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/*
* Copyright (c) 2022, yzrh <yzrh@noema.org>
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <stdbool.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
static const uint16_t _LSZ[0x71] = {
0x5a1d,
0x2586, 0x1114, 0x080b, 0x03d8, 0x01da, 0x00e5, 0x006f, 0x0036,
0x001a, 0x000d, 0x0006, 0x0003, 0x0001, 0x5a7f, 0x3f25, 0x2cf2,
0x207c, 0x17b9, 0x1182, 0x0cef, 0x09a1, 0x072f, 0x055c, 0x0406,
0x0303, 0x0240, 0x01b1, 0x0144, 0x00f5, 0x00b7, 0x008a, 0x0068,
0x004e, 0x003b, 0x002c, 0x5ae1, 0x484c, 0x3a0d, 0x2ef1, 0x261f,
0x1f33, 0x19a8, 0x1518, 0x1177, 0x0e74, 0x0bfb, 0x09f8, 0x0861,
0x0706, 0x05cd, 0x04de, 0x040f, 0x0363, 0x02d4, 0x025c, 0x01f8,
0x01a4, 0x0160, 0x0125, 0x00f6, 0x00cb, 0x00ab, 0x008f, 0x5b12,
0x4d04, 0x412c, 0x37d8, 0x2fe8, 0x293c, 0x2379, 0x1edf, 0x1aa9,
0x174e, 0x1424, 0x119c, 0x0f6b, 0x0d51, 0x0bb6, 0x0a40, 0x5832,
0x4d1c, 0x438e, 0x3bdd, 0x34ee, 0x2eae, 0x299a, 0x2516, 0x5570,
0x4ca9, 0x44d9, 0x3e22, 0x3824, 0x32b4, 0x2e17, 0x56a8, 0x4f46,
0x47e5, 0x41cf, 0x3c3d, 0x375e, 0x5231, 0x4c0f, 0x4639, 0x415e,
0x5627, 0x50e7, 0x4b85, 0x5597, 0x504f, 0x5a10, 0x5522, 0x59eb
};
static const uint8_t _NLPS[0x71] = {
1,
14, 16, 18, 20, 23, 25, 28, 30,
33, 35, 9, 10, 12, 15, 36, 38,
39, 40, 42, 43, 45, 46, 48, 49,
51, 52, 54, 56, 57, 59, 60, 62,
63, 32, 33, 37, 64, 65, 67, 68,
69, 70, 72, 73, 74, 75, 77, 78,
79, 48, 50, 50, 51, 52, 53, 54,
55, 56, 57, 58, 59, 61, 61, 65,
80, 81, 82, 83, 84, 86, 87, 87,
72, 72, 74, 74, 75, 77, 77, 80,
88, 89, 90, 91, 92, 93, 86, 88,
95, 96, 97, 99, 99, 93, 95, 101,
102, 103, 104, 99, 105, 106, 107, 103,
105, 108, 109, 110, 111, 110, 112, 112
};
static const uint8_t _NMPS[0x71] = {
1,
2, 3, 4, 5, 6, 7, 8, 9,
10, 11, 12, 13, 13, 15, 16, 17,
18, 19, 20, 21, 22, 23, 24, 25,
26, 27, 28, 29, 30, 31, 32, 33,
34, 35, 9, 37, 38, 39, 40, 41,
42, 43, 44, 45, 46, 47, 48, 49,
50, 51, 52, 53, 54, 55, 56, 57,
58, 59, 60, 61, 62, 63, 32, 65,
66, 67, 68, 69, 70, 71, 72, 73,
74, 75, 76, 77, 78, 79, 48, 81,
82, 83, 84, 85, 86, 87, 71, 89,
90, 91, 92, 93, 94, 86, 96, 97,
98, 99, 100, 93, 102, 103, 104, 99,
106, 107, 103, 109, 107, 111, 109, 111
};
static const bool _SWTCH[0x71] = {
1,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 1, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 1, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 1,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 1,
0, 0, 0, 0, 0, 0, 0, 1,
0, 0, 0, 0, 0, 0, 1, 0,
0, 0, 0, 0, 0, 0, 0, 0,
1, 0, 0, 0, 0, 1, 0, 1
};
static uint8_t _ct;
static uint8_t _pix;
static uint16_t _reg_a;
static uint32_t _reg_c;
static uint8_t _mps[0x1000];
static uint8_t _st[0x1000];
static int _width;
static int _height;
static int _width_padded;
static int _ret_pos;
static unsigned char *_ret;
static int _scd_size;
static unsigned char *_scd;
static void
_bytein(void)
{
if (_ret_pos < _scd_size)
_reg_c += _scd[_ret_pos++] << 8;
_ct = 8;
