481 lines
12 KiB
C
Executable File
481 lines
12 KiB
C
Executable File
/*
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jbig2dec
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Copyright (C) 2001-2005 Artifex Software, Inc.
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This software is distributed under license and may not
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be copied, modified or distributed except as expressly
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authorized under the terms of the license contained in
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the file LICENSE in this distribution.
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For further licensing information refer to http://artifex.com/ or
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contact Artifex Software, Inc., 7 Mt. Lassen Drive - Suite A-134,
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San Rafael, CA 94903, U.S.A., +1(415)492-9861.
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*/
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/* Huffman table decoding procedures
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-- See Annex B of the JBIG2 specification */
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include "os_types.h"
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#include <stdlib.h>
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#include <string.h>
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#ifdef JBIG2_DEBUG
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#include <stdio.h>
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#endif
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#include "jbig2.h"
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#include "jbig2_priv.h"
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#include "jbig2_huffman.h"
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#include "jbig2_hufftab.h"
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#define JBIG2_HUFFMAN_FLAGS_ISOOB 1
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#define JBIG2_HUFFMAN_FLAGS_ISLOW 2
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#define JBIG2_HUFFMAN_FLAGS_ISEXT 4
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struct _Jbig2HuffmanState {
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/* The current bit offset is equal to (offset * 8) + offset_bits.
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The MSB of this_word is the current bit offset. The MSB of next_word
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is (offset + 4) * 8. */
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uint32_t this_word;
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uint32_t next_word;
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int offset_bits;
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int offset;
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Jbig2WordStream *ws;
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};
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/** Allocate and initialize a new huffman coding state
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* the returned pointer can simply be freed; this does
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* not affect the associated Jbig2WordStream.
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*/
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Jbig2HuffmanState *
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jbig2_huffman_new (Jbig2Ctx *ctx, Jbig2WordStream *ws)
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{
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Jbig2HuffmanState *result;
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result = (Jbig2HuffmanState *)jbig2_alloc(ctx->allocator,
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sizeof(Jbig2HuffmanState));
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if (result != NULL) {
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result->offset = 0;
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result->offset_bits = 0;
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result->this_word = ws->get_next_word (ws, 0);
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result->next_word = ws->get_next_word (ws, 4);
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result->ws = ws;
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}
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return result;
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}
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/** Free an allocated huffman coding state.
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* This just calls jbig2_free() if the pointer is not NULL
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*/
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void
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jbig2_huffman_free (Jbig2Ctx *ctx, Jbig2HuffmanState *hs)
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{
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if (hs != NULL) free(hs);
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return;
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}
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/** debug routines **/
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#ifdef JBIG2_DEBUG
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/** print current huffman state */
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void jbig2_dump_huffman_state(Jbig2HuffmanState *hs) {
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fprintf(stderr, "huffman state %08x %08x offset %d.%d\n",
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hs->this_word, hs->next_word, hs->offset, hs->offset_bits);
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}
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/** print the binary string we're reading from */
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void jbig2_dump_huffman_binary(Jbig2HuffmanState *hs)
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{
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const uint32_t word = hs->this_word;
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int i;
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fprintf(stderr, "huffman binary ");
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for (i = 31; i >= 0; i--)
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fprintf(stderr, ((word >> i) & 1) ? "1" : "0");
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fprintf(stderr, "\n");
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}
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#endif /* JBIG2_DEBUG */
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/** Skip bits up to the next byte boundary
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*/
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void
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jbig2_huffman_skip(Jbig2HuffmanState *hs)
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{
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int bits = hs->offset_bits & 7;
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if (bits) {
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bits = 8 - bits;
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hs->offset_bits += bits;
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hs->this_word = (hs->this_word << bits) |
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(hs->next_word >> (32 - hs->offset_bits));
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}
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if (hs->offset_bits >= 32) {
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Jbig2WordStream *ws = hs->ws;
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hs->this_word = hs->next_word;
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hs->offset += 4;
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hs->next_word = ws->get_next_word (ws, hs->offset + 4);
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hs->offset_bits -= 32;
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if (hs->offset_bits) {
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hs->this_word = (hs->this_word << hs->offset_bits) |
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(hs->next_word >> (32 - hs->offset_bits));
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}
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}
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}
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/* skip ahead a specified number of bytes in the word stream
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*/
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void jbig2_huffman_advance(Jbig2HuffmanState *hs, int offset)
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{
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Jbig2WordStream *ws = hs->ws;
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hs->offset += offset & ~3;
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hs->offset_bits += (offset & 3) << 3;
