mirror of
https://github.com/tesseract-ocr/tesseract.git
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358 lines
7.0 KiB
C
358 lines
7.0 KiB
C
/*
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* The authors of this software are Rob Pike and Ken Thompson.
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* Copyright (c) 2002 by Lucent Technologies.
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* Permission to use, copy, modify, and distribute this software for any
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* purpose without fee is hereby granted, provided that this entire notice
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* is included in all copies of any software which is or includes a copy
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* or modification of this software and in all copies of the supporting
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* documentation for such software.
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* THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
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* WARRANTY. IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES MAKE ANY
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* REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
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* OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
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*/
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#include <stdarg.h>
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#include <string.h>
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#include "third_party/utf/utf.h"
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#include "third_party/utf/utfdef.h"
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enum
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{
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Bit1 = 7,
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Bitx = 6,
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Bit2 = 5,
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Bit3 = 4,
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Bit4 = 3,
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Bit5 = 2,
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T1 = ((1<<(Bit1+1))-1) ^ 0xFF, /* 0000 0000 */
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Tx = ((1<<(Bitx+1))-1) ^ 0xFF, /* 1000 0000 */
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T2 = ((1<<(Bit2+1))-1) ^ 0xFF, /* 1100 0000 */
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T3 = ((1<<(Bit3+1))-1) ^ 0xFF, /* 1110 0000 */
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T4 = ((1<<(Bit4+1))-1) ^ 0xFF, /* 1111 0000 */
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T5 = ((1<<(Bit5+1))-1) ^ 0xFF, /* 1111 1000 */
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Rune1 = (1<<(Bit1+0*Bitx))-1, /* 0000 0000 0111 1111 */
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Rune2 = (1<<(Bit2+1*Bitx))-1, /* 0000 0111 1111 1111 */
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Rune3 = (1<<(Bit3+2*Bitx))-1, /* 1111 1111 1111 1111 */
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Rune4 = (1<<(Bit4+3*Bitx))-1,
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/* 0001 1111 1111 1111 1111 1111 */
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Maskx = (1<<Bitx)-1, /* 0011 1111 */
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Testx = Maskx ^ 0xFF, /* 1100 0000 */
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Bad = Runeerror,
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};
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/*
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* Modified by Wei-Hwa Huang, Google Inc., on 2004-09-24
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* This is a slower but "safe" version of the old chartorune
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* that works on strings that are not necessarily null-terminated.
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*
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* If you know for sure that your string is null-terminated,
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* chartorune will be a bit faster.
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*
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* It is guaranteed not to attempt to access "length"
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* past the incoming pointer. This is to avoid
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* possible access violations. If the string appears to be
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* well-formed but incomplete (i.e., to get the whole Rune
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* we'd need to read past str+length) then we'll set the Rune
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* to Bad and return 0.
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*
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* Note that if we have decoding problems for other
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* reasons, we return 1 instead of 0.
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*/
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int
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charntorune(Rune *rune, const char *str, int length)
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{
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int c, c1, c2, c3;
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long l;
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/* When we're not allowed to read anything */
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if(length <= 0) {
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goto badlen;
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}
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/*
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* one character sequence (7-bit value)
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* 00000-0007F => T1
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*/
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c = *(uchar*)str;
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if(c < Tx) {
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*rune = c;
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return 1;
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}
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// If we can't read more than one character we must stop
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if(length <= 1) {
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goto badlen;
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}
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/*
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* two character sequence (11-bit value)
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* 0080-07FF => T2 Tx
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*/
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c1 = *(uchar*)(str+1) ^ Tx;
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if(c1 & Testx)
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goto bad;
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if(c < T3) {
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if(c < T2)
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goto bad;
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l = ((c << Bitx) | c1) & Rune2;
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if(l <= Rune1)
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goto bad;
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*rune = l;
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return 2;
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}
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// If we can't read more than two characters we must stop
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if(length <= 2) {
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goto badlen;
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}
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/*
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* three character sequence (16-bit value)
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* 0800-FFFF => T3 Tx Tx
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*/
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c2 = *(uchar*)(str+2) ^ Tx;
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if(c2 & Testx)
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goto bad;
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if(c < T4) {
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l = ((((c << Bitx) | c1) << Bitx) | c2) & Rune3;
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if(l <= Rune2)
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goto bad;
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*rune = l;
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return 3;
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}
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if (length <= 3)
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goto badlen;
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/*
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* four character sequence (21-bit value)
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* 10000-1FFFFF => T4 Tx Tx Tx
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*/
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c3 = *(uchar*)(str+3) ^ Tx;
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if (c3 & Testx)
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goto bad;
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if (c < T5) {
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l = ((((((c << Bitx) | c1) << Bitx) | c2) << Bitx) | c3) & Rune4;
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if (l <= Rune3)
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goto bad;
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if (l > Runemax)
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goto bad;
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*rune = l;
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return 4;
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}
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// Support for 5-byte or longer UTF-8 would go here, but
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// since we don't have that, we'll just fall through to bad.
