
+                } else if(b==UDX) {
+                    isSingleByteMode=true;
+                    cnv->toUBytes[0]=b;
+                    cnv->toULength=1;
+                    state=definePairOne;
+                    goto singleByteMode;
+                } else if(b==UQU) {
+                    cnv->toUBytes[0]=b;
+                    cnv->toULength=1;
+                    state=quotePairOne;
+                } else /* Urs */ {
+                    /* callback(illegal) */
+                    *pErrorCode=U_ILLEGAL_CHAR_FOUND;
+                    cnv->toUBytes[0]=b;
+                    cnv->toULength=1;
+                    goto endloop;
+                }
+                break;
+            case quotePairOne:
+                byteOne=b;
+                cnv->toUBytes[1]=b;
+                cnv->toULength=2;
+                state=quotePairTwo;
+                break;
+            case quotePairTwo:
+                *target++=(char16_t)((byteOne<<8)|b);
+                state=readCommand;
+                goto fastUnicode;
+            }
+        }
+    }
+endloop:
+
+    /* set the converter state back into UConverter */
+    if(U_FAILURE(*pErrorCode) && *pErrorCode!=U_BUFFER_OVERFLOW_ERROR) {
+        /* reset to deal with the next character */
+        state=readCommand;
+    } else if(state==readCommand) {
+        /* not in a multi-byte sequence, reset toULength */
+        cnv->toULength=0;
+    }
+    scsu->toUIsSingleByteMode=isSingleByteMode;
+    scsu->toUState=state;
+    scsu->toUQuoteWindow=quoteWindow;
+    scsu->toUDynamicWindow=dynamicWindow;
+    scsu->toUByteOne=byteOne;
+
+    /* write back the updated pointers */
+    pArgs->source=(const char *)source;
+    pArgs->target=target;
+    return;
+}
+U_CDECL_END
+/* SCSU-from-Unicode conversion functions ----------------------------------- */
+
+/*
+ * This SCSU Encoder is fairly simple but uses all SCSU commands to achieve
+ * reasonable results. The lookahead is minimal.
+ * Many cases are simple:
+ * A character fits directly into the current mode, a dynamic or static window,
+ * or is not compressible. These cases are tested first.
+ * Real compression heuristics are applied to the rest, in code branches for
+ * single/Unicode mode and BMP/supplementary code points.
+ * The heuristics used here are extremely simple.
+ */
+
+/* get the number of the window that this character is in, or -1 */
+static int8_t
+getWindow(const uint32_t offsets[8], uint32_t c) {
+    int i;
+    for(i=0; i<8; ++i) {
+        if((uint32_t)(c-offsets[i])<=0x7f) {
+            return (int8_t)(i);
+        }
+    }
+    return -1;
+}
+
+/* is the character in the dynamic window starting at the offset, or in the direct-encoded range? */
+static UBool
+isInOffsetWindowOrDirect(uint32_t offset, uint32_t c) {
+    return (UBool)(c<=offset+0x7f &&
+          (c>=offset || (c<=0x7f &&
+                        (c>=0x20 || (1UL<<c)&0x2601))));
+                                /* binary 0010 0110 0000 0001,
+                                   check for b==0xd || b==0xa || b==9 || b==0 */
+}
+
+/*
+ * getNextDynamicWindow returns the next dynamic window to be redefined
+ */
+static int8_t
+getNextDynamicWindow(SCSUData *scsu) {
+    int8_t window=scsu->windowUse[scsu->nextWindowUseIndex];
+    if(++scsu->nextWindowUseIndex==8) {
+        scsu->nextWindowUseIndex=0;
+    }
+    return window;
+}
+
+/*
+ * useDynamicWindow() adjusts
+ * windowUse[] and nextWindowUseIndex for the algorithm to choose
+ * the next dynamic window to be defined;
+ * a subclass may override it and provide its own algorithm.
+ */
+static void
+useDynamicWindow(SCSUData *scsu, int8_t window) {
+    /*
+     * move the existing window, which just became the most recently used one,
+     * up in windowUse[] to nextWindowUseIndex-1
+     */
+
+    /* first, find the index of the window - backwards to favor the more recently used windows */
+    int i, j;
+
+    i=scsu->nextWindowUseIndex;
+    do {
+        if(--i<0) {
+            i=7;
+        }
+    } while(scsu->windowUse[i]!=window);
+
+    /* now copy each windowUse[i+1] to [i] */
+    j=i+1;
+    if(j==8) {
+        j=0;
+    }
+    while(j!=scsu->nextWindowUseIndex) {
+        scsu->windowUse[i]=scsu->windowUse[j];
+        i=j;
+        if(++j==8) { j=0; }
+    }
+
+    /* finally, set the window into the most recently used index */
+    scsu->windowUse[i]=window;
+}
+
+/*
+ * calculate the offset and the code for a dynamic window that contains the character
+ * takes fixed offsets into account
+ * the offset of the window is stored in the offset variable,
+ * the code is returned
+ *
+ * return offset code: -1 none  <=0xff code for SDn/UDn  else code for SDX/UDX, subtract 0x200 to get the true code
+ */
+static int
+getDynamicOffset(uint32_t c, uint32_t *pOffset) {
+    int i;
+
+    for(i=0; i<7; ++i) {
+        if((uint32_t)(c-fixedOffsets[i])<=0x7f) {
+            *pOffset=fixedOffsets[i];
+            return 0xf9+i;
+        }
+    }
+
+    if(c<0x80) {
+        /* No dynamic window for US-ASCII. */
+        return -1;
+    } else if(c<0x3400 ||
+              (uint32_t)(c-0x10000)<(0x14000-0x10000) ||
+              (uint32_t)(c-0x1d000)<=(0x1ffff-0x1d000)
+    ) {
+        /* This character is in a code range for a "small", i.e., reasonably windowable, script. */
+        *pOffset=c&0x7fffff80;
+        return (int)(c>>7);
+    } else if(0xe000<=c && c!=0xfeff && c<0xfff0) {
+        /* For these characters we need to take the gapOffset into account. */
+        *pOffset=c&0x7fffff80;
+        return (int)((c-gapOffset)>>7);
+    } else {
+        return -1;
+    }
+}
+U_CDECL_BEGIN
+/*
+ * Idea for compression:
+ *  - save SCSUData and other state before really starting work
+ *  - at endloop, see if compression could be better with just unicode mode
+ *  - don't do this if a callback has been called
+ *  - if unicode mode would be smaller, then override the results with it - may need SCU at the beginning
+ *  - different buffer handling!
