Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

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

1 files changed, 1084 insertions, 0 deletions

diff --git a/intl/icu/source/tools/makeconv/gencnvex.c b/intl/icu/source/tools/makeconv/gencnvex.c
new file mode 100644
index 0000000000..837a2d2c50
--- /dev/null
+++ b/intl/icu/source/tools/makeconv/gencnvex.c
@@ -0,0 +1,1084 @@
+// © 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+/*
+*******************************************************************************
+*
+*   Copyright (C) 2003-2014, International Business Machines
+*   Corporation and others.  All Rights Reserved.
+*
+*******************************************************************************
+*   file name:  gencnvex.c
+*   encoding:   UTF-8
+*   tab size:   8 (not used)
+*   indentation:4
+*
+*   created on: 2003oct12
+*   created by: Markus W. Scherer
+*/
+
+#include <stdbool.h>
+#include <stdio.h>
+#include "unicode/utypes.h"
+#include "unicode/ustring.h"
+#include "cstring.h"
+#include "cmemory.h"
+#include "ucnv_cnv.h"
+#include "ucnvmbcs.h"
+#include "toolutil.h"
+#include "unewdata.h"
+#include "ucm.h"
+#include "makeconv.h"
+#include "genmbcs.h"
+
+static void
+CnvExtClose(NewConverter *cnvData);
+
+static UBool
+CnvExtIsValid(NewConverter *cnvData,
+              const uint8_t *bytes, int32_t length);
+
+static UBool
+CnvExtAddTable(NewConverter *cnvData, UCMTable *table, UConverterStaticData *staticData);
+
+static uint32_t
+CnvExtWrite(NewConverter *cnvData, const UConverterStaticData *staticData,
+            UNewDataMemory *pData, int32_t tableType);
+
+typedef struct CnvExtData {
+    NewConverter newConverter;
+
+    UCMFile *ucm;
+
+    /* toUnicode (state table in ucm->states) */
+    UToolMemory *toUTable, *toUUChars;
+
+    /* fromUnicode */
+    UToolMemory *fromUTableUChars, *fromUTableValues, *fromUBytes;
+
+    uint16_t stage1[MBCS_STAGE_1_SIZE];
+    uint16_t stage2[MBCS_STAGE_2_SIZE];
+    uint16_t stage3[0x10000<<UCNV_EXT_STAGE_2_LEFT_SHIFT]; /* 0x10000 because of 16-bit stage 2/3 indexes */
+    uint32_t stage3b[0x10000];
+
+    int32_t stage1Top, stage2Top, stage3Top, stage3bTop;
+
+    /* for stage3 compaction of <subchar1> |2 mappings */
+    uint16_t stage3Sub1Block;
+
+    /* statistics */
+    int32_t
+        maxInBytes, maxOutBytes, maxBytesPerUChar,
+        maxInUChars, maxOutUChars, maxUCharsPerByte;
+} CnvExtData;
+
+NewConverter *
+CnvExtOpen(UCMFile *ucm) {
+    CnvExtData *extData;
+    
+    extData=(CnvExtData *)uprv_malloc(sizeof(CnvExtData));
+    if(extData==NULL) {
+        printf("out of memory\n");
+        exit(U_MEMORY_ALLOCATION_ERROR);
+    }
+    uprv_memset(extData, 0, sizeof(CnvExtData));
+
+    extData->ucm=ucm; /* aliased, not owned */
+
+    extData->newConverter.close=CnvExtClose;
+    extData->newConverter.isValid=CnvExtIsValid;
+    extData->newConverter.addTable=CnvExtAddTable;
+    extData->newConverter.write=CnvExtWrite;
+    return &extData->newConverter;
+}
+
+static void
+CnvExtClose(NewConverter *cnvData) {
+    CnvExtData *extData=(CnvExtData *)cnvData;
+    if(extData!=NULL) {
+        utm_close(extData->toUTable);
+        utm_close(extData->toUUChars);
+        utm_close(extData->fromUTableUChars);
+        utm_close(extData->fromUTableValues);
+        utm_close(extData->fromUBytes);
+        uprv_free(extData);
+    }
+}
+
+/* we do not expect this to be called */
+static UBool
+CnvExtIsValid(NewConverter *cnvData,
+        const uint8_t *bytes, int32_t length) {
+    // suppress compiler warnings about unused variables
+    (void)cnvData;
+    (void)bytes;
+    (void)length;
+    return false;
+}
+
+static uint32_t
+CnvExtWrite(NewConverter *cnvData, const UConverterStaticData *staticData,
+            UNewDataMemory *pData, int32_t tableType) {
+    (void) staticData; // suppress compiler warnings about unused variable
+    CnvExtData *extData=(CnvExtData *)cnvData;
+    int32_t length, top, headerSize;
+
+    int32_t indexes[UCNV_EXT_INDEXES_MIN_LENGTH]={ 0 };
+
+    if(tableType&TABLE_BASE) {
+        headerSize=0;
+    } else {
