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
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
|
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <glib.h>
#include <string.h>
#include "huffman.h"
#include "jpeg_debug.h"
#define DEBUG printf
/* misc helper function definitions */
static char *sprintbits (char *str, unsigned int bits, int n);
void
huffman_table_dump (HuffmanTable * table)
{
unsigned int n_bits;
unsigned int code;
char str[33];
int i;
HuffmanEntry *entry;
JPEG_DEBUG (4, "dumping huffman table %p\n", table);
for (i = 0; i < table->len; i++) {
entry = &g_array_index (table, HuffmanEntry, i);
n_bits = entry->n_bits;
code = entry->symbol >> (16 - n_bits);
sprintbits (str, code, n_bits);
JPEG_DEBUG (4, "%s --> %d\n", str, entry->value);
}
}
HuffmanTable *
huffman_table_new (void)
{
HuffmanTable *table;
table = g_array_new (FALSE, TRUE, sizeof (HuffmanEntry));
return table;
}
void
huffman_table_free (HuffmanTable * table)
{
g_array_free (table, TRUE);
}
void
huffman_table_add (HuffmanTable * table, guint32 code, gint n_bits, gint value)
{
HuffmanEntry entry;
entry.value = value;
entry.symbol = code << (16 - n_bits);
entry.mask = 0xffff ^ (0xffff >> n_bits);
entry.n_bits = n_bits;
g_array_append_val (table, entry);
}
unsigned int
huffman_table_decode_jpeg (HuffmanTable * tab, bits_t * bits)
{
unsigned int code;
int i;
char str[33];
HuffmanEntry *entry;
code = peekbits (bits, 16);
for (i = 0; i < tab->len; i++) {
entry = &g_array_index (tab, HuffmanEntry, i);
if ((code & entry->mask) == entry->symbol) {
code = getbits (bits, entry->n_bits);
sprintbits (str, code, entry->n_bits);
JPEG_DEBUG (4, "%s --> %d\n", str, entry->value);
return entry->value;
}
}
printf ("huffman sync lost\n");
return -1;
}
int
huffman_table_decode_macroblock (short *block, HuffmanTable * dc_tab,
HuffmanTable * ac_tab, bits_t * bits)
{
int r, s, x, rs;
int k;
char str[33];
memset (block, 0, sizeof (short) * 64);
s = huffman_table_decode_jpeg (dc_tab, bits);
if (s < 0)
return -1;
x = getbits (bits, s);
if ((x >> (s - 1)) == 0) {
x -= (1 << s) - 1;
}
JPEG_DEBUG (4, "s=%d (block[0]=%d)\n", s, x);
block[0] = x;
for (k = 1; k < 64; k++) {
rs = huffman_table_decode_jpeg (ac_tab, bits);
if (rs < 0) {
JPEG_DEBUG (0, "huffman error\n");
return -1;
}
if (bits->ptr > bits->end) {
JPEG_DEBUG (0, "overrun\n");
return -1;
}
s = rs & 0xf;
r = rs >> 4;
if (s == 0) {
if (r == 15) {
JPEG_DEBUG (4, "r=%d s=%d (skip 16)\n", r, s);
k += 15;
} else {
JPEG_DEBUG (4, "r=%d s=%d (eob)\n", r, s);
break;
}
} else {
k += r;
if (k >= 64) {
printf ("macroblock overrun\n");
return -1;
}
x = getbits (bits, s);
sprintbits (str, x, s);
if ((x >> (s - 1)) == 0) {
x -= (1 << s) - 1;
}
block[k] = x;
JPEG_DEBUG (4, "r=%d s=%d (%s -> block[%d]=%d)\n", r, s, str, k, x);
}
}
return 0;
}
int
huffman_table_decode (HuffmanTable * dc_tab, HuffmanTable * ac_tab,
bits_t * bits)
{
short zz[64];
int ret;
int i;
short *q;
while (bits->ptr < bits->end) {
ret = huffman_table_decode_macroblock (zz, dc_tab, ac_tab, bits);
if (ret < 0)
return -1;
q = zz;
for (i = 0; i < 8; i++) {
DEBUG ("%3d %3d %3d %3d %3d %3d %3d %3d\n",
q[0], q[1], q[2], q[3], q[4], q[5], q[6], q[7]);
q += 8;
}
}
return 0;
}
/* misc helper functins */
static char *
sprintbits (char *str, unsigned int bits, int n)
{
int i;
int bit = 1 << (n - 1);
for (i = 0; i < n; i++) {
str[i] = (bits & bit) ? '1' : '0';
bit >>= 1;
}
str[i] = 0;
return str;
}
|