+ *
+ * Drawback or need for corrective handling:
+ * it is desirable to encode U+feff as SQU fe ff for the SCSU signature, and
+ * it is desirable to start a document in US-ASCII/Latin-1 for as long as possible
+ * not only for compression but also for HTML/XML documents with following charset/encoding announcers.
+ *
+ * How to achieve both?
+ *  - Only replace the result after an SDX or SCU?
+ */
+
+static void U_CALLCONV
+_SCSUFromUnicodeWithOffsets(UConverterFromUnicodeArgs *pArgs,
+                            UErrorCode *pErrorCode) {
+    UConverter *cnv;
+    SCSUData *scsu;
+    const char16_t *source, *sourceLimit;
+    uint8_t *target;
+    int32_t targetCapacity;
+    int32_t *offsets;
+
+    UBool isSingleByteMode;
+    uint8_t dynamicWindow;
+    uint32_t currentOffset;
+
+    uint32_t c, delta;
+
+    int32_t sourceIndex, nextSourceIndex;
+
+    int32_t length;
+
+    /* variables for compression heuristics */
+    uint32_t offset;
+    char16_t lead, trail;
+    int code;
+    int8_t window;
+
+    /* set up the local pointers */
+    cnv=pArgs->converter;
+    scsu=(SCSUData *)cnv->extraInfo;
+
+    /* set up the local pointers */
+    source=pArgs->source;
+    sourceLimit=pArgs->sourceLimit;
+    target=(uint8_t *)pArgs->target;
+    targetCapacity=(int32_t)(pArgs->targetLimit-pArgs->target);
+    offsets=pArgs->offsets;
+
+    /* get the state machine state */
+    isSingleByteMode=scsu->fromUIsSingleByteMode;
+    dynamicWindow=scsu->fromUDynamicWindow;
+    currentOffset=scsu->fromUDynamicOffsets[dynamicWindow];
+
+    c=cnv->fromUChar32;
+
+    /* sourceIndex=-1 if the current character began in the previous buffer */
+    sourceIndex= c==0 ? 0 : -1;
+    nextSourceIndex=0;
+
+    /* similar conversion "loop" as in toUnicode */
+loop:
+    if(isSingleByteMode) {
+        if(c!=0 && targetCapacity>0) {
+            goto getTrailSingle;
+        }
+
+        /* state machine for single-byte mode */
+/* singleByteMode: */
+        while(source<sourceLimit) {
+            if(targetCapacity<=0) {
+                /* target is full */
+                *pErrorCode=U_BUFFER_OVERFLOW_ERROR;
+                break;
+            }
+            c=*source++;
+            ++nextSourceIndex;
+
+            if((c-0x20)<=0x5f) {
+                /* pass US-ASCII graphic character through */
+                *target++=(uint8_t)c;
+                if(offsets!=nullptr) {
+                    *offsets++=sourceIndex;
+                }
+                --targetCapacity;
+            } else if(c<0x20) {
+                if((1UL<<c)&0x2601 /* binary 0010 0110 0000 0001, check for b==0xd || b==0xa || b==9 || b==0 */) {
+                    /* CR/LF/TAB/NUL */
+                    *target++=(uint8_t)c;
+                    if(offsets!=nullptr) {
+                        *offsets++=sourceIndex;
+                    }
+                    --targetCapacity;
+                } else {
+                    /* quote C0 control character */
+                    c|=SQ0<<8;
+                    length=2;
+                    goto outputBytes;
+                }
+            } else if((delta=c-currentOffset)<=0x7f) {
+                /* use the current dynamic window */
+                *target++=(uint8_t)(delta|0x80);
+                if(offsets!=nullptr) {
+                    *offsets++=sourceIndex;
+                }
+                --targetCapacity;
+            } else if(U16_IS_SURROGATE(c)) {
+                if(U16_IS_SURROGATE_LEAD(c)) {
+getTrailSingle:
+                    lead=(char16_t)c;
+                    if(source<sourceLimit) {
+                        /* test the following code unit */
+                        trail=*source;
+                        if(U16_IS_TRAIL(trail)) {
+                            ++source;
+                            ++nextSourceIndex;
+                            c=U16_GET_SUPPLEMENTARY(c, trail);
+                            /* convert this surrogate code point */
+                            /* exit this condition tree */
+                        } else {
+                            /* this is an unmatched lead code unit (1st surrogate) */
+                            /* callback(illegal) */
+                            *pErrorCode=U_ILLEGAL_CHAR_FOUND;
+                            goto endloop;
+                        }
+                    } else {
+                        /* no more input */
+                        break;
+                    }
+                } else {
+                    /* this is an unmatched trail code unit (2nd surrogate) */
+                    /* callback(illegal) */
+                    *pErrorCode=U_ILLEGAL_CHAR_FOUND;
+                    goto endloop;
+                }
+
+                /* compress supplementary character U+10000..U+10ffff */
+                if((delta=c-currentOffset)<=0x7f) {
+                    /* use the current dynamic window */
+                    *target++=(uint8_t)(delta|0x80);
+                    if(offsets!=nullptr) {
+                        *offsets++=sourceIndex;
+                    }
+                    --targetCapacity;
+                } else if((window=getWindow(scsu->fromUDynamicOffsets, c))>=0) {
+                    /* there is a dynamic window that contains this character, change to it */
+                    dynamicWindow=window;
+                    currentOffset=scsu->fromUDynamicOffsets[dynamicWindow];
+                    useDynamicWindow(scsu, dynamicWindow);
+                    c=((uint32_t)(SC0+dynamicWindow)<<8)|(c-currentOffset)|0x80;
+                    length=2;
+                    goto outputBytes;
+                } else if((code=getDynamicOffset(c, &offset))>=0) {
+                    /* might check if there are more characters in this window to come */
+                    /* define an extended window with this character */
+                    code-=0x200;
+                    dynamicWindow=getNextDynamicWindow(scsu);
+                    currentOffset=scsu->fromUDynamicOffsets[dynamicWindow]=offset;
+                    useDynamicWindow(scsu, dynamicWindow);
+                    c=((uint32_t)SDX<<24)|((uint32_t)dynamicWindow<<21)|((uint32_t)code<<8)|(c-currentOffset)|0x80;
+                    length=4;
+                    goto outputBytes;
+                } else {
+                    /* change to Unicode mode and output this (lead, trail) pair */
