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540 lines
19 KiB
C
540 lines
19 KiB
C
/*
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* Copyright 2001-2004 Unicode, Inc.
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*
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* Disclaimer
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*
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* This source code is provided as is by Unicode, Inc. No claims are
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* made as to fitness for any particular purpose. No warranties of any
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* kind are expressed or implied. The recipient agrees to determine
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* applicability of information provided. If this file has been
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* purchased on magnetic or optical media from Unicode, Inc., the
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* sole remedy for any claim will be exchange of defective media
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* within 90 days of receipt.
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*
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* Limitations on Rights to Redistribute This Code
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*
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* Unicode, Inc. hereby grants the right to freely use the information
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* supplied in this file in the creation of products supporting the
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* Unicode Standard, and to make copies of this file in any form
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* for internal or external distribution as long as this notice
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* remains attached.
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*/
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/* ---------------------------------------------------------------------
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Conversions between UTF32, UTF-16, and UTF-8. Source code file.
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Author: Mark E. Davis, 1994.
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Rev History: Rick McGowan, fixes & updates May 2001.
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Sept 2001: fixed const & error conditions per
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mods suggested by S. Parent & A. Lillich.
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June 2002: Tim Dodd added detection and handling of incomplete
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source sequences, enhanced error detection, added casts
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to eliminate compiler warnings.
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July 2003: slight mods to back out aggressive FFFE detection.
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Jan 2004: updated switches in from-UTF8 conversions.
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Oct 2004: updated to use UNI_MAX_LEGAL_UTF32 in UTF-32 conversions.
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See the header file "ConvertUTF.h" for complete documentation.
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------------------------------------------------------------------------ */
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#include "ConvertUTF.h"
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#ifdef CVTUTF_DEBUG
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#include <stdio.h>
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#endif
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static const int halfShift = 10; /* used for shifting by 10 bits */
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static const UTF32 halfBase = 0x0010000UL;
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static const UTF32 halfMask = 0x3FFUL;
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#define UNI_SUR_HIGH_START (UTF32)0xD800
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#define UNI_SUR_HIGH_END (UTF32)0xDBFF
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#define UNI_SUR_LOW_START (UTF32)0xDC00
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#define UNI_SUR_LOW_END (UTF32)0xDFFF
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#define false 0
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#define true 1
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/* --------------------------------------------------------------------- */
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ConversionResult ConvertUTF32toUTF16 (
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const UTF32** sourceStart, const UTF32* sourceEnd,
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UTF16** targetStart, UTF16* targetEnd, ConversionFlags flags) {
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ConversionResult result = conversionOK;
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const UTF32* source = *sourceStart;
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UTF16* target = *targetStart;
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while (source < sourceEnd) {
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UTF32 ch;
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if (target >= targetEnd) {
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result = targetExhausted; break;
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}
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ch = *source++;
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if (ch <= UNI_MAX_BMP) { /* Target is a character <= 0xFFFF */
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/* UTF-16 surrogate values are illegal in UTF-32; 0xffff or 0xfffe are both reserved values */
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if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END) {
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if (flags == strictConversion) {
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--source; /* return to the illegal value itself */
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result = sourceIllegal;
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break;
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} else {
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*target++ = UNI_REPLACEMENT_CHAR;
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}
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} else {
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*target++ = (UTF16)ch; /* normal case */
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}
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} else if (ch > UNI_MAX_LEGAL_UTF32) {
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if (flags == strictConversion) {
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result = sourceIllegal;
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} else {
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*target++ = UNI_REPLACEMENT_CHAR;
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}
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} else {
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/* target is a character in range 0xFFFF - 0x10FFFF. */
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if (target + 1 >= targetEnd) {
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--source; /* Back up source pointer! */
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result = targetExhausted; break;
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}
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ch -= halfBase;
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*target++ = (UTF16)((ch >> halfShift) + UNI_SUR_HIGH_START);
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*target++ = (UTF16)((ch & halfMask) + UNI_SUR_LOW_START);
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}
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}
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*sourceStart = source;
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*targetStart = target;
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return result;
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}
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/* --------------------------------------------------------------------- */
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ConversionResult ConvertUTF16toUTF32 (
