/src/xpdf-4.06/xpdf/JArithmeticDecoder.cc

Source
//========================================================================
//
// JArithmeticDecoder.cc
//
// Copyright 2002-2004 Glyph & Cog, LLC
//
//========================================================================

#include <aconf.h>

#include "gmempp.h"
#include "Object.h"
#include "Stream.h"
#include "JArithmeticDecoder.h"

//------------------------------------------------------------------------
// JArithmeticDecoderStates
//------------------------------------------------------------------------

JArithmeticDecoderStats::JArithmeticDecoderStats(int contextSizeA) {
  contextSize = contextSizeA;
  cxTab = (Guchar *)gmallocn(contextSize, sizeof(Guchar));
  reset();
}

JArithmeticDecoderStats::~JArithmeticDecoderStats() {
  gfree(cxTab);
}

JArithmeticDecoderStats *JArithmeticDecoderStats::copy() {
  JArithmeticDecoderStats *stats;

  stats = new JArithmeticDecoderStats(contextSize);
  memcpy(stats->cxTab, cxTab, contextSize);
  return stats;
}

void JArithmeticDecoderStats::reset() {
  memset(cxTab, 0, contextSize);
}

void JArithmeticDecoderStats::copyFrom(JArithmeticDecoderStats *stats) {
  memcpy(cxTab, stats->cxTab, contextSize);
}

void JArithmeticDecoderStats::setEntry(Guint cx, int i, int mps) {
  cxTab[cx] = (Guchar)((i << 1) + mps);
}

//------------------------------------------------------------------------
// JArithmeticDecoder
//------------------------------------------------------------------------

Guint JArithmeticDecoder::qeTab[47] = {
  0x56010000, 0x34010000, 0x18010000, 0x0AC10000,
  0x05210000, 0x02210000, 0x56010000, 0x54010000,
  0x48010000, 0x38010000, 0x30010000, 0x24010000,
  0x1C010000, 0x16010000, 0x56010000, 0x54010000,
  0x51010000, 0x48010000, 0x38010000, 0x34010000,
  0x30010000, 0x28010000, 0x24010000, 0x22010000,
  0x1C010000, 0x18010000, 0x16010000, 0x14010000,
  0x12010000, 0x11010000, 0x0AC10000, 0x09C10000,
  0x08A10000, 0x05210000, 0x04410000, 0x02A10000,
  0x02210000, 0x01410000, 0x01110000, 0x00850000,
  0x00490000, 0x00250000, 0x00150000, 0x00090000,
  0x00050000, 0x00010000, 0x56010000
};

int JArithmeticDecoder::nmpsTab[47] = {
   1,  2,  3,  4,  5, 38,  7,  8,  9, 10, 11, 12, 13, 29, 15, 16,
  17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32,
  33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 45, 46
};

int JArithmeticDecoder::nlpsTab[47] = {
   1,  6,  9, 12, 29, 33,  6, 14, 14, 14, 17, 18, 20, 21, 14, 14,
  15, 16, 17, 18, 19, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29,
  30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 46
};

int JArithmeticDecoder::switchTab[47] = {
  1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

JArithmeticDecoder::JArithmeticDecoder() {
  str = NULL;
  dataLen = 0;
  limitStream = gFalse;
  nBytesRead = 0;
  readBufNext = 0;
  readBufLength = 0;
}

inline Guint JArithmeticDecoder::readByte() {
  if (limitStream) {
    if (readBufNext < readBufLength) {
      return readBuf[readBufNext++];
    }
    --dataLen;
    if (dataLen < 0) {
      return 0xff;
    }
  }
  ++nBytesRead;
  return (Guint)str->getChar() & 0xff;
}

JArithmeticDecoder::~JArithmeticDecoder() {
  cleanup();
}

void JArithmeticDecoder::start() {
  buf0 = readByte();
  buf1 = readByte();

