ref: 678523a15572456b68612fafc422d4dee29ca59c
dir: /jbig2dec.c/
/*
jbig2dec
Copyright (c) 2001 artofcode LLC.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
$Id: jbig2dec.c,v 1.9 2001/06/26 00:30:00 giles Exp $
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "jbig2dec.h"
typedef struct _Jbig2SegmentHeader Jbig2SegmentHeader;
typedef struct _Jbig2SymbolDictionary Jbig2SymbolDictionary;
typedef struct _Jbig2PageInfo Jbig2PageInfo;
/* our main 'context' structure for decoding a jbig2 bitstream */
struct _Jbig2Ctx {
FILE *f;
int offset;
int32 n_pages;
byte flags;
};
/* useful masks for parsing the flags field */
#define JBIG2_FILE_FLAGS_SEQUENTIAL_ACCESS 0x01
#define JBIG2_FILE_FLAGS_PAGECOUNT_UNKNOWN 0x02
struct _Jbig2SegmentHeader {
int32 segment_number;
byte flags;
int referred_to_segment_count;
int32 page_association;
int data_length;
};
struct _Jbig2SymbolDictionary {
int16 flags;
int8 SDAT_flags[8];
byte SDRAT_flags[4];
int32 SDNUMEXSYMS;
int32 SDNUMNEWSYMS;
};
struct _Jbig2PageInfo {
int32 height, width; /* in pixels */
int32 x_resolution,
y_resolution; /* in pixels per meter */
int16 stripe_size;
bool striped;
byte flags;
};
int32
get_bytes (Jbig2Ctx *ctx, byte *buf, int size, int off)
{
fseek (ctx->f, off, SEEK_SET);
return fread (buf, 1, size, ctx->f);
}
int16
get_int16 (Jbig2Ctx *ctx, int off)
{
byte buf[2];
get_bytes (ctx, buf, 2, off);
return (buf[0] << 8) | buf[1];
}
byte
get_byte (Jbig2Ctx *ctx, int off)
{
byte buf;
get_bytes (ctx, &buf, 1, off);
return buf;
}
int32
get_int32 (Jbig2Ctx *ctx, int off)
{
byte buf[4];
get_bytes (ctx, buf, 4, off);
return (buf[0] << 24) | (buf[1] << 16) | (buf[2] << 8) | buf[3];
}
static Jbig2Ctx *
jbig2_open (FILE *f)
{
byte buf[9];
const byte header[8] = { 0x97, 0x4a, 0x42, 0x32, 0x0d, 0x0a, 0x1a, 0x0a };
Jbig2Ctx *ctx;
/* Annex D.4 */
ctx = (Jbig2Ctx *)malloc (sizeof(Jbig2Ctx));
ctx->f = f;
get_bytes (ctx, buf, 9, 0);
if (memcmp (buf, header, 8))
{
printf ("not a JBIG2 file\n");
return NULL;
}
ctx->flags = buf[8];
if (ctx->flags & JBIG2_FILE_FLAGS_PAGECOUNT_UNKNOWN)
{
ctx->offset = 9; /* number of pages unknown */
ctx->n_pages = 0;
}
else
{
ctx->offset = 13;
ctx->n_pages = get_int32 (ctx, 9);
}
if(!ctx->flags & JBIG2_FILE_FLAGS_SEQUENTIAL_ACCESS) {
printf("warning: random access header organization.\n");
printf("we don't handle that yet.\n");
free(ctx);
return NULL;
}
return ctx;
}
static Jbig2SegmentHeader *
jbig2_read_segment_header (Jbig2Ctx *ctx)
{
Jbig2SegmentHeader *result = (Jbig2SegmentHeader *)malloc(sizeof(Jbig2SegmentHeader));
int offset = ctx->offset;
byte rtscarf;
int32 rtscarf_long;
int referred_to_segment_count;
/* 7.2.2 */
result->segment_number = get_int32 (ctx, offset);
/* 7.2.3 */
get_bytes (ctx, &result->flags, 1, offset + 4);
/* 7.2.4 */
