4
* Copyright (C) 1991-1996, Thomas G. Lane.
5
* Modified 2009-2011 by Guido Vollbeding.
6
* This file is part of the Independent JPEG Group's software.
7
* For conditions of distribution and use, see the accompanying README file.
9
* This file contains tables and miscellaneous utility routines needed
10
* for both compression and decompression.
11
* Note we prefix all global names with "j" to minimize conflicts with
12
* a surrounding application.
15
#define JPEG_INTERNALS
21
* jpeg_zigzag_order[i] is the zigzag-order position of the i'th element
22
* of a DCT block read in natural order (left to right, top to bottom).
25
#if 0 /* This table is not actually needed in v6a */
27
const int jpeg_zigzag_order[DCTSIZE2] = {
28
0, 1, 5, 6, 14, 15, 27, 28,
29
2, 4, 7, 13, 16, 26, 29, 42,
30
3, 8, 12, 17, 25, 30, 41, 43,
31
9, 11, 18, 24, 31, 40, 44, 53,
32
10, 19, 23, 32, 39, 45, 52, 54,
33
20, 22, 33, 38, 46, 51, 55, 60,
34
21, 34, 37, 47, 50, 56, 59, 61,
35
35, 36, 48, 49, 57, 58, 62, 63
41
* jpeg_natural_order[i] is the natural-order position of the i'th element
44
* When reading corrupted data, the Huffman decoders could attempt
45
* to reference an entry beyond the end of this array (if the decoded
46
* zero run length reaches past the end of the block). To prevent
47
* wild stores without adding an inner-loop test, we put some extra
48
* "63"s after the real entries. This will cause the extra coefficient
49
* to be stored in location 63 of the block, not somewhere random.
50
* The worst case would be a run-length of 15, which means we need 16
54
const int jpeg_natural_order[DCTSIZE2+16] = {
55
0, 1, 8, 16, 9, 2, 3, 10,
56
17, 24, 32, 25, 18, 11, 4, 5,
57
12, 19, 26, 33, 40, 48, 41, 34,
58
27, 20, 13, 6, 7, 14, 21, 28,
59
35, 42, 49, 56, 57, 50, 43, 36,
60
29, 22, 15, 23, 30, 37, 44, 51,
61
58, 59, 52, 45, 38, 31, 39, 46,
62
53, 60, 61, 54, 47, 55, 62, 63,
63
63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */
64
63, 63, 63, 63, 63, 63, 63, 63
67
const int jpeg_natural_order7[7*7+16] = {
68
0, 1, 8, 16, 9, 2, 3, 10,
69
17, 24, 32, 25, 18, 11, 4, 5,
70
12, 19, 26, 33, 40, 48, 41, 34,
71
27, 20, 13, 6, 14, 21, 28, 35,
72
42, 49, 50, 43, 36, 29, 22, 30,
73
37, 44, 51, 52, 45, 38, 46, 53,
75
63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */
76
63, 63, 63, 63, 63, 63, 63, 63
79
const int jpeg_natural_order6[6*6+16] = {
80
0, 1, 8, 16, 9, 2, 3, 10,
81
17, 24, 32, 25, 18, 11, 4, 5,
82
12, 19, 26, 33, 40, 41, 34, 27,
83
20, 13, 21, 28, 35, 42, 43, 36,
85
63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */
86
63, 63, 63, 63, 63, 63, 63, 63
89
const int jpeg_natural_order5[5*5+16] = {
90
0, 1, 8, 16, 9, 2, 3, 10,
91
17, 24, 32, 25, 18, 11, 4, 12,
92
19, 26, 33, 34, 27, 20, 28, 35,
94
63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */
95
63, 63, 63, 63, 63, 63, 63, 63
98
const int jpeg_natural_order4[4*4+16] = {
99
0, 1, 8, 16, 9, 2, 3, 10,
100
17, 24, 25, 18, 11, 19, 26, 27,
101
63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */
102
63, 63, 63, 63, 63, 63, 63, 63
105
const int jpeg_natural_order3[3*3+16] = {
106
0, 1, 8, 16, 9, 2, 10, 17,
108
63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */
109
63, 63, 63, 63, 63, 63, 63, 63
112
const int jpeg_natural_order2[2*2+16] = {
114
63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */
115
63, 63, 63, 63, 63, 63, 63, 63
120
* Arithmetic utilities
124
jdiv_round_up (long a, long b)
125
/* Compute a/b rounded up to next integer, ie, ceil(a/b) */
126
/* Assumes a >= 0, b > 0 */
128
return (a + b - 1L) / b;
133
jround_up (long a, long b)
134
/* Compute a rounded up to next multiple of b, ie, ceil(a/b)*b */
135
/* Assumes a >= 0, b > 0 */
142
/* On normal machines we can apply MEMCOPY() and MEMZERO() to sample arrays
143
* and coefficient-block arrays. This won't work on 80x86 because the arrays
144
* are FAR and we're assuming a small-pointer memory model. However, some
145
* DOS compilers provide far-pointer versions of memcpy() and memset() even
146
* in the small-model libraries. These will be used if USE_FMEM is defined.
147
* Otherwise, the routines below do it the hard way. (The performance cost
148
* is not all that great, because these routines aren't very heavily used.)
151
#ifndef NEED_FAR_POINTERS /* normal case, same as regular macro */
152
#define FMEMCOPY(dest,src,size) MEMCOPY(dest,src,size)
153
#else /* 80x86 case, define if we can */
155
#define FMEMCOPY(dest,src,size) _fmemcpy((void FAR *)(dest), (const void FAR *)(src), (size_t)(size))
157
/* This function is for use by the FMEMZERO macro defined in jpegint.h.
158
* Do not call this function directly, use the FMEMZERO macro instead.
161
jzero_far (void FAR * target, size_t bytestozero)
162
/* Zero out a chunk of FAR memory. */
163
/* This might be sample-array data, block-array data, or alloc_large data. */
165
register char FAR * ptr = (char FAR *) target;
166
register size_t count;
168
for (count = bytestozero; count > 0; count--) {
177
jcopy_sample_rows (JSAMPARRAY input_array, int source_row,
178
JSAMPARRAY output_array, int dest_row,
179
int num_rows, JDIMENSION num_cols)
180
/* Copy some rows of samples from one place to another.
181
* num_rows rows are copied from input_array[source_row++]
182
* to output_array[dest_row++]; these areas may overlap for duplication.
183
* The source and destination arrays must be at least as wide as num_cols.
186
register JSAMPROW inptr, outptr;
188
register size_t count = (size_t) (num_cols * SIZEOF(JSAMPLE));
190
register JDIMENSION count;
194
input_array += source_row;
195
output_array += dest_row;
197
for (row = num_rows; row > 0; row--) {
198
inptr = *input_array++;
199
outptr = *output_array++;
201
FMEMCOPY(outptr, inptr, count);
203
for (count = num_cols; count > 0; count--)
204
*outptr++ = *inptr++; /* needn't bother with GETJSAMPLE() here */
211
jcopy_block_row (JBLOCKROW input_row, JBLOCKROW output_row,
212
JDIMENSION num_blocks)
213
/* Copy a row of coefficient blocks from one place to another. */
216
FMEMCOPY(output_row, input_row, num_blocks * (DCTSIZE2 * SIZEOF(JCOEF)));
218
register JCOEFPTR inptr, outptr;
221
inptr = (JCOEFPTR) input_row;
222
outptr = (JCOEFPTR) output_row;
223
for (count = (long) num_blocks * DCTSIZE2; count > 0; count--) {
224
*outptr++ = *inptr++;
added
removed
jpg/jutils.c
