| /* |
| ******************************************************************************* |
| * |
| * Copyright (C) 1999-2000, International Business Machines |
| * Corporation and others. All Rights Reserved. |
| * |
| ******************************************************************************* |
| * file name: utf_impl.c |
| * encoding: US-ASCII |
| * tab size: 8 (not used) |
| * indentation:4 |
| * |
| * created on: 1999sep13 |
| * created by: Markus W. Scherer |
| * |
| * This file provides implementation functions for macros in the utfXX.h |
| * that would otherwise be too long as macros. |
| */ |
| |
| #include "unicode/umachine.h" |
| #include "unicode/utf.h" |
| |
| /* |
| * This table could be replaced on many machines by |
| * a few lines of assembler code using an |
| * "index of first 0-bit from msb" instruction and |
| * one or two more integer instructions. |
| * |
| * For example, on an i386, do something like |
| * - MOV AL, leadByte |
| * - NOT AL (8-bit, leave b15..b8==0..0, reverse only b7..b0) |
| * - MOV AH, 0 |
| * - BSR BX, AX (16-bit) |
| * - MOV AX, 6 (result) |
| * - JZ finish (ZF==1 if leadByte==0xff) |
| * - SUB AX, BX (result) |
| * -finish: |
| * (BSR: Bit Scan Reverse, scans for a 1-bit, starting from the MSB) |
| */ |
| U_CAPI uint8_t U_EXPORT2 |
| utf8_countTrailBytes[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, |
| 0, 0 /* illegal bytes 0xfe and 0xff */ |
| }; |
| |
| static UChar32 |
| utf8_minRegular[4]={ 0, 0x80, 0x800, 0x10000 }; |
| |
| static UChar32 |
| utf8_errorValue[6]={ |
| UTF8_ERROR_VALUE_1, UTF8_ERROR_VALUE_2, UTF_ERROR_VALUE, 0x10ffff, |
| 0x3ffffff, 0x7fffffff |
| }; |
| |
| U_CAPI UChar32 U_EXPORT2 |
| utf8_nextCharSafeBody(const uint8_t *s, UTextOffset *pi, UTextOffset length, UChar32 c, UBool strict) { |
| UTextOffset i=*pi; |
| uint8_t count=UTF8_COUNT_TRAIL_BYTES(c); |
| if((i)+count<=(length)) { |
| uint8_t trail, illegal=0; |
| |
| UTF8_MASK_LEAD_BYTE((c), count); |
| /* count==0 for illegally leading trail bytes and the illegal bytes 0xfe and 0xff */ |
| switch(count) { |
| /* each branch falls through to the next one */ |
| case 5: |
| trail=s[(i)++]; |
| (c)=((c)<<6)|(trail&0x3f); |
| illegal|=(trail&0xc0)^0x80; |
| case 4: |
| trail=s[(i)++]; |
| (c)=((c)<<6)|(trail&0x3f); |
| illegal|=(trail&0xc0)^0x80; |
| case 3: |
| trail=s[(i)++]; |
| (c)=((c)<<6)|(trail&0x3f); |
| if(c<0x110) { |
| illegal|=(trail&0xc0)^0x80; |
| } else { |
| /* code point>0x10ffff, outside Unicode */ |
| i+=2; |
| illegal=1; |
| break; |
| } |
| case 2: |
| trail=s[(i)++]; |
| (c)=((c)<<6)|(trail&0x3f); |
| illegal|=(trail&0xc0)^0x80; |
| case 1: |
| trail=s[(i)++]; |
| (c)=((c)<<6)|(trail&0x3f); |
| illegal|=(trail&0xc0)^0x80; |
| break; |
| case 0: |
| illegal=1; |
| /* no default branch to optimize switch() - all values are covered */ |
| break; |
| } |
| |
| /* |
| * All the error handling should return a value |
| * that needs count bytes so that UTF8_GET_CHAR_SAFE() works right. |
| */ |
| |
| /* correct sequence - all trail bytes have (b7..b6)==(10)? */ |
| if(illegal) { |
| /* error handling */ |
| uint8_t errorCount=count; |
| /* don't go beyond this sequence */ |
| (i)-=count; |
| while(count>0 && UTF8_IS_TRAIL(s[i])) { |
| ++(i); |
| --count; |
| } |
| c=utf8_errorValue[errorCount-count]; |
| } else if((strict) && |
| (UTF_IS_SURROGATE(c) || |
| count>=4 || (c)<utf8_minRegular[count] || |
| ((c)&0xfffe)==0xfffe) |
| ) { |
| /* irregular sequence */ |
| c=utf8_errorValue[count]; |
| } |
| } else /* too few bytes left */ { |
| /* error handling */ |
| UTextOffset i0=i; |
