1 #if !defined(_FX_JPEG_TURBO_)
2 /*
3 * jutils.c
4 *
5 * Copyright (C) 1991-1996, Thomas G. Lane.
6 * This file is part of the Independent JPEG Group's software.
7 * For conditions of distribution and use, see the accompanying README file.
8 *
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.
13 */
14
15 #define JPEG_INTERNALS
16 #include "jinclude.h"
17 #include "jpeglib.h"
18
19
20 /*
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).
23 */
24
25 #if 0 /* This table is not actually needed in v6a */
26
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
36 };
37
38 #endif
39
40 /*
41 * jpeg_natural_order[i] is the natural-order position of the i'th element
42 * of zigzag order.
43 *
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
51 * fake entries.
52 */
53
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
65 };
66
67
68 /*
69 * Arithmetic utilities
70 */
71
72 GLOBAL(long)
jdiv_round_up(long a,long b)73 jdiv_round_up (long a, long b)
74 /* Compute a/b rounded up to next integer, ie, ceil(a/b) */
75 /* Assumes a >= 0, b > 0 */
76 {
77 return (a + b - 1L) / b;
78 }
79
80
81 GLOBAL(long)
jround_up(long a,long b)82 jround_up (long a, long b)
83 /* Compute a rounded up to next multiple of b, ie, ceil(a/b)*b */
84 /* Assumes a >= 0, b > 0 */
85 {
86 a += b - 1L;
87 return a - (a % b);
88 }
89
90
91 /* On normal machines we can apply MEMCOPY() and MEMZERO() to sample arrays
92 * and coefficient-block arrays. This won't work on 80x86 because the arrays
93 * are FAR and we're assuming a small-pointer memory model. However, some
94 * DOS compilers provide far-pointer versions of memcpy() and memset() even
95 * in the small-model libraries. These will be used if USE_FMEM is defined.
96 * Otherwise, the routines below do it the hard way. (The performance cost
97 * is not all that great, because these routines aren't very heavily used.)
98 */
99
100 #ifndef NEED_FAR_POINTERS /* normal case, same as regular macros */
101 #define FMEMCOPY(dest,src,size) MEMCOPY(dest,src,size)
102 #define FMEMZERO(target,size) MEMZERO(target,size)
103 #else /* 80x86 case, define if we can */
104 #ifdef USE_FMEM
105 #define FMEMCOPY(dest,src,size) _fmemcpy((void FAR *)(dest), (const void FAR *)(src), (size_t)(size))
106 #define FMEMZERO(target,size) _fmemset((void FAR *)(target), 0, (size_t)(size))
107 #endif
108 #endif
109
110
111 GLOBAL(void)
jcopy_sample_rows(JSAMPARRAY input_array,int source_row,JSAMPARRAY output_array,int dest_row,int num_rows,JDIMENSION num_cols)112 jcopy_sample_rows (JSAMPARRAY input_array, int source_row,
113 JSAMPARRAY output_array, int dest_row,
114 int num_rows, JDIMENSION num_cols)
115 /* Copy some rows of samples from one place to another.
116 * num_rows rows are copied from input_array[source_row++]
117 * to output_array[dest_row++]; these areas may overlap for duplication.
118 * The source and destination arrays must be at least as wide as num_cols.
119 */
120 {
121 register JSAMPROW inptr, outptr;
122 #ifdef FMEMCOPY
123 register size_t count = (size_t) (num_cols * SIZEOF(JSAMPLE));
124 #else
125 register JDIMENSION count;
126 #endif
127 register int row;
128
129 input_array += source_row;
130 output_array += dest_row;
131
132 for (row = num_rows; row > 0; row--) {
133 inptr = *input_array++;
134 outptr = *output_array++;
135 #ifdef FMEMCOPY
136 FMEMCOPY(outptr, inptr, count);
137 #else
138 for (count = num_cols; count > 0; count--)
139 *outptr++ = *inptr++; /* needn't bother with GETJSAMPLE() here */
140 #endif
141 }
142 }
143
144
145 GLOBAL(void)
jcopy_block_row(JBLOCKROW input_row,JBLOCKROW output_row,JDIMENSION num_blocks)146 jcopy_block_row (JBLOCKROW input_row, JBLOCKROW output_row,
147 JDIMENSION num_blocks)
148 /* Copy a row of coefficient blocks from one place to another. */
149 {
150 #ifdef FMEMCOPY
151 FMEMCOPY(output_row, input_row, num_blocks * (DCTSIZE2 * SIZEOF(JCOEF)));
152 #else
153 register JCOEFPTR inptr, outptr;
154 register long count;
155
156 inptr = (JCOEFPTR) input_row;
157 outptr = (JCOEFPTR) output_row;
158 for (count = (long) num_blocks * DCTSIZE2; count > 0; count--) {
159 *outptr++ = *inptr++;
160 }
161 #endif
162 }
163
164
165 GLOBAL(void)
jzero_far(void FAR * target,size_t bytestozero)166 jzero_far (void FAR * target, size_t bytestozero)
167 /* Zero out a chunk of FAR memory. */
168 /* This might be sample-array data, block-array data, or alloc_large data. */
169 {
170 #ifdef FMEMZERO
171 FMEMZERO(target, bytestozero);
172 #else
173 register char FAR * ptr = (char FAR *) target;
174 register size_t count;
175
176 for (count = bytestozero; count > 0; count--) {
177 *ptr++ = 0;
178 }
179 #endif
180 }
181
182 #endif //_FX_JPEG_TURBO_
183