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const UTF16** sourceStart, const UTF16* sourceEnd,
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UTF32** targetStart, UTF32* targetEnd, ConversionFlags flags) {
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ConversionResult result = conversionOK;
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const UTF16* source = *sourceStart;
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UTF32* target = *targetStart;
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UTF32 ch, ch2;
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while (source < sourceEnd) {
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const UTF16* oldSource = source; /* In case we have to back up because of target overflow. */
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ch = *source++;
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/* If we have a surrogate pair, convert to UTF32 first. */
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if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_HIGH_END) {
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/* If the 16 bits following the high surrogate are in the source buffer... */
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if (source < sourceEnd) {
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ch2 = *source;
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/* If it's a low surrogate, convert to UTF32. */
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if (ch2 >= UNI_SUR_LOW_START && ch2 <= UNI_SUR_LOW_END) {
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ch = ((ch - UNI_SUR_HIGH_START) << halfShift)
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+ (ch2 - UNI_SUR_LOW_START) + halfBase;
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++source;
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} else if (flags == strictConversion) { /* it's an unpaired high surrogate */
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--source; /* return to the illegal value itself */
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result = sourceIllegal;
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break;
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}
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} else { /* We don't have the 16 bits following the high surrogate. */
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--source; /* return to the high surrogate */
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result = sourceExhausted;
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break;
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}
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} else if (flags == strictConversion) {
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/* UTF-16 surrogate values are illegal in UTF-32 */
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if (ch >= UNI_SUR_LOW_START && ch <= UNI_SUR_LOW_END) {
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--source; /* return to the illegal value itself */
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result = sourceIllegal;
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break;
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}
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}
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if (target >= targetEnd) {
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source = oldSource; /* Back up source pointer! */
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result = targetExhausted; break;
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}
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*target++ = ch;
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}
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*sourceStart = source;
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*targetStart = target;
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#ifdef CVTUTF_DEBUG
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if (result == sourceIllegal) {
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fprintf(stderr, "ConvertUTF16toUTF32 illegal seq 0x%04x,%04x\n", ch, ch2);
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fflush(stderr);
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}
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#endif
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return result;
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}
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/* --------------------------------------------------------------------- */
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/*
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* Index into the table below with the first byte of a UTF-8 sequence to
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* get the number of trailing bytes that are supposed to follow it.
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* Note that *legal* UTF-8 values can't have 4 or 5-bytes. The table is
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* left as-is for anyone who may want to do such conversion, which was
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* allowed in earlier algorithms.
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*/
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static const char trailingBytesForUTF8[256] = {
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0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
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0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
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0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
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0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
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0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
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0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
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1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
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2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2, 3,3,3,3,3,3,3,3,4,4,4,4,5,5,5,5
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};
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/*
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* Magic values subtracted from a buffer value during UTF8 conversion.
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* This table contains as many values as there might be trailing bytes
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* in a UTF-8 sequence.
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*/
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static const UTF32 offsetsFromUTF8[6] = { 0x00000000UL, 0x00003080UL, 0x000E2080UL,
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0x03C82080UL, 0xFA082080UL, 0x82082080UL };
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/*
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* Once the bits are split out into bytes of UTF-8, this is a mask OR-ed
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* into the first byte, depending on how many bytes follow. There are
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* as many entries in this table as there are UTF-8 sequence types.
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* (I.e., one byte sequence, two byte... etc.). Remember that sequencs
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* for *legal* UTF-8 will be 4 or fewer bytes total.
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*/
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static const UTF8 firstByteMark[7] = { 0x00, 0x00, 0xC0, 0xE0, 0xF0, 0xF8, 0xFC };
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/* --------------------------------------------------------------------- */
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/* The interface converts a whole buffer to avoid function-call overhead.
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* Constants have been gathered. Loops & conditionals have been removed as
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* much as possible for efficiency, in favor of drop-through switches.
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* (See "Note A" at the bottom of the file for equivalent code.)
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* If your compiler supports it, the "isLegalUTF8" call can be turned
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* into an inline function.
