ref: fa37e9a7b8c933da66c2850a22c10559f38c68bb
dir: /jbig2_arith.c/
#include <stdio.h>
#include <stdlib.h>
#include "jbig2.h"
#include "jbig2_arith.h"
struct _Jbig2ArithState {
uint32 C;
int A;
int I_CX;
int MPS_CX;
int CT;
uint32 next_word;
int next_word_bytes;
Jbig2WordStream *ws;
int offset;
};
#define SOFTWARE_CONVENTION
static void
jbig2_arith_bytein (Jbig2ArithState *as)
{
byte B;
if (as->next_word_bytes == 0)
{
Jbig2WordStream *ws = as->ws;
as->next_word = ws->get_next_word (ws, as->offset);
as->offset += 4;
as->next_word_bytes = 4;
}
/* Figure F.3 */
B = (as->next_word >> 24) & 0xFF;
if (B == 0xFF)
{
byte B1;
if (as->next_word_bytes == 1)
{
Jbig2WordStream *ws = as->ws;
as->next_word = ws->get_next_word (ws, as->offset);
as->offset += 4;
B1 = (as->next_word >> 24) & 0xFF;
if (B1 > 0x8F)
{
printf ("read %02x (aa)\n", B);
#ifndef SOFTWARE_CONVENTION
as->C += 0xFF00;
#endif
as->CT = 8;
as->next_word = (0xFF00 | B1) << 16;
as->next_word_bytes = 2;
}
else
{
printf ("read %02x (a)\n", B);
#ifdef SOFTWARE_CONVENTION
as->C += 0xFE00 - (B << 8);
#else
as->C += 0xFF00;
#endif
as->CT = 7;
as->next_word_bytes = 4;
}
}
else
{
B1 = (as->next_word >> 16) & 0xFF;
if (B1 > 0x8F)
{
printf ("read %02x (ba)\n", B);
#ifndef SOFTWARE_CONVENTION
as->C += 0xFF00;
#endif
as->CT = 8;
}
else
{
as->next_word_bytes--;
as->next_word <<= 8;
printf ("read %02x (b)\n", B);
#ifdef SOFTWARE_CONVENTION
as->C += 0xFE00 - (B << 8);
#else
as->C += 0xFF00;
#endif
as->CT = 7;
}
}
}
else
{
printf ("read %02x\n", B);
#ifdef SOFTWARE_CONVENTION
as->C += 0xFF00 - (B << 8);
#else
as->C += (B << 8);
#endif
as->CT = 8;
as->next_word <<= 8;
as->next_word_bytes--;
}
}
#ifdef DEBUG
#include <stdio.h>
static void
jbig2_arith_trace (Jbig2ArithState *as)
{
printf ("I = %2d, A = %04x, CT = %2d, C = %08x\n",
as->I_CX, as->A, as->CT, as->C);
}
#endif
Jbig2ArithState *
jbig2_arith_new (Jbig2WordStream *ws)
{
Jbig2ArithState *result = (Jbig2ArithState *)malloc (sizeof(Jbig2ArithState));
result->ws = ws;
result->next_word = ws->get_next_word (ws, 0);
result->next_word_bytes = 4;
result->offset = 4;
/* Figure F.1 */
#ifdef SOFTWARE_CONVENTION
result->C = (~(result->next_word >> 8)) & 0xFF0000;
#else
result->C = (result->next_word >> 8) & 0xFF0000;
#endif
result->next_word <<= 8;
result->next_word_bytes--;
jbig2_arith_bytein (result);
result->C <<= 7;
result->CT -= 7;
result->A = 0x8000;
/* note: these are merely defaults; it may be necessary to provide
additional arguments to initialize these to non-default values. */
result->I_CX = 0;
result->MPS_CX = 0;
return result;
};
/* could put bit fields in to minimize memory usage */
typedef struct {
int Qe;
int NMPS;
int NLPS;
bool SWITCH;
} Jbig2ArithQe;
const Jbig2ArithQe jbig2_arith_Qe[] = {
{ 0x5601, 1, 1, 1 },
{ 0x3401, 2, 6, 0 },
{ 0x1801, 3, 9, 0 },
{ 0x0AC1, 4, 12, 0 },