+                    isSingleByteMode=false;
+                    *target++=(uint8_t)SCU;
+                    if(offsets!=nullptr) {
+                        *offsets++=sourceIndex;
+                    }
+                    --targetCapacity;
+                    c=((uint32_t)lead<<16)|trail;
+                    length=4;
+                    goto outputBytes;
+                }
+            } else if(c<0xa0) {
+                /* quote C1 control character */
+                c=(c&0x7f)|(SQ0+1)<<8; /* SQ0+1==SQ1 */
+                length=2;
+                goto outputBytes;
+            } else if(c==0xfeff || c>=0xfff0) {
+                /* quote signature character=byte order mark and specials */
+                c|=SQU<<16;
+                length=3;
+                goto outputBytes;
+            } else {
+                /* compress all other BMP characters */
+                if((window=getWindow(scsu->fromUDynamicOffsets, c))>=0) {
+                    /* there is a window defined that contains this character - switch to it or quote from it? */
+                    if(source>=sourceLimit || isInOffsetWindowOrDirect(scsu->fromUDynamicOffsets[window], *source)) {
+                        /* change to dynamic window */
+                        dynamicWindow=window;
+                        currentOffset=scsu->fromUDynamicOffsets[dynamicWindow];
+                        useDynamicWindow(scsu, dynamicWindow);
+                        c=((uint32_t)(SC0+dynamicWindow)<<8)|(c-currentOffset)|0x80;
+                        length=2;
+                        goto outputBytes;
+                    } else {
+                        /* quote from dynamic window */
+                        c=((uint32_t)(SQ0+window)<<8)|(c-scsu->fromUDynamicOffsets[window])|0x80;
+                        length=2;
+                        goto outputBytes;
+                    }
+                } else if((window=getWindow(staticOffsets, c))>=0) {
+                    /* quote from static window */
+                    c=((uint32_t)(SQ0+window)<<8)|(c-staticOffsets[window]);
+                    length=2;
+                    goto outputBytes;
+                } else if((code=getDynamicOffset(c, &offset))>=0) {
+                    /* define a dynamic window with this character */
+                    dynamicWindow=getNextDynamicWindow(scsu);
+                    currentOffset=scsu->fromUDynamicOffsets[dynamicWindow]=offset;
+                    useDynamicWindow(scsu, dynamicWindow);
+                    c=((uint32_t)(SD0+dynamicWindow)<<16)|((uint32_t)code<<8)|(c-currentOffset)|0x80;
+                    length=3;
+                    goto outputBytes;
+                } else if((uint32_t)(c-0x3400)<(0xd800-0x3400) &&
+                          (source>=sourceLimit || (uint32_t)(*source-0x3400)<(0xd800-0x3400))
+                ) {
+                    /*
+                     * this character is not compressible (a BMP ideograph or similar);
+                     * switch to Unicode mode if this is the last character in the block
+                     * or there is at least one more ideograph following immediately
+                     */
+                    isSingleByteMode=false;
+                    c|=SCU<<16;
+                    length=3;
+                    goto outputBytes;
+                } else {
+                    /* quote Unicode */
+                    c|=SQU<<16;
+                    length=3;
+                    goto outputBytes;
+                }
+            }
+
+            /* normal end of conversion: prepare for a new character */
+            c=0;
+            sourceIndex=nextSourceIndex;
+        }
+    } else {
+        if(c!=0 && targetCapacity>0) {
+            goto getTrailUnicode;
+        }
+
+        /* state machine for Unicode mode */
+/* unicodeByteMode: */
+        while(source<sourceLimit) {
+            if(targetCapacity<=0) {
+                /* target is full */
+                *pErrorCode=U_BUFFER_OVERFLOW_ERROR;
+                break;
+            }
+            c=*source++;
+            ++nextSourceIndex;
+
+            if((uint32_t)(c-0x3400)<(0xd800-0x3400)) {
+                /* not compressible, write character directly */
+                if(targetCapacity>=2) {
+                    *target++=(uint8_t)(c>>8);
+                    *target++=(uint8_t)c;
+                    if(offsets!=nullptr) {
+                        *offsets++=sourceIndex;
+                        *offsets++=sourceIndex;
+                    }
+                    targetCapacity-=2;
+                } else {
+                    length=2;
+                    goto outputBytes;
+                }
+            } else if((uint32_t)(c-0x3400)>=(0xf300-0x3400) /* c<0x3400 || c>=0xf300 */) {
+                /* compress BMP character if the following one is not an uncompressible ideograph */
+                if(!(source<sourceLimit && (uint32_t)(*source-0x3400)<(0xd800-0x3400))) {
+                    if(((uint32_t)(c-0x30)<10 || (uint32_t)(c-0x61)<26 || (uint32_t)(c-0x41)<26)) {
+                        /* ASCII digit or letter */
+                        isSingleByteMode=true;
+                        c|=((uint32_t)(UC0+dynamicWindow)<<8)|c;
+                        length=2;
+                        goto outputBytes;
+                    } else if((window=getWindow(scsu->fromUDynamicOffsets, c))>=0) {
+                        /* there is a dynamic window that contains this character, change to it */
+                        isSingleByteMode=true;
+                        dynamicWindow=window;
+                        currentOffset=scsu->fromUDynamicOffsets[dynamicWindow];
+                        useDynamicWindow(scsu, dynamicWindow);
+                        c=((uint32_t)(UC0+dynamicWindow)<<8)|(c-currentOffset)|0x80;
+                        length=2;
+                        goto outputBytes;
+                    } else if((code=getDynamicOffset(c, &offset))>=0) {
+                        /* define a dynamic window with this character */
+                        isSingleByteMode=true;
+                        dynamicWindow=getNextDynamicWindow(scsu);
+                        currentOffset=scsu->fromUDynamicOffsets[dynamicWindow]=offset;
+                        useDynamicWindow(scsu, dynamicWindow);
