1 /* 2 * jddctmgr.c 3 * 4 * Copyright (C) 1994-1996, 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 the inverse-DCT management logic. 9 * This code selects a particular IDCT implementation to be used, 10 * and it performs related housekeeping chores. No code in this file 11 * is executed per IDCT step, only during output pass setup. 12 * 13 * Note that the IDCT routines are responsible for performing coefficient 14 * dequantization as well as the IDCT proper. This module sets up the 15 * dequantization multiplier table needed by the IDCT routine. 16 */ 17 18 #define JPEG_INTERNALS 19 #include "jinclude.h" 20 #include "jpeglib.h" 21 #include "jdct.h" /* Private declarations for DCT subsystem */ 22 23 #ifdef ANDROID_ARMV6_IDCT 24 #undef ANDROID_ARMV6_IDCT 25 #ifdef __arm__ 26 #include <machine/cpu-features.h> 27 #if __ARM_ARCH__ >= 6 28 #define ANDROID_ARMV6_IDCT 29 #else 30 #warning "ANDROID_ARMV6_IDCT is disabled" 31 #endif 32 #endif 33 #endif 34 35 #ifdef ANDROID_ARMV6_IDCT 36 37 /* Intentionally declare the prototype with arguments of primitive types instead 38 * of type-defined ones. This will at least generate some warnings if jmorecfg.h 39 * is changed and becomes incompatible with the assembly code. 40 */ 41 extern void armv6_idct(short *coefs, int *quans, unsigned char **rows, int col); 42 43 void jpeg_idct_armv6 (j_decompress_ptr cinfo, jpeg_component_info * compptr, 44 JCOEFPTR coef_block, 45 JSAMPARRAY output_buf, JDIMENSION output_col) 46 { 47 IFAST_MULT_TYPE *dct_table = (IFAST_MULT_TYPE *)compptr->dct_table; 48 armv6_idct(coef_block, dct_table, output_buf, output_col); 49 } 50 51 #endif 52 53 /* 54 * The decompressor input side (jdinput.c) saves away the appropriate 55 * quantization table for each component at the start of the first scan 56 * involving that component. (This is necessary in order to correctly 57 * decode files that reuse Q-table slots.) 58 * When we are ready to make an output pass, the saved Q-table is converted 59 * to a multiplier table that will actually be used by the IDCT routine. 60 * The multiplier table contents are IDCT-method-dependent. To support 61 * application changes in IDCT method between scans, we can remake the 62 * multiplier tables if necessary. 63 * In buffered-image mode, the first output pass may occur before any data 64 * has been seen for some components, and thus before their Q-tables have 65 * been saved away. To handle this case, multiplier tables are preset 66 * to zeroes; the result of the IDCT will be a neutral gray level. 67 */ 68 69 70 /* Private subobject for this module */ 71 72 typedef struct { 73 struct jpeg_inverse_dct pub; /* public fields */ 74 75 /* This array contains the IDCT method code that each multiplier table 76 * is currently set up for, or -1 if it's not yet set up. 77 * The actual multiplier tables are pointed to by dct_table in the 78 * per-component comp_info structures. 79 */ 80 int cur_method[MAX_COMPONENTS]; 81 } my_idct_controller; 82 83 typedef my_idct_controller * my_idct_ptr; 84 85 86 /* Allocated multiplier tables: big enough for any supported variant */ 87 88 typedef union { 89 ISLOW_MULT_TYPE islow_array[DCTSIZE2]; 90 #ifdef DCT_IFAST_SUPPORTED 91 IFAST_MULT_TYPE ifast_array[DCTSIZE2]; 92 #endif 93 #ifdef DCT_FLOAT_SUPPORTED 94 FLOAT_MULT_TYPE float_array[DCTSIZE2]; 95 #endif 96 } multiplier_table; 97 98 99 /* The current scaled-IDCT routines require ISLOW-style multiplier tables, 100 * so be sure to compile that code if either ISLOW or SCALING is requested. 