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if (hs->offset_bits >= 32) {
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hs->offset += 4;
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hs->offset_bits -= 32;
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}
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hs->this_word = ws->get_next_word (ws, hs->offset);
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hs->next_word = ws->get_next_word (ws, hs->offset + 4);
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if (hs->offset_bits > 0)
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hs->this_word = (hs->this_word << hs->offset_bits) |
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(hs->next_word >> (32 - hs->offset_bits));
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}
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/* return the offset of the huffman decode pointer (in bytes)
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* from the beginning of the WordStream
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*/
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int
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jbig2_huffman_offset(Jbig2HuffmanState *hs)
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{
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return hs->offset + (hs->offset_bits >> 3);
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}
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/* read a number of bits directly from the huffman state
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* without decoding against a table
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*/
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int32_t
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jbig2_huffman_get_bits (Jbig2HuffmanState *hs, const int bits)
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{
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uint32_t this_word = hs->this_word;
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int32_t result;
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result = this_word >> (32 - bits);
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hs->offset_bits += bits;
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if (hs->offset_bits >= 32) {
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hs->offset += 4;
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hs->offset_bits -= 32;
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hs->this_word = hs->next_word;
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hs->next_word = hs->ws->get_next_word(hs->ws, hs->offset + 4);
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if (hs->offset_bits) {
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hs->this_word = (hs->this_word << hs->offset_bits) |
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(hs->next_word >> (32 - hs->offset_bits));
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} else {
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hs->this_word = (hs->this_word << hs->offset_bits);
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}
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} else {
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hs->this_word = (this_word << bits) |
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(hs->next_word >> (32 - hs->offset_bits));
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}
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return result;
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}
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int32_t
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jbig2_huffman_get (Jbig2HuffmanState *hs,
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const Jbig2HuffmanTable *table, bool *oob)
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{
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Jbig2HuffmanEntry *entry;
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byte flags;
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int offset_bits = hs->offset_bits;
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uint32_t this_word = hs->this_word;
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uint32_t next_word;
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int RANGELEN;
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int32_t result;
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for (;;)
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{
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int log_table_size = table->log_table_size;
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int PREFLEN;
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entry = &table->entries[this_word >> (32 - log_table_size)];
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flags = entry->flags;
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PREFLEN = entry->PREFLEN;
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next_word = hs->next_word;
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offset_bits += PREFLEN;
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if (offset_bits >= 32)
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{
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Jbig2WordStream *ws = hs->ws;
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this_word = next_word;
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hs->offset += 4;
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next_word = ws->get_next_word (ws, hs->offset + 4);
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offset_bits -= 32;
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hs->next_word = next_word;
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PREFLEN = offset_bits;
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}
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if (PREFLEN)
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this_word = (this_word << PREFLEN) |
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(next_word >> (32 - offset_bits));
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if (flags & JBIG2_HUFFMAN_FLAGS_ISEXT)
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{
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table = entry->u.ext_table;
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}
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else
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break;
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}
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result = entry->u.RANGELOW;
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RANGELEN = entry->RANGELEN;
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if (RANGELEN > 0)
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{
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int32_t HTOFFSET;
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HTOFFSET = this_word >> (32 - RANGELEN);
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if (flags & JBIG2_HUFFMAN_FLAGS_ISLOW)
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result -= HTOFFSET;
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else
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result += HTOFFSET;
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offset_bits += RANGELEN;
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if (offset_bits >= 32)
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{
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Jbig2WordStream *ws = hs->ws;
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this_word = next_word;
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hs->offset += 4;
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next_word = ws->get_next_word (ws, hs->offset + 4);
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offset_bits -= 32;
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hs->next_word = next_word;
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RANGELEN = offset_bits;
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}
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if (RANGELEN)
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this_word = (this_word << RANGELEN) |
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(next_word >> (32 - offset_bits));
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}
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hs->this_word = this_word;
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hs->offset_bits = offset_bits;
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if (oob != NULL)
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*oob = (flags & JBIG2_HUFFMAN_FLAGS_ISOOB);
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return result;
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}
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/* TODO: more than 8 bits here is wasteful of memory. We have support
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for sub-trees in jbig2_huffman_get() above, but don't use it here.