  // INITDEC
  c = (buf0 ^ 0xff) << 16;
  byteIn();
  c <<= 7;
  ct -= 7;
  a = 0x80000000;
}

void JArithmeticDecoder::restart(int dataLenA) {
  Guint cAdd;
  GBool prevFF;
  int k, nBits;

  if (dataLen >= 0) {
    dataLen = dataLenA;
  } else if (dataLen == -1) {
    dataLen = dataLenA;
    buf1 = readByte();
  } else {
    k = (-dataLen - 1) * 8 - ct;
    dataLen = dataLenA;
    cAdd = 0;
    prevFF = gFalse;
    while (k > 0) {
      buf0 = readByte();
      if (prevFF) {
  cAdd += 0xfe00 - (buf0 << 9);
  nBits = 7;
      } else {
  cAdd += 0xff00 - (buf0 << 8);
  nBits = 8;
      }
      prevFF = buf0 == 0xff;
      if (k > nBits) {
  cAdd <<= nBits;
  k -= nBits;
      } else {
  cAdd <<= k;
  ct = nBits - k;
  k = 0;
      }
    }
    c += cAdd;
    buf1 = readByte();
  }
}

void JArithmeticDecoder::cleanup() {
  if (limitStream) {
    // This saves up to sizeof(readBuf) extra bytes of data from the
    // end of packet i, to be used in packet i+1. It's not clear from
    // the JPEG 2000 spec exactly how this should work, but this
    // kludge does seem to fix decode of some problematic JPEG 2000
    // streams. The buffer may need to larger, but I haven't run into
    // that case. (And the buffer was originally just one byte, which
    // works for almost all cases.)
    readBufLength = 0;
    while (dataLen > 0) {
      if (readBufLength < (int)sizeof(readBuf)) {
  readBuf[readBufLength++] = (Guchar)str->getChar();
  ++nBytesRead;
      }
      --dataLen;
    }
    readBufNext = 0;
  }
}

int JArithmeticDecoder::decodeBit(Guint context,
          JArithmeticDecoderStats *stats) {
  int bit;
  Guint qe;
  int iCX, mpsCX;

  iCX = stats->cxTab[context] >> 1;
  mpsCX = stats->cxTab[context] & 1;
  qe = qeTab[iCX];
  a -= qe;
  if (c < a) {
    if (a & 0x80000000) {
      bit = mpsCX;
    } else {
      // MPS_EXCHANGE
      if (a < qe) {
  bit = 1 - mpsCX;
  if (switchTab[iCX]) {
    stats->cxTab[context] = (Guchar)((nlpsTab[iCX] << 1) | (1 - mpsCX));
  } else {
    stats->cxTab[context] = (Guchar)((nlpsTab[iCX] << 1) | mpsCX);
  }
      } else {
  bit = mpsCX;
  stats->cxTab[context] = (Guchar)((nmpsTab[iCX] << 1) | mpsCX);
      }
      // RENORMD
      do {
  if (ct == 0) {
    byteIn();
  }
  a <<= 1;
  c <<= 1;
  --ct;
      } while (!(a & 0x80000000));
    }
  } else {
    c -= a;
    // LPS_EXCHANGE
    if (a < qe) {
      bit = mpsCX;
      stats->cxTab[context] = (Guchar)((nmpsTab[iCX] << 1) | mpsCX);
    } else {
      bit = 1 - mpsCX;
      if (switchTab[iCX]) {
  stats->cxTab[context] = (Guchar)((nlpsTab[iCX] << 1) | (1 - mpsCX));
      } else {
  stats->cxTab[context] = (Guchar)((nlpsTab[iCX] << 1) | mpsCX);
      }
    }
    a = qe;
    // RENORMD
    do {
      if (ct == 0) {
  byteIn();
      }
      a <<= 1;
      c <<= 1;
      --ct;
    } while (!(a & 0x80000000));
  }
  return bit;
}

int JArithmeticDecoder::decodeByte(Guint context,
           JArithmeticDecoderStats *stats) {
  int byte;
  int i;

  byte = 0;
  for (i = 0; i < 8; ++i) {
    byte = (byte << 1) | decodeBit(context, stats);
  }
  return byte;
}

GBool JArithmeticDecoder::decodeInt(int *x, JArithmeticDecoderStats *stats) {
  int s;
  Guint v;
  int i;

