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) 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) 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) 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) 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) 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
