1 /* 2 * jdct.h 3 * 4 * Copyright (C) 1994-1996, Thomas G. Lane. 5 * Modified 2002-2015 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 include file contains common declarations for the forward and 10 * inverse DCT modules. These declarations are private to the DCT managers 11 * (jcdctmgr.c, jddctmgr.c) and the individual DCT algorithms. 12 * The individual DCT algorithms are kept in separate files to ease 13 * machine-dependent tuning (e.g., assembly coding). 14 */ 15 16 17 /* 18 * A forward DCT routine is given a pointer to an input sample array and 19 * a pointer to a work area of type DCTELEM[]; the DCT is to be performed 20 * in-place in that buffer. Type DCTELEM is int for 8-bit samples, INT32 21 * for 12-bit samples. (NOTE: Floating-point DCT implementations use an 22 * array of type FAST_FLOAT, instead.) 23 * The input data is to be fetched from the sample array starting at a 24 * specified column. (Any row offset needed will be applied to the array 25 * pointer before it is passed to the FDCT code.) 26 * Note that the number of samples fetched by the FDCT routine is 27 * DCT_h_scaled_size * DCT_v_scaled_size. 28 * The DCT outputs are returned scaled up by a factor of 8; they therefore 29 * have a range of +-8K for 8-bit data, +-128K for 12-bit data. This 30 * convention improves accuracy in integer implementations and saves some 31 * work in floating-point ones. 32 * Quantization of the output coefficients is done by jcdctmgr.c. 33 */ 34 35 #if BITS_IN_JSAMPLE == 8 36 typedef int DCTELEM; /* 16 or 32 bits is fine */ 37 #else 38 typedef INT32 DCTELEM; /* must have 32 bits */ 39 #endif 40 41 typedef JMETHOD(void, forward_DCT_method_ptr, (DCTELEM * data, 42 JSAMPARRAY sample_data, 43 JDIMENSION start_col)); 44 typedef JMETHOD(void, float_DCT_method_ptr, (FAST_FLOAT * data, 45 JSAMPARRAY sample_data, 46 JDIMENSION start_col)); 47 48 49 /* 50 * An inverse DCT routine is given a pointer to the input JBLOCK and a pointer 51 * to an output sample array. The routine must dequantize the input data as 52 * well as perform the IDCT; for dequantization, it uses the multiplier table 53 * pointed to by compptr->dct_table. The output data is to be placed into the 54 * sample array starting at a specified column. (Any row offset needed will 55 * be applied to the array pointer before it is passed to the IDCT code.) 56 * Note that the number of samples emitted by the IDCT routine is 57 * DCT_h_scaled_size * DCT_v_scaled_size. 58 */ 59 60 /* typedef inverse_DCT_method_ptr is declared in jpegint.h */ 61 62 /* 63 * Each IDCT routine has its own ideas about the best dct_table element type. 64 */ 65 66 typedef MULTIPLIER ISLOW_MULT_TYPE; /* short or int, whichever is faster */ 67 #if BITS_IN_JSAMPLE == 8 68 typedef MULTIPLIER IFAST_MULT_TYPE; /* 16 bits is OK, use short if faster */ 69 #define IFAST_SCALE_BITS 2 /* fractional bits in scale factors */ 70 #else 71 typedef INT32 IFAST_MULT_TYPE; /* need 32 bits for scaled quantizers */ 72 #define IFAST_SCALE_BITS 13 /* fractional bits in scale factors */ 73 #endif 74 typedef FAST_FLOAT FLOAT_MULT_TYPE; /* preferred floating type */ 75 76 77 /* 78 * Each IDCT routine is responsible for range-limiting its results and 79 * converting them to unsigned form (0..MAXJSAMPLE). The raw outputs could 80 * be quite far out of range if the input data is corrupt, so a bulletproof 81 * range-limiting step is required. We use a mask-and-table-lookup method 82 * to do the combined operations quickly, assuming that MAXJSAMPLE+1 83 * is a power of 2. See the comments with prepare_range_limit_table 84 * (in jdmaster.c) for more info. 85 */ 86 87 #define RANGE_MASK (MAXJSAMPLE * 4 + 3) /* 2 bits wider than legal samples */ 88 #define RANGE_CENTER (MAXJSAMPLE * 2 + 2) 89 #define RANGE_SUBSET (RANGE_CENTER - CENTERJSAMPLE) 90 91 #define IDCT_range_limit(cinfo) ((cinfo)->sample_range_limit - RANGE_SUBSET) 92 93 94 /* Short forms of external names for systems with brain-damaged linkers. */ 95 96 #ifdef NEED_SHORT_EXTERNAL_NAMES 97 #define jpeg_fdct_islow jFDislow 98 #define jpeg_fdct_ifast jFDifast 99 #define jpeg_fdct_float jFDfloat 100 #define jpeg_fdct_7x7 jFD7x7 101 #define jpeg_fdct_6x6 jFD6x6 102 #define jpeg_fdct_5x5 jFD5x5 103 #define jpeg_fdct_4x4 jFD4x4 104 #define jpeg_fdct_3x3 jFD3x3 105 #define jpeg_fdct_2x2 jFD2x2 106 #define jpeg_fdct_1x1 jFD1x1 107 #define jpeg_fdct_9x9 jFD9x9 108 #define jpeg_fdct_10x10 jFD10x10 109 #define jpeg_fdct_11x11 jFD11x11 110 #define jpeg_fdct_12x12 jFD12x12 111 #define jpeg_fdct_13x13 jFD13x13 112 #define jpeg_fdct_14x14 jFD14x14 113 #define jpeg_fdct_15x15 jFD15x15 114 #define jpeg_fdct_16x16 jFD16x16 115 #define jpeg_fdct_16x8 