duilib 快速入门专栏：https://blog.csdn.net/shuilan0066/category-8007774

/* * Copyright 2001-2004 Unicode, Inc. * * Disclaimer * * This source code is provided as is by Unicode, Inc. No claims are * made as to fitness for any particular purpose. No warranties of any * kind are expressed or implied. The recipient agrees to determine * applicability of information provided. If this file has been * purchased on magnetic or optical media from Unicode, Inc., the * sole remedy for any claim will be exchange of defective media * within 90 days of receipt. * * Limitations on Rights to Redistribute This Code * * Unicode, Inc. hereby grants the right to freely use the information * supplied in this file in the creation of products supporting the * Unicode Standard, and to make copies of this file in any form * for internal or external distribution as long as this notice * remains attached. */ /* $Id: ConvertUTF.c 8178 2007-08-05 13:55:26Z leonardo $*/ /* --------------------------------------------------------------------- Conversions between UTF32, UTF-16, and UTF-8. Source code file. Author: Mark E. Davis, 1994. Rev History: Rick McGowan, fixes & updates May 2001. Sept 2001: fixed const & error conditions per mods suggested by S. Parent & A. Lillich. June 2002: Tim Dodd added detection and handling of incomplete source sequences, enhanced error detection, added casts to eliminate compiler warnings. July 2003: slight mods to back out aggressive FFFE detection. Jan 2004: updated switches in from-UTF8 conversions. Oct 2004: updated to use UNI_MAX_LEGAL_UTF32 in UTF-32 conversions. See the header file "ConvertUTF.h" for complete documentation. ------------------------------------------------------------------------ */ #include "ConvertUTF.h" #ifdef CVTUTF_DEBUG #include <stdio.h> #endif static const int halfShift = 10; /* used for shifting by 10 bits */ static const UTF32 halfBase = 0x0010000UL; static const UTF32 halfMask = 0x3FFUL; #define UNI_SUR_HIGH_START (UTF32)0xD800 #define UNI_SUR_HIGH_END (UTF32)0xDBFF #define UNI_SUR_LOW_START (UTF32)0xDC00 #define UNI_SUR_LOW_END (UTF32)0xDFFF #define false 0 #define true 1 /* --------------------------------------------------------------------- */ ConversionResult ConvertUTF32toUTF16 ( const UTF32** sourceStart, const UTF32* sourceEnd, UTF16** targetStart, UTF16* targetEnd, ConversionFlags flags) { ConversionResult result = conversionOK; const UTF32* source = *sourceStart; UTF16* target = *targetStart; while (source < sourceEnd) { UTF32 ch; if (target >= targetEnd) { result = targetExhausted; break; } ch = *source++; if (ch <= UNI_MAX_BMP) { /* Target is a character <= 0xFFFF */ /* UTF-16 surrogate values are illegal in UTF-32; 0xffff or 0xfffe are both reserved values */ if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END) { if (flags == strictConversion) { --source; /* return to the illegal value itself */ result = sourceIllegal; break; } else { *target++ = UNI_REPLACEMENT_CHAR; } } else { *target++ = (UTF16)ch; /* normal case */ } } else if (ch > UNI_MAX_LEGAL_UTF32) { if (flags == strictConversion) { result = sourceIllegal; } else { *target++ = UNI_REPLACEMENT_CHAR; } } else { /* target is a character in range 0xFFFF - 0x10FFFF. */ if (target + 1 >= targetEnd) { --source; /* Back up source pointer! */ result = targetExhausted; break; } ch -= halfBase; *target++ = (UTF16)((ch >> halfShift) + UNI_SUR_HIGH_START); *target++ = (UTF16)((ch & halfMask) + UNI_SUR_LOW_START); } } *sourceStart = source; *targetStart = target; return result; } /* --------------------------------------------------------------------- */ ConversionResult ConvertUTF16toUTF32 ( const UTF16** sourceStart, const UTF16* sourceEnd, UTF32** targetStart, UTF32* targetEnd, ConversionFlags flags) { ConversionResult result = conversionOK; const UTF16* source = *sourceStart; UTF32* target = *targetStart; UTF32 ch, ch2; while (source < sourceEnd) { const UTF16* oldSource = source; /* In case we have to back up because of target overflow. */ ch = *source++; /* If we have a surrogate pair, convert to UTF32 first. */ if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_HIGH_END) { /* If the 16 bits following the high surrogate are in the source buffer... */ if (source < sourceEnd) { ch2 = *source; /* If it's a low surrogate, convert to UTF32. */ if (ch2 >= UNI_SUR_LOW_START && ch2 <= UNI_SUR_LOW_END) { ch = ((ch - UNI_SUR_HIGH_START) << halfShift) + (ch2 - UNI_SUR_LOW_START) + halfBase; ++source; } else if (flags == strictConversion) { /* it's an unpaired high surrogate */ --source; /* return to the illegal value itself */ result = sourceIllegal; break; } } else { /* We don't have the 16 bits following the high surrogate. */ --source; /* return to the high surrogate */ result = sourceExhausted; break; } } else if (flags == strictConversion) { /* UTF-16 surrogate values are illegal in UTF-32 */ if (ch >= UNI_SUR_LOW_START && ch <= UNI_SUR_LOW_END) { --source; /* return to the illegal value itself */ result = sourceIllegal; break; } } if (target >= targetEnd) { source = oldSource; /* Back up source pointer! */ result = targetExhausted; break; } *target++ = ch; } *sourceStart = source; *targetStart = target; #ifdef CVTUTF_DEBUG if (result == sourceIllegal) { fprintf(stderr, "ConvertUTF16toUTF32 illegal seq 0x%04x,%04x\n", ch, ch2); fflush(stderr); } #endif return result; } /* --------------------------------------------------------------------- */ /* * Index into the table below with the first byte of a UTF-8 sequence to * get the number of trailing bytes that are supposed to follow it. * Note that *legal* UTF-8 values can't have 4 or 5-bytes. The table is * left as-is for anyone who may want to do such conversion, which was * allowed in earlier algorithms. */ static const char trailingBytesForUTF8[256] = { 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, 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, 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, 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, 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, 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, 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, 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 }; /* * Magic values subtracted from a buffer value during UTF8 conversion. * This table contains as many values as there might be trailing bytes * in a UTF-8 sequence. */ static const UTF32 offsetsFromUTF8[6] = { 0x00000000UL, 0x00003080UL, 0x000E2080UL, 0x03C82080UL, 0xFA082080UL, 0x82082080UL }; /* * Once the bits are split out into bytes of UTF-8, this is a mask OR-ed * into the first byte, depending on how many bytes follow. There are * as many entries in this table as there are UTF-8 sequence types. * (I.e., one byte sequence, two byte... etc.). Remember that sequencs * for *legal* UTF-8 will be 4 or fewer bytes total. */ static const UTF8 firstByteMark[7] = { 0x00, 0x00, 0xC0, 0xE0, 0xF0, 0xF8, 0xFC }; /* --------------------------------------------------------------------- */ /* The interface converts a whole buffer to avoid function-call overhead. * Constants have been gathered. Loops & conditionals have been removed as * much as possible for efficiency, in favor of drop-through switches. * (See "Note A" at the bottom of the file for eq