+        _MBCSHeader header={ { 0, 0, 0, 0 }, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
+
+        /* write the header and base table name for an extension-only table */
+        length=(int32_t)uprv_strlen(extData->ucm->baseName)+1;
+        while(length&3) {
+            /* add padding */
+            extData->ucm->baseName[length++]=0;
+        }
+
+        headerSize=MBCS_HEADER_V4_LENGTH*4+length;
+
+        /* fill the header */
+        header.version[0]=4;
+        header.version[1]=2;
+        header.flags=(uint32_t)((headerSize<<8)|MBCS_OUTPUT_EXT_ONLY);
+
+        /* write the header and the base table name */
+        udata_writeBlock(pData, &header, MBCS_HEADER_V4_LENGTH*4);
+        udata_writeBlock(pData, extData->ucm->baseName, length);
+    }
+
+    /* fill indexes[] - offsets/indexes are in units of the target array */
+    top=0;
+
+    indexes[UCNV_EXT_INDEXES_LENGTH]=length=UCNV_EXT_INDEXES_MIN_LENGTH;
+    top+=length*4;
+
+    indexes[UCNV_EXT_TO_U_INDEX]=top;
+    indexes[UCNV_EXT_TO_U_LENGTH]=length=utm_countItems(extData->toUTable);
+    top+=length*4;
+
+    indexes[UCNV_EXT_TO_U_UCHARS_INDEX]=top;
+    indexes[UCNV_EXT_TO_U_UCHARS_LENGTH]=length=utm_countItems(extData->toUUChars);
+    top+=length*2;
+
+    indexes[UCNV_EXT_FROM_U_UCHARS_INDEX]=top;
+    length=utm_countItems(extData->fromUTableUChars);
+    top+=length*2;
+
+    if(top&3) {
+        /* add padding */
+        *((UChar *)utm_alloc(extData->fromUTableUChars))=0;
+        *((uint32_t *)utm_alloc(extData->fromUTableValues))=0;
+        ++length;
+        top+=2;
+    }
+    indexes[UCNV_EXT_FROM_U_LENGTH]=length;
+
+    indexes[UCNV_EXT_FROM_U_VALUES_INDEX]=top;
+    top+=length*4;
+
+    indexes[UCNV_EXT_FROM_U_BYTES_INDEX]=top;
+    length=utm_countItems(extData->fromUBytes);
+    top+=length;
+
+    if(top&1) {
+        /* add padding */
+        *((uint8_t *)utm_alloc(extData->fromUBytes))=0;
+        ++length;
+        ++top;
+    }
+    indexes[UCNV_EXT_FROM_U_BYTES_LENGTH]=length;
+
+    indexes[UCNV_EXT_FROM_U_STAGE_12_INDEX]=top;
+    indexes[UCNV_EXT_FROM_U_STAGE_1_LENGTH]=length=extData->stage1Top;
+    indexes[UCNV_EXT_FROM_U_STAGE_12_LENGTH]=length+=extData->stage2Top;
+    top+=length*2;
+
+    indexes[UCNV_EXT_FROM_U_STAGE_3_INDEX]=top;
+    length=extData->stage3Top;
+    top+=length*2;
+
+    if(top&3) {
+        /* add padding */
+        extData->stage3[extData->stage3Top++]=0;
+        ++length;
+        top+=2;
+    }
+    indexes[UCNV_EXT_FROM_U_STAGE_3_LENGTH]=length;
+
+    indexes[UCNV_EXT_FROM_U_STAGE_3B_INDEX]=top;
+    indexes[UCNV_EXT_FROM_U_STAGE_3B_LENGTH]=length=extData->stage3bTop;
+    top+=length*4;
+
+    indexes[UCNV_EXT_SIZE]=top;
+
+    /* statistics */
+    indexes[UCNV_EXT_COUNT_BYTES]=
+        (extData->maxInBytes<<16)|
+        (extData->maxOutBytes<<8)|
+        extData->maxBytesPerUChar;
+    indexes[UCNV_EXT_COUNT_UCHARS]=
+        (extData->maxInUChars<<16)|
+        (extData->maxOutUChars<<8)|
+        extData->maxUCharsPerByte;
+
+    indexes[UCNV_EXT_FLAGS]=extData->ucm->ext->unicodeMask;
+
+    /* write the extension data */
+    udata_writeBlock(pData, indexes, sizeof(indexes));
+    udata_writeBlock(pData, utm_getStart(extData->toUTable), indexes[UCNV_EXT_TO_U_LENGTH]*4);
+    udata_writeBlock(pData, utm_getStart(extData->toUUChars), indexes[UCNV_EXT_TO_U_UCHARS_LENGTH]*2);
+
+    udata_writeBlock(pData, utm_getStart(extData->fromUTableUChars), indexes[UCNV_EXT_FROM_U_LENGTH]*2);
+    udata_writeBlock(pData, utm_getStart(extData->fromUTableValues), indexes[UCNV_EXT_FROM_U_LENGTH]*4);
+    udata_writeBlock(pData, utm_getStart(extData->fromUBytes), indexes[UCNV_EXT_FROM_U_BYTES_LENGTH]);
+
+    udata_writeBlock(pData, extData->stage1, extData->stage1Top*2);
+    udata_writeBlock(pData, extData->stage2, extData->stage2Top*2);
+    udata_writeBlock(pData, extData->stage3, extData->stage3Top*2);
+    udata_writeBlock(pData, extData->stage3b, extData->stage3bTop*4);
+
+#if 0
+    {
+        int32_t i, j;
+
+        length=extData->stage1Top;
+        printf("\nstage1[%x]:\n", length);
+
+        for(i=0; i<length; ++i) {
+            if(extData->stage1[i]!=length) {