  prev = 1;
  s = decodeIntBit(stats);
  if (decodeIntBit(stats)) {
    if (decodeIntBit(stats)) {
      if (decodeIntBit(stats)) {
  if (decodeIntBit(stats)) {
    if (decodeIntBit(stats)) {
      v = 0;
      for (i = 0; i < 32; ++i) {
        v = (v << 1) | decodeIntBit(stats);
      }
      v += 4436;
    } else {
      v = 0;
      for (i = 0; i < 12; ++i) {
        v = (v << 1) | decodeIntBit(stats);
      }
      v += 340;
    }
  } else {
    v = 0;
    for (i = 0; i < 8; ++i) {
      v = (v << 1) | decodeIntBit(stats);
    }
    v += 84;
  }
      } else {
  v = 0;
  for (i = 0; i < 6; ++i) {
    v = (v << 1) | decodeIntBit(stats);
  }
  v += 20;
      }
    } else {
      v = decodeIntBit(stats);
      v = (v << 1) | decodeIntBit(stats);
      v = (v << 1) | decodeIntBit(stats);
      v = (v << 1) | decodeIntBit(stats);
      v += 4;
    }
  } else {
    v = decodeIntBit(stats);
    v = (v << 1) | decodeIntBit(stats);
  }

  if (s) {
    if (v == 0) {
      return gFalse;
    }
    *x = -(int)v;
  } else {
    *x = (int)v;
  }
  return gTrue;
}

int JArithmeticDecoder::decodeIntBit(JArithmeticDecoderStats *stats) {
  int bit;

  bit = decodeBit(prev, stats);
  if (prev < 0x100) {
    prev = (prev << 1) | bit;
  } else {
    prev = (((prev << 1) | bit) & 0x1ff) | 0x100;
  }
  return bit;
}

Guint JArithmeticDecoder::decodeIAID(Guint codeLen,
             JArithmeticDecoderStats *stats) {
  Guint i;
  int bit;

  prev = 1;
  for (i = 0; i < codeLen; ++i) {
    bit = decodeBit(prev, stats);
    prev = (prev << 1) | bit;
  }
  return prev - (1 << codeLen);
}

void JArithmeticDecoder::byteIn() {
  if (buf0 == 0xff) {
    if (buf1 > 0x8f) {
      if (limitStream) {
  buf0 = buf1;
  buf1 = readByte();
  c = c + 0xff00 - (buf0 << 8);
      }
      ct = 8;
    } else {
      buf0 = buf1;
      buf1 = readByte();
      c = c + 0xfe00 - (buf0 << 9);
      ct = 7;
    }
  } else {
    buf0 = buf1;
    buf1 = readByte();
    c = c + 0xff00 - (buf0 << 8);
    ct = 8;
  }
}

