/* ****************************************************************************** * * 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. */ #include "base/third_party/icu/icu_utf.h" namespace base_icu { /** * UTF8_ERROR_VALUE_1 and UTF8_ERROR_VALUE_2 are special error values for UTF-8, * which need 1 or 2 bytes in UTF-8: * \code * U+0015 = NAK = Negative Acknowledge, C0 control character * U+009f = highest C1 control character * \endcode * * These are used by UTF8_..._SAFE macros so that they can return an error value * that needs the same number of code units (bytes) as were seen by * a macro. They should be tested with UTF_IS_ERROR() or UTF_IS_VALID(). * * @deprecated ICU 2.4. Obsolete, see utf_old.h. */ #define CBUTF8_ERROR_VALUE_1 0x15 /** * See documentation on UTF8_ERROR_VALUE_1 for details. * * @deprecated ICU 2.4. Obsolete, see utf_old.h. */ #define CBUTF8_ERROR_VALUE_2 0x9f /** * Error value for all UTFs. This code point value will be set by macros with e> * checking if an error is detected. * * @deprecated ICU 2.4. Obsolete, see utf_old.h. */ #define CBUTF_ERROR_VALUE 0xffff /* * 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. */ 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]={ CBUTF8_ERROR_VALUE_1, CBUTF8_ERROR_VALUE_2, CBUTF_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. */ UChar32 utf8_nextCharSafeBody(const uint8_t* s, int32_t* pi, int32_t length, UChar32 c, UBool strict) { int32_t i = *pi; uint8_t count = CBU8_COUNT_TRAIL_BYTES(c); if((i)+count<=(length)) { uint8_t trail, illegal = 0; CBU8_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 CBUTF8_ERROR_VALUE_1; } else { return CBU_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 && CBU8_IS_TRAIL(s[i])) { ++(i); --count; } if(strict>=0) { c=utf8_errorValue[errorCount-count]; } else { c=CBU_SENTINEL; } } else if((strict)>0 && CBU_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) && CBU8_IS_TRAIL(s[i])) { ++(i); } if(strict>=0) { c=utf8_errorValue[i-i0]; } else { c=CBU_SENTINEL; } } *pi=i; return c; } } // namespace base_icu