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Diffstat (limited to 'src/pkg/runtime/rune.c')
| -rw-r--r-- | src/pkg/runtime/rune.c | 224 |
1 files changed, 224 insertions, 0 deletions
diff --git a/src/pkg/runtime/rune.c b/src/pkg/runtime/rune.c new file mode 100644 index 000000000..86ee76ddd --- /dev/null +++ b/src/pkg/runtime/rune.c @@ -0,0 +1,224 @@ +/* + * The authors of this software are Rob Pike and Ken Thompson. + * Copyright (c) 2002 by Lucent Technologies. + * Portions Copyright 2009 The Go Authors. All rights reserved. + * Permission to use, copy, modify, and distribute this software for any + * purpose without fee is hereby granted, provided that this entire notice + * is included in all copies of any software which is or includes a copy + * or modification of this software and in all copies of the supporting + * documentation for such software. + * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED + * WARRANTY. IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES MAKE ANY + * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY + * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE. + */ + +/* + * This code is copied, with slight editing due to type differences, + * from a subset of ../lib9/utf/rune.c + */ + +#include "runtime.h" + +enum +{ + Bit1 = 7, + Bitx = 6, + Bit2 = 5, + Bit3 = 4, + Bit4 = 3, + Bit5 = 2, + + T1 = ((1<<(Bit1+1))-1) ^ 0xFF, /* 0000 0000 */ + Tx = ((1<<(Bitx+1))-1) ^ 0xFF, /* 1000 0000 */ + T2 = ((1<<(Bit2+1))-1) ^ 0xFF, /* 1100 0000 */ + T3 = ((1<<(Bit3+1))-1) ^ 0xFF, /* 1110 0000 */ + T4 = ((1<<(Bit4+1))-1) ^ 0xFF, /* 1111 0000 */ + T5 = ((1<<(Bit5+1))-1) ^ 0xFF, /* 1111 1000 */ + + Rune1 = (1<<(Bit1+0*Bitx))-1, /* 0000 0000 0111 1111 */ + Rune2 = (1<<(Bit2+1*Bitx))-1, /* 0000 0111 1111 1111 */ + Rune3 = (1<<(Bit3+2*Bitx))-1, /* 1111 1111 1111 1111 */ + Rune4 = (1<<(Bit4+3*Bitx))-1, /* 0001 1111 1111 1111 1111 1111 */ + + Maskx = (1<<Bitx)-1, /* 0011 1111 */ + Testx = Maskx ^ 0xFF, /* 1100 0000 */ + + Runeerror = 0xFFFD, + Runeself = 0x80, + + Bad = Runeerror, + + Runemax = 0x10FFFF, /* maximum rune value */ +}; + +/* + * Modified by Wei-Hwa Huang, Google Inc., on 2004-09-24 + * This is a slower but "safe" version of the old chartorune + * that works on strings that are not necessarily null-terminated. + * + * If you know for sure that your string is null-terminated, + * chartorune will be a bit faster. + * + * It is guaranteed not to attempt to access "length" + * past the incoming pointer. This is to avoid + * possible access violations. If the string appears to be + * well-formed but incomplete (i.e., to get the whole Rune + * we'd need to read past str+length) then we'll set the Rune + * to Bad and return 0. + * + * Note that if we have decoding problems for other + * reasons, we return 1 instead of 0. + */ +int32 +runtime·charntorune(int32 *rune, uint8 *str, int32 length) +{ + int32 c, c1, c2, c3, l; + + /* When we're not allowed to read anything */ + if(length <= 0) { + goto badlen; + } + + /* + * one character sequence (7-bit value) + * 00000-0007F => T1 + */ + c = *(uint8*)str; + if(c < Tx) { + *rune = c; + return 1; + } + + // If we can't read more than one character we must stop + if(length <= 1) { + goto badlen; + } + + /* + * two character sequence (11-bit value) + * 0080-07FF => T2 Tx + */ + c1 = *(uint8*)(str+1) ^ Tx; + if(c1 & Testx) + goto bad; + if(c < T3) { + if(c < T2) + goto bad; + l = ((c << Bitx) | c1) & Rune2; + if(l <= Rune1) + goto bad; + *rune = l; + return 2; + } + + // If we can't read more than two characters we must stop + if(length <= 2) { + goto badlen; + } + + /* + * three character sequence (16-bit value) + * 0800-FFFF => T3 Tx Tx + */ + c2 = *(uint8*)(str+2) ^ Tx; + if(c2 & Testx) + goto bad; + if(c < T4) { + l = ((((c << Bitx) | c1) << Bitx) | c2) & Rune3; + if(l <= Rune2) + goto bad; + *rune = l; + return 3; + } + + if (length <= 3) + goto badlen; + + /* + * four character sequence (21-bit value) + * 10000-1FFFFF => T4 Tx Tx Tx + */ + c3 = *(uint8*)(str+3) ^ Tx; + if (c3 & Testx) + goto bad; + if (c < T5) { + l = ((((((c << Bitx) | c1) << Bitx) | c2) << Bitx) | c3) & Rune4; + if (l <= Rune3 || l > Runemax) + goto bad; + *rune = l; + return 4; + } + + // Support for 5-byte or longer UTF-8 would go here, but + // since we don't have that, we'll just fall through to bad. + + /* + * bad decoding + */ +bad: + *rune = Bad; + return 1; +badlen: + // was return 0, but return 1 is more convenient for the runtime. + *rune = Bad; + return 1; + +} + +int32 +runtime·runetochar(byte *str, int32 rune) /* note: in original, arg2 was pointer */ +{ + /* Runes are signed, so convert to unsigned for range check. */ + uint32 c; + + /* + * one character sequence + * 00000-0007F => 00-7F + */ + c = rune; + if(c <= Rune1) { + str[0] = c; + return 1; + } + + /* + * two character sequence + * 0080-07FF => T2 Tx + */ + if(c <= Rune2) { + str[0] = T2 | (c >> 1*Bitx); + str[1] = Tx | (c & Maskx); + return 2; + } + + /* + * If the Rune is out of range, convert it to the error rune. + * Do this test here because the error rune encodes to three bytes. + * Doing it earlier would duplicate work, since an out of range + * Rune wouldn't have fit in one or two bytes. + */ + if (c > Runemax) + c = Runeerror; + + /* + * three character sequence + * 0800-FFFF => T3 Tx Tx + */ + if (c <= Rune3) { + str[0] = T3 | (c >> 2*Bitx); + str[1] = Tx | ((c >> 1*Bitx) & Maskx); + str[2] = Tx | (c & Maskx); + return 3; + } + + /* + * four character sequence (21-bit value) + * 10000-1FFFFF => T4 Tx Tx Tx + */ + str[0] = T4 | (c >> 3*Bitx); + str[1] = Tx | ((c >> 2*Bitx) & Maskx); + str[2] = Tx | ((c >> 1*Bitx) & Maskx); + str[3] = Tx | (c & Maskx); + return 4; +} |