ref: 4369688dfbf2235ed466f38af4ddd11ab781ceaf
dir: /jbig2_huffman.c/
/* Huffman table decoding procedures */
#include <stdlib.h>
#include "jbig2.h"
#include "jbig2_huffman.h"
#define JBIG2_HUFFMAN_FLAGS_ISOOB 1
#define JBIG2_HUFFMAN_FLAGS_ISLOW 2
#define JBIG2_HUFFMAN_FLAGS_ISEXT 4
typedef struct _Jbig2HuffmanEntry Jbig2HuffmanEntry;
struct _Jbig2HuffmanEntry {
union {
int32 RANGELOW;
Jbig2HuffmanTable *ext_table;
} u;
byte PREFLEN;
byte RANGELEN;
byte flags;
};
struct _Jbig2HuffmanTable {
int log_table_size;
Jbig2HuffmanEntry *entries;
};
struct _Jbig2HuffmanState {
/* The current bit offset is equal to (offset * 8) + offset_bits.
The MSB of this_word is the current bit offset. The MSB of next_word
is (offset + 4) * 8. */
uint32 this_word;
uint32 next_word;
int offset_bits;
int offset;
Jbig2WordStream *ws;
};
Jbig2HuffmanState *
jbig2_huffman_new (Jbig2WordStream *ws)
{
Jbig2HuffmanState *result = (Jbig2HuffmanState *)malloc (sizeof(Jbig2HuffmanState));
result->offset = 0;
result->offset_bits = 0;
result->this_word = ws->get_next_word (ws, 0);
result->next_word = ws->get_next_word (ws, 4);
result->ws = ws;
return result;
}
int32
jbig2_huffman_get (Jbig2HuffmanState *hs,
const Jbig2HuffmanTable *table, bool *oob)
{
Jbig2HuffmanEntry *entry;
byte flags;
int offset_bits = hs->offset_bits;
uint32 this_word = hs->this_word;
uint32 next_word;
int RANGELEN;
int32 result;
for (;;)
{
int log_table_size = table->log_table_size;
int PREFLEN;
entry = &table->entries[this_word >> (32 - log_table_size)];
flags = entry->flags;
PREFLEN = entry->PREFLEN;
next_word = hs->next_word;
offset_bits += PREFLEN;
if (offset_bits >= 32)
{
Jbig2WordStream *ws = hs->ws;
this_word = next_word;
hs->offset += 4;
next_word = ws->get_next_word (ws, hs->offset + 4);
offset_bits -= 32;
hs->next_word = next_word;
PREFLEN = offset_bits;
}
this_word = (this_word << PREFLEN) |
(next_word >> (32 - offset_bits));
if (flags & JBIG2_HUFFMAN_FLAGS_ISEXT)
{
table = entry->u.ext_table;
}
else
break;
}
result = entry->u.RANGELOW;
RANGELEN = entry->RANGELEN;
if (RANGELEN > 0)
{
int32 HTOFFSET;
HTOFFSET = this_word >> (32 - RANGELEN);
if (flags & JBIG2_HUFFMAN_FLAGS_ISLOW)
result -= HTOFFSET;
else
result += HTOFFSET;
offset_bits += RANGELEN;
if (offset_bits >= 32)
{
Jbig2WordStream *ws = hs->ws;
this_word = next_word;
hs->offset += 4;
next_word = ws->get_next_word (ws, hs->offset + 4);
offset_bits -= 32;
hs->next_word = next_word;
RANGELEN = offset_bits;
}
this_word = (this_word << RANGELEN) |
(next_word >> (32 - offset_bits));
}
hs->this_word = this_word;
hs->offset_bits = offset_bits;
if (oob != NULL)
*oob = (flags & JBIG2_HUFFMAN_FLAGS_ISOOB);
return result;
}
typedef struct _Jbig2HuffmanLine Jbig2HuffmanLine;
struct _Jbig2HuffmanLine {
int PREFLEN;
int RANGELEN;
int RANGELOW;
};
struct _Jbig2HuffmanParams {
bool HTOOB;
int n_lines;
const Jbig2HuffmanLine *lines;
};
/* Table B.1 */
const Jbig2HuffmanLine
jbig_huffman_lines_A[] = {
{ 1, 4, 0 },
{ 2, 8, 16 },
{ 3, 16, 272 },
{ 0, 32, -1 }, /* low */
{ 3, 32, 65808 } /* high */
};
const Jbig2HuffmanParams
jbig_huffman_params_A = { FALSE, 5, jbig_huffman_lines_A };
/* Table B.2 */
const Jbig2HuffmanLine
jbig_huffman_lines_B[] = {
{ 1, 0, 0 },
{ 2, 0, 1 },
{ 3, 0, 2 },
{ 4, 3, 3 },
{ 5, 6, 11 },
{ 0, 32, -1 }, /* low */
{ 6, 32, 75 }, /* high */
{ 6, 0, 0 }
};
const Jbig2HuffmanParams
jbig_huffman_params_B = { TRUE, 8, jbig_huffman_lines_B };
/* Table B.3 */
const Jbig2HuffmanLine
jbig_huffman_lines_C[] = {
{ 8, 8, -256 },
{ 1, 0, 0 },
{ 2, 0, 1 },
{ 3, 0, 2 },
{ 4, 3, 3 },
{ 5, 6, 11 },
{ 8, 32, -257 }, /* low */
{ 7, 32, 75 }, /* high */
{ 6, 0, 0 } /* OOB */
};
const Jbig2HuffmanParams
jbig_huffman_params_C = { TRUE, 9, jbig_huffman_lines_C };
