| OLD | NEW |
| (Empty) |
| 1 /* | |
| 2 * jutils.c | |
| 3 * | |
| 4 * Copyright (C) 1991-1996, Thomas G. Lane. | |
| 5 * This file is part of the Independent JPEG Group's software. | |
| 6 * For conditions of distribution and use, see the accompanying README file. | |
| 7 * | |
| 8 * This file contains tables and miscellaneous utility routines needed | |
| 9 * for both compression and decompression. | |
| 10 * Note we prefix all global names with "j" to minimize conflicts with | |
| 11 * a surrounding application. | |
| 12 */ | |
| 13 | |
| 14 #define JPEG_INTERNALS | |
| 15 #include "jinclude.h" | |
| 16 #include "jpeglib.h" | |
| 17 | |
| 18 | |
| 19 /* | |
| 20 * jpeg_zigzag_order[i] is the zigzag-order position of the i'th element | |
| 21 * of a DCT block read in natural order (left to right, top to bottom). | |
| 22 */ | |
| 23 | |
| 24 #if 0 /* This table is not actually needed in v6a */ | |
| 25 | |
| 26 const int jpeg_zigzag_order[DCTSIZE2] = { | |
| 27 0, 1, 5, 6, 14, 15, 27, 28, | |
| 28 2, 4, 7, 13, 16, 26, 29, 42, | |
| 29 3, 8, 12, 17, 25, 30, 41, 43, | |
| 30 9, 11, 18, 24, 31, 40, 44, 53, | |
| 31 10, 19, 23, 32, 39, 45, 52, 54, | |
| 32 20, 22, 33, 38, 46, 51, 55, 60, | |
| 33 21, 34, 37, 47, 50, 56, 59, 61, | |
| 34 35, 36, 48, 49, 57, 58, 62, 63 | |
| 35 }; | |
| 36 | |
| 37 #endif | |
| 38 | |
| 39 /* | |
| 40 * jpeg_natural_order[i] is the natural-order position of the i'th element | |
| 41 * of zigzag order. | |
| 42 * | |
| 43 * When reading corrupted data, the Huffman decoders could attempt | |
| 44 * to reference an entry beyond the end of this array (if the decoded | |
| 45 * zero run length reaches past the end of the block). To prevent | |
| 46 * wild stores without adding an inner-loop test, we put some extra | |
| 47 * "63"s after the real entries. This will cause the extra coefficient | |
| 48 * to be stored in location 63 of the block, not somewhere random. | |
| 49 * The worst case would be a run-length of 15, which means we need 16 | |
| 50 * fake entries. | |
| 51 */ | |
| 52 | |
| 53 const int jpeg_natural_order[DCTSIZE2+16] = { | |
| 54 0, 1, 8, 16, 9, 2, 3, 10, | |
| 55 17, 24, 32, 25, 18, 11, 4, 5, | |
| 56 12, 19, 26, 33, 40, 48, 41, 34, | |
| 57 27, 20, 13, 6, 7, 14, 21, 28, | |
| 58 35, 42, 49, 56, 57, 50, 43, 36, | |
| 59 29, 22, 15, 23, 30, 37, 44, 51, | |
| 60 58, 59, 52, 45, 38, 31, 39, 46, | |
| 61 53, 60, 61, 54, 47, 55, 62, 63, | |
| 62 63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */ | |
| 63 63, 63, 63, 63, 63, 63, 63, 63 | |
| 64 }; | |
| 65 | |
| 66 | |
| 67 /* | |
| 68 * Arithmetic utilities | |
| 69 */ | |
| 70 | |
| 71 GLOBAL(long) | |
| 72 jdiv_round_up (long a, long b) | |
| 73 /* Compute a/b rounded up to next integer, ie, ceil(a/b) */ | |
| 74 /* Assumes a >= 0, b > 0 */ | |
| 75 { | |
| 76 return (a + b - 1L) / b; | |
| 77 } | |
| 78 | |
| 79 | |
| 80 GLOBAL(long) | |
| 81 jround_up (long a, long b) | |
| 82 /* Compute a rounded up to next multiple of b, ie, ceil(a/b)*b */ | |
| 83 /* Assumes a >= 0, b > 0 */ | |
| 84 { | |
| 85 a += b - 1L; | |
| 86 return a - (a % b); | |
| 87 } | |
| 88 | |
| 89 | |
| 90 /* On normal machines we can apply MEMCOPY() and MEMZERO() to sample arrays | |
| 91 * and coefficient-block arrays. This won't work on 80x86 because the arrays | |
| 92 * are FAR and we're assuming a small-pointer memory model. However, some | |