jFD16x8 116 #define jpeg_fdct_14x7 jFD14x7 117 #define jpeg_fdct_12x6 jFD12x6 118 #define jpeg_fdct_10x5 jFD10x5 119 #define jpeg_fdct_8x4 jFD8x4 120 #define jpeg_fdct_6x3 jFD6x3 121 #define jpeg_fdct_4x2 jFD4x2 122 #define jpeg_fdct_2x1 jFD2x1 123 #define jpeg_fdct_8x16 jFD8x16 124 #define jpeg_fdct_7x14 jFD7x14 125 #define jpeg_fdct_6x12 jFD6x12 126 #define jpeg_fdct_5x10 jFD5x10 127 #define jpeg_fdct_4x8 jFD4x8 128 #define jpeg_fdct_3x6 jFD3x6 129 #define jpeg_fdct_2x4 jFD2x4 130 #define jpeg_fdct_1x2 jFD1x2 131 #define jpeg_idct_islow jRDislow 132 #define jpeg_idct_ifast jRDifast 133 #define jpeg_idct_float jRDfloat 134 #define jpeg_idct_7x7 jRD7x7 135 #define jpeg_idct_6x6 jRD6x6 136 #define jpeg_idct_5x5 jRD5x5 137 #define jpeg_idct_4x4 jRD4x4 138 #define jpeg_idct_3x3 jRD3x3 139 #define jpeg_idct_2x2 jRD2x2 140 #define jpeg_idct_1x1 jRD1x1 141 #define jpeg_idct_9x9 jRD9x9 142 #define jpeg_idct_10x10 jRD10x10 143 #define jpeg_idct_11x11 jRD11x11 144 #define jpeg_idct_12x12 jRD12x12 145 #define jpeg_idct_13x13 jRD13x13 146 #define jpeg_idct_14x14 jRD14x14 147 #define jpeg_idct_15x15 jRD15x15 148 #define jpeg_idct_16x16 jRD16x16 149 #define jpeg_idct_16x8 jRD16x8 150 #define jpeg_idct_14x7 jRD14x7 151 #define jpeg_idct_12x6 jRD12x6 152 #define jpeg_idct_10x5 jRD10x5 153 #define jpeg_idct_8x4 jRD8x4 154 #define jpeg_idct_6x3 jRD6x3 155 #define jpeg_idct_4x2 jRD4x2 156 #define jpeg_idct_2x1 jRD2x1 157 #define jpeg_idct_8x16 jRD8x16 158 #define jpeg_idct_7x14 jRD7x14 159 #define jpeg_idct_6x12 jRD6x12 160 #define jpeg_idct_5x10 jRD5x10 161 #define jpeg_idct_4x8 jRD4x8 162 #define jpeg_idct_3x6 jRD3x8 163 #define jpeg_idct_2x4 jRD2x4 164 #define jpeg_idct_1x2 jRD1x2 165 #endif /* NEED_SHORT_EXTERNAL_NAMES */ 166 167 /* Extern declarations for the forward and inverse DCT routines. */ 168 169 EXTERN(void) jpeg_fdct_islow 170 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 171 EXTERN(void) jpeg_fdct_ifast 172 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 173 EXTERN(void) jpeg_fdct_float 174 JPP((FAST_FLOAT * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 175 EXTERN(void) jpeg_fdct_7x7 176 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 177 EXTERN(void) jpeg_fdct_6x6 178 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 179 EXTERN(void) jpeg_fdct_5x5 180 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 181 EXTERN(void) jpeg_fdct_4x4 182 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 183 EXTERN(void) jpeg_fdct_3x3 184 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 185 EXTERN(void) jpeg_fdct_2x2 186 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 187 EXTERN(void) jpeg_fdct_1x1 188 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 189 EXTERN(void) jpeg_fdct_9x9 190 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 191 EXTERN(void) jpeg_fdct_10x10 192 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 193 EXTERN(void) jpeg_fdct_11x11 194 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 195 EXTERN(void) jpeg_fdct_12x12 196 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 197 EXTERN(void) jpeg_fdct_13x13 198 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 199 EXTERN(void) jpeg_fdct_14x14 200 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 201 EXTERN(void) jpeg_fdct_15x15 202 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 203 EXTERN(void) jpeg_fdct_16x16 204 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 205 EXTERN(void) jpeg_fdct_16x8 206 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 207 EXTERN(void) jpeg_fdct_14x7 208 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 209 EXTERN(void) jpeg_fdct_12x6 210 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 211 EXTERN(void) jpeg_fdct_10x5 212 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 213 EXTERN(void) jpeg_fdct_8x4 214 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 215 EXTERN(void) jpeg_fdct_6x3 216 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 217 EXTERN(void) jpeg_fdct_4x2 218 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 219 EXTERN(void) jpeg_fdct_2x1 220 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 221 EXTERN(void) jpeg_fdct_8x16 222 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 223 EXTERN(void) jpeg_fdct_7x14 224 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 225 EXTERN(void) jpeg_fdct_6x12 226 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 227 EXTERN(void) jpeg_fdct_5x10 228 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 229 EXTERN(void) jpeg_fdct_4x8 230 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 231 EXTERN(void) jpeg_fdct_3x6 232 