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/*
* 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,
SurrogateMin = 0xD800,
SurrogateMax = 0xDFFF,
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;
if (SurrogateMin <= l && l <= SurrogateMax)
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 or a surrogate half, 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;
if (SurrogateMin <= c && c <= SurrogateMax)
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;
}
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