| 93 * DOS compilers provide far-pointer versions of memcpy() and memset() even | |
| 94 * in the small-model libraries. These will be used if USE_FMEM is defined. | |
| 95 * Otherwise, the routines below do it the hard way. (The performance cost | |
| 96 * is not all that great, because these routines aren't very heavily used.) | |
| 97 */ | |
| 98 | |
| 99 #ifndef NEED_FAR_POINTERS /* normal case, same as regular macros */ | |
| 100 #define FMEMCOPY(dest,src,size) MEMCOPY(dest,src,size) | |
| 101 #define FMEMZERO(target,size) MEMZERO(target,size) | |
| 102 #else /* 80x86 case, define if we can */ | |
| 103 #ifdef USE_FMEM | |
| 104 #define FMEMCOPY(dest,src,size) _fmemcpy((void FAR *)(dest), (const void FAR *)(
src), (size_t)(size)) | |
| 105 #define FMEMZERO(target,size) _fmemset((void FAR *)(target), 0, (size_t)(size)
) | |
| 106 #endif | |
| 107 #endif | |
| 108 | |
| 109 | |
| 110 GLOBAL(void) | |
| 111 jcopy_sample_rows (JSAMPARRAY input_array, int source_row, | |
| 112 JSAMPARRAY output_array, int dest_row, | |
| 113 int num_rows, JDIMENSION num_cols) | |
| 114 /* Copy some rows of samples from one place to another. | |
| 115 * num_rows rows are copied from input_array[source_row++] | |
| 116 * to output_array[dest_row++]; these areas may overlap for duplication. | |
| 117 * The source and destination arrays must be at least as wide as num_cols. | |
| 118 */ | |
| 119 { | |
| 120 register JSAMPROW inptr, outptr; | |
| 121 #ifdef FMEMCOPY | |
| 122 register size_t count = (size_t) (num_cols * SIZEOF(JSAMPLE)); | |
| 123 #else | |
| 124 register JDIMENSION count; | |
| 125 #endif | |
| 126 register int row; | |
| 127 | |
| 128 input_array += source_row; | |
| 129 output_array += dest_row; | |
| 130 | |
| 131 for (row = num_rows; row > 0; row--) { | |
| 132 inptr = *input_array++; | |
| 133 outptr = *output_array++; | |
| 134 #ifdef FMEMCOPY | |
| 135 FMEMCOPY(outptr, inptr, count); | |
| 136 #else | |
| 137 for (count = num_cols; count > 0; count--) | |
| 138 *outptr++ = *inptr++; /* needn't bother with GETJSAMPLE() here */ | |
| 139 #endif | |
| 140 } | |
| 141 } | |
| 142 | |
| 143 | |
| 144 GLOBAL(void) | |
| 145 jcopy_block_row (JBLOCKROW input_row, JBLOCKROW output_row, | |
| 146 JDIMENSION num_blocks) | |
| 147 /* Copy a row of coefficient blocks from one place to another. */ | |
| 148 { | |
| 149 #ifdef FMEMCOPY | |
| 150 FMEMCOPY(output_row, input_row, num_blocks * (DCTSIZE2 * SIZEOF(JCOEF))); | |
| 151 #else | |
| 152 register JCOEFPTR inptr, outptr; | |
| 153 register long count; | |
| 154 | |
| 155 inptr = (JCOEFPTR) input_row; | |
| 156 outptr = (JCOEFPTR) output_row; | |
| 157 for (count = (long) num_blocks * DCTSIZE2; count > 0; count--) { | |
| 158 *outptr++ = *inptr++; | |
| 159 } | |
| 160 #endif | |
| 161 } | |
| 162 | |
| 163 | |
| 164 GLOBAL(void) | |
| 165 jzero_far (void FAR * target, size_t bytestozero) | |
| 166 /* Zero out a chunk of FAR memory. */ | |
| 167 /* This might be sample-array data, block-array data, or alloc_large data. */ | |
| 168 { | |
| 169 #ifdef FMEMZERO | |
| 170 FMEMZERO(target, bytestozero); | |
| 171 #else | |
| 172 register char FAR * ptr = (char FAR *) target; | |
| 173 register size_t count; | |
| 174 | |
| 175 for (count = bytestozero; count > 0; count--) { | |
| 176 *ptr++ = 0; | |
| 177 } | |
| 178 #endif | |
| 179 } | |
| OLD | NEW |