+                printf("stage1[%04x]=%04x\n", i, extData->stage1[i]);
+            }
+        }
+
+        j=length;
+        length=extData->stage2Top;
+        printf("\nstage2[%x]:\n", length);
+
+        for(i=0; i<length; ++j, ++i) {
+            if(extData->stage2[i]!=0) {
+                printf("stage12[%04x]=%04x\n", j, extData->stage2[i]);
+            }
+        }
+
+        length=extData->stage3Top;
+        printf("\nstage3[%x]:\n", length);
+
+        for(i=0; i<length; ++i) {
+            if(extData->stage3[i]!=0) {
+                printf("stage3[%04x]=%04x\n", i, extData->stage3[i]);
+            }
+        }
+
+        length=extData->stage3bTop;
+        printf("\nstage3b[%x]:\n", length);
+
+        for(i=0; i<length; ++i) {
+            if(extData->stage3b[i]!=0) {
+                printf("stage3b[%04x]=%08x\n", i, extData->stage3b[i]);
+            }
+        }
+    }
+#endif
+
+    if(VERBOSE) {
+        printf("size of extension data: %ld\n", (long)top);
+    }
+
+    /* return the number of bytes that should have been written */
+    return (uint32_t)(headerSize+top);
+}
+
+/* to Unicode --------------------------------------------------------------- */
+
+/*
+ * Remove fromUnicode fallbacks and SUB mappings which are irrelevant for
+ * the toUnicode table.
+ * This includes mappings with MBCS_FROM_U_EXT_FLAG which were suitable
+ * for the base toUnicode table but not for the base fromUnicode table.
+ * The table must be sorted.
+ * Modifies previous data in the reverseMap.
+ */
+static int32_t
+reduceToUMappings(UCMTable *table) {
+    UCMapping *mappings;
+    int32_t *map;
+    int32_t i, j, count;
+    int8_t flag;
+
+    mappings=table->mappings;
+    map=table->reverseMap;
+    count=table->mappingsLength;
+
+    /* leave the map alone for the initial mappings with desired flags */
+    for(i=j=0; i<count; ++i) {
+        flag=mappings[map[i]].f;
+        if(flag!=0 && flag!=3) {
+            break;
+        }
+    }
+
+    /* reduce from here to the rest */
+    for(j=i; i<count; ++i) {
+        flag=mappings[map[i]].f;
+        if(flag==0 || flag==3) {
+            map[j++]=map[i];
+        }
+    }
+
+    return j;
+}
+
+static uint32_t
+getToUnicodeValue(CnvExtData *extData, UCMTable *table, UCMapping *m) {
+    UChar32 *u32;
+    UChar *u;
+    uint32_t value;
+    int32_t u16Length, ratio;
+    UErrorCode errorCode;
+
+    /* write the Unicode result code point or string index */
+    if(m->uLen==1) {
+        u16Length=U16_LENGTH(m->u);
+        value=(uint32_t)(UCNV_EXT_TO_U_MIN_CODE_POINT+m->u);
+    } else {
+        /* the parser enforces m->uLen<=UCNV_EXT_MAX_UCHARS */
+
+        /* get the result code point string and its 16-bit string length */
+        u32=UCM_GET_CODE_POINTS(table, m);
+        errorCode=U_ZERO_ERROR;
+        u_strFromUTF32(NULL, 0, &u16Length, u32, m->uLen, &errorCode);
+        if(U_FAILURE(errorCode) && errorCode!=U_BUFFER_OVERFLOW_ERROR) {
+            exit(errorCode);
+        }
+
+        /* allocate it and put its length and index into the value */
+        value=
+            (((uint32_t)u16Length+UCNV_EXT_TO_U_LENGTH_OFFSET)<<UCNV_EXT_TO_U_LENGTH_SHIFT)|
+            ((uint32_t)utm_countItems(extData->toUUChars));
+        u=utm_allocN(extData->toUUChars, u16Length);
+
+        /* write the result 16-bit string */
+        errorCode=U_ZERO_ERROR;
+        u_strFromUTF32(u, u16Length, NULL, u32, m->uLen, &errorCode);
+        if(U_FAILURE(errorCode) && errorCode!=U_BUFFER_OVERFLOW_ERROR) {
+            exit(errorCode);
+        }
+    }
+    if(m->f==0) {
+        value|=UCNV_EXT_TO_U_ROUNDTRIP_FLAG;
+    }
+
+    /* update statistics */
+    if(m->bLen>extData->maxInBytes) {
+        extData->maxInBytes=m->bLen;
+    }
+    if(u16Length>extData->maxOutUChars) {
+        extData->maxOutUChars=u16Length;
+    }
+
+    ratio=(u16Length+(m->bLen-1))/m->bLen;
+    if(ratio>extData->maxUCharsPerByte) {
+        extData->maxUCharsPerByte=ratio;
+    }
+
+    return value;
+}
+
+/*
+ * Recursive toUTable generator core function.
+ * Preconditions:
+ * - start<limit (There is at least one mapping.)