+                        c=((uint32_t)(UD0+dynamicWindow)<<16)|((uint32_t)code<<8)|(c-currentOffset)|0x80;
+                        length=3;
+                        goto outputBytes;
+                    }
+                }
+
+                /* don't know how to compress this character, just write it directly */
+                length=2;
+                goto outputBytes;
+            } else if(c<0xe000) {
+                /* c is a surrogate */
+                if(U16_IS_SURROGATE_LEAD(c)) {
+getTrailUnicode:
+                    lead=(char16_t)c;
+                    if(source<sourceLimit) {
+                        /* test the following code unit */
+                        trail=*source;
+                        if(U16_IS_TRAIL(trail)) {
+                            ++source;
+                            ++nextSourceIndex;
+                            c=U16_GET_SUPPLEMENTARY(c, trail);
+                            /* convert this surrogate code point */
+                            /* exit this condition tree */
+                        } else {
+                            /* this is an unmatched lead code unit (1st surrogate) */
+                            /* callback(illegal) */
+                            *pErrorCode=U_ILLEGAL_CHAR_FOUND;
+                            goto endloop;
+                        }
+                    } else {
+                        /* no more input */
+                        break;
+                    }
+                } else {
+                    /* this is an unmatched trail code unit (2nd surrogate) */
+                    /* callback(illegal) */
+                    *pErrorCode=U_ILLEGAL_CHAR_FOUND;
+                    goto endloop;
+                }
+
+                /* compress supplementary character */
+                if( (window=getWindow(scsu->fromUDynamicOffsets, c))>=0 &&
+                    !(source<sourceLimit && (uint32_t)(*source-0x3400)<(0xd800-0x3400))
+                ) {
+                    /*
+                     * there is a dynamic window that contains this character and
+                     * the following character is not uncompressible,
+                     * change to the window
+                     */
+                    isSingleByteMode=true;
+                    dynamicWindow=window;
+                    currentOffset=scsu->fromUDynamicOffsets[dynamicWindow];
+                    useDynamicWindow(scsu, dynamicWindow);
+                    c=((uint32_t)(UC0+dynamicWindow)<<8)|(c-currentOffset)|0x80;
+                    length=2;
+                    goto outputBytes;
+                } else if(source<sourceLimit && lead==*source && /* too lazy to check trail in same window as source[1] */
+                          (code=getDynamicOffset(c, &offset))>=0
+                ) {
+                    /* two supplementary characters in (probably) the same window - define an extended one */
+                    isSingleByteMode=true;
+                    code-=0x200;
+                    dynamicWindow=getNextDynamicWindow(scsu);
+                    currentOffset=scsu->fromUDynamicOffsets[dynamicWindow]=offset;
+                    useDynamicWindow(scsu, dynamicWindow);
+                    c=((uint32_t)UDX<<24)|((uint32_t)dynamicWindow<<21)|((uint32_t)code<<8)|(c-currentOffset)|0x80;
+                    length=4;
+                    goto outputBytes;
+                } else {
+                    /* don't know how to compress this character, just write it directly */
+                    c=((uint32_t)lead<<16)|trail;
+                    length=4;
+                    goto outputBytes;
+                }
+            } else /* 0xe000<=c<0xf300 */ {
+                /* quote to avoid SCSU tags */
+                c|=UQU<<16;
+                length=3;
+                goto outputBytes;
+            }
+
+            /* normal end of conversion: prepare for a new character */
+            c=0;
+            sourceIndex=nextSourceIndex;
+        }
+    }
+endloop:
+
+    /* set the converter state back into UConverter */
+    scsu->fromUIsSingleByteMode=isSingleByteMode;
+    scsu->fromUDynamicWindow=dynamicWindow;
+
+    cnv->fromUChar32=c;
+
+    /* write back the updated pointers */
+    pArgs->source=source;
+    pArgs->target=(char *)target;
+    pArgs->offsets=offsets;
+    return;
+
+outputBytes:
+    /* write the output character bytes from c and length [code copied from ucnvmbcs.c] */
+    /* from the first if in the loop we know that targetCapacity>0 */
+    if(length<=targetCapacity) {
+        if(offsets==nullptr) {
+            switch(length) {
+                /* each branch falls through to the next one */
+            case 4:
+                *target++=(uint8_t)(c>>24);
+                U_FALLTHROUGH;
+            case 3:
+                *target++=(uint8_t)(c>>16);
+                U_FALLTHROUGH;
+            case 2:
+                *target++=(uint8_t)(c>>8);
+                U_FALLTHROUGH;
+            case 1:
+                *target++=(uint8_t)c;
+                U_FALLTHROUGH;
+            default:
+                /* will never occur */
+                break;
+            }
+        } else {
+            switch(length) {
+                /* each branch falls through to the next one */
+            case 4:
+                *target++=(uint8_t)(c>>24);
+                *offsets++=sourceIndex;
+                U_FALLTHROUGH;
+            case 3:
+                *target++=(uint8_t)(c>>16);
+                *offsets++=sourceIndex;
+                U_FALLTHROUGH;
+            case 2:
+                *target++=(uint8_t)(c>>8);
+                *offsets++=sourceIndex;
+                U_FALLTHROUGH;
+            case 1:
+                *target++=(uint8_t)c;
+                *offsets++=sourceIndex;
+                U_FALLTHROUGH;
+            default:
+                /* will never occur */
+                break;
+            }
+        }
+        targetCapacity-=length;
+
+        /* normal end of conversion: prepare for a new character */
+        c=0;
+        sourceIndex=nextSourceIndex;
+        goto loop;
+    } else {
+        uint8_t *p;
+
+        /*
+         * We actually do this backwards here:
+         * In order to save an intermediate variable, we output
+         * first to the overflow buffer what does not fit into the
+         * regular target.