}
static void
_initdec(void)
{
memset(_mps, 0, 0x1000);
memset(_st, 0, 0x1000);
_reg_c = 0;
_bytein();
_reg_c <<= 8;
_bytein();
_reg_c <<= 8;
_bytein();
_reg_a = 0x0000;
}
static void
_exchange_lps(uint16_t cx)
{
uint8_t st_cx = _st[cx];
uint16_t lsz_st_cx = _LSZ[_st[cx]];
if (_reg_a < lsz_st_cx) {
_pix = _mps[cx];
_st[cx] = _NMPS[st_cx];
} else {
_pix = 1 - _mps[cx];
if (_SWTCH[st_cx])
_mps[cx] = _pix;
_st[cx] = _NLPS[st_cx];
}
_reg_c -= _reg_a << 16;
_reg_a = lsz_st_cx;
}
static void
_exchange_mps(uint16_t cx)
{
uint8_t st_cx = _st[cx];
uint16_t lsz_st_cx = _LSZ[_st[cx]];
if (_reg_a < lsz_st_cx) {
_pix = 1 - _mps[cx];
if (_SWTCH[st_cx])
_mps[cx] = _pix;
_st[cx] = _NLPS[st_cx];
} else {
_pix = _mps[cx];
_st[cx] = _NMPS[st_cx];
}
}
static void
_renormd(void)
{
do {
if (_ct == 0)
_bytein();
_reg_a <<= 1;
_reg_c <<= 1;
_ct--;
} while (_reg_a < 0x8000);
if (_ct == 0)
_bytein();
}
static void
_decode(uint16_t cx)
{
_reg_a -= _LSZ[_st[cx]];
if (_reg_a > _reg_c >> 16) {
if (_reg_a < 0x8000) {
_exchange_mps(cx);
_renormd();
} else {
_pix = _mps[cx];
}
} else {
_exchange_lps(cx);
_renormd();
}
}
static void
_procline(int line, char *a, char *b, char *c)
{
/* The encoder must be erroneous */
uint16_t cx = 0;
if (line > 0) {
cx += (_ret[_width_padded * (_height - line)] & 0x20) << 2;
cx += _ret[_width_padded * (_height - line)] & 0x40;
cx += (_ret[_width_padded * (_height - line)] & 0x80) >> 2;
}
if (line > 1) {
cx += (_ret[_width_padded * (_height - line + 1)] & 0x40) >> 4;
cx += (_ret[_width_padded * (_height - line + 1)] & 0x80) >> 6;
}
for (int i = 0; i < _width; i++) {
_decode(cx);
cx >>= 1;
if (_pix == 1) {
_ret[_width_padded * (_height - line - 1) + i / 8] |= _pix << (7 - (i & 0x07));
c[i] = 1;
cx |= 0x0200;
} else {
cx &= 0xfdff;
}
if (i + 2 < _width && a[i + 2] == 1)
cx |= 0x0004;
else
cx &= 0xfffb;
if (i + 3 < _width && b[i + 3] == 1)
cx |= 0x0080;
else
cx &= 0xff7f;
}
}
static int
_procstripe(void)
{
if (_height <= 0 || _width_padded <= 0)
return 1;
int pix_size = 8 * _width_padded;
char *buf = malloc(3 * pix_size);
if (buf == NULL)
return 1;
memset(buf, 0, 3 * pix_size);
char *a = buf;
char *b = a + pix_size;
char *c = b + pix_size;
char *z;
for (int i = 0; i < _height; i++) {
_decode(0x029c);
if (_pix == 1) {
if (i > 0)
memcpy(_ret + _width_padded * (_height - i - 1),
_ret + _width_padded * (_height - i),
_width_padded);
memcpy(c, b, pix_size);
} else {
/* line atypical */
memset(c, 0, pix_size);
_procline(i, a, b, c);
}
z = a;
a = b;
b = c;
c = z;
}
free(buf);
return 0;
}
int
strdec_jbig(char **bitmap, int width, int height,
const char * restrict jbig, int jbig_size)
{
_width = width;
_height = height;
_width_padded = (_width + 7) / 8;
memset(*bitmap, 0, _height * _width_padded);
_ret_pos = 0;
_ret = (unsigned char *) *bitmap;
_scd_size = jbig_size;
_scd = (unsigned char *) jbig;
_initdec();
return _procstripe();
}
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