+ * - The mappings are sorted lexically. (Access is through the reverseMap.)
+ * - All mappings between start and limit have input sequences that share
+ *   the same prefix of unitIndex length, and therefore all of these sequences
+ *   are at least unitIndex+1 long.
+ * - There are only relevant mappings available through the reverseMap,
+ *   see reduceToUMappings().
+ *
+ * One function invocation generates one section table.
+ *
+ * Steps:
+ * 1. Count the number of unique unit values and get the low/high unit values
+ *    that occur at unitIndex.
+ * 2. Allocate the section table with possible optimization for linear access.
+ * 3. Write temporary version of the section table with start indexes of
+ *    subsections, each corresponding to one unit value at unitIndex.
+ * 4. Iterate through the table once more, and depending on the subsection length:
+ *    0: write 0 as a result value (unused byte in linear-access section table)
+ *   >0: if there is one mapping with an input unit sequence of unitIndex+1
+ *       then defaultValue=compute the mapping result for this whole sequence
+ *       else defaultValue=0
+ *
+ *       recurse into the subsection
+ */
+static UBool
+generateToUTable(CnvExtData *extData, UCMTable *table,
+                 int32_t start, int32_t limit, int32_t unitIndex,
+                 uint32_t defaultValue) {
+    UCMapping *mappings, *m;
+    int32_t *map;
+    int32_t i, j, uniqueCount, count, subStart, subLimit;
+
+    uint8_t *bytes;
+    int32_t low, high, prev;
+
+    uint32_t *section;
+
+    mappings=table->mappings;
+    map=table->reverseMap;
+
+    /* step 1: examine the input units; set low, high, uniqueCount */
+    m=mappings+map[start];
+    bytes=UCM_GET_BYTES(table, m);
+    low=bytes[unitIndex];
+    uniqueCount=1;
+
+    prev=high=low;
+    for(i=start+1; i<limit; ++i) {
+        m=mappings+map[i];
+        bytes=UCM_GET_BYTES(table, m);
+        high=bytes[unitIndex];
+
+        if(high!=prev) {
+            prev=high;
+            ++uniqueCount;
+        }
+    }
+
+    /* step 2: allocate the section; set count, section */
+    count=(high-low)+1;
+    if(count<0x100 && (unitIndex==0 || uniqueCount>=(3*count)/4)) {
+        /*
+         * for the root table and for fairly full tables:
+         * allocate for direct, linear array access
+         * by keeping count, to write an entry for each unit value
+         * from low to high
+         * exception: use a compact table if count==0x100 because
+         * that cannot be encoded in the length byte
+         */
+    } else {
+        count=uniqueCount;
+    }
+
+    if(count>=0x100) {
+        fprintf(stderr, "error: toUnicode extension table section overflow: %ld section entries\n", (long)count);
+        return false;
+    }
+
+    /* allocate the section: 1 entry for the header + count for the items */
+    section=(uint32_t *)utm_allocN(extData->toUTable, 1+count);
+
+    /* write the section header */
+    *section++=((uint32_t)count<<UCNV_EXT_TO_U_BYTE_SHIFT)|defaultValue;
+
+    /* step 3: write temporary section table with subsection starts */
+    prev=low-1; /* just before low to prevent empty subsections before low */
+    j=0; /* section table index */
+    for(i=start; i<limit; ++i) {
+        m=mappings+map[i];
+        bytes=UCM_GET_BYTES(table, m);
+        high=bytes[unitIndex];
+
+        if(high!=prev) {
+            /* start of a new subsection for unit high */
+            if(count>uniqueCount) {
+                /* write empty subsections for unused units in a linear table */
+                while(++prev<high) {
+                    section[j++]=((uint32_t)prev<<UCNV_EXT_TO_U_BYTE_SHIFT)|(uint32_t)i;
+                }
+            } else {
+                prev=high;
+            }
+
+            /* write the entry with the subsection start */
+            section[j++]=((uint32_t)high<<UCNV_EXT_TO_U_BYTE_SHIFT)|(uint32_t)i;
+        }
+    }
+    /* assert(j==count) */
+
+    /* step 4: recurse and write results */
+    subLimit=UCNV_EXT_TO_U_GET_VALUE(section[0]);
+    for(j=0; j<count; ++j) {
+        subStart=subLimit;
+        subLimit= (j+1)<count ? UCNV_EXT_TO_U_GET_VALUE(section[j+1]) : limit;
+
+        /* remove the subStart temporary value */
+        section[j]&=~UCNV_EXT_TO_U_VALUE_MASK;
+
+        if(subStart==subLimit) {
+            /* leave the value zero: empty subsection for unused unit in a linear table */
+            continue;
+        }
+
+        /* see if there is exactly one input unit sequence of length unitIndex+1 */
+        defaultValue=0;
+        m=mappings+map[subStart];
+        if(m->bLen==unitIndex+1) {
+            /* do not include this in generateToUTable() */
+            ++subStart;
+
+            if(subStart<subLimit && mappings[map[subStart]].bLen==unitIndex+1) {
+                /* print error for multiple same-input-sequence mappings */
+                fprintf(stderr, "error: multiple mappings from same bytes\n");
+                ucm_printMapping(table, m, stderr);
+                ucm_printMapping(table, mappings+map[subStart], stderr);
+                return false;
+            }
+
+            defaultValue=getToUnicodeValue(extData, table, m);
+        }
+
+        if(subStart==subLimit) {
+            /* write the result for the input sequence ending here */
+            section[j]|=defaultValue;
+        } else {
+            /* write the index to the subsection table */
+            section[j]|=(uint32_t)utm_countItems(extData->toUTable);
+
+            /* recurse */
+            if(!generateToUTable(extData, table, subStart, subLimit, unitIndex+1, defaultValue)) {
+                return false;
+            }
+        }
+    }
+    return true;
+}
+
+/*
+ * Generate the toUTable and toUUChars from the input table.