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We should, and then revert to 8 bits */
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#define LOG_TABLE_SIZE_MAX 16
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/** Build an in-memory representation of a Huffman table from the
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* set of template params provided by the spec or a table segment
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*/
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Jbig2HuffmanTable *
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jbig2_build_huffman_table (Jbig2Ctx *ctx, const Jbig2HuffmanParams *params)
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{
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int *LENCOUNT;
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int LENMAX = -1;
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const int lencountsize = 256 * sizeof(*LENCOUNT);
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const Jbig2HuffmanLine *lines = params->lines;
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int n_lines = params->n_lines;
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int i, j;
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int max_j;
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int log_table_size = 0;
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Jbig2HuffmanTable *result;
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Jbig2HuffmanEntry *entries;
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int CURLEN;
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int firstcode = 0;
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int CURCODE;
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int CURTEMP;
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LENCOUNT = jbig2_alloc(ctx->allocator, lencountsize);
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if (LENCOUNT == NULL) {
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jbig2_error(ctx, JBIG2_SEVERITY_FATAL, -1,
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"couldn't allocate storage for huffman histogram");
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return NULL;
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}
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memset(LENCOUNT, 0, lencountsize);
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/* B.3, 1. */
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for (i = 0; i < params->n_lines; i++)
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{
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int PREFLEN = lines[i].PREFLEN;
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int lts;
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if (PREFLEN > LENMAX)
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{
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for (j = LENMAX + 1; j < PREFLEN + 1; j++)
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LENCOUNT[j] = 0;
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LENMAX = PREFLEN;
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}
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LENCOUNT[PREFLEN]++;
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lts = PREFLEN + lines[i].RANGELEN;
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if (lts > LOG_TABLE_SIZE_MAX)
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lts = PREFLEN;
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if (lts <= LOG_TABLE_SIZE_MAX && log_table_size < lts)
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log_table_size = lts;
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}
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jbig2_error(ctx, JBIG2_SEVERITY_DEBUG, -1,
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"constructing huffman table log size %d", log_table_size);
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max_j = 1 << log_table_size;
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result = (Jbig2HuffmanTable *)jbig2_alloc(ctx->allocator, sizeof(Jbig2HuffmanTable));
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result->log_table_size = log_table_size;
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entries = (Jbig2HuffmanEntry *)jbig2_alloc(ctx->allocator, max_j * sizeof(Jbig2HuffmanEntry));
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result->entries = entries;
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LENCOUNT[0] = 0;
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for (CURLEN = 1; CURLEN <= LENMAX; CURLEN++)
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{
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int shift = log_table_size - CURLEN;
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/* B.3 3.(a) */
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firstcode = (firstcode + LENCOUNT[CURLEN - 1]) << 1;
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CURCODE = firstcode;
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/* B.3 3.(b) */
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for (CURTEMP = 0; CURTEMP < n_lines; CURTEMP++)
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{
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int PREFLEN = lines[CURTEMP].PREFLEN;
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if (PREFLEN == CURLEN)
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{
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int RANGELEN = lines[CURTEMP].RANGELEN;
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int start_j = CURCODE << shift;
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int end_j = (CURCODE + 1) << shift;
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byte eflags = 0;
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if (end_j > max_j) {
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jbig2_error(ctx, JBIG2_SEVERITY_FATAL, -1,
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"ran off the end of the entries table! (%d >= %d)",
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end_j, max_j);
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jbig2_free(ctx->allocator, result->entries);
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jbig2_free(ctx->allocator, result);
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jbig2_free(ctx->allocator, LENCOUNT);
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return NULL;
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}
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/* todo: build extension tables */
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if (params->HTOOB && CURTEMP == n_lines - 1)
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eflags |= JBIG2_HUFFMAN_FLAGS_ISOOB;
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if (CURTEMP == n_lines - (params->HTOOB ? 3 : 2))
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eflags |= JBIG2_HUFFMAN_FLAGS_ISLOW;
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if (PREFLEN + RANGELEN > LOG_TABLE_SIZE_MAX) {
