/* ****************************************************************************** * * Copyright (C) 1999-2006, 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. */ /* set import/export definitions */ #ifndef U_UTF8_IMPL # define U_UTF8_IMPL #endif #include "unicode/utypes.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) * * In Unicode, all UTF-8 byte sequences with more than 4 bytes are illegal; * lead bytes above 0xf4 are illegal. * We keep them in this table for skipping long ISO 10646-UTF-8 sequences. */ U_EXPORT const uint8_t 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, /* illegal in Unicode */ 4, 4, 4, 4, /* illegal in Unicode */ 5, 5, /* illegal in Unicode */ 0, 0 /* illegal bytes 0xfe and 0xff */ }; static const UChar32 utf8_minLegal[4]={ 0, 0x80, 0x800, 0x10000 }; static const UChar32 utf8_errorValue[6]={ UTF8_ERROR_VALUE_1, UTF8_ERROR_VALUE_2, UTF_ERROR_VALUE, 0x10ffff, 0x3ffffff, 0x7fffffff }; /* * Handle the non-inline part of the U8_NEXT() macro and its obsolete sibling * UTF8_NEXT_CHAR_SAFE(). * * The "strict" parameter controls the error behavior: * <0 "Safe" behavior of U8_NEXT(): All illegal byte sequences yield a negative * code point result. * 0 Obsolete "safe" behavior of UTF8_NEXT_CHAR_SAFE(..., FALSE): * All illegal byte sequences yield a positive code point such that this * result code point would be encoded with the same number of bytes as * the illegal sequence. * >0 Obsolete "strict" behavior of UTF8_NEXT_CHAR_SAFE(..., TRUE): * Same as the obsolete "safe" behavior, but non-characters are also treated * like illegal sequences. * * The special negative (<0) value -2 is used for lenient treatment of surrogate * code points as legal. Some implementations use this for roundtripping of * Unicode 16-bit strings that are not well-formed UTF-16, that is, they * contain unpaired surrogates. * * Note that a UBool is the same as an int8_t. */ U_CAPI UChar32 U_EXPORT2 utf8_nextCharSafeBody(const uint8_t *s, int32_t *pi, int32_t length, UChar32 c, UBool strict) { int32_t 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: case 4: /* count>=4 is always illegal: no more than 3 trail bytes in Unicode's UTF-8 */ illegal=1; break; case 3: trail=s[(i)++]; (c)=((c)<<6)|(trail&0x3f); if(c<0x110) { illegal|=(trail&0xc0)^0x80; } else { /* code point>0x10ffff, outside Unicode */ 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: if(strict>=0) { return UTF8_ERROR_VALUE_1; } else { return U_SENTINEL; } /* no default branch to optimize switch() - all values are covered */ } /* * All the error handling should return a value * that needs count bytes so that UTF8_GET_CHAR_SAFE() works right. * * Starting with Unicode 3.0.1, non-shortest forms are illegal. * Starting with Unicode 3.2, surrogate code points must not be * encoded in UTF-8, and there are no irregular sequences any more. * * U8_ macros (new in ICU 2.4) return negative values for error conditions. */ /* correct sequence - all trail bytes have (b7..b6)==(10)? */ /* illegal is also set if count>=4 */ if(illegal || (c)0 && UTF8_IS_TRAIL(s[i])) { ++(i); --count; } if(strict>=0) { c=utf8_errorValue[errorCount-count]; } else { c=U_SENTINEL; } } else if((strict)>0 && UTF_IS_UNICODE_NONCHAR(c)) { /* strict: forbid non-characters like U+fffe */ c=utf8_errorValue[count]; } } else /* too few bytes left */ { /* error handling */ int32_t i0=i; /* don't just set (i)=(length) in case there is an illegal sequence */ while((i)<(length) && UTF8_IS_TRAIL(s[i])) { ++(i); } if(strict>=0) { c=utf8_errorValue[i-i0]; } else { c=U_SENTINEL; } } *pi=i; return c; } U_CAPI int32_t U_EXPORT2 utf8_appendCharSafeBody(uint8_t *s, int32_t i, int32_t length, UChar32 c, UBool *pIsError) { if((uint32_t)(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) { /* Starting with Unicode 3.2, surrogate code points must not be encoded in UTF-8. */ if((i)+2<(length) && !U_IS_SURROGATE(c)) { (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 */ if(pIsError!=NULL) { *pIsError=TRUE; } else { length-=i; if(length>0) { int32_t offset; if(length>3) { length=3; } s+=i; offset=0; c=utf8_errorValue[length-1]; UTF8_APPEND_CHAR_UNSAFE(s, offset, c); i=i+offset; } } return i; } U_CAPI UChar32 U_EXPORT2 utf8_prevCharSafeBody(const uint8_t *s, int32_t start, int32_t *pi, UChar32 c, UBool strict) { int32_t 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 */ if(strict>=0) { return UTF8_ERROR_VALUE_1; } else { return U_SENTINEL; } /*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<=4 || c>0x10ffff || c0 && UTF_IS_UNICODE_NONCHAR(c))) { /* illegal sequence or (strict and non-character) */ if(count>=4) { count=3; } if(strict>=0) { c=utf8_errorValue[count]; } else { c=U_SENTINEL; } } 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=0) { c=utf8_errorValue[count]; } else { c=U_SENTINEL; } } else { if(strict>=0) { c=UTF8_ERROR_VALUE_1; } else { c=U_SENTINEL; } } } break; } else if(count<5) { /* trail byte */ c|=(UChar32)(b&0x3f)<=0) { c=UTF8_ERROR_VALUE_1; } else { c=U_SENTINEL; } break; } } else { /* single-byte character precedes trailing bytes */ if(strict>=0) { c=UTF8_ERROR_VALUE_1; } else { c=U_SENTINEL; } break; } } return c; } U_CAPI int32_t U_EXPORT2 utf8_back1SafeBody(const uint8_t *s, int32_t start, int32_t i) { /* i had been decremented once before the function call */ int32_t 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 */ do { 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; } } } while(Z<=--I); /* return i itself to be consistent with the FWD_1 macro */ return i; }