+ * The input table must be sorted, and all precision flags must be 0..3.
+ * This function will modify the table's reverseMap.
+ */
+static UBool
+makeToUTable(CnvExtData *extData, UCMTable *table) {
+    int32_t toUCount;
+
+    toUCount=reduceToUMappings(table);
+
+    extData->toUTable=utm_open("cnv extension toUTable", 0x10000, UCNV_EXT_TO_U_MIN_CODE_POINT, 4);
+    extData->toUUChars=utm_open("cnv extension toUUChars", 0x10000, UCNV_EXT_TO_U_INDEX_MASK+1, 2);
+
+    return generateToUTable(extData, table, 0, toUCount, 0, 0);
+}
+
+/* from Unicode ------------------------------------------------------------- */
+
+/*
+ * preprocessing:
+ * rebuild reverseMap with mapping indexes for mappings relevant for from Unicode
+ * change each Unicode string to encode all but the first code point in 16-bit form
+ *
+ * generation:
+ * for each unique code point
+ *   write an entry in the 3-stage trie
+ *   check that there is only one single-code point sequence
+ *   start recursion for following 16-bit input units
+ */
+
+/*
+ * Remove toUnicode fallbacks and non-<subchar1> SUB mappings
+ * which are irrelevant for the fromUnicode extension table.
+ * Remove MBCS_FROM_U_EXT_FLAG bits.
+ * Overwrite the reverseMap with an index array to the relevant mappings.
+ * Modify the code point sequences to a generator-friendly format where
+ * the first code points remains unchanged but the following are recoded
+ * into 16-bit Unicode string form.
+ * The table must be sorted.
+ * Destroys previous data in the reverseMap.
+ */
+static int32_t
+prepareFromUMappings(UCMTable *table) {
+    UCMapping *mappings, *m;
+    int32_t *map;
+    int32_t i, j, count;
+    int8_t flag;
+
+    mappings=table->mappings;
+    map=table->reverseMap;
+    count=table->mappingsLength;
+
+    /*
+     * we do not go through the map on input because the mappings are
+     * sorted lexically
+     */
+    m=mappings;
+
+    for(i=j=0; i<count; ++m, ++i) {
+        flag=m->f;
+        if(flag>=0) {
+            flag&=MBCS_FROM_U_EXT_MASK;
+            m->f=flag;
+        }
+        if(flag==0 || flag==1 || (flag==2 && m->bLen==1) || flag==4) {
+            map[j++]=i;
+
+            if(m->uLen>1) {
+                /* recode all but the first code point to 16-bit Unicode */
+                UChar32 *u32;
+                UChar *u;
+                UChar32 c;
+                int32_t q, r;
+
+                u32=UCM_GET_CODE_POINTS(table, m);
+                u=(UChar *)u32; /* destructive in-place recoding */
+                for(r=2, q=1; q<m->uLen; ++q) {
+                    c=u32[q];
+                    U16_APPEND_UNSAFE(u, r, c);
+                }
+
+                /* counts the first code point always at 2 - the first 16-bit unit is at 16-bit index 2 */
+                m->uLen=(int8_t)r;
+            }
+        }
+    }
+
+    return j;
+}
+
+static uint32_t
+getFromUBytesValue(CnvExtData *extData, UCMTable *table, UCMapping *m) {
+    uint8_t *bytes, *resultBytes;
+    uint32_t value;
+    int32_t u16Length, ratio;
+
+    if(m->f==2) {
+        /*
+         * no mapping, <subchar1> preferred
+         *
+         * no need to count in statistics because the subchars are already
+         * counted for maxOutBytes and maxBytesPerUChar in UConverterStaticData,
+         * and this non-mapping does not count for maxInUChars which are always
+         * trivially at least two if counting unmappable supplementary code points
+         */
+        return UCNV_EXT_FROM_U_SUBCHAR1;
+    }
+
+    bytes=UCM_GET_BYTES(table, m);
+    value=0;
+    switch(m->bLen) {
+        /* 1..3: store the bytes in the value word */
+    case 3:
+        value=((uint32_t)*bytes++)<<16;
+    case 2:
+        value|=((uint32_t)*bytes++)<<8;
+    case 1:
+        value|=*bytes;
+        break;
+    default:
+        /* the parser enforces m->bLen<=UCNV_EXT_MAX_BYTES */
+        /* store the bytes in fromUBytes[] and the index in the value word */
+        value=(uint32_t)utm_countItems(extData->fromUBytes);
+        resultBytes=utm_allocN(extData->fromUBytes, m->bLen);
+        uprv_memcpy(resultBytes, bytes, m->bLen);
+        break;
+    }
+    value|=(uint32_t)m->bLen<<UCNV_EXT_FROM_U_LENGTH_SHIFT;
+    if(m->f==0) {
+        value|=UCNV_EXT_FROM_U_ROUNDTRIP_FLAG;
+    } else if(m->f==4) {
+        value|=UCNV_EXT_FROM_U_GOOD_ONE_WAY_FLAG;
+    }
+
+    /* calculate the real UTF-16 length (see recoding in prepareFromUMappings()) */
+    if(m->uLen==1) {
+        u16Length=U16_LENGTH(m->u);
+    } else {