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*/
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/* --------------------------------------------------------------------- */
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ConversionResult ConvertUTF16toUTF8 (
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const UTF16** sourceStart, const UTF16* sourceEnd,
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UTF8** targetStart, UTF8* targetEnd, ConversionFlags flags) {
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ConversionResult result = conversionOK;
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const UTF16* source = *sourceStart;
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UTF8* target = *targetStart;
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while (source < sourceEnd) {
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UTF32 ch;
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unsigned short bytesToWrite = 0;
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const UTF32 byteMask = 0xBF;
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const UTF32 byteMark = 0x80;
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const UTF16* oldSource = source; /* In case we have to back up because of target overflow. */
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ch = *source++;
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/* If we have a surrogate pair, convert to UTF32 first. */
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if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_HIGH_END) {
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/* If the 16 bits following the high surrogate are in the source buffer... */
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if (source < sourceEnd) {
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UTF32 ch2 = *source;
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/* If it's a low surrogate, convert to UTF32. */
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if (ch2 >= UNI_SUR_LOW_START && ch2 <= UNI_SUR_LOW_END) {
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ch = ((ch - UNI_SUR_HIGH_START) << halfShift)
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+ (ch2 - UNI_SUR_LOW_START) + halfBase;
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++source;
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} else if (flags == strictConversion) { /* it's an unpaired high surrogate */
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--source; /* return to the illegal value itself */
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result = sourceIllegal;
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break;
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}
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} else { /* We don't have the 16 bits following the high surrogate. */
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--source; /* return to the high surrogate */
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result = sourceExhausted;
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break;
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}
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} else if (flags == strictConversion) {
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/* UTF-16 surrogate values are illegal in UTF-32 */
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if (ch >= UNI_SUR_LOW_START && ch <= UNI_SUR_LOW_END) {
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--source; /* return to the illegal value itself */
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result = sourceIllegal;
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break;
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}
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}
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/* Figure out how many bytes the result will require */
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if (ch < (UTF32)0x80) { bytesToWrite = 1;
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} else if (ch < (UTF32)0x800) { bytesToWrite = 2;
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} else if (ch < (UTF32)0x10000) { bytesToWrite = 3;
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} else if (ch < (UTF32)0x110000) { bytesToWrite = 4;
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} else { bytesToWrite = 3;
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ch = UNI_REPLACEMENT_CHAR;
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}
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target += bytesToWrite;
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if (target > targetEnd) {
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source = oldSource; /* Back up source pointer! */
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target -= bytesToWrite; result = targetExhausted; break;
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}
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switch (bytesToWrite) { /* note: everything falls through. */
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case 4: *--target = (UTF8)((ch | byteMark) & byteMask); ch >>= 6;
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case 3: *--target = (UTF8)((ch | byteMark) & byteMask); ch >>= 6;
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case 2: *--target = (UTF8)((ch | byteMark) & byteMask); ch >>= 6;
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case 1: *--target = (UTF8)(ch | firstByteMark[bytesToWrite]);
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}
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target += bytesToWrite;
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}
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*sourceStart = source;
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*targetStart = target;
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return result;
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}
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/* --------------------------------------------------------------------- */
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/*
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* Utility routine to tell whether a sequence of bytes is legal UTF-8.
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* This must be called with the length pre-determined by the first byte.
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* If not calling this from ConvertUTF8to*, then the length can be set by:
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* length = trailingBytesForUTF8[*source]+1;
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* and the sequence is illegal right away if there aren't that many bytes
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* available.
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* If presented with a length > 4, this returns false. The Unicode
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* definition of UTF-8 goes up to 4-byte sequences.
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*/
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static Boolean isLegalUTF8(const UTF8 *source, int length) {
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UTF8 a;
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const UTF8 *srcptr = source+length;
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switch (length) {
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default: return false;
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/* Everything else falls through when "true"... */
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case 4: if ((a = (*--srcptr)) < 0x80 || a > 0xBF) return false;
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case 3: if ((a = (*--srcptr)) < 0x80 || a > 0xBF) return false;
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case 2: if ((a = (*--srcptr)) > 0xBF) return false;
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switch (*source) {
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/* no fall-through in this inner switch */
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case 0xE0: if (a < 0xA0) return false; break;
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case 0xED: if (a > 0x9F) return false; break;
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case 0xF0: if (a < 0x90) return false; break;
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case 0xF4: if (a > 0x8F) return false; break;
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default: if (a < 0x80) return false;
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}
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case 1: if (*source >= 0x80 && *source < 0xC2) return false;
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}
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if (*source > 0xF4) return false;
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return true;
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}
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/* --------------------------------------------------------------------- */
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/*
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* Exported function to return whether a UTF-8 sequence is legal or not.
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* This is not used here; it's just exported.