+         */
+        /* we know that 0<=targetCapacity<length<=4 */
+        /* targetCapacity==0 when SCU+supplementary where SCU used up targetCapacity==1 */
+        length-=targetCapacity;
+        p=(uint8_t *)cnv->charErrorBuffer;
+        switch(length) {
+            /* each branch falls through to the next one */
+        case 4:
+            *p++=(uint8_t)(c>>24);
+            U_FALLTHROUGH;
+        case 3:
+            *p++=(uint8_t)(c>>16);
+            U_FALLTHROUGH;
+        case 2:
+            *p++=(uint8_t)(c>>8);
+            U_FALLTHROUGH;
+        case 1:
+            *p=(uint8_t)c;
+            U_FALLTHROUGH;
+        default:
+            /* will never occur */
+            break;
+        }
+        cnv->charErrorBufferLength=(int8_t)length;
+
+        /* now output what fits into the regular target */
+        c>>=8*length; /* length was reduced by targetCapacity */
+        switch(targetCapacity) {
+            /* each branch falls through to the next one */
+        case 3:
+            *target++=(uint8_t)(c>>16);
+            if(offsets!=nullptr) {
+                *offsets++=sourceIndex;
+            }
+            U_FALLTHROUGH;
+        case 2:
+            *target++=(uint8_t)(c>>8);
+            if(offsets!=nullptr) {
+                *offsets++=sourceIndex;
+            }
+            U_FALLTHROUGH;
+        case 1:
+            *target++=(uint8_t)c;
+            if(offsets!=nullptr) {
+                *offsets++=sourceIndex;
+            }
+            U_FALLTHROUGH;
+        default:
+            break;
+        }
+
+        /* target overflow */
+        targetCapacity=0;
+        *pErrorCode=U_BUFFER_OVERFLOW_ERROR;
+        c=0;
+        goto endloop;
+    }
+}
+
+/*
+ * Identical to _SCSUFromUnicodeWithOffsets but without offset handling.
+ * If a change is made in the original function, then either
+ * change this function the same way or
+ * re-copy the original function and remove the variables
+ * offsets, sourceIndex, and nextSourceIndex.
+ */
+static void U_CALLCONV
+_SCSUFromUnicode(UConverterFromUnicodeArgs *pArgs,
+                 UErrorCode *pErrorCode) {
+    UConverter *cnv;
+    SCSUData *scsu;
+    const char16_t *source, *sourceLimit;
+    uint8_t *target;
+    int32_t targetCapacity;
+
+    UBool isSingleByteMode;
+    uint8_t dynamicWindow;
+    uint32_t currentOffset;
+
+    uint32_t c, delta;
+
+    int32_t length;
+
+    /* variables for compression heuristics */
+    uint32_t offset;
+    char16_t lead, trail;
+    int code;
+    int8_t window;
+
+    /* set up the local pointers */
+    cnv=pArgs->converter;
+    scsu=(SCSUData *)cnv->extraInfo;
+
+    /* set up the local pointers */
+    source=pArgs->source;
+    sourceLimit=pArgs->sourceLimit;
+    target=(uint8_t *)pArgs->target;
+    targetCapacity=(int32_t)(pArgs->targetLimit-pArgs->target);
+
+    /* get the state machine state */
+    isSingleByteMode=scsu->fromUIsSingleByteMode;
+    dynamicWindow=scsu->fromUDynamicWindow;
+    currentOffset=scsu->fromUDynamicOffsets[dynamicWindow];
+
+    c=cnv->fromUChar32;
+
+    /* similar conversion "loop" as in toUnicode */
+loop:
+    if(isSingleByteMode) {
+        if(c!=0 && targetCapacity>0) {
+            goto getTrailSingle;
+        }
+
+        /* state machine for single-byte mode */
+/* singleByteMode: */
+        while(source<sourceLimit) {
+            if(targetCapacity<=0) {
+                /* target is full */
+                *pErrorCode=U_BUFFER_OVERFLOW_ERROR;
+                break;
+            }
+            c=*source++;
+
+            if((c-0x20)<=0x5f) {
+                /* pass US-ASCII graphic character through */
+                *target++=(uint8_t)c;
+                --targetCapacity;
+            } else if(c<0x20) {
+                if((1UL<<c)&0x2601 /* binary 0010 0110 0000 0001, check for b==0xd || b==0xa || b==9 || b==0 */) {
+                    /* CR/LF/TAB/NUL */
+                    *target++=(uint8_t)c;
+                    --targetCapacity;
+                } else {
+                    /* quote C0 control character */
+                    c|=SQ0<<8;
+                    length=2;
+                    goto outputBytes;
+                }
+            } else if((delta=c-currentOffset)<=0x7f) {
+                /* use the current dynamic window */
+                *target++=(uint8_t)(delta|0x80);
+                --targetCapacity;
+            } else if(U16_IS_SURROGATE(c)) {
+                if(U16_IS_SURROGATE_LEAD(c)) {
+getTrailSingle:
+                    lead=(char16_t)c;
+                    if(source<sourceLimit) {
+                        /* test the following code unit */
+                        trail=*source;
+                        if(U16_IS_TRAIL(trail)) {
+                            ++source;
+                            c=U16_GET_SUPPLEMENTARY(c, trail);
+                            /* convert this surrogate code point */
+                            /* exit this condition tree */
+                        } else {
+                            /* this is an unmatched lead code unit (1st surrogate) */
+                            /* callback(illegal) */
+                            *pErrorCode=U_ILLEGAL_CHAR_FOUND;
+                            goto endloop;
+                        }
+                    } else {
+                        /* no more input */
+                        break;
+                    }
+                } else {
+                    /* this is an unmatched trail code unit (2nd surrogate) */
+                    /* callback(illegal) */
+                    *pErrorCode=U_ILLEGAL_CHAR_FOUND;
+                    goto endloop;
+                }
+
+                /* compress supplementary character U+10000..U+10ffff */
+                if((delta=c-currentOffset)<=0x7f) {
+                    /* use the current dynamic window */
+                    *target++=(uint8_t)(delta|0x80);
+                    --targetCapacity;
+                } else if((window=getWindow(scsu->fromUDynamicOffsets, c))>=0) {
+                    /* there is a dynamic window that contains this character, change to it */
+                    dynamicWindow=window;