/* Table B.4 */
const Jbig2HuffmanLine
jbig_huffman_lines_D[] = {
{ 1, 0, 1 },
{ 2, 0, 2 },
{ 3, 0, 3 },
{ 4, 3, 4 },
{ 5, 6, 12 },
{ 0, 32, -1 }, /* low */
{ 5, 32, 76 }, /* high */
};
const Jbig2HuffmanParams
jbig_huffman_params_D = { FALSE, 7, jbig_huffman_lines_D };
/* Table B.14 */
const Jbig2HuffmanLine
jbig_huffman_lines_N[] = {
{ 3, 0, -2 },
{ 3, 0, -1 },
{ 1, 0, 0 },
{ 3, 3, 1 },
{ 3, 6, 2 },
{ 0, 32, -1 }, /* low */
{ 0, 32, 3 }, /* high */
};
const Jbig2HuffmanParams
jbig_huffman_params_N = { FALSE, 7, jbig_huffman_lines_N };
#define LOG_TABLE_SIZE_MAX 8
Jbig2HuffmanTable *
jbig2_build_huffman_table (const Jbig2HuffmanParams *params)
{
int LENCOUNT[256];
int LENMAX = -1;
const Jbig2HuffmanLine *lines = params->lines;
int n_lines = params->n_lines;
int i, j;
int log_table_size = 0;
Jbig2HuffmanTable *result;
Jbig2HuffmanEntry *entries;
int CURLEN;
int firstcode = 0;
int CURCODE;
int CURTEMP;
/* B.3, 1. */
for (i = 0; i < params->n_lines; i++)
{
int PREFLEN = lines[i].PREFLEN;
int lts;
if (PREFLEN > LENMAX)
{
for (j = LENMAX + 1; j < PREFLEN + 1; j++)
LENCOUNT[j] = 0;
LENMAX = PREFLEN;
}
LENCOUNT[PREFLEN]++;
lts = PREFLEN + lines[i].RANGELEN;
if (lts > LOG_TABLE_SIZE_MAX)
lts = PREFLEN;
if (lts <= LOG_TABLE_SIZE_MAX && log_table_size < lts)
log_table_size = lts;
}
result = (Jbig2HuffmanTable *)malloc (sizeof(Jbig2HuffmanTable));
result->log_table_size = log_table_size;
entries = (Jbig2HuffmanEntry *)malloc (sizeof(Jbig2HuffmanEntry) << log_table_size);
result->entries = entries;
LENCOUNT[0] = 0;
for (CURLEN = 1; CURLEN <= LENMAX; CURLEN++)
{
int shift = log_table_size - CURLEN;
/* B.3 3.(a) */
firstcode = (firstcode + LENCOUNT[CURLEN - 1]) << 1;
CURCODE = firstcode;
/* B.3 3.(b) */
for (CURTEMP = 0; CURTEMP < n_lines; CURTEMP++)
{
int PREFLEN = lines[CURTEMP].PREFLEN;
if (PREFLEN == CURLEN)
{
int RANGELEN = lines[CURTEMP].RANGELEN;
int start_j = CURCODE << shift;
int end_j = (CURCODE + 1) << shift;
byte eflags = 0;
/* todo: build extension tables */
if (params->HTOOB && CURTEMP == n_lines - 1)
eflags |= JBIG2_HUFFMAN_FLAGS_ISOOB;
if (CURTEMP == n_lines - (params->HTOOB ? 3 : 2))
eflags |= JBIG2_HUFFMAN_FLAGS_ISLOW;
if (PREFLEN + RANGELEN > LOG_TABLE_SIZE_MAX)
{
for (j = start_j; j < end_j; j++)
{
entries[j].u.RANGELOW = lines[CURTEMP].RANGELOW;
entries[j].PREFLEN = PREFLEN;
entries[j].RANGELEN = RANGELEN;
entries[j].flags = eflags;
}
}
else
{
for (j = start_j; j < end_j; j++)
{
int32 HTOFFSET = (j >> (shift - RANGELEN)) &
((1 << RANGELEN) - 1);
if (eflags & JBIG2_HUFFMAN_FLAGS_ISLOW)
entries[j].u.RANGELOW = lines[CURTEMP].RANGELOW -
HTOFFSET;
else
entries[j].u.RANGELOW = lines[CURTEMP].RANGELOW +
HTOFFSET;
entries[j].PREFLEN = PREFLEN + RANGELEN;
entries[j].RANGELEN = 0;
entries[j].flags = eflags;
}
}
CURCODE++;
}
}
}
return result;
}
#ifdef TEST
#include <stdio.h>
static int32
test_get_word (Jbig2WordStream *self, int offset)
{
if (offset == 0)
return 0xe9cbf400;
else
return 0;
}
int
main (int argc, char **argv)
{
Jbig2HuffmanTable *b1;
Jbig2HuffmanTable *b2;
Jbig2HuffmanTable *b4;
Jbig2HuffmanState *hs;
Jbig2WordStream ws;
bool oob;
int32 code;
b1 = jbig2_build_huffman_table (&jbig_huffman_params_A);
b2 = jbig2_build_huffman_table (&jbig_huffman_params_B);
b4 = jbig2_build_huffman_table (&jbig_huffman_params_D);
ws.get_next_word = test_get_word;
hs = jbig2_huffman_new (&ws);
code = jbig2_huffman_get (hs, b4, &oob);
printf ("%d %s\n", code, oob ? "OOB" : "");
code = jbig2_huffman_get (hs, b2, &oob);
printf ("%d %s\n", code, oob ? "OOB" : "");
code = jbig2_huffman_get (hs, b2, &oob);
printf ("%d %s\n", code, oob ? "OOB" : "");
code = jbig2_huffman_get (hs, b1, &oob);
printf ("%d %s\n", code, oob ? "OOB" : "");
return 0;
}
#endif