101 */ 102 #ifdef DCT_ISLOW_SUPPORTED 103 #define PROVIDE_ISLOW_TABLES 104 #else 105 #ifdef IDCT_SCALING_SUPPORTED 106 #define PROVIDE_ISLOW_TABLES 107 #endif 108 #endif 109 110 111 /* 112 * Prepare for an output pass. 113 * Here we select the proper IDCT routine for each component and build 114 * a matching multiplier table. 115 */ 116 117 METHODDEF(void) 118 start_pass (j_decompress_ptr cinfo) 119 { 120 my_idct_ptr idct = (my_idct_ptr) cinfo->idct; 121 int ci, i; 122 jpeg_component_info *compptr; 123 int method = 0; 124 inverse_DCT_method_ptr method_ptr = NULL; 125 JQUANT_TBL * qtbl; 126 127 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 128 ci++, compptr++) { 129 /* Select the proper IDCT routine for this component's scaling */ 130 switch (compptr->DCT_scaled_size) { 131 #ifdef IDCT_SCALING_SUPPORTED 132 case 1: 133 method_ptr = jpeg_idct_1x1; 134 method = JDCT_ISLOW; /* jidctred uses islow-style table */ 135 break; 136 case 2: 137 method_ptr = jpeg_idct_2x2; 138 method = JDCT_ISLOW; /* jidctred uses islow-style table */ 139 break; 140 case 4: 141 method_ptr = jpeg_idct_4x4; 142 method = JDCT_ISLOW; /* jidctred uses islow-style table */ 143 break; 144 #endif 145 case DCTSIZE: 146 switch (cinfo->dct_method) { 147 #ifdef ANDROID_ARMV6_IDCT 148 case JDCT_ISLOW: 149 case JDCT_IFAST: 150 method_ptr = jpeg_idct_armv6; 151 method = JDCT_IFAST; 152 break; 153 #else /* ANDROID_ARMV6_IDCT */ 154 #ifdef DCT_ISLOW_SUPPORTED 155 case JDCT_ISLOW: 156 method_ptr = jpeg_idct_islow; 157 method = JDCT_ISLOW; 158 break; 159 #endif 160 #ifdef DCT_IFAST_SUPPORTED 161 case JDCT_IFAST: 162 method_ptr = jpeg_idct_ifast; 163 method = JDCT_IFAST; 164 break; 165 #endif 166 #endif /* ANDROID_ARMV6_IDCT */ 167 #ifdef DCT_FLOAT_SUPPORTED 168 case JDCT_FLOAT: 169 method_ptr = jpeg_idct_float; 170 method = JDCT_FLOAT; 171 break; 172 #endif 173 default: 174 ERREXIT(cinfo, JERR_NOT_COMPILED); 175 break; 176 } 177 break; 178 default: 179 ERREXIT1(cinfo, JERR_BAD_DCTSIZE, compptr->DCT_scaled_size); 180 break; 181 } 182 idct->pub.inverse_DCT[ci] = method_ptr; 183 /* Create multiplier table from quant table. 184 * However, we can skip this if the component is uninteresting 185 * or if we already built the table. Also, if no quant table 186 * has yet been saved for the component, we leave the 187 * multiplier table all-zero; we'll be reading zeroes from the 188 * coefficient controller's buffer anyway. 189 */ 190 if (! compptr->component_needed || idct->cur_method[ci] == method) 191 continue; 192 qtbl = compptr->quant_table; 193 if (qtbl == NULL) /* happens if no data yet for component */ 194 continue; 195 idct->cur_method[ci] = method; 196 switch (method) { 197 #ifdef PROVIDE_ISLOW_TABLES 198 case JDCT_ISLOW: 199 { 200 /* For LL&M IDCT method, multipliers are equal to raw quantization 201 * coefficients, but are stored as ints to ensure access efficiency. 202 */ 203 ISLOW_MULT_TYPE * ismtbl = (ISLOW_MULT_TYPE *) compptr->dct_table; 204 for (i = 0; i < DCTSIZE2; i++) { 205 ismtbl[i] = (ISLOW_MULT_TYPE) qtbl->quantval[i]; 206 } 207 } 208 break; 209 #endif 210 #ifdef DCT_IFAST_SUPPORTED 211 case JDCT_IFAST: 212 { 213 /* For AA&N IDCT method, multipliers are equal to quantization 214 * coefficients scaled by scalefactor[row]*scalefactor[col], where 215 * scalefactor[0] = 1 216 * scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7 217 * For integer operation, the multiplier table is to be scaled by 218 * IFAST_SCALE_BITS. 219 */ 220 IFAST_MULT_TYPE * ifmtbl = (IFAST_MULT_TYPE *) compptr->dct_table; 221 #ifdef ANDROID_ARMV6_IDCT 