+                    currentOffset=scsu->fromUDynamicOffsets[dynamicWindow];
+                    useDynamicWindow(scsu, dynamicWindow);
+                    c=((uint32_t)(SC0+dynamicWindow)<<8)|(c-currentOffset)|0x80;
+                    length=2;
+                    goto outputBytes;
+                } else if((code=getDynamicOffset(c, &offset))>=0) {
+                    /* might check if there are more characters in this window to come */
+                    /* define an extended window with this character */
+                    code-=0x200;
+                    dynamicWindow=getNextDynamicWindow(scsu);
+                    currentOffset=scsu->fromUDynamicOffsets[dynamicWindow]=offset;
+                    useDynamicWindow(scsu, dynamicWindow);
+                    c=((uint32_t)SDX<<24)|((uint32_t)dynamicWindow<<21)|((uint32_t)code<<8)|(c-currentOffset)|0x80;
+                    length=4;
+                    goto outputBytes;
+                } else {
+                    /* change to Unicode mode and output this (lead, trail) pair */
+                    isSingleByteMode=false;
+                    *target++=(uint8_t)SCU;
+                    --targetCapacity;
+                    c=((uint32_t)lead<<16)|trail;
+                    length=4;
+                    goto outputBytes;
+                }
+            } else if(c<0xa0) {
+                /* quote C1 control character */
+                c=(c&0x7f)|(SQ0+1)<<8; /* SQ0+1==SQ1 */
+                length=2;
+                goto outputBytes;
+            } else if(c==0xfeff || c>=0xfff0) {
+                /* quote signature character=byte order mark and specials */
+                c|=SQU<<16;
+                length=3;
+                goto outputBytes;
+            } else {
+                /* compress all other BMP characters */
+                if((window=getWindow(scsu->fromUDynamicOffsets, c))>=0) {
+                    /* there is a window defined that contains this character - switch to it or quote from it? */
+                    if(source>=sourceLimit || isInOffsetWindowOrDirect(scsu->fromUDynamicOffsets[window], *source)) {
+                        /* change to dynamic window */
+                        dynamicWindow=window;
+                        currentOffset=scsu->fromUDynamicOffsets[dynamicWindow];
+                        useDynamicWindow(scsu, dynamicWindow);
+                        c=((uint32_t)(SC0+dynamicWindow)<<8)|(c-currentOffset)|0x80;
+                        length=2;
+                        goto outputBytes;
+                    } else {
+                        /* quote from dynamic window */
+                        c=((uint32_t)(SQ0+window)<<8)|(c-scsu->fromUDynamicOffsets[window])|0x80;
+                        length=2;
+                        goto outputBytes;
+                    }
+                } else if((window=getWindow(staticOffsets, c))>=0) {
+                    /* quote from static window */
+                    c=((uint32_t)(SQ0+window)<<8)|(c-staticOffsets[window]);
+                    length=2;
+                    goto outputBytes;
+                } else if((code=getDynamicOffset(c, &offset))>=0) {
+                    /* define a dynamic window with this character */
+                    dynamicWindow=getNextDynamicWindow(scsu);
+                    currentOffset=scsu->fromUDynamicOffsets[dynamicWindow]=offset;
+                    useDynamicWindow(scsu, dynamicWindow);
+                    c=((uint32_t)(SD0+dynamicWindow)<<16)|((uint32_t)code<<8)|(c-currentOffset)|0x80;
+                    length=3;
+                    goto outputBytes;
+                } else if((uint32_t)(c-0x3400)<(0xd800-0x3400) &&
+                          (source>=sourceLimit || (uint32_t)(*source-0x3400)<(0xd800-0x3400))
+                ) {
+                    /*
+                     * this character is not compressible (a BMP ideograph or similar);
+                     * switch to Unicode mode if this is the last character in the block
+                     * or there is at least one more ideograph following immediately
+                     */
+                    isSingleByteMode=false;
+                    c|=SCU<<16;
+                    length=3;
+                    goto outputBytes;
+                } else {
+                    /* quote Unicode */
+                    c|=SQU<<16;
+                    length=3;
+                    goto outputBytes;
+                }
+            }
+
+            /* normal end of conversion: prepare for a new character */
+            c=0;
+        }
+    } else {
+        if(c!=0 && targetCapacity>0) {
+            goto getTrailUnicode;
+        }
+
+        /* state machine for Unicode mode */
+/* unicodeByteMode: */
+        while(source<sourceLimit) {
+            if(targetCapacity<=0) {
+                /* target is full */
+                *pErrorCode=U_BUFFER_OVERFLOW_ERROR;
+                break;
+            }
+            c=*source++;
+
+            if((uint32_t)(c-0x3400)<(0xd800-0x3400)) {
+                /* not compressible, write character directly */
+                if(targetCapacity>=2) {
+                    *target++=(uint8_t)(c>>8);
+                    *target++=(uint8_t)c;
+                    targetCapacity-=2;
+                } else {
+                    length=2;
+                    goto outputBytes;
+                }
+            } else if((uint32_t)(c-0x3400)>=(0xf300-0x3400) /* c<0x3400 || c>=0xf300 */) {
+                /* compress BMP character if the following one is not an uncompressible ideograph */
+                if(!(source<sourceLimit && (uint32_t)(*source-0x3400)<(0xd800-0x3400))) {
+                    if(((uint32_t)(c-0x30)<10 || (uint32_t)(c-0x61)<26 || (uint32_t)(c-0x41)<26)) {
+                        /* ASCII digit or letter */
+                        isSingleByteMode=true;
+                        c|=((uint32_t)(UC0+dynamicWindow)<<8)|c;
+                        length=2;
+                        goto outputBytes;
+                    } else if((window=getWindow(scsu->fromUDynamicOffsets, c))>=0) {
+                        /* there is a dynamic window that contains this character, change to it */
