2 * CDE - Common Desktop Environment
4 * Copyright (c) 1993-2012, The Open Group. All rights reserved.
6 * These libraries and programs are free software; you can
7 * redistribute them and/or modify them under the terms of the GNU
8 * Lesser General Public License as published by the Free Software
9 * Foundation; either version 2 of the License, or (at your option)
12 * These libraries and programs are distributed in the hope that
13 * they will be useful, but WITHOUT ANY WARRANTY; without even the
14 * implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
15 * PURPOSE. See the GNU Lesser General Public License for more
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with these librararies and programs; if not, write
20 * to the Free Software Foundation, Inc., 51 Franklin Street, Fifth
21 * Floor, Boston, MA 02110-1301 USA
23 /* $XConsortium: jutils.c /main/2 1996/05/09 03:54:23 drk $ */
27 * Copyright (C) 1991-1996, Thomas G. Lane.
28 * This file is part of the Independent JPEG Group's software.
29 * For conditions of distribution and use, see the accompanying README file.
31 * This file contains tables and miscellaneous utility routines needed
32 * for both compression and decompression.
33 * Note we prefix all global names with "j" to minimize conflicts with
34 * a surrounding application.
37 #define JPEG_INTERNALS
43 * jpeg_zigzag_order[i] is the zigzag-order position of the i'th element
44 * of a DCT block read in natural order (left to right, top to bottom).
47 #if 0 /* This table is not actually needed in v6a */
49 const int jpeg_zigzag_order[DCTSIZE2] = {
50 0, 1, 5, 6, 14, 15, 27, 28,
51 2, 4, 7, 13, 16, 26, 29, 42,
52 3, 8, 12, 17, 25, 30, 41, 43,
53 9, 11, 18, 24, 31, 40, 44, 53,
54 10, 19, 23, 32, 39, 45, 52, 54,
55 20, 22, 33, 38, 46, 51, 55, 60,
56 21, 34, 37, 47, 50, 56, 59, 61,
57 35, 36, 48, 49, 57, 58, 62, 63
63 * jpeg_natural_order[i] is the natural-order position of the i'th element
66 * When reading corrupted data, the Huffman decoders could attempt
67 * to reference an entry beyond the end of this array (if the decoded
68 * zero run length reaches past the end of the block). To prevent
69 * wild stores without adding an inner-loop test, we put some extra
70 * "63"s after the real entries. This will cause the extra coefficient
71 * to be stored in location 63 of the block, not somewhere random.
72 * The worst case would be a run-length of 15, which means we need 16
76 const int jpeg_natural_order[DCTSIZE2+16] = {
77 0, 1, 8, 16, 9, 2, 3, 10,
78 17, 24, 32, 25, 18, 11, 4, 5,
79 12, 19, 26, 33, 40, 48, 41, 34,
80 27, 20, 13, 6, 7, 14, 21, 28,
81 35, 42, 49, 56, 57, 50, 43, 36,
82 29, 22, 15, 23, 30, 37, 44, 51,
83 58, 59, 52, 45, 38, 31, 39, 46,
84 53, 60, 61, 54, 47, 55, 62, 63,
85 63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */
86 63, 63, 63, 63, 63, 63, 63, 63
91 * Arithmetic utilities
95 jdiv_round_up (long a, long b)
96 /* Compute a/b rounded up to next integer, ie, ceil(a/b) */
97 /* Assumes a >= 0, b > 0 */
99 return (a + b - 1L) / b;
104 jround_up (long a, long b)
105 /* Compute a rounded up to next multiple of b, ie, ceil(a/b)*b */
106 /* Assumes a >= 0, b > 0 */
113 /* On normal machines we can apply MEMCOPY() and MEMZERO() to sample arrays
114 * and coefficient-block arrays. This won't work on 80x86 because the arrays
115 * are FAR and we're assuming a small-pointer memory model. However, some
116 * DOS compilers provide far-pointer versions of memcpy() and memset() even
117 * in the small-model libraries. These will be used if USE_FMEM is defined.
118 * Otherwise, the routines below do it the hard way. (The performance cost
119 * is not all that great, because these routines aren't very heavily used.)
122 #ifndef NEED_FAR_POINTERS /* normal case, same as regular macros */
123 #define FMEMCOPY(dest,src,size) MEMCOPY(dest,src,size)
124 #define FMEMZERO(target,size) MEMZERO(target,size)
125 #else /* 80x86 case, define if we can */
127 #define FMEMCOPY(dest,src,size) _fmemcpy((void FAR *)(dest), (const void FAR *)(src), (size_t)(size))
128 #define FMEMZERO(target,size) _fmemset((void FAR *)(target), 0, (size_t)(size))
134 jcopy_sample_rows (JSAMPARRAY input_array, int source_row,
135 JSAMPARRAY output_array, int dest_row,
136 int num_rows, JDIMENSION num_cols)
137 /* Copy some rows of samples from one place to another.
138 * num_rows rows are copied from input_array[source_row++]
139 * to output_array[dest_row++]; these areas may overlap for duplication.
140 * The source and destination arrays must be at least as wide as num_cols.
143 register JSAMPROW inptr, outptr;
145 register size_t count = (size_t) (num_cols * SIZEOF(JSAMPLE));
147 register JDIMENSION count;
151 input_array += source_row;
152 output_array += dest_row;
154 for (row = num_rows; row > 0; row--) {
155 inptr = *input_array++;
156 outptr = *output_array++;
158 FMEMCOPY(outptr, inptr, count);
160 for (count = num_cols; count > 0; count--)
161 *outptr++ = *inptr++; /* needn't bother with GETJSAMPLE() here */
168 jcopy_block_row (JBLOCKROW input_row, JBLOCKROW output_row,
169 JDIMENSION num_blocks)
170 /* Copy a row of coefficient blocks from one place to another. */
173 FMEMCOPY(output_row, input_row, num_blocks * (DCTSIZE2 * SIZEOF(JCOEF)));
175 register JCOEFPTR inptr, outptr;
178 inptr = (JCOEFPTR) input_row;
179 outptr = (JCOEFPTR) output_row;
180 for (count = (long) num_blocks * DCTSIZE2; count > 0; count--) {
181 *outptr++ = *inptr++;
188 jzero_far (void FAR * target, size_t bytestozero)
189 /* Zero out a chunk of FAR memory. */
190 /* This might be sample-array data, block-array data, or alloc_large data. */
193 FMEMZERO(target, bytestozero);
195 register char FAR * ptr = (char FAR *) target;
196 register size_t count;
198 for (count = bytestozero; count > 0; count--) {