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*/
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Boolean isLegalUTF8Sequence(const UTF8 *source, const UTF8 *sourceEnd) {
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int length = trailingBytesForUTF8[*source]+1;
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if (source+length > sourceEnd) {
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return false;
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}
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return isLegalUTF8(source, length);
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}
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/* --------------------------------------------------------------------- */
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ConversionResult ConvertUTF8toUTF16 (
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const UTF8** sourceStart, const UTF8* sourceEnd,
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UTF16** targetStart, UTF16* targetEnd, ConversionFlags flags) {
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ConversionResult result = conversionOK;
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const UTF8* source = *sourceStart;
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UTF16* target = *targetStart;
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while (source < sourceEnd) {
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UTF32 ch = 0;
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unsigned short extraBytesToRead = trailingBytesForUTF8[*source];
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if (source + extraBytesToRead >= sourceEnd) {
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result = sourceExhausted; break;
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}
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/* Do this check whether lenient or strict */
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if (! isLegalUTF8(source, extraBytesToRead+1)) {
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result = sourceIllegal;
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break;
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}
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/*
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* The cases all fall through. See "Note A" below.
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*/
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switch (extraBytesToRead) {
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case 5: ch += *source++; ch <<= 6; /* remember, illegal UTF-8 */
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case 4: ch += *source++; ch <<= 6; /* remember, illegal UTF-8 */
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case 3: ch += *source++; ch <<= 6;
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case 2: ch += *source++; ch <<= 6;
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case 1: ch += *source++; ch <<= 6;
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case 0: ch += *source++;
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}
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ch -= offsetsFromUTF8[extraBytesToRead];
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if (target >= targetEnd) {
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source -= (extraBytesToRead+1); /* Back up source pointer! */
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result = targetExhausted; break;
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}
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if (ch <= UNI_MAX_BMP) { /* Target is a character <= 0xFFFF */
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/* UTF-16 surrogate values are illegal in UTF-32 */
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if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END) {
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if (flags == strictConversion) {
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source -= (extraBytesToRead+1); /* return to the illegal value itself */
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result = sourceIllegal;
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break;
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} else {
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*target++ = UNI_REPLACEMENT_CHAR;
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}
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} else {
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*target++ = (UTF16)ch; /* normal case */
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}
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} else if (ch > UNI_MAX_UTF16) {
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if (flags == strictConversion) {
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result = sourceIllegal;
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source -= (extraBytesToRead+1); /* return to the start */
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break; /* Bail out; shouldn't continue */
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} else {
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*target++ = UNI_REPLACEMENT_CHAR;
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}
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} else {
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/* target is a character in range 0xFFFF - 0x10FFFF. */
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if (target + 1 >= targetEnd) {
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source -= (extraBytesToRead+1); /* Back up source pointer! */
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result = targetExhausted; break;
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}
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ch -= halfBase;
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*target++ = (UTF16)((ch >> halfShift) + UNI_SUR_HIGH_START);
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*target++ = (UTF16)((ch & halfMask) + UNI_SUR_LOW_START);
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}
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}
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*sourceStart = source;
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*targetStart = target;
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return result;
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}
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/* --------------------------------------------------------------------- */
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ConversionResult ConvertUTF32toUTF8 (
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const UTF32** sourceStart, const UTF32* sourceEnd,
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UTF8** targetStart, UTF8* targetEnd, ConversionFlags flags) {
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ConversionResult result = conversionOK;
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const UTF32* source = *sourceStart;
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UTF8* target = *targetStart;
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while (source < sourceEnd) {
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UTF32 ch;
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unsigned short bytesToWrite = 0;
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const UTF32 byteMask = 0xBF;
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const UTF32 byteMark = 0x80;
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ch = *source++;
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if (flags == strictConversion ) {
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/* UTF-16 surrogate values are illegal in UTF-32 */
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if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END) {
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--source; /* return to the illegal value itself */
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result = sourceIllegal;
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break;
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}
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}
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/*
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* Figure out how many bytes the result will require. Turn any
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* illegally large UTF32 things (> Plane 17) into replacement chars.