Coverage Report

Created: 2026-08-13 06:56

Line	Count	Source
1		//========================================================================
2		//
3		// JArithmeticDecoder.cc
4		//
5		// Copyright 2002-2004 Glyph & Cog, LLC
6		//
7		//========================================================================
8
9		#include <aconf.h>
10
11		#include "gmempp.h"
12		#include "Object.h"
13		#include "Stream.h"
14		#include "JArithmeticDecoder.h"
15
16		//------------------------------------------------------------------------
17		// JArithmeticDecoderStates
18		//------------------------------------------------------------------------
19
20	4.70M	JArithmeticDecoderStats::JArithmeticDecoderStats(int contextSizeA) {
21	4.70M	contextSize = contextSizeA;
22	4.70M	cxTab = (Guchar *)gmallocn(contextSize, sizeof(Guchar));
23	4.70M	reset();
24	4.70M	}
25
26	4.69M	JArithmeticDecoderStats::~JArithmeticDecoderStats() {
27	4.69M	gfree(cxTab);
28	4.69M	}
29
30	3.92k	JArithmeticDecoderStats *JArithmeticDecoderStats::copy() {
31	3.92k	JArithmeticDecoderStats *stats;
32
33	3.92k	stats = new JArithmeticDecoderStats(contextSize);
34	3.92k	memcpy(stats->cxTab, cxTab, contextSize);
35	3.92k	return stats;
36	3.92k	}
37
38	6.38M	void JArithmeticDecoderStats::reset() {
39	6.38M	memset(cxTab, 0, contextSize);
40	6.38M	}
41
42	0	void JArithmeticDecoderStats::copyFrom(JArithmeticDecoderStats *stats) {
43	0	memcpy(cxTab, stats->cxTab, contextSize);
44	0	}
45
46	5.70M	void JArithmeticDecoderStats::setEntry(Guint cx, int i, int mps) {
47	5.70M	cxTab[cx] = (Guchar)((i << 1) + mps);
48	5.70M	}
49
50		//------------------------------------------------------------------------
51		// JArithmeticDecoder
52		//------------------------------------------------------------------------
53
54		Guint JArithmeticDecoder::qeTab[47] = {
55		0x56010000, 0x34010000, 0x18010000, 0x0AC10000,
56		0x05210000, 0x02210000, 0x56010000, 0x54010000,
57		0x48010000, 0x38010000, 0x30010000, 0x24010000,
58		0x1C010000, 0x16010000, 0x56010000, 0x54010000,
59		0x51010000, 0x48010000, 0x38010000, 0x34010000,
60		0x30010000, 0x28010000, 0x24010000, 0x22010000,
61		0x1C010000, 0x18010000, 0x16010000, 0x14010000,
62		0x12010000, 0x11010000, 0x0AC10000, 0x09C10000,
63		0x08A10000, 0x05210000, 0x04410000, 0x02A10000,
64		0x02210000, 0x01410000, 0x01110000, 0x00850000,
65		0x00490000, 0x00250000, 0x00150000, 0x00090000,
66		0x00050000, 0x00010000, 0x56010000
67		};
68
69		int JArithmeticDecoder::nmpsTab[47] = {
70		1, 2, 3, 4, 5, 38, 7, 8, 9, 10, 11, 12, 13, 29, 15, 16,
71		17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32,
72		33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 45, 46
73		};
74
75		int JArithmeticDecoder::nlpsTab[47] = {
76		1, 6, 9, 12, 29, 33, 6, 14, 14, 14, 17, 18, 20, 21, 14, 14,
77		15, 16, 17, 18, 19, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29,
78		30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 46
79		};
80
81		int JArithmeticDecoder::switchTab[47] = {
82		1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0,
83		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
84		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
85		};
86
87	580k	JArithmeticDecoder::JArithmeticDecoder() {
88	580k	str = NULL;
89	580k	dataLen = 0;
90	580k	limitStream = gFalse;
91	580k	nBytesRead = 0;
92	580k	readBufNext = 0;
93	580k	readBufLength = 0;
94	580k	}
95
96	8.50M	inline Guint JArithmeticDecoder::readByte() {
97	8.50M	if (limitStream) {
98	7.34M	if (readBufNext < readBufLength) {
