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778 lines
24 KiB
C
778 lines
24 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
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ConvertUTF32toUTF16( const UTF32** sourceStart,
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const UTF32* sourceEnd,
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UTF16** targetStart,
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UTF16* targetEnd,
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ConversionFlags flags )
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{
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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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{
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UTF32 ch;
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if( target >= targetEnd )
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{
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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
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both reserved values */
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if( ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END )
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{
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if( flags == strictConversion )
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{
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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
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{
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*target++ = UNI_REPLACEMENT_CHAR;
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}
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}
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else
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{
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*target++ = (UTF16)ch; /* normal case */
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}
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}
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else if( ch > UNI_MAX_LEGAL_UTF32 )
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{
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if( flags == strictConversion )
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{
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result = sourceIllegal;
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}
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else
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{
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*target++ = UNI_REPLACEMENT_CHAR;
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}
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}
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else
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{
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/* target is a character in range 0xFFFF - 0x10FFFF. */
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if( target + 1 >= targetEnd )
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{
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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
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ConvertUTF16toUTF32( const UTF16** sourceStart,
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const UTF16* sourceEnd,
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UTF32** targetStart,
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UTF32* targetEnd,
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ConversionFlags flags )
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{
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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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{
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const UTF16* oldSource = source; /* In case we have to back up because
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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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{
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/* If the 16 bits following the high surrogate are in the source
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buffer... */
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if( source < sourceEnd )
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{
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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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{
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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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}
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else if( flags == strictConversion ) /* it's an unpaired high
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surrogate */
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{
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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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else /* We don't have the 16 bits following the high surrogate. */
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{
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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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}
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else if( flags == strictConversion )
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{
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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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{
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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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{
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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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{
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fprintf( stderr, "ConvertUTF16toUTF32 illegal seq 0x%04x,%04x\n",
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ch,
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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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] =
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{ 0x00000000UL, 0x00003080UL,
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0x000E2080UL,
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0x03C82080UL, 0xFA082080UL,
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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] =
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{ 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
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ConvertUTF16toUTF8( const UTF16** sourceStart,
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const UTF16* sourceEnd,
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UTF8** targetStart,
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UTF8* targetEnd,
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ConversionFlags flags )
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{
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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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{
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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
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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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{
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/* If the 16 bits following the high surrogate are in the source
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buffer... */
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if( source < sourceEnd )
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{
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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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{
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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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}
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else if( flags == strictConversion ) /* it's an unpaired high
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surrogate */
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{
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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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else /* We don't have the 16 bits following the high surrogate. */
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{
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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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}
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else if( flags == strictConversion )
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{
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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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{
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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 )
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{
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bytesToWrite = 1;
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}
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else if( ch < (UTF32)0x800 )