+        u16Length=U16_LENGTH(UCM_GET_CODE_POINTS(table, m)[0])+(m->uLen-2);
+    }
+
+    /* update statistics */
+    if(u16Length>extData->maxInUChars) {
+        extData->maxInUChars=u16Length;
+    }
+    if(m->bLen>extData->maxOutBytes) {
+        extData->maxOutBytes=m->bLen;
+    }
+
+    ratio=(m->bLen+(u16Length-1))/u16Length;
+    if(ratio>extData->maxBytesPerUChar) {
+        extData->maxBytesPerUChar=ratio;
+    }
+
+    return value;
+}
+
+/*
+ * works like generateToUTable(), except that the
+ * output section consists of two arrays, one for input UChars and one
+ * for result values
+ *
+ * also, fromUTable sections are always stored in a compact form for
+ * access via binary search
+ */
+static UBool
+generateFromUTable(CnvExtData *extData, UCMTable *table,
+                   int32_t start, int32_t limit, int32_t unitIndex,
+                   uint32_t defaultValue) {
+    UCMapping *mappings, *m;
+    int32_t *map;
+    int32_t i, j, uniqueCount, count, subStart, subLimit;
+
+    UChar *uchars;
+    UChar32 low, high, prev;
+
+    UChar *sectionUChars;
+    uint32_t *sectionValues;
+
+    mappings=table->mappings;
+    map=table->reverseMap;
+
+    /* step 1: examine the input units; set low, high, uniqueCount */
+    m=mappings+map[start];
+    uchars=(UChar *)UCM_GET_CODE_POINTS(table, m);
+    low=uchars[unitIndex];
+    uniqueCount=1;
+
+    prev=high=low;
+    for(i=start+1; i<limit; ++i) {
+        m=mappings+map[i];
+        uchars=(UChar *)UCM_GET_CODE_POINTS(table, m);
+        high=uchars[unitIndex];
+
+        if(high!=prev) {
+            prev=high;
+            ++uniqueCount;
+        }
+    }
+
+    /* step 2: allocate the section; set count, section */
+    /* the fromUTable always stores for access via binary search */
+    count=uniqueCount;
+
+    /* allocate the section: 1 entry for the header + count for the items */
+    sectionUChars=(UChar *)utm_allocN(extData->fromUTableUChars, 1+count);
+    sectionValues=(uint32_t *)utm_allocN(extData->fromUTableValues, 1+count);
+
+    /* write the section header */
+    *sectionUChars++=(UChar)count;
+    *sectionValues++=defaultValue;
+
+    /* step 3: write temporary section table with subsection starts */
+    prev=low-1; /* just before low to prevent empty subsections before low */
+    j=0; /* section table index */
+    for(i=start; i<limit; ++i) {
+        m=mappings+map[i];
+        uchars=(UChar *)UCM_GET_CODE_POINTS(table, m);
+        high=uchars[unitIndex];
+
+        if(high!=prev) {
+            /* start of a new subsection for unit high */
+            prev=high;
+
+            /* write the entry with the subsection start */
+            sectionUChars[j]=(UChar)high;
+            sectionValues[j]=(uint32_t)i;
+            ++j;
+        }
+    }
+    /* assert(j==count) */
+
+    /* step 4: recurse and write results */
+    subLimit=(int32_t)(sectionValues[0]);
+    for(j=0; j<count; ++j) {
+        subStart=subLimit;
+        subLimit= (j+1)<count ? (int32_t)(sectionValues[j+1]) : limit;
+
+        /* see if there is exactly one input unit sequence of length unitIndex+1 */
+        defaultValue=0;
+        m=mappings+map[subStart];
+        if(m->uLen==unitIndex+1) {
+            /* do not include this in generateToUTable() */
+            ++subStart;
+
+            if(subStart<subLimit && mappings[map[subStart]].uLen==unitIndex+1) {
+                /* print error for multiple same-input-sequence mappings */
+                fprintf(stderr, "error: multiple mappings from same Unicode code points\n");
+                ucm_printMapping(table, m, stderr);
+                ucm_printMapping(table, mappings+map[subStart], stderr);
+                return false;
+            }
+
+            defaultValue=getFromUBytesValue(extData, table, m);
+        }
+
+        if(subStart==subLimit) {
+            /* write the result for the input sequence ending here */
+            sectionValues[j]=defaultValue;
+        } else {
+            /* write the index to the subsection table */
+            sectionValues[j]=(uint32_t)utm_countItems(extData->fromUTableValues);
+
+            /* recurse */
+            if(!generateFromUTable(extData, table, subStart, subLimit, unitIndex+1, defaultValue)) {
+                return false;
+            }
+        }
+    }
+    return true;
+}
+
+/*
+ * add entries to the fromUnicode trie,
+ * assume to be called with code points in ascending order
+ * and use that to build the trie in precompacted form
+ */
+static void