{ 0x0521, 5, 29, 0 },
{ 0x0221, 38, 33, 0 },
{ 0x5601, 7, 6, 1 },
{ 0x5401, 8, 14, 0 },
{ 0x4801, 9, 14, 0 },
{ 0x3801, 10, 14, 0 },
{ 0x3001, 11, 17, 0 },
{ 0x2401, 12, 18, 0 },
{ 0x1C01, 13, 20, 0 },
{ 0x1601, 29, 21, 0 },
{ 0x5601, 15, 14, 1 },
{ 0x5401, 16, 14, 0 },
{ 0x5101, 17, 15, 0 },
{ 0x4801, 18, 16, 0 },
{ 0x3801, 19, 17, 0 },
{ 0x3401, 20, 18, 0 },
{ 0x3001, 21, 19, 0 },
{ 0x2801, 22, 19, 0 },
{ 0x2401, 23, 20, 0 },
{ 0x2201, 24, 21, 0 },
{ 0x1C01, 25, 22, 0 },
{ 0x1801, 26, 23, 0 },
{ 0x1601, 27, 24, 0 },
{ 0x1401, 28, 25, 0 },
{ 0x1201, 29, 26, 0 },
{ 0x1101, 30, 27, 0 },
{ 0x0AC1, 31, 28, 0 },
{ 0x09C1, 32, 29, 0 },
{ 0x08A1, 33, 30, 0 },
{ 0x0521, 34, 31, 0 },
{ 0x0441, 35, 32, 0 },
{ 0x02A1, 36, 33, 0 },
{ 0x0221, 37, 34, 0 },
{ 0x0141, 38, 35, 0 },
{ 0x0111, 39, 36, 0 },
{ 0x0085, 40, 37, 0 },
{ 0x0049, 41, 38, 0 },
{ 0x0025, 42, 39, 0 },
{ 0x0015, 43, 40, 0 },
{ 0x0009, 44, 41, 0 },
{ 0x0005, 45, 42, 0 },
{ 0x0001, 45, 43, 0 },
{ 0x5601, 46, 46, 0 }
};
static void
jbig2_arith_renormd (Jbig2ArithState *as)
{
/* Figure E.18 */
do
{
if (as->CT == 0)
jbig2_arith_bytein (as);
as->A <<= 1;
as->C <<= 1;
as->CT--;
}
while ((as->A & 0x8000) == 0);
}
bool
jbig2_arith_decode (Jbig2ArithState *as)
{
const Jbig2ArithQe *pqe = &jbig2_arith_Qe[as->I_CX];
bool D;
/* Figure F.2 */
as->A -= pqe->Qe;
if (
#ifdef SOFTWARE_CONVENTION
(as->C) >> 16 < as->A
#else
!((as->C >> 16) < pqe->Qe)
#endif
)
{
#ifndef SOFTWARE_CONVENTION
as->C -= pqe->Qe << 16;
#endif
if ((as->A & 0x8000) == 0)
{
/* MPS_EXCHANGE, Figure E.16 */
if (as->A < pqe->Qe)
{
D = 1 - as->MPS_CX;
as->MPS_CX ^= pqe->SWITCH;
as->I_CX = pqe->NLPS;
}
else
{
D = as->MPS_CX;
as->I_CX = pqe->NMPS;
}
jbig2_arith_renormd (as);
return D;
}
else
return as->MPS_CX;
}
else
{
#ifdef SOFTWARE_CONVENTION
as->C -= (as->A) << 16;
#endif
/* LPS_EXCHANGE, Figure E.17 */
if (as->A < pqe->Qe)
{
as->A = pqe->Qe;
D = as->MPS_CX;
as->I_CX = pqe->NMPS;
}
else
{
as->A = pqe->Qe;
D = 1 - as->MPS_CX;
as->MPS_CX ^= pqe->SWITCH;
as->I_CX = pqe->NLPS;
}
jbig2_arith_renormd (as);
return D;
}
}
#ifdef TEST
static int32
test_get_word (Jbig2WordStream *self, int offset)
{
byte stream[] = {
0x84, 0xC7, 0x3B, 0xFC, 0xE1, 0xA1, 0x43, 0x04, 0x02, 0x20, 0x00, 0x00,
0x41, 0x0D, 0xBB, 0x86, 0xF4, 0x31, 0x7F, 0xFF, 0x88, 0xFF, 0x37, 0x47,
0x1A, 0xDB, 0x6A, 0xDF, 0xFF, 0xAC,
0x00, 0x00
};
if (offset >= sizeof(stream))
return 0;
else
return (stream[offset] << 24) | (stream[offset + 1] << 16) |
(stream[offset + 2] << 8) | stream[offset + 3];
}
int
main (int argc, char **argv)
{
Jbig2WordStream ws;
Jbig2ArithState *as;
int i;
ws.get_next_word = test_get_word;
as = jbig2_arith_new (&ws);
jbig2_arith_trace (as);
for (i = 0; i < 256; i++)
{
bool D;
D = jbig2_arith_decode (as);
printf ("%3d: D = %d, ", i, D);
jbig2_arith_trace (as);
}
return 0;
}
#endif