get_bytes (ctx, &rtscarf, 1, offset + 5);
if ((rtscarf & 0xe0) == 0xe0)
{
/* FIXME: we break on non-seekable streams with this,
but for now it's shorter */
rtscarf_long = get_int32(ctx, offset + 5);
referred_to_segment_count = (rtscarf_long & 0x1ffffffc) >> 2;
offset += 5 + 4 + (referred_to_segment_count + 1)/8;
}
else
{
referred_to_segment_count = (rtscarf >> 5);
offset += 6 + referred_to_segment_count;
}
result->referred_to_segment_count = referred_to_segment_count;
/* todo: read referred to segment numbers */
/* 7.2.6 */
if (result->flags & 0x40) {
result->page_association = get_int32(ctx, offset);
offset += 4;
} else {
byte spa;
get_bytes (ctx, &spa, 1, offset);
result->page_association = spa;
offset += 1;
}
/* 7.2.7 */
result->data_length = get_int32 (ctx, offset);
ctx->offset = offset + 4;
return result;
}
/* parse the symbol dictionary starting at ctx->offset
a pointer to a new Jbig2SymbolDictionary struct is returned
the ctx->offset pointer is not advanced; the caller must
take care of that, using the data_length field of the
segment header.
*/
static Jbig2SymbolDictionary *
jbig2_read_symbol_dictionary (Jbig2Ctx *ctx)
{
Jbig2SymbolDictionary *result = (Jbig2SymbolDictionary *)malloc(sizeof(Jbig2SymbolDictionary));
int offset = ctx->offset;
bool SDHUFF, SDREFAGG, SDRTEMPLATE;
int sdat_bytes;
/* 7.4.2.1.1 */
result->flags = get_int16 (ctx, offset);
offset += 2;
SDHUFF = result->flags & 1;
SDREFAGG = (result->flags >> 1) & 1;
SDRTEMPLATE = (result->flags >> 12) & 1;
/* FIXME: there are quite a few of these conditions to check */
/* maybe #ifdef CONFORMANCE and a separate routine */
if(!SDHUFF && !(result->flags & 0x0006)) {
printf("warning: SDHUFF is zero, but contrary to spec SDHUFFDH is not.\n");
}
if(!SDHUFF && !(result->flags & 0x0018)) {
printf("warning: SDHUFF is zero, but contrary to spec SDHUFFDW is not.\n");
}
/* 7.4.2.1.2 - Symbol dictionary AT flags */
if (!SDHUFF)
{
int SDTEMPLATE = (result->flags >> 10) & 3;
if (SDTEMPLATE == 0)
sdat_bytes = 8;
else
sdat_bytes = 2;
}
else
sdat_bytes = 0;
get_bytes (ctx, result->SDAT_flags, sdat_bytes, offset);
memset (&result->SDAT_flags + sdat_bytes, 0, 8 - sdat_bytes);
offset += sdat_bytes;
/* 7.4.2.1.3 - Symbol dictionary refinement AT flags */
if (SDREFAGG && !SDRTEMPLATE)
{
get_bytes (ctx, result->SDRAT_flags, 4, offset);
offset += 4;
}
/* 7.4.2.1.4 */
result->SDNUMEXSYMS = get_int32 (ctx, offset);
/* 7.4.2.1.5 */
result->SDNUMNEWSYMS = get_int32 (ctx, offset + 4);
offset += 8;
/* hardwire for the first annex-h example */
return result;
}
/* parse the page info segment data starting at ctx->offset
a pointer to a new Jbig2PageInfo struct is returned
the ctx->offset pointer is not advanced; the caller must
take care of that, using the data_length field of the
segment header.
