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
27const 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
54const 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
67const 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
79const 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
89const 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
98const 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
105const 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
112const 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
123GLOBAL(long)
124jdiv_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
132GLOBAL(long)
133jround_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 */
160GLOBAL(void)
161jzero_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
176GLOBAL(void)
177jcopy_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
210GLOBAL(void)
211jcopy_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