222 /* Precomputed values scaled up by 15 bits. */ 223 static const unsigned short scales[DCTSIZE2] = { 224 32768, 45451, 42813, 38531, 32768, 25746, 17734, 9041, 225 45451, 63042, 59384, 53444, 45451, 35710, 24598, 12540, 226 42813, 59384, 55938, 50343, 42813, 33638, 23170, 11812, 227 38531, 53444, 50343, 45308, 38531, 30274, 20853, 10631, 228 32768, 45451, 42813, 38531, 32768, 25746, 17734, 9041, 229 25746, 35710, 33638, 30274, 25746, 20228, 13933, 7103, 230 17734, 24598, 23170, 20853, 17734, 13933, 9598, 4893, 231 9041, 12540, 11812, 10631, 9041, 7103, 4893, 2494, 232 }; 233 /* Inverse map of [7, 5, 1, 3, 0, 2, 4, 6]. */ 234 static const char orders[DCTSIZE] = {4, 2, 5, 3, 6, 1, 7, 0}; 235 /* Reorder the columns after transposing. */ 236 for (i = 0; i < DCTSIZE2; ++i) { 237 int j = ((i & 7) << 3) + orders[i >> 3]; 238 ifmtbl[j] = (qtbl->quantval[i] * scales[i] + 2) >> 2; 239 } 240 #else /* ANDROID_ARMV6_IDCT */ 241 242 #define CONST_BITS 14 243 static const INT16 aanscales[DCTSIZE2] = { 244 /* precomputed values scaled up by 14 bits */ 245 16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520, 246 22725, 31521, 29692, 26722, 22725, 17855, 12299, 6270, 247 21407, 29692, 27969, 25172, 21407, 16819, 11585, 5906, 248 19266, 26722, 25172, 22654, 19266, 15137, 10426, 5315, 249 16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520, 250 12873, 17855, 16819, 15137, 12873, 10114, 6967, 3552, 251 8867, 12299, 11585, 10426, 8867, 6967, 4799, 2446, 252 4520, 6270, 5906, 5315, 4520, 3552, 2446, 1247 253 }; 254 SHIFT_TEMPS 255 256 for (i = 0; i < DCTSIZE2; i++) { 257 ifmtbl[i] = (IFAST_MULT_TYPE) 258 DESCALE(MULTIPLY16V16((INT32) qtbl->quantval[i], 259 (INT32) aanscales[i]), 260 CONST_BITS-IFAST_SCALE_BITS); 261 } 262 #endif /* ANDROID_ARMV6_IDCT */ 263 } 264 break; 265 #endif 266 #ifdef DCT_FLOAT_SUPPORTED 267 case JDCT_FLOAT: 268 { 269 /* For float AA&N IDCT method, multipliers are equal to quantization 270 * coefficients scaled by scalefactor[row]*scalefactor[col], where 271 * scalefactor[0] = 1 272 * scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7 273 */ 274 FLOAT_MULT_TYPE * fmtbl = (FLOAT_MULT_TYPE *) compptr->dct_table; 275 int row, col; 276 static const double aanscalefactor[DCTSIZE] = { 277 1.0, 1.387039845, 1.306562965, 1.175875602, 278 1.0, 0.785694958, 0.541196100, 0.275899379 279 }; 280 281 i = 0; 282 for (row = 0; row < DCTSIZE; row++) { 283 for (col = 0; col < DCTSIZE; col++) { 284 fmtbl[i] = (FLOAT_MULT_TYPE) 285 ((double) qtbl->quantval[i] * 286 aanscalefactor[row] * aanscalefactor[col]); 287 i++; 288 } 289 } 290 } 291 break; 292 #endif 293 default: 294 ERREXIT(cinfo, JERR_NOT_COMPILED); 295 break; 296 } 297 } 298 } 299 300 301 /* 302 * Initialize IDCT manager. 303 */ 304 305 GLOBAL(void) 306 jinit_inverse_dct (j_decompress_ptr cinfo) 307 { 308 my_idct_ptr idct; 309 int ci; 310 jpeg_component_info *compptr; 311 312 idct = (my_idct_ptr) 313 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 314 SIZEOF(my_idct_controller)); 315 cinfo->idct = (struct jpeg_inverse_dct *) idct; 316 idct->pub.start_pass = start_pass; 317 318 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 319 ci++, compptr++) { 320 /* Allocate and pre-zero a multiplier table for each component */ 321 compptr->dct_table = 322 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 323 SIZEOF(multiplier_table)); 324 MEMZERO(compptr->dct_table, SIZEOF(multiplier_table)); 325 /* Mark multiplier table not yet set up for any method */ 326 idct->cur_method[ci] = -1; 327 } 328 } 329