*/
static Jbig2PageInfo *
jbig2_read_page_info (Jbig2Ctx *ctx) {
Jbig2PageInfo *info = (Jbig2PageInfo *)malloc(sizeof(Jbig2PageInfo));
int offset = ctx->offset;
if (info == NULL) {
printf("unable to allocate memory to parse page info segment\n");
return NULL;
}
info->width = get_int32(ctx, offset);
info->height = get_int32(ctx, offset + 4);
offset += 8;
info->x_resolution = get_int32(ctx, offset);
info->y_resolution = get_int32(ctx, offset);
offset += 8;
get_bytes(ctx, &(info->flags), 1, offset++);
{
int16 striping = get_int16(ctx, offset);
if (striping & 0x8000) {
info->striped = TRUE;
info->stripe_size = striping & 0x7FFF;
} else {
info->striped = FALSE;
info->stripe_size = 0; /* would info->height be better? */
}
offset += 2;
}
return info;
}
static void
dump_symbol_dictionary (Jbig2SymbolDictionary *sd)
{
printf ("symbol dictionary: flags = %04x, %d new symbols, %d exported\n",
sd->flags, sd->SDNUMNEWSYMS, sd->SDNUMEXSYMS);
}
static void
dump_page_info(Jbig2PageInfo *info)
{
printf("image is %dx%d ", info->width, info->height);
if (info->x_resolution == 0) {
printf("(unknown res) ");
} else if (info->x_resolution == info->y_resolution) {
printf("(%d ppm) ", info->x_resolution);
} else {
printf("(%dx%d ppm) ", info->x_resolution, info->y_resolution);
}
if (info->striped) {
printf("\tmaximum stripe size: %d\n", info->stripe_size);
} else {
printf("\tno striping\n");
}
}
static bool
dump_segment (Jbig2Ctx *ctx)
{
Jbig2SegmentHeader *sh;
Jbig2SymbolDictionary *sd;
Jbig2PageInfo *page_info;
sh = jbig2_read_segment_header (ctx);
printf("segment %d (%d bytes)\t", sh->segment_number, sh->data_length);
switch (sh->flags & 63)
{
case 0:
sd = jbig2_read_symbol_dictionary (ctx);
printf("\n");
dump_symbol_dictionary (sd);
break;
case 4:
printf("intermediate text region:");
break;
case 6:
printf("immediate text region:");
break;
case 7:
printf("immediate lossless text region:");
break;
case 16:
printf("pattern dictionary:");
break;
case 20:
printf("intermediate halftone region:");
break;
case 22:
printf("immediate halftone region:");
break;
case 23:
printf("immediate lossless halftone region:");
break;
case 36:
printf("intermediate generic region:");
break;
case 38:
printf("immediate generic region:");
break;
case 39:
printf("immediate lossless generic region:");
break;
case 40:
printf("intermediate generic refinement region:");
break;
case 42:
printf("immediate generic refinement region:");
break;
case 43:
printf("immediate lossless generic refinement region:");
break;
case 48:
page_info = jbig2_read_page_info(ctx);
printf("page info:\n");
if (page_info) dump_page_info(page_info);
break;
case 49:
printf("end of page");
break;
case 50:
printf("end of stripe");
break;
case 51:
printf ("end of file\n");
return TRUE;
break;
case 52:
printf("profiles:");
break;
case 53:
printf("tables:");
break;
case 62:
printf("extension:");
break;
default:
printf("UNKNOWN SEGMENT TYPE!!!");
}
printf ("\tflags = %02x, page %d\n",
sh->flags, sh->page_association);
ctx->offset += sh->data_length;
return FALSE;
}
static void
dump_jbig2 (FILE *f)
{
Jbig2Ctx *ctx;
bool last;
ctx = jbig2_open (f);
if (!ctx) return;
printf ("Number of pages = %d\n", ctx->n_pages);
for (;;)
{
last = dump_segment (ctx);
if (last)
break;
}
}
int
main (int argc, char **argv)
{
FILE *f;
if (argc < 2)
return -1;
f = fopen (argv[1], "rb");
if (f == NULL)
return -1;
dump_jbig2 (f);
fclose (f);
return 0;
}