ref: 4369688dfbf2235ed466f38af4ddd11ab781ceaf
dir: /jbig2dec.c/
#include <stdio.h> #include <stdlib.h> #include <string.h> #include "jbig2.h" typedef struct _Jbig2SegmentHeader Jbig2SegmentHeader; typedef struct _Jbig2SymbolDictionary Jbig2SymbolDictionary; struct _Jbig2Ctx { FILE *f; int offset; byte flags; int32 n_pages; }; 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; }; 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]; } 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 & 2) { ctx->offset = 9; } else { ctx->offset = 13; ctx->n_pages = get_int32 (ctx, 9); } return ctx; } static Jbig2SegmentHeader * jbig2_read_segment_header (Jbig2Ctx *ctx) { Jbig2SegmentHeader *result = (Jbig2SegmentHeader *)malloc(sizeof(Jbig2SegmentHeader)); int32 offset = ctx->offset; byte rtscarf; int referred_to_segment_count; byte spa; /* 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) { printf ("long form of rtscarf, can't handle!\n"); } 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 */ get_bytes (ctx, &spa, 1, offset); if (result->flags & 64) { printf ("long form of spa, can't handle!\n"); } result->page_association = spa; /* 7.2.7 */ result->data_length = get_int32 (ctx, offset + 1); ctx->offset = offset + 5; return result; } static Jbig2SymbolDictionary * jbig2_read_symbol_dictionary (Jbig2Ctx *ctx) { Jbig2SymbolDictionary *result = (Jbig2SymbolDictionary *)malloc(sizeof(Jbig2SymbolDictionary)); int32 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; /* 7.4.2.1.2 */ 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 */ 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; return result; } static void dump_symbol_dictionary (Jbig2SymbolDictionary *sd) { printf ("segment type = symbol dictionary, flags = %04x, numexsyms = %d, numnewsyms = %d\n", sd->flags, sd->SDNUMEXSYMS, sd->SDNUMNEWSYMS); } static bool dump_segment (Jbig2Ctx *ctx) { Jbig2SegmentHeader *sh; int32 offset; Jbig2SymbolDictionary *sd; sh = jbig2_read_segment_header (ctx); offset = ctx->offset; printf ("segment number = %d, flags = %02x, page %d, %d bytes\n", sh->segment_number, sh->flags, sh->page_association, sh->data_length); switch (sh->flags & 63) { case 0: sd = jbig2_read_symbol_dictionary (ctx); dump_symbol_dictionary (sd); break; case 51: printf ("segment type = end of file\n"); return TRUE; } ctx->offset = offset + sh->data_length; return FALSE; } static void dump_jbig2 (FILE *f) { Jbig2Ctx *ctx; bool last; ctx = jbig2_open (f); 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; }