+addFromUTrieEntry(CnvExtData *extData, UChar32 c, uint32_t value) {
+    int32_t i1, i2, i3, i3b, nextOffset, min, newBlock;
+
+    if(value==0) {
+        return;
+    }
+
+    /*
+     * compute the index for each stage,
+     * allocate a stage block if necessary,
+     * and write the stage value
+     */
+    i1=c>>10;
+    if(i1>=extData->stage1Top) {
+        extData->stage1Top=i1+1;
+    }
+
+    nextOffset=(c>>4)&0x3f;
+
+    if(extData->stage1[i1]==0) {
+        /* allocate another block in stage 2; overlap with the previous block */
+        newBlock=extData->stage2Top;
+        min=newBlock-nextOffset; /* minimum block start with overlap */
+        while(min<newBlock && extData->stage2[newBlock-1]==0) {
+            --newBlock;
+        }
+
+        extData->stage1[i1]=(uint16_t)newBlock;
+        extData->stage2Top=newBlock+MBCS_STAGE_2_BLOCK_SIZE;
+        if(extData->stage2Top>UPRV_LENGTHOF(extData->stage2)) {
+            fprintf(stderr, "error: too many stage 2 entries at U+%04x\n", (int)c);
+            exit(U_MEMORY_ALLOCATION_ERROR);
+        }
+    }
+
+    i2=extData->stage1[i1]+nextOffset;
+    nextOffset=c&0xf;
+
+    if(extData->stage2[i2]==0) {
+        /* allocate another block in stage 3; overlap with the previous block */
+        newBlock=extData->stage3Top;
+        min=newBlock-nextOffset; /* minimum block start with overlap */
+        while(min<newBlock && extData->stage3[newBlock-1]==0) {
+            --newBlock;
+        }
+
+        /* round up to a multiple of stage 3 granularity >1 (similar to utrie.c) */
+        newBlock=(newBlock+(UCNV_EXT_STAGE_3_GRANULARITY-1))&~(UCNV_EXT_STAGE_3_GRANULARITY-1);
+        extData->stage2[i2]=(uint16_t)(newBlock>>UCNV_EXT_STAGE_2_LEFT_SHIFT);
+
+        extData->stage3Top=newBlock+MBCS_STAGE_3_BLOCK_SIZE;
+        if(extData->stage3Top>UPRV_LENGTHOF(extData->stage3)) {
+            fprintf(stderr, "error: too many stage 3 entries at U+%04x\n", (int)c);
+            exit(U_MEMORY_ALLOCATION_ERROR);
+        }
+    }
+
+    i3=((int32_t)extData->stage2[i2]<<UCNV_EXT_STAGE_2_LEFT_SHIFT)+nextOffset;
+    /*
+     * assume extData->stage3[i3]==0 because we get
+     * code points in strictly ascending order
+     */
+
+    if(value==UCNV_EXT_FROM_U_SUBCHAR1) {
+        /* <subchar1> SUB mapping, see getFromUBytesValue() and prepareFromUMappings() */
+        extData->stage3[i3]=1;
+
+        /*
+         * precompaction is not optimal for <subchar1> |2 mappings because
+         * stage3 values for them are all the same, unlike for other mappings
+         * which all have unique values;
+         * use a simple compaction of reusing a whole block filled with these
+         * mappings
+         */
+
+        /* is the entire block filled with <subchar1> |2 mappings? */
+        if(nextOffset==MBCS_STAGE_3_BLOCK_SIZE-1) {
+            for(min=i3-nextOffset;
+                min<i3 && extData->stage3[min]==1;
+                ++min) {}
+
+            if(min==i3) {
+                /* the entire block is filled with these mappings */
+                if(extData->stage3Sub1Block!=0) {
+                    /* point to the previous such block and remove this block from stage3 */
+                    extData->stage2[i2]=extData->stage3Sub1Block;
+                    extData->stage3Top-=MBCS_STAGE_3_BLOCK_SIZE;
+                    uprv_memset(extData->stage3+extData->stage3Top, 0, MBCS_STAGE_3_BLOCK_SIZE*2);
+                } else {
+                    /* remember this block's stage2 entry */
+                    extData->stage3Sub1Block=extData->stage2[i2];
+                }
+            }
+        }
+    } else {
+        if((i3b=extData->stage3bTop++)>=UPRV_LENGTHOF(extData->stage3b)) {
+            fprintf(stderr, "error: too many stage 3b entries at U+%04x\n", (int)c);
+            exit(U_MEMORY_ALLOCATION_ERROR);
+        }
+
+        /* roundtrip or fallback mapping */
+        extData->stage3[i3]=(uint16_t)i3b;
+        extData->stage3b[i3b]=value;
+    }
+}
+
+static UBool
+generateFromUTrie(CnvExtData *extData, UCMTable *table, int32_t mapLength) {
+    UCMapping *mappings, *m;
+    int32_t *map;
+    uint32_t value;
+    int32_t subStart, subLimit;
+
+    UChar32 *codePoints;
+    UChar32 c, next;
+
+    if(mapLength==0) {
+        return true;
+    }
+
+    mappings=table->mappings;
+    map=table->reverseMap;
+
+    /*
+     * iterate over same-initial-code point mappings,
+     * enter the initial code point into the trie,
+     * and start a recursion on the corresponding mappings section