+                        isSingleByteMode=true;
+                        dynamicWindow=window;
+                        currentOffset=scsu->fromUDynamicOffsets[dynamicWindow];
+                        useDynamicWindow(scsu, dynamicWindow);
+                        c=((uint32_t)(UC0+dynamicWindow)<<8)|(c-currentOffset)|0x80;
+                        length=2;
+                        goto outputBytes;
+                    } else if((code=getDynamicOffset(c, &offset))>=0) {
+                        /* define a dynamic window with this character */
+                        isSingleByteMode=true;
+                        dynamicWindow=getNextDynamicWindow(scsu);
+                        currentOffset=scsu->fromUDynamicOffsets[dynamicWindow]=offset;
+                        useDynamicWindow(scsu, dynamicWindow);
+                        c=((uint32_t)(UD0+dynamicWindow)<<16)|((uint32_t)code<<8)|(c-currentOffset)|0x80;
+                        length=3;
+                        goto outputBytes;
+                    }
+                }
+
+                /* don't know how to compress this character, just write it directly */
+                length=2;
+                goto outputBytes;
+            } else if(c<0xe000) {
+                /* c is a surrogate */
+                if(U16_IS_SURROGATE_LEAD(c)) {
+getTrailUnicode:
+                    lead=(char16_t)c;
+                    if(source<sourceLimit) {
+                        /* test the following code unit */
+                        trail=*source;
+                        if(U16_IS_TRAIL(trail)) {
+                            ++source;
+                            c=U16_GET_SUPPLEMENTARY(c, trail);
+                            /* convert this surrogate code point */
+                            /* exit this condition tree */
+                        } else {
+                            /* this is an unmatched lead code unit (1st surrogate) */
+                            /* callback(illegal) */
+                            *pErrorCode=U_ILLEGAL_CHAR_FOUND;
+                            goto endloop;
+                        }
+                    } else {
+                        /* no more input */
+                        break;
+                    }
+                } else {
+                    /* this is an unmatched trail code unit (2nd surrogate) */
+                    /* callback(illegal) */
+                    *pErrorCode=U_ILLEGAL_CHAR_FOUND;
+                    goto endloop;
+                }
+
+                /* compress supplementary character */
+                if( (window=getWindow(scsu->fromUDynamicOffsets, c))>=0 &&
+                    !(source<sourceLimit && (uint32_t)(*source-0x3400)<(0xd800-0x3400))
+                ) {
+                    /*
+                     * there is a dynamic window that contains this character and
+                     * the following character is not uncompressible,
+                     * change to the window
+                     */
+                    isSingleByteMode=true;
+                    dynamicWindow=window;
+                    currentOffset=scsu->fromUDynamicOffsets[dynamicWindow];
+                    useDynamicWindow(scsu, dynamicWindow);
+                    c=((uint32_t)(UC0+dynamicWindow)<<8)|(c-currentOffset)|0x80;
+                    length=2;
+                    goto outputBytes;
+                } else if(source<sourceLimit && lead==*source && /* too lazy to check trail in same window as source[1] */
+                          (code=getDynamicOffset(c, &offset))>=0
+                ) {
+                    /* two supplementary characters in (probably) the same window - define an extended one */
+                    isSingleByteMode=true;
+                    code-=0x200;
+                    dynamicWindow=getNextDynamicWindow(scsu);
+                    currentOffset=scsu->fromUDynamicOffsets[dynamicWindow]=offset;
+                    useDynamicWindow(scsu, dynamicWindow);
+                    c=((uint32_t)UDX<<24)|((uint32_t)dynamicWindow<<21)|((uint32_t)code<<8)|(c-currentOffset)|0x80;
+                    length=4;
+                    goto outputBytes;
+                } else {
+                    /* don't know how to compress this character, just write it directly */
+                    c=((uint32_t)lead<<16)|trail;
+                    length=4;
+                    goto outputBytes;
+                }
+            } else /* 0xe000<=c<0xf300 */ {
+                /* quote to avoid SCSU tags */
+                c|=UQU<<16;
+                length=3;
+                goto outputBytes;
+            }
+
+            /* normal end of conversion: prepare for a new character */
+            c=0;
+        }
+    }
+endloop:
+
+    /* set the converter state back into UConverter */
+    scsu->fromUIsSingleByteMode=isSingleByteMode;
+    scsu->fromUDynamicWindow=dynamicWindow;
+
+    cnv->fromUChar32=c;
+
+    /* write back the updated pointers */
+    pArgs->source=source;
+    pArgs->target=(char *)target;
+    return;
+
+outputBytes:
+    /* write the output character bytes from c and length [code copied from ucnvmbcs.c] */
+    /* from the first if in the loop we know that targetCapacity>0 */
+    if(length<=targetCapacity) {
+        switch(length) {
+            /* each branch falls through to the next one */
+        case 4:
+            *target++=(uint8_t)(c>>24);
+            U_FALLTHROUGH;
+        case 3:
+            *target++=(uint8_t)(c>>16);
+            U_FALLTHROUGH;
+        case 2:
+            *target++=(uint8_t)(c>>8);
+            U_FALLTHROUGH;
+        case 1:
+            *target++=(uint8_t)c;
+            U_FALLTHROUGH;
+        default:
+            /* will never occur */
+            break;
+        }
+        targetCapacity-=length;
+
+        /* normal end of conversion: prepare for a new character */
+        c=0;
+        goto loop;
+    } else {
+        uint8_t *p;
+
+        /*
+         * We actually do this backwards here:
+         * In order to save an intermediate variable, we output
+         * first to the overflow buffer what does not fit into the
+         * regular target.