99	1.31M	return readBuf[readBufNext++];
100	1.31M	}
101	6.02M	--dataLen;
102	6.02M	if (dataLen < 0) {
103	3.68M	return 0xff;
104	3.68M	}
105	6.02M	}
106	3.51M	++nBytesRead;
107	3.51M	return (Guint)str->getChar() & 0xff;
108	8.50M	}
109
110	579k	JArithmeticDecoder::~JArithmeticDecoder() {
111	579k	cleanup();
112	579k	}
113
114	823k	void JArithmeticDecoder::start() {
115	823k	buf0 = readByte();
116	823k	buf1 = readByte();
117
118		// INITDEC
119	823k	c = (buf0 ^ 0xff) << 16;
120	823k	byteIn();
121	823k	c <<= 7;
122	823k	ct -= 7;
123	823k	a = 0x80000000;
124	823k	}
125
126	40.0k	void JArithmeticDecoder::restart(int dataLenA) {
127	40.0k	Guint cAdd;
128	40.0k	GBool prevFF;
129	40.0k	int k, nBits;
130
131	40.0k	if (dataLen >= 0) {
132	25.2k	dataLen = dataLenA;
133	25.2k	} else if (dataLen == -1) {
134	1.71k	dataLen = dataLenA;
135	1.71k	buf1 = readByte();
136	13.1k	} else {
137	13.1k	k = (-dataLen - 1) * 8 - ct;
138	13.1k	dataLen = dataLenA;
139	13.1k	cAdd = 0;
140	13.1k	prevFF = gFalse;
141	529k	while (k > 0) {
142	516k	buf0 = readByte();
143	516k	if (prevFF) {
144	403k	cAdd += 0xfe00 - (buf0 << 9);
145	403k	nBits = 7;
146	403k	} else {
147	113k	cAdd += 0xff00 - (buf0 << 8);
148	113k	nBits = 8;
149	113k	}
150	516k	prevFF = buf0 == 0xff;
151	516k	if (k > nBits) {
152	503k	cAdd <<= nBits;
153	503k	k -= nBits;
154	503k	} else {
155	13.1k	cAdd <<= k;
156	13.1k	ct = nBits - k;
157	13.1k	k = 0;
158	13.1k	}
159	516k	}
160	13.1k	c += cAdd;
161	13.1k	buf1 = readByte();
162	13.1k	}
163	40.0k	}
164
165	1.57M	void JArithmeticDecoder::cleanup() {
166	1.57M	if (limitStream) {
167		// This saves up to sizeof(readBuf) extra bytes of data from the
168		// end of packet i, to be used in packet i+1. It's not clear from
169		// the JPEG 2000 spec exactly how this should work, but this
170		// kludge does seem to fix decode of some problematic JPEG 2000
171		// streams. The buffer may need to larger, but I haven't run into
172		// that case. (And the buffer was originally just one byte, which
173		// works for almost all cases.)
174	1.30M	readBufLength = 0;
175	6.21G	while (dataLen > 0) {
176	6.21G	if (readBufLength < (int)sizeof(readBuf)) {
177	9.30M	readBuf[readBufLength++] = (Guchar)str->getChar();
178	9.30M	++nBytesRead;
179	9.30M	}
180	6.21G	--dataLen;
181	6.21G	}
182	1.30M	readBufNext = 0;
183	1.30M	}
184	1.57M	}
185
186		int JArithmeticDecoder::decodeBit(Guint context,
187	476M	JArithmeticDecoderStats *stats) {
188	476M	int bit;
189	476M	Guint qe;
190	476M	int iCX, mpsCX;
191
192	476M	iCX = stats->cxTab[context] >> 1;
193	476M	mpsCX = stats->cxTab[context] & 1;
194	476M	qe = qeTab[iCX];
195	476M	a -= qe;
196	476M	if (c < a) {
197	437M	if (a & 0x80000000) {
198	394M	bit = mpsCX;
199	394M	} else {
200		// MPS_EXCHANGE
201	43.3M	if (a < qe) {
202	6.71M	bit = 1 - mpsCX;
203	6.71M	if (switchTab[iCX]) {
204	3.85M	stats->cxTab[context] = (Guchar)((nlpsTab[iCX] << 1) \| (1 - mpsCX));
205	3.85M	} else {
206	2.86M	stats->cxTab[context] = (Guchar)((nlpsTab[iCX] << 1) \| mpsCX);
207	2.86M	}
208	36.6M	} else {
209	36.6M	bit = mpsCX;
210	36.6M	stats->cxTab[context] = (Guchar)((nmpsTab[iCX] << 1) \| mpsCX);
211	36.6M	}
212		// RENORMD
213	46.0M	do {
214	46.0M	if (ct == 0) {
215	5.81M	byteIn();
216	5.81M	}
217	46.0M	a <<= 1;
218	46.0M	c <<= 1;
219	46.0M	--ct;
220	46.0M	} while (!(a & 0x80000000));
221	43.3M	}
222	437M	} else {
223	39.0M	c -= a;
224		// LPS_EXCHANGE
225	39.0M	if (a < qe) {
226	7.77M	bit = mpsCX;
227	7.77M	stats->cxTab[context] = (Guchar)((nmpsTab[iCX] << 1) \| mpsCX);
228	31.2M	} else {
