1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
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
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
|
/* Copyright (C) 2001-2021 Artifex Software, Inc.
All Rights Reserved.
This software is provided AS-IS with no warranty, either express or
implied.
This software is distributed under license and may not be copied,
modified or distributed except as expressly authorized under the terms
of the license contained in the file LICENSE in this distribution.
Refer to licensing information at http://www.artifex.com or contact
Artifex Software, Inc., 1305 Grant Avenue - Suite 200, Novato,
CA 94945, U.S.A., +1(415)492-9861, for further information.
*/
/*
jbig2dec
*/
/* Annex A */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "os_types.h"
#include <stddef.h>
#include <string.h> /* memset() */
#include "jbig2.h"
#include "jbig2_priv.h"
#include "jbig2_arith.h"
#include "jbig2_arith_int.h"
struct _Jbig2ArithIntCtx {
Jbig2ArithCx IAx[512];
};
Jbig2ArithIntCtx *
jbig2_arith_int_ctx_new(Jbig2Ctx *ctx)
{
Jbig2ArithIntCtx *result = jbig2_new(ctx, Jbig2ArithIntCtx, 1);
if (result == NULL) {
jbig2_error(ctx, JBIG2_SEVERITY_FATAL, JBIG2_UNKNOWN_SEGMENT_NUMBER, "failed to allocate arithmetic integer coding state");
return NULL;
} else {
memset(result->IAx, 0, sizeof(result->IAx));
}
return result;
}
/* A.2 */
/* Return value: -1 on error, 0 on normal value, 1 on OOB return. */
int
jbig2_arith_int_decode(Jbig2Ctx *ctx, Jbig2ArithIntCtx *actx, Jbig2ArithState *as, int32_t *p_result)
{
Jbig2ArithCx *IAx = actx->IAx;
int PREV = 1;
int S;
int32_t V;
int bit;
int n_tail, offset;
int i;
S = jbig2_arith_decode(ctx, as, &IAx[PREV]);
if (S < 0)
return jbig2_error(ctx, JBIG2_SEVERITY_WARNING, JBIG2_UNKNOWN_SEGMENT_NUMBER, "failed to decode IAx S");
PREV = (PREV << 1) | S;
bit = jbig2_arith_decode(ctx, as, &IAx[PREV]);
if (bit < 0)
return jbig2_error(ctx, JBIG2_SEVERITY_WARNING, JBIG2_UNKNOWN_SEGMENT_NUMBER, "failed to decode IAx decision bit 0");
PREV = (PREV << 1) | bit;
if (bit) {
bit = jbig2_arith_decode(ctx, as, &IAx[PREV]);
if (bit < 0)
return jbig2_error(ctx, JBIG2_SEVERITY_WARNING, JBIG2_UNKNOWN_SEGMENT_NUMBER, "failed to decode IAx decision bit 1");
PREV = (PREV << 1) | bit;
if (bit) {
bit = jbig2_arith_decode(ctx, as, &IAx[PREV]);
if (bit < 0)
return jbig2_error(ctx, JBIG2_SEVERITY_WARNING, JBIG2_UNKNOWN_SEGMENT_NUMBER, "failed to decode IAx decision bit 2");
PREV = (PREV << 1) | bit;
if (bit) {
bit = jbig2_arith_decode(ctx, as, &IAx[PREV]);
if (bit < 0)
return jbig2_error(ctx, JBIG2_SEVERITY_WARNING, JBIG2_UNKNOWN_SEGMENT_NUMBER, "failed to decode IAx decision bit 3");
PREV = (PREV << 1) | bit;
if (bit) {
bit = jbig2_arith_decode(ctx, as, &IAx[PREV]);
if (bit < 0)
return jbig2_error(ctx, JBIG2_SEVERITY_WARNING, JBIG2_UNKNOWN_SEGMENT_NUMBER, "failed to decode IAx decision bit 4");
PREV = (PREV << 1) | bit;
if (bit) {
n_tail = 32;
offset = 4436;
} else {
n_tail = 12;
offset = 340;
}
} else {
n_tail = 8;
offset = 84;
}
} else {
n_tail = 6;
offset = 20;
}
} else {
n_tail = 4;
offset = 4;
}
} else {
n_tail = 2;
offset = 0;
}
V = 0;
for (i = 0; i < n_tail; i++) {
bit = jbig2_arith_decode(ctx, as, &IAx[PREV]);
if (bit < 0)
return jbig2_error(ctx, JBIG2_SEVERITY_WARNING, JBIG2_UNKNOWN_SEGMENT_NUMBER, "failed to decode IAx V bit %d", i);
PREV = ((PREV << 1) & 511) | (PREV & 256) | bit;
V = (V << 1) | bit;
}
/* offset is always >=0, so underflow can't happen. */
/* avoid overflow by clamping 32 bit value. */
if (V > INT32_MAX - offset)
V = INT32_MAX;
else
V += offset;
V = S ? -V : V;
*p_result = V;
return S && V == 0 ? 1 : 0;
}
void
jbig2_arith_int_ctx_free(Jbig2Ctx *ctx, Jbig2ArithIntCtx *iax)
{
jbig2_free(ctx->allocator, iax);
}
|