+     * with generateFromUTable()
+     */
+    m=mappings+map[0];
+    codePoints=UCM_GET_CODE_POINTS(table, m);
+    next=codePoints[0];
+    subLimit=0;
+    while(subLimit<mapLength) {
+        /* get a new subsection of mappings starting with the same code point */
+        subStart=subLimit;
+        c=next;
+        while(next==c && ++subLimit<mapLength) {
+            m=mappings+map[subLimit];
+            codePoints=UCM_GET_CODE_POINTS(table, m);
+            next=codePoints[0];
+        }
+
+        /*
+         * compute the value for this code point;
+         * if there is a mapping for this code point alone, it is at subStart
+         * because the table is sorted lexically
+         */
+        value=0;
+        m=mappings+map[subStart];
+        codePoints=UCM_GET_CODE_POINTS(table, m);
+        if(m->uLen==1) {
+            /* do not include this in generateFromUTable() */
+            ++subStart;
+
+            if(subStart<subLimit && mappings[map[subStart]].uLen==1) {
+                /* print error for multiple same-input-sequence mappings */
+                fprintf(stderr, "error: multiple mappings from same Unicode code points\n");
+                ucm_printMapping(table, m, stderr);
+                ucm_printMapping(table, mappings+map[subStart], stderr);
+                return false;
+            }
+
+            value=getFromUBytesValue(extData, table, m);
+        }
+
+        if(subStart==subLimit) {
+            /* write the result for this one code point */
+            addFromUTrieEntry(extData, c, value);
+        } else {
+            /* write the index to the subsection table */
+            addFromUTrieEntry(extData, c, (uint32_t)utm_countItems(extData->fromUTableValues));
+
+            /* recurse, starting from 16-bit-unit index 2, the first 16-bit unit after c */
+            if(!generateFromUTable(extData, table, subStart, subLimit, 2, value)) {
+                return false;
+            }
+        }
+    }
+    return true;
+}
+
+/*
+ * Generate the fromU data structures from the input table.
+ * The input table must be sorted, and all precision flags must be 0..3.
+ * This function will modify the table's reverseMap.
+ */
+static UBool
+makeFromUTable(CnvExtData *extData, UCMTable *table) {
+    uint16_t *stage1;
+    int32_t i, stage1Top, fromUCount;
+
+    fromUCount=prepareFromUMappings(table);
+
+    extData->fromUTableUChars=utm_open("cnv extension fromUTableUChars", 0x10000, UCNV_EXT_FROM_U_DATA_MASK+1, 2);
+    extData->fromUTableValues=utm_open("cnv extension fromUTableValues", 0x10000, UCNV_EXT_FROM_U_DATA_MASK+1, 4);
+    extData->fromUBytes=utm_open("cnv extension fromUBytes", 0x10000, UCNV_EXT_FROM_U_DATA_MASK+1, 1);
+
+    /* allocate all-unassigned stage blocks */
+    extData->stage2Top=MBCS_STAGE_2_FIRST_ASSIGNED;
+    extData->stage3Top=MBCS_STAGE_3_FIRST_ASSIGNED;
+
+    /*
+     * stage 3b stores only unique values, and in
+     * index 0: 0 for "no mapping"
+     * index 1: "no mapping" with preference for <subchar1> rather than <subchar>
+     */
+    extData->stage3b[1]=UCNV_EXT_FROM_U_SUBCHAR1;
+    extData->stage3bTop=2;
+
+    /* allocate the first entry in the fromUTable because index 0 means "no result" */
+    utm_alloc(extData->fromUTableUChars);
+    utm_alloc(extData->fromUTableValues);
+
+    if(!generateFromUTrie(extData, table, fromUCount)) {
+        return false;
+    }
+
+    /*
+     * offset the stage 1 trie entries by stage1Top because they will
+     * be stored in a single array
+     */
+    stage1=extData->stage1;
+    stage1Top=extData->stage1Top;
+    for(i=0; i<stage1Top; ++i) {
+        stage1[i]=(uint16_t)(stage1[i]+stage1Top);
+    }
+
+    return true;
+}
+
+/* -------------------------------------------------------------------------- */
+
+static UBool
+CnvExtAddTable(NewConverter *cnvData, UCMTable *table, UConverterStaticData *staticData) {
+    CnvExtData *extData;
+
+    if(table->unicodeMask&UCNV_HAS_SURROGATES) {
+        fprintf(stderr, "error: contains mappings for surrogate code points\n");
+        return false;
+    }
+
+    staticData->conversionType=UCNV_MBCS;
+
+    extData=(CnvExtData *)cnvData;
+
+    /*
+     * assume that the table is sorted
+     *
+     * call the functions in this order because
+     * makeToUTable() modifies the original reverseMap,
+     * makeFromUTable() writes a whole new mapping into reverseMap
+     */
+    return
+        makeToUTable(extData, table) &&
+        makeFromUTable(extData, table);
+}