229	31.2M	bit = 1 - mpsCX;
230	31.2M	if (switchTab[iCX]) {
231	5.58M	stats->cxTab[context] = (Guchar)((nlpsTab[iCX] << 1) \| (1 - mpsCX));
232	25.6M	} else {
233	25.6M	stats->cxTab[context] = (Guchar)((nlpsTab[iCX] << 1) \| mpsCX);
234	25.6M	}
235	31.2M	}
236	39.0M	a = qe;
237		// RENORMD
238	60.6M	do {
239	60.6M	if (ct == 0) {
240	7.65M	byteIn();
241	7.65M	}
242	60.6M	a <<= 1;
243	60.6M	c <<= 1;
244	60.6M	--ct;
245	60.6M	} while (!(a & 0x80000000));
246	39.0M	}
247	476M	return bit;
248	476M	}
249
250		int JArithmeticDecoder::decodeByte(Guint context,
251	0	JArithmeticDecoderStats *stats) {
252	0	int byte;
253	0	int i;
254
255	0	byte = 0;
256	0	for (i = 0; i < 8; ++i) {
257	0	byte = (byte << 1) \| decodeBit(context, stats);
258	0	}
259	0	return byte;
260	0	}
261
262	4.28M	GBool JArithmeticDecoder::decodeInt(int x, JArithmeticDecoderStats stats) {
263	4.28M	int s;
264	4.28M	Guint v;
265	4.28M	int i;
266
267	4.28M	prev = 1;
268	4.28M	s = decodeIntBit(stats);
269	4.28M	if (decodeIntBit(stats)) {
270	1.72M	if (decodeIntBit(stats)) {
271	421k	if (decodeIntBit(stats)) {
272	110k	if (decodeIntBit(stats)) {
273	70.9k	if (decodeIntBit(stats)) {
274	15.8k	v = 0;
275	524k	for (i = 0; i < 32; ++i) {
276	508k	v = (v << 1) \| decodeIntBit(stats);
277	508k	}
278	15.8k	v += 4436;
279	55.0k	} else {
280	55.0k	v = 0;
281	716k	for (i = 0; i < 12; ++i) {
282	661k	v = (v << 1) \| decodeIntBit(stats);
283	661k	}
284	55.0k	v += 340;
285	55.0k	}
286	70.9k	} else {
287	39.5k	v = 0;
288	355k	for (i = 0; i < 8; ++i) {
289	316k	v = (v << 1) \| decodeIntBit(stats);
290	316k	}
291	39.5k	v += 84;
292	39.5k	}
293	310k	} else {
294	310k	v = 0;
295	2.17M	for (i = 0; i < 6; ++i) {
296	1.86M	v = (v << 1) \| decodeIntBit(stats);
297	1.86M	}
298	310k	v += 20;
299	310k	}
300	1.29M	} else {
301	1.29M	v = decodeIntBit(stats);
302	1.29M	v = (v << 1) \| decodeIntBit(stats);
303	1.29M	v = (v << 1) \| decodeIntBit(stats);
304	1.29M	v = (v << 1) \| decodeIntBit(stats);
305	1.29M	v += 4;
306	1.29M	}
307	2.56M	} else {
308	2.56M	v = decodeIntBit(stats);
309	2.56M	v = (v << 1) \| decodeIntBit(stats);
310	2.56M	}
311
312	4.28M	if (s) {
313	1.71M	if (v == 0) {
314	1.17M	return gFalse;
315	1.17M	}
316	537k	*x = -(int)v;
317	2.56M	} else {
318	2.56M	*x = (int)v;
319	2.56M	}
320	3.10M	return gTrue;
321	4.28M	}
322
323	24.5M	int JArithmeticDecoder::decodeIntBit(JArithmeticDecoderStats *stats) {
324	24.5M	int bit;
325
326	24.5M	bit = decodeBit(prev, stats);
327	24.5M	if (prev < 0x100) {
328	22.7M	prev = (prev << 1) \| bit;
329	22.7M	} else {
330	1.84M	prev = (((prev << 1) \| bit) & 0x1ff) \| 0x100;
331	1.84M	}
332	24.5M	return bit;
333	24.5M	}
334
335		Guint JArithmeticDecoder::decodeIAID(Guint codeLen,
336	619k	JArithmeticDecoderStats *stats) {
337	619k	Guint i;
338	619k	int bit;
339
340	619k	prev = 1;
341	7.98M	for (i = 0; i < codeLen; ++i) {
342	7.36M	bit = decodeBit(prev, stats);
343	7.36M	prev = (prev << 1) \| bit;
344	7.36M	}
345	619k	return prev - (1 << codeLen);
346	619k	}
347
348	14.2M	void JArithmeticDecoder::byteIn() {
349	14.2M	if (buf0 == 0xff) {
350	11.2M	if (buf1 > 0x8f) {
351	11.2M	if (limitStream) {
352	3.28M	buf0 = buf1;
353	3.28M	buf1 = readByte();
354	3.28M	c = c + 0xff00 - (buf0 << 8);
355	3.28M	}
356	11.2M	ct = 8;
357	11.2M	} else {
358	21.6k	buf0 = buf1;
359	21.6k	buf1 = readByte();
360	21.6k	c = c + 0xfe00 - (buf0 << 9);
361	21.6k	ct = 7;
362	21.6k	}
363	11.2M	} else {
364	3.02M	buf0 = buf1;
365	3.02M	buf1 = readByte();
366	3.02M	c = c + 0xff00 - (buf0 << 8);
367	3.02M	ct = 8;
368	3.02M	}
369	14.2M	}