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/*
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* bad decoding
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*/
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bad:
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*rune = Bad;
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return 1;
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badlen:
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*rune = Bad;
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return 0;
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}
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/*
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* This is the older "unsafe" version, which works fine on
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* null-terminated strings.
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*/
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int
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chartorune(Rune *rune, const char *str)
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{
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int c, c1, c2, c3;
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long l;
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/*
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* one character sequence
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* 00000-0007F => T1
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*/
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c = *(uchar*)str;
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if(c < Tx) {
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*rune = c;
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return 1;
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}
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/*
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* two character sequence
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* 0080-07FF => T2 Tx
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*/
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c1 = *(uchar*)(str+1) ^ Tx;
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if(c1 & Testx)
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goto bad;
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if(c < T3) {
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if(c < T2)
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goto bad;
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l = ((c << Bitx) | c1) & Rune2;
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if(l <= Rune1)
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goto bad;
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*rune = l;
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return 2;
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}
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/*
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* three character sequence
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* 0800-FFFF => T3 Tx Tx
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*/
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c2 = *(uchar*)(str+2) ^ Tx;
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if(c2 & Testx)
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goto bad;
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if(c < T4) {
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l = ((((c << Bitx) | c1) << Bitx) | c2) & Rune3;
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if(l <= Rune2)
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goto bad;
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*rune = l;
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return 3;
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}
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/*
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* four character sequence (21-bit value)
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* 10000-1FFFFF => T4 Tx Tx Tx
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*/
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c3 = *(uchar*)(str+3) ^ Tx;
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if (c3 & Testx)
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goto bad;
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if (c < T5) {
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l = ((((((c << Bitx) | c1) << Bitx) | c2) << Bitx) | c3) & Rune4;
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if (l <= Rune3)
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goto bad;
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if (l > Runemax)
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goto bad;
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*rune = l;
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return 4;
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}
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/*
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* Support for 5-byte or longer UTF-8 would go here, but
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* since we don't have that, we'll just fall through to bad.
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*/
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/*
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* bad decoding
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*/
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bad:
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*rune = Bad;
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return 1;
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}
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int
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isvalidcharntorune(const char* str, int length, Rune* rune, int* consumed) {
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*consumed = charntorune(rune, str, length);
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return *rune != Runeerror || *consumed == 3;
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}
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int
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runetochar(char *str, const Rune *rune)
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{
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/* Runes are signed, so convert to unsigned for range check. */
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unsigned long c;
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/*
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* one character sequence
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* 00000-0007F => 00-7F
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*/
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c = *rune;
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if(c <= Rune1) {
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str[0] = c;
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return 1;
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}
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/*
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* two character sequence
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* 0080-07FF => T2 Tx
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*/
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if(c <= Rune2) {
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str[0] = T2 | (c >> 1*Bitx);
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str[1] = Tx | (c & Maskx);
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return 2;
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}
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/*
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* If the Rune is out of range, convert it to the error rune.
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* Do this test here because the error rune encodes to three bytes.
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* Doing it earlier would duplicate work, since an out of range
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* Rune wouldn't have fit in one or two bytes.
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*/
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if (c > Runemax)
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c = Runeerror;
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/*
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* three character sequence
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* 0800-FFFF => T3 Tx Tx
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*/
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if (c <= Rune3) {
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str[0] = T3 | (c >> 2*Bitx);
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str[1] = Tx | ((c >> 1*Bitx) & Maskx);
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str[2] = Tx | (c & Maskx);
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return 3;
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}
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/*
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* four character sequence (21-bit value)
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* 10000-1FFFFF => T4 Tx Tx Tx
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*/
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str[0] = T4 | (c >> 3*Bitx);
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str[1] = Tx | ((c >> 2*Bitx) & Maskx);
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str[2] = Tx | ((c >> 1*Bitx) & Maskx);
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str[3] = Tx | (c & Maskx);
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return 4;
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}
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int
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runelen(Rune rune)
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{
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char str[10];
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return runetochar(str, &rune);
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}
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int
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runenlen(const Rune *r, int nrune)
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{
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int nb;
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ulong c; /* Rune is signed, so use unsigned for range check. */
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nb = 0;
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while(nrune--) {
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c = *r++;
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if (c <= Rune1)
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nb++;
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else if (c <= Rune2)
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nb += 2;
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else if (c <= Rune3)
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nb += 3;
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else if (c <= Runemax)
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nb += 4;
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else
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nb += 3; /* Runeerror = 0xFFFD, see runetochar */
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}
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return nb;
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}
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int
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fullrune(const char *str, int n)
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{
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if (n > 0) {
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int c = *(uchar*)str;
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if (c < Tx)
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return 1;
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if (n > 1) {
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if (c < T3)
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return 1;
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if (n > 2) {
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if (c < T4 || n > 3)
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return 1;
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}
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}
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}
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return 0;
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}
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