1 /*
2 * jutils.c
3 *
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.
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 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,
74 54,
75 63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */
76 63, 63, 63, 63, 63, 63, 63, 63
77 };
78
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,
84 29, 37, 44, 45,
85 63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */
86 63, 63, 63, 63, 63, 63, 63, 63
87 };
88
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,
93 36,
94 63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */
95 63, 63, 63, 63, 63, 63, 63, 63
96 };
97
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
103 };
104
105 const int jpeg_natural_order3[3*3+16] = {
106 0, 1, 8, 16, 9, 2, 10, 17,
107 18,
108 63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */
109 63, 63, 63, 63, 63, 63, 63, 63
110 };
111
112 const int jpeg_natural_order2[2*2+16] = {
113 0, 1, 8, 9,
114 63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */
115 63, 63, 63, 63, 63, 63, 63, 63
116 };
117
118
119 /*
120 * Arithmetic utilities
121 */
122
123 GLOBAL(long)
jdiv_round_up(long a,long b)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 */
127 {
128 return (a + b - 1L) / b;
129 }
130
131
132 GLOBAL(long)
jround_up(long a,long 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 */
136 {
137 a += b - 1L;
138 return a - (a % b);
139 }
140
141
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.)
149 */
150
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 */
154 #ifdef USE_FMEM
155 #define FMEMCOPY(dest,src,size) _fmemcpy((void FAR *)(dest), (const void FAR *)(src), (size_t)(size))
156 #else
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.
159 */
160 GLOBAL(void)
jzero_far(void FAR * target,size_t bytestozero)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. */
164 {
165 register char FAR * ptr = (char FAR *) target;
166 register size_t count;
167
168 for (count = bytestozero; count > 0; count--) {
169 *ptr++ = 0;
170 }
171 }
172 #endif
173 #endif
174
175
176 GLOBAL(void)
jcopy_sample_rows(JSAMPARRAY input_array,int source_row,JSAMPARRAY output_array,int dest_row,int num_rows,JDIMENSION num_cols)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.
184 */
185 {
186 register JSAMPROW inptr, outptr;
187 #ifdef FMEMCOPY
188 register size_t count = (size_t) (num_cols * SIZEOF(JSAMPLE));
189 #else
190 register JDIMENSION count;
191 #endif
192 register int row;
193
194 input_array += source_row;
195 output_array += dest_row;
196
197 for (row = num_rows; row > 0; row--) {
198 inptr = *input_array++;
199 outptr = *output_array++;
200 #ifdef FMEMCOPY
201 FMEMCOPY(outptr, inptr, count);
202 #else
203 for (count = num_cols; count > 0; count--)
204 *outptr++ = *inptr++; /* needn't bother with GETJSAMPLE() here */
205 #endif
206 }
207 }
208
209
210 GLOBAL(void)
jcopy_block_row(JBLOCKROW input_row,JBLOCKROW output_row,JDIMENSION num_blocks)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. */
214 {
215 #ifdef FMEMCOPY
216 FMEMCOPY(output_row, input_row, num_blocks * (DCTSIZE2 * SIZEOF(JCOEF)));
217 #else
218 register JCOEFPTR inptr, outptr;
219 register long count;
220
221 inptr = (JCOEFPTR) input_row;
222 outptr = (JCOEFPTR) output_row;
223 for (count = (long) num_blocks * DCTSIZE2; count > 0; count--) {
224 *outptr++ = *inptr++;
225 }
226 #endif
227 }
228