| /* don't just set (i)=(length) in case there is an illegal sequence */ |
| while((i)<(length) && UTF8_IS_TRAIL(s[i])) { |
| ++(i); |
| } |
| c=utf8_errorValue[i-i0]; |
| } |
| *pi=i; |
| return c; |
| } |
| |
| U_CAPI UTextOffset U_EXPORT2 |
| utf8_appendCharSafeBody(uint8_t *s, UTextOffset i, UTextOffset length, UChar32 c) { |
| if((c)<=0x7ff) { |
| if((i)+1<(length)) { |
| (s)[(i)++]=(uint8_t)((c)>>6)|0xc0; |
| (s)[(i)++]=(uint8_t)(c)&0x3f|0x80; |
| return i; |
| } |
| } else if((uint32_t)(c)<=0xffff) { |
| if((i)+2<(length)) { |
| (s)[(i)++]=(uint8_t)((c)>>12)|0xe0; |
| (s)[(i)++]=(uint8_t)((c)>>6)&0x3f|0x80; |
| (s)[(i)++]=(uint8_t)(c)&0x3f|0x80; |
| return i; |
| } |
| } else if((uint32_t)(c)<=0x10ffff) { |
| if((i)+3<(length)) { |
| (s)[(i)++]=(uint8_t)((c)>>18)|0xf0; |
| (s)[(i)++]=(uint8_t)((c)>>12)&0x3f|0x80; |
| (s)[(i)++]=(uint8_t)((c)>>6)&0x3f|0x80; |
| (s)[(i)++]=(uint8_t)(c)&0x3f|0x80; |
| return i; |
| } |
| } |
| /* c>0x10ffff or not enough space, write an error value */ |
| length-=i; |
| if(length>0) { |
| if(length>3) { |
| length=3; |
| } |
| s+=i; |
| c=utf8_errorValue[length-1]; |
| UTF8_APPEND_CHAR_SAFE(s, i, length, c); |
| } |
| return i; |
| } |
| |
| U_CAPI UChar32 U_EXPORT2 |
| utf8_prevCharSafeBody(const uint8_t *s, UTextOffset start, UTextOffset *pi, UChar32 c, UBool strict) { |
| UTextOffset i=*pi; |
| uint8_t b, count=1, shift=6; |
| |
| /* extract value bits from the last trail byte */ |
| c&=0x3f; |
| |
| for(;;) { |
| if(i<=start) { |
| /* no lead byte at all */ |
| c=UTF8_ERROR_VALUE_1; |
| break; |
| } |
| |
| /* read another previous byte */ |
| b=s[--i]; |
| if((uint8_t)(b-0x80)<0x7e) { /* 0x80<=b<0xfe */ |
| if(b&0x40) { |
| /* lead byte, this will always end the loop */ |
| uint8_t shouldCount=UTF8_COUNT_TRAIL_BYTES(b); |
| |
| if(count==shouldCount) { |
| /* set the new position */ |
| *pi=i; |
| UTF8_MASK_LEAD_BYTE(b, count); |
| c|=(UChar32)b<<shift; |
| if( c>0x10ffff || |
| (strict) && |
| (UTF_IS_SURROGATE(c) || |
| count>=4 || (c)<utf8_minRegular[count] || ((c)&0xfffe)==0xfffe) |
| ) { |
| /* irregular sequence */ |
| c=utf8_errorValue[count]; |
| } else { |
| /* exit with correct c */ |
| } |
| } else { |
| /* the lead byte does not match the number of trail bytes */ |
| /* only set the position to the lead byte if it would |
| include the trail byte that we started with */ |
| if(count<shouldCount) { |
| *pi=i; |
| c=utf8_errorValue[count]; |
| } else { |
| c=UTF8_ERROR_VALUE_1; |
| } |
| } |
| break; |
| } else if(count<5) { |
| /* trail byte */ |
| c|=(UChar32)(b&0x3f)<<shift; |
| ++count; |
| shift+=6; |
| } else { |
| /* more than 5 trail bytes is illegal */ |
| c=UTF8_ERROR_VALUE_1; |
| break; |
| } |
| } else { |
| /* single-byte character precedes trailing bytes */ |
| c=UTF8_ERROR_VALUE_1; |
| break; |
| } |
| } |
| return c; |
| } |
| |
| U_CAPI UTextOffset U_EXPORT2 |
| utf8_back1SafeBody(const uint8_t *s, UTextOffset start, UTextOffset i) { |
| /* i had been decremented once before the function call */ |
| UTextOffset I=i, Z; |
| uint8_t b; |
| |
| /* read at most the 6 bytes s[Z] to s[i], inclusively */ |
| if(I-5>start) { |
| Z=I-5; |
| } else { |
| Z=start; |
| } |
| |
| /* return I if the sequence starting there is long enough to include i */ |
| for(;;) { |
| b=s[I]; |
| if((uint8_t)(b-0x80)>=0x7e) { /* not 0x80<=b<0xfe */ |
| break; |
| } else if(b>=0xc0) { |
| if(UTF8_COUNT_TRAIL_BYTES(b)>=(i-I)) { |
| return I; |
| } else { |
| break; |
| } |
| } else if(Z<I) { |
| --I; |
| } else { |
| break; |
| } |
| } |
| |
| /* return i itself to be consistent with the FWD_1 macro */ |
| return i; |
| } |