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*/
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if (ch < (UTF32)0x80) { bytesToWrite = 1;
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} else if (ch < (UTF32)0x800) { bytesToWrite = 2;
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} else if (ch < (UTF32)0x10000) { bytesToWrite = 3;
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} else if (ch <= UNI_MAX_LEGAL_UTF32) { bytesToWrite = 4;
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} else { bytesToWrite = 3;
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ch = UNI_REPLACEMENT_CHAR;
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result = sourceIllegal;
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}
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target += bytesToWrite;
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if (target > targetEnd) {
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--source; /* Back up source pointer! */
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target -= bytesToWrite; result = targetExhausted; break;
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}
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|
switch (bytesToWrite) { /* note: everything falls through. */
|
|
case 4: *--target = (UTF8)((ch | byteMark) & byteMask); ch >>= 6;
|
|
case 3: *--target = (UTF8)((ch | byteMark) & byteMask); ch >>= 6;
|
|
case 2: *--target = (UTF8)((ch | byteMark) & byteMask); ch >>= 6;
|
|
case 1: *--target = (UTF8) (ch | firstByteMark[bytesToWrite]);
|
|
}
|
|
target += bytesToWrite;
|
|
}
|
|
*sourceStart = source;
|
|
*targetStart = target;
|
|
return result;
|
|
}
|
|
|
|
/* --------------------------------------------------------------------- */
|
|
|
|
ConversionResult ConvertUTF8toUTF32 (
|
|
const UTF8** sourceStart, const UTF8* sourceEnd,
|
|
UTF32** targetStart, UTF32* targetEnd, ConversionFlags flags) {
|
|
ConversionResult result = conversionOK;
|
|
const UTF8* source = *sourceStart;
|
|
UTF32* target = *targetStart;
|
|
while (source < sourceEnd) {
|
|
UTF32 ch = 0;
|
|
unsigned short extraBytesToRead = trailingBytesForUTF8[*source];
|
|
if (source + extraBytesToRead >= sourceEnd) {
|
|
result = sourceExhausted; break;
|
|
}
|
|
/* Do this check whether lenient or strict */
|
|
if (! isLegalUTF8(source, extraBytesToRead+1)) {
|
|
result = sourceIllegal;
|
|
break;
|
|
}
|
|
/*
|
|
* The cases all fall through. See "Note A" below.
|
|
*/
|
|
switch (extraBytesToRead) {
|
|
case 5: ch += *source++; ch <<= 6;
|
|
case 4: ch += *source++; ch <<= 6;
|
|
case 3: ch += *source++; ch <<= 6;
|
|
case 2: ch += *source++; ch <<= 6;
|
|
case 1: ch += *source++; ch <<= 6;
|
|
case 0: ch += *source++;
|
|
}
|
|
ch -= offsetsFromUTF8[extraBytesToRead];
|
|
|
|
if (target >= targetEnd) {
|
|
source -= (extraBytesToRead+1); /* Back up the source pointer! */
|
|
result = targetExhausted; break;
|
|
}
|
|
if (ch <= UNI_MAX_LEGAL_UTF32) {
|
|
/*
|
|
* UTF-16 surrogate values are illegal in UTF-32, and anything
|
|
* over Plane 17 (> 0x10FFFF) is illegal.
|
|
*/
|
|
if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END) {
|
|
if (flags == strictConversion) {
|
|
source -= (extraBytesToRead+1); /* return to the illegal value itself */
|
|
result = sourceIllegal;
|
|
break;
|
|
} else {
|
|
*target++ = UNI_REPLACEMENT_CHAR;
|
|
}
|
|
} else {
|
|
*target++ = ch;
|
|
}
|
|
} else { /* i.e., ch > UNI_MAX_LEGAL_UTF32 */
|
|
result = sourceIllegal;
|
|
*target++ = UNI_REPLACEMENT_CHAR;
|
|
}
|
|
}
|
|
*sourceStart = source;
|
|
*targetStart = target;
|
|
return result;
|
|
}
|
|
|
|
/* ---------------------------------------------------------------------
|
|
|
|
Note A.
|
|
The fall-through switches in UTF-8 reading code save a
|
|
temp variable, some decrements & conditionals. The switches
|
|
are equivalent to the following loop:
|
|
{
|
|
int tmpBytesToRead = extraBytesToRead+1;
|
|
do {
|
|
ch += *source++;
|
|
--tmpBytesToRead;
|
|
if (tmpBytesToRead) ch <<= 6;
|
|
} while (tmpBytesToRead > 0);
|
|
}
|
|
In UTF-8 writing code, the switches on "bytesToWrite" are
|
|
similarly unrolled loops.
|
|
|
|
--------------------------------------------------------------------- */
|