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Diffstat (limited to 'deps/icu-small/source/common/utf_impl.c')
| -rw-r--r-- | deps/icu-small/source/common/utf_impl.c | 326 |
1 files changed, 326 insertions, 0 deletions
diff --git a/deps/icu-small/source/common/utf_impl.c b/deps/icu-small/source/common/utf_impl.c new file mode 100644 index 0000000000..a1f43b9465 --- /dev/null +++ b/deps/icu-small/source/common/utf_impl.c @@ -0,0 +1,326 @@ +/* +****************************************************************************** +* +* Copyright (C) 1999-2012, 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" +#include "unicode/utf.h" +#include "unicode/utf8.h" +#include "unicode/utf_old.h" +#include "uassert.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 +}; + +static UChar32 +errorValue(int32_t count, int8_t strict) { + if(strict>=0) { + return utf8_errorValue[count]; + } else if(strict==-3) { + return 0xfffd; + } else { + return U_SENTINEL; + } +} + +/* + * Handle the non-inline part of the U8_NEXT() and U8_NEXT_FFFD() macros + * and their obsolete sibling UTF8_NEXT_CHAR_SAFE(). + * + * U8_NEXT() supports NUL-terminated strings indicated via length<0. + * + * The "strict" parameter controls the error behavior: + * <0 "Safe" behavior of U8_NEXT(): + * -1: All illegal byte sequences yield U_SENTINEL=-1. + * -2: Same as -1, except 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. + * -3: All illegal byte sequences yield U+FFFD. + * 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. + * + * 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=U8_COUNT_TRAIL_BYTES(c); + U_ASSERT(count <= 5); /* U8_COUNT_TRAIL_BYTES returns value 0...5 */ + if(i+count<=length || length<0) { + uint8_t trail; + + U8_MASK_LEAD_BYTE(c, count); + /* support NUL-terminated strings: do not read beyond the first non-trail byte */ + switch(count) { + /* each branch falls through to the next one */ + case 0: + /* count==0 for illegally leading trail bytes and the illegal bytes 0xfe and 0xff */ + case 5: + case 4: + /* count>=4 is always illegal: no more than 3 trail bytes in Unicode's UTF-8 */ + break; + case 3: + trail=s[i++]-0x80; + c=(c<<6)|trail; + /* c>=0x110 would result in code point>0x10ffff, outside Unicode */ + if(c>=0x110 || trail>0x3f) { break; } + case 2: + trail=s[i++]-0x80; + c=(c<<6)|trail; + /* + * test for a surrogate d800..dfff unless we are lenient: + * before the last (c<<6), a surrogate is c=360..37f + */ + if(((c&0xffe0)==0x360 && strict!=-2) || trail>0x3f) { break; } + case 1: + trail=s[i++]-0x80; + c=(c<<6)|trail; + if(trail>0x3f) { break; } + /* correct sequence - all trail bytes have (b7..b6)==(10) */ + if(c>=utf8_minLegal[count] && + /* strict: forbid non-characters like U+fffe */ + (strict<=0 || !U_IS_UNICODE_NONCHAR(c))) { + *pi=i; + return c; + } + /* no default branch to optimize switch() - all values are covered */ + } + } else { + /* too few bytes left */ + count=length-i; + } + + /* error handling */ + i=*pi; + while(count>0 && U8_IS_TRAIL(s[i])) { + ++i; + --count; + } + c=errorValue(i-*pi, strict); + *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; + + if(!U8_IS_TRAIL(c)) { return errorValue(0, strict); } + + /* extract value bits from the last trail byte */ + c&=0x3f; + + for(;;) { + if(i<=start) { + /* no lead byte at all */ + return errorValue(0, strict); + } + + /* 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=U8_COUNT_TRAIL_BYTES(b); + + if(count==shouldCount) { + /* set the new position */ + *pi=i; + U8_MASK_LEAD_BYTE(b, count); + c|=(UChar32)b<<shift; + if(count>=4 || c>0x10ffff || c<utf8_minLegal[count] || (U_IS_SURROGATE(c) && strict!=-2) || (strict>0 && U_IS_UNICODE_NONCHAR(c))) { + /* illegal sequence or (strict and non-character) */ + if(count>=4) { + count=3; + } + c=errorValue(count, strict); + } 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=errorValue(count, strict); + } else { + c=errorValue(0, strict); + } + } + break; + } else if(count<5) { + /* trail byte */ + c|=(UChar32)(b&0x3f)<<shift; + ++count; + shift+=6; + } else { + /* more than 5 trail bytes is illegal */ + c=errorValue(0, strict); + break; + } + } else { + /* single-byte character precedes trailing bytes */ + c=errorValue(0, strict); + 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(U8_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; +} |