+         */
+        /* we know that 0<=targetCapacity<length<=4 */
+        /* targetCapacity==0 when SCU+supplementary where SCU used up targetCapacity==1 */
+        length-=targetCapacity;
+        p=(uint8_t *)cnv->charErrorBuffer;
+        switch(length) {
+            /* each branch falls through to the next one */
+        case 4:
+            *p++=(uint8_t)(c>>24);
+            U_FALLTHROUGH;
+        case 3:
+            *p++=(uint8_t)(c>>16);
+            U_FALLTHROUGH;
+        case 2:
+            *p++=(uint8_t)(c>>8);
+            U_FALLTHROUGH;
+        case 1:
+            *p=(uint8_t)c;
+            U_FALLTHROUGH;
+        default:
+            /* will never occur */
+            break;
+        }
+        cnv->charErrorBufferLength=(int8_t)length;
+
+        /* now output what fits into the regular target */
+        c = (length == 4) ? 0 : c >> 8*length; /* length was reduced by targetCapacity */
+        switch(targetCapacity) {
+            /* each branch falls through to the next one */
+        case 3:
+            *target++=(uint8_t)(c>>16);
+            U_FALLTHROUGH;
+        case 2:
+            *target++=(uint8_t)(c>>8);
+            U_FALLTHROUGH;
+        case 1:
+            *target++=(uint8_t)c;
+            U_FALLTHROUGH;
+        default:
+            break;
+        }
+
+        /* target overflow */
+        targetCapacity=0;
+        *pErrorCode=U_BUFFER_OVERFLOW_ERROR;
+        c=0;
+        goto endloop;
+    }
+}
+
+/* miscellaneous ------------------------------------------------------------ */
+
+static const char *  U_CALLCONV
+_SCSUGetName(const UConverter *cnv) {
+    SCSUData *scsu=(SCSUData *)cnv->extraInfo;
+
+    switch(scsu->locale) {
+    case l_ja:
+        return "SCSU,locale=ja";
+    default:
+        return "SCSU";
+    }
+}
+
+/* structure for SafeClone calculations */
+struct cloneSCSUStruct
+{
+    UConverter cnv;
+    SCSUData mydata;
+};
+
+static UConverter *  U_CALLCONV
+_SCSUSafeClone(const UConverter *cnv, 
+               void *stackBuffer, 
+               int32_t *pBufferSize, 
+               UErrorCode *status)
+{
+    struct cloneSCSUStruct * localClone;
+    int32_t bufferSizeNeeded = sizeof(struct cloneSCSUStruct);
+
+    if (U_FAILURE(*status)){
+        return 0;
+    }
+
+    if (*pBufferSize == 0){ /* 'preflighting' request - set needed size into *pBufferSize */
+        *pBufferSize = bufferSizeNeeded;
+        return 0;
+    }
+
+    localClone = (struct cloneSCSUStruct *)stackBuffer;
+    /* ucnv.c/ucnv_safeClone() copied the main UConverter already */
+
+    uprv_memcpy(&localClone->mydata, cnv->extraInfo, sizeof(SCSUData));
+    localClone->cnv.extraInfo = &localClone->mydata;
+    localClone->cnv.isExtraLocal = true;
+
+    return &localClone->cnv;
+}
+U_CDECL_END
+
+static const UConverterImpl _SCSUImpl={
+    UCNV_SCSU,
+
+    nullptr,
+    nullptr,
+
+    _SCSUOpen,
+    _SCSUClose,
+    _SCSUReset,
+
+    _SCSUToUnicode,
+    _SCSUToUnicodeWithOffsets,
+    _SCSUFromUnicode,
+    _SCSUFromUnicodeWithOffsets,
+    nullptr,
+
+    nullptr,
+    _SCSUGetName,
+    nullptr,
+    _SCSUSafeClone,
+    ucnv_getCompleteUnicodeSet,
+    nullptr,
+    nullptr
+};
+
+static const UConverterStaticData _SCSUStaticData={
+    sizeof(UConverterStaticData),
+    "SCSU",
+    1212, /* CCSID for SCSU */
+    UCNV_IBM, UCNV_SCSU,
+    1, 3, /* one char16_t generates at least 1 byte and at most 3 bytes */
+    /*
+     * The subchar here is ignored because _SCSUOpen() sets U+fffd as a Unicode
+     * substitution string.
+     */
+    { 0x0e, 0xff, 0xfd, 0 }, 3,
+    false, false,
+    0,
+    0,
+    { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 } /* reserved */
+};
+
+const UConverterSharedData _SCSUData=
+        UCNV_IMMUTABLE_SHARED_DATA_INITIALIZER(&_SCSUStaticData, &_SCSUImpl);
+
+#endif