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{
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bytesToWrite = 2;
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}
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else if( ch < (UTF32)0x10000 )
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{
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bytesToWrite = 3;
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}
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else if( ch < (UTF32)0x110000 )
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{
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bytesToWrite = 4;
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}
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else
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{
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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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{
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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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{
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case 4:
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*--target =
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(UTF8)( ( ch | byteMark ) & byteMask ); ch >>= 6;
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case 3:
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*--target =
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(UTF8)( ( ch | byteMark ) & byteMask ); ch >>= 6;
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case 2:
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*--target =
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(UTF8)( ( ch | byteMark ) & byteMask ); ch >>= 6;
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case 1:
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*--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
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isLegalUTF8( const UTF8 *source,
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int length )
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{
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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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{
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default:
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return false;
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/* Everything else falls through when "true"... */
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case 4:
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if( ( a = ( *--srcptr ) ) < 0x80 || a > 0xBF ) return false;
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case 3:
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if( ( a = ( *--srcptr ) ) < 0x80 || a > 0xBF ) return false;
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case 2:
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if( ( a = ( *--srcptr ) ) > 0xBF ) return false;
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switch( *source )
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{
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/* no fall-through in this inner switch */
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case 0xE0:
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if( a < 0xA0 ) return false;break;
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case 0xED:
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if( a > 0x9F ) return false;break;
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case 0xF0:
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if( a < 0x90 ) return false;break;
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case 0xF4:
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if( a > 0x8F ) return false;break;
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default:
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if( a < 0x80 ) return false;
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}
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case 1:
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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
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isLegalUTF8Sequence( const UTF8 *source,
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const UTF8 *sourceEnd )
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{
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int length = trailingBytesForUTF8[*source] + 1;
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if( source + length > sourceEnd )
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{
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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
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ConvertUTF8toUTF16( const UTF8** sourceStart,
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const UTF8* sourceEnd,
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UTF16** targetStart,
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UTF16* targetEnd,
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ConversionFlags flags )
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{
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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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{
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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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{
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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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{
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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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{
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case 5:
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ch += *source++; ch <<= 6; /* remember, illegal UTF-8 */
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case 4:
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ch += *source++; ch <<= 6; /* remember, illegal UTF-8 */
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case 3:
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ch += *source++; ch <<= 6;
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case 2:
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ch += *source++; ch <<= 6;
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case 1:
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ch += *source++; ch <<= 6;
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case 0:
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ch += *source++;
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}
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ch -= offsetsFromUTF8[extraBytesToRead];
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|
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if( target >= targetEnd )
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{
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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 */
|
|
{ /* UTF-16 surrogate values are illegal in UTF-32 */
|
|
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 */
|
|
result = sourceIllegal;
|
|
break;
|
|
}
|
|
else
|
|
{
|
|
*target++ = UNI_REPLACEMENT_CHAR;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
*target++ = (UTF16)ch; /* normal case */
|
|
}
|
|
}
|
|
else if( ch > UNI_MAX_UTF16 )
|
|
{
|
|
if( flags == strictConversion )
|
|
{
|
|
result = sourceIllegal;
|
|
source -= ( extraBytesToRead + 1 ); /* return to the start */
|
|
break; /* Bail out; shouldn't continue */
|
|
}
|
|
else
|
|
{
|
|
*target++ = UNI_REPLACEMENT_CHAR;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
/* target is a character in range 0xFFFF - 0x10FFFF. */
|
|
if( target + 1 >= targetEnd )
|
|
{
|
|
source -= ( extraBytesToRead + 1 ); /* 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
|
|
ConvertUTF32toUTF8( const UTF32** sourceStart,
|
|
const UTF32* sourceEnd,
|
|
UTF8** targetStart,
|
|
UTF8* targetEnd,
|
|
ConversionFlags flags )
|
|
{
|
|
ConversionResult result = conversionOK;
|
|
const UTF32* source = *sourceStart;
|
|
UTF8* target = *targetStart;
|
|
|
|
while( source < sourceEnd )
|
|
{
|
|
UTF32 ch;
|
|
unsigned short bytesToWrite = 0;
|
|
const UTF32 byteMask = 0xBF;
|
|
const UTF32 byteMark = 0x80;
|
|
ch = *source++;
|
|
if( flags == strictConversion )
|
|
{
|
|
/* UTF-16 surrogate values are illegal in UTF-32 */
|
|
if( ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END )
|
|
{
|
|
--source; /* return to the illegal value itself */
|
|
result = sourceIllegal;
|
|
break;
|
|
}
|
|
}
|
|
/*
|
|
* Figure out how many bytes the result will require. Turn any
|
|
* illegally large UTF32 things (> Plane 17) into replacement chars.
|
|
*/
|
|
if( ch < (UTF32)0x80 )
|
|
{
|
|
bytesToWrite = 1;
|
|
}
|
|
else if( ch < (UTF32)0x800 )
|
|
{
|
|
bytesToWrite = 2;
|
|
}
|
|
else if( ch < (UTF32)0x10000 )
|
|
{
|
|
bytesToWrite = 3;
|
|
}
|
|
else if( ch <= UNI_MAX_LEGAL_UTF32 )
|
|
{
|
|
bytesToWrite = 4;
|
|
}
|
|
else
|
|
{
|
|
bytesToWrite = 3;
|
|
ch = UNI_REPLACEMENT_CHAR;
|
|
result = sourceIllegal;
|
|
}
|
|
|
|
target += bytesToWrite;
|
|
if( target > targetEnd )
|
|
{
|
|
--source; /* Back up source pointer! */
|
|
target -= bytesToWrite; result = targetExhausted; break;
|
|
}
|
|
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.
|
|
|
|
--------------------------------------------------------------------- */
|