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) 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) 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) 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) 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) 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