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 233 EXTERN(void) jpeg_fdct_2x4 234 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 235 EXTERN(void) jpeg_fdct_1x2 236 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col)); 237 238 EXTERN(void) jpeg_idct_islow 239 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 240 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 241 EXTERN(void) jpeg_idct_ifast 242 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 243 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 244 EXTERN(void) jpeg_idct_float 245 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 246 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 247 EXTERN(void) jpeg_idct_7x7 248 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 249 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 250 EXTERN(void) jpeg_idct_6x6 251 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 252 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 253 EXTERN(void) jpeg_idct_5x5 254 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 255 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 256 EXTERN(void) jpeg_idct_4x4 257 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 258 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 259 EXTERN(void) jpeg_idct_3x3 260 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 261 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 262 EXTERN(void) jpeg_idct_2x2 263 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 264 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 265 EXTERN(void) jpeg_idct_1x1 266 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 267 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 268 EXTERN(void) jpeg_idct_9x9 269 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 270 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 271 EXTERN(void) jpeg_idct_10x10 272 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 273 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 274 EXTERN(void) jpeg_idct_11x11 275 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 276 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 277 EXTERN(void) jpeg_idct_12x12 278 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 279 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 280 EXTERN(void) jpeg_idct_13x13 281 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 282 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 283 EXTERN(void) jpeg_idct_14x14 284 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 285 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 286 EXTERN(void) jpeg_idct_15x15 287 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 288 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 289 EXTERN(void) jpeg_idct_16x16 290 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 291 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 292 EXTERN(void) jpeg_idct_16x8 293 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 294 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 295 EXTERN(void) jpeg_idct_14x7 296 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 297 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 298 EXTERN(void) jpeg_idct_12x6 299 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 300 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 301 EXTERN(void) jpeg_idct_10x5 302 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 303 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 304 EXTERN(void) jpeg_idct_8x4 305 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 306 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 307 EXTERN(void) jpeg_idct_6x3 308 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 309 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 310 EXTERN(void) jpeg_idct_4x2 311 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 312 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 313 EXTERN(void) jpeg_idct_2x1 314 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 315 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 316 EXTERN(void) jpeg_idct_8x16 317 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 318 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 319 EXTERN(void) jpeg_idct_7x14 320 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 321 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 322 EXTERN(void) jpeg_idct_6x12 323 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 324 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 325 EXTERN(void) jpeg_idct_5x10 326 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 327 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 328 EXTERN