1 //========================================================================
3 // JArithmeticDecoder.cc
5 // Copyright 2002-2004 Glyph & Cog, LLC
7 //========================================================================
11 #ifdef USE_GCC_PRAGMAS
12 #pragma implementation
17 #include "JArithmeticDecoder.h"
19 //------------------------------------------------------------------------
20 // JArithmeticDecoderStates
21 //------------------------------------------------------------------------
23 JArithmeticDecoderStats::JArithmeticDecoderStats(int contextSizeA) {
24 contextSize = contextSizeA;
25 cxTab = (Guchar *)gmalloc(contextSize * sizeof(Guchar));
29 JArithmeticDecoderStats::~JArithmeticDecoderStats() {
33 JArithmeticDecoderStats *JArithmeticDecoderStats::copy() {
34 JArithmeticDecoderStats *stats;
36 stats = new JArithmeticDecoderStats(contextSize);
37 memcpy(stats->cxTab, cxTab, contextSize);
41 void JArithmeticDecoderStats::reset() {
42 memset(cxTab, 0, contextSize);
45 void JArithmeticDecoderStats::copyFrom(JArithmeticDecoderStats *stats) {
46 memcpy(cxTab, stats->cxTab, contextSize);
49 void JArithmeticDecoderStats::setEntry(Guint cx, int i, int mps) {
50 cxTab[cx] = (i << 1) + mps;
53 //------------------------------------------------------------------------
55 //------------------------------------------------------------------------
57 Guint JArithmeticDecoder::qeTab[47] = {
58 0x56010000, 0x34010000, 0x18010000, 0x0AC10000,
59 0x05210000, 0x02210000, 0x56010000, 0x54010000,
60 0x48010000, 0x38010000, 0x30010000, 0x24010000,
61 0x1C010000, 0x16010000, 0x56010000, 0x54010000,
62 0x51010000, 0x48010000, 0x38010000, 0x34010000,
63 0x30010000, 0x28010000, 0x24010000, 0x22010000,
64 0x1C010000, 0x18010000, 0x16010000, 0x14010000,
65 0x12010000, 0x11010000, 0x0AC10000, 0x09C10000,
66 0x08A10000, 0x05210000, 0x04410000, 0x02A10000,
67 0x02210000, 0x01410000, 0x01110000, 0x00850000,
68 0x00490000, 0x00250000, 0x00150000, 0x00090000,
69 0x00050000, 0x00010000, 0x56010000
72 int JArithmeticDecoder::nmpsTab[47] = {
73 1, 2, 3, 4, 5, 38, 7, 8, 9, 10, 11, 12, 13, 29, 15, 16,
74 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32,
75 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 45, 46
78 int JArithmeticDecoder::nlpsTab[47] = {
79 1, 6, 9, 12, 29, 33, 6, 14, 14, 14, 17, 18, 20, 21, 14, 14,
80 15, 16, 17, 18, 19, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29,
81 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 46
84 int JArithmeticDecoder::switchTab[47] = {
85 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0,
86 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
87 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
90 JArithmeticDecoder::JArithmeticDecoder() {
94 JArithmeticDecoder::~JArithmeticDecoder() {
100 inline Guint JArithmeticDecoder::readByte() {
107 return (Guint)str->getChar() & 0xff;
110 void JArithmeticDecoder::start() {
115 c = (buf0 ^ 0xff) << 16;
122 int JArithmeticDecoder::decodeBit(Guint context,
123 JArithmeticDecoderStats *stats) {
128 iCX = stats->cxTab[context] >> 1;
129 mpsCX = stats->cxTab[context] & 1;
133 if (a & 0x80000000) {
139 if (switchTab[iCX]) {
140 stats->cxTab[context] = (nlpsTab[iCX] << 1) | (1 - mpsCX);
142 stats->cxTab[context] = (nlpsTab[iCX] << 1) | mpsCX;
146 stats->cxTab[context] = (nmpsTab[iCX] << 1) | mpsCX;
156 } while (!(a & 0x80000000));
163 stats->cxTab[context] = (nmpsTab[iCX] << 1) | mpsCX;
166 if (switchTab[iCX]) {
167 stats->cxTab[context] = (nlpsTab[iCX] << 1) | (1 - mpsCX);
169 stats->cxTab[context] = (nlpsTab[iCX] << 1) | mpsCX;
181 } while (!(a & 0x80000000));
186 int JArithmeticDecoder::decodeByte(Guint context,
187 JArithmeticDecoderStats *stats) {
192 for (i = 0; i < 8; ++i) {
193 byte = (byte << 1) | decodeBit(context, stats);
198 GBool JArithmeticDecoder::decodeInt(int *x, JArithmeticDecoderStats *stats) {
204 s = decodeIntBit(stats);
205 if (decodeIntBit(stats)) {
206 if (decodeIntBit(stats)) {
207 if (decodeIntBit(stats)) {
208 if (decodeIntBit(stats)) {
209 if (decodeIntBit(stats)) {
211 for (i = 0; i < 32; ++i) {
212 v = (v << 1) | decodeIntBit(stats);
217 for (i = 0; i < 12; ++i) {
218 v = (v << 1) | decodeIntBit(stats);
224 for (i = 0; i < 8; ++i) {
225 v = (v << 1) | decodeIntBit(stats);
231 for (i = 0; i < 6; ++i) {
232 v = (v << 1) | decodeIntBit(stats);
237 v = decodeIntBit(stats);
238 v = (v << 1) | decodeIntBit(stats);
239 v = (v << 1) | decodeIntBit(stats);
240 v = (v << 1) | decodeIntBit(stats);
244 v = decodeIntBit(stats);
245 v = (v << 1) | decodeIntBit(stats);
259 int JArithmeticDecoder::decodeIntBit(JArithmeticDecoderStats *stats) {
262 bit = decodeBit(prev, stats);
264 prev = (prev << 1) | bit;
266 prev = (((prev << 1) | bit) & 0x1ff) | 0x100;
271 Guint JArithmeticDecoder::decodeIAID(Guint codeLen,
272 JArithmeticDecoderStats *stats) {
277 for (i = 0; i < codeLen; ++i) {
278 bit = decodeBit(prev, stats);
279 prev = (prev << 1) | bit;
281 return prev - (1 << codeLen);
284 void JArithmeticDecoder::byteIn() {
291 c = c + 0xfe00 - (buf0 << 9);
297 c = c + 0xff00 - (buf0 << 8);