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for (j = start_j; j < end_j; j++) {
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entries[j].u.RANGELOW = lines[CURTEMP].RANGELOW;
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entries[j].PREFLEN = PREFLEN;
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entries[j].RANGELEN = RANGELEN;
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entries[j].flags = eflags;
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}
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} else {
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for (j = start_j; j < end_j; j++) {
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int32_t HTOFFSET = (j >> (shift - RANGELEN)) &
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((1 << RANGELEN) - 1);
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if (eflags & JBIG2_HUFFMAN_FLAGS_ISLOW)
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entries[j].u.RANGELOW = lines[CURTEMP].RANGELOW -
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HTOFFSET;
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else
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entries[j].u.RANGELOW = lines[CURTEMP].RANGELOW +
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HTOFFSET;
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entries[j].PREFLEN = PREFLEN + RANGELEN;
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entries[j].RANGELEN = 0;
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entries[j].flags = eflags;
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}
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}
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CURCODE++;
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}
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}
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}
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jbig2_free(ctx->allocator, LENCOUNT);
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return result;
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}
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/** Free the memory associated with the representation of table */
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void
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jbig2_release_huffman_table (Jbig2Ctx *ctx, Jbig2HuffmanTable *table)
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{
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if (table != NULL) {
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jbig2_free(ctx->allocator, table->entries);
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jbig2_free(ctx->allocator, table);
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}
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return;
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}
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#ifdef TEST
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#include <stdio.h>
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/* a test bitstream, and a list of the table indicies
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to use in decoding it. 1 = table B.1 (A), 2 = table B.2 (B), and so on */
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/* this test stream should decode to { 8, 5, oob, 8 } */
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const byte test_stream[] = { 0xe9, 0xcb, 0xf4, 0x00 };
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const byte test_tabindex[] = { 4, 2, 2, 1 };
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static uint32_t
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test_get_word (Jbig2WordStream *self, int offset)
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{
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/* assume test_stream[] is at least 4 bytes */
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if (offset+3 > sizeof(test_stream))
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return 0;
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else
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return ( (test_stream[offset] << 24) |
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(test_stream[offset+1] << 16) |
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(test_stream[offset+2] << 8) |
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(test_stream[offset+3]) );
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}
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int
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main (int argc, char **argv)
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{
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Jbig2Ctx *ctx;
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Jbig2HuffmanTable *tables[5];
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Jbig2HuffmanState *hs;
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Jbig2WordStream ws;
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bool oob;
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int32_t code;
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ctx = jbig2_ctx_new(NULL, 0, NULL, NULL, NULL);
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tables[0] = NULL;
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tables[1] = jbig2_build_huffman_table (ctx, &jbig2_huffman_params_A);
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tables[2] = jbig2_build_huffman_table (ctx, &jbig2_huffman_params_B);
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tables[3] = NULL;
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tables[4] = jbig2_build_huffman_table (ctx, &jbig2_huffman_params_D);
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ws.get_next_word = test_get_word;
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hs = jbig2_huffman_new (ctx, &ws);
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printf("testing jbig2 huffmann decoding...");
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printf("\t(should be 8 5 (oob) 8)\n");
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{
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int i;
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int sequence_length = sizeof(test_tabindex);
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for (i = 0; i < sequence_length; i++) {
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code = jbig2_huffman_get (hs, tables[test_tabindex[i]], &oob);
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if (oob) printf("(oob) ");
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else printf("%d ", code);
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}
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}
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printf("\n");
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jbig2_ctx_free(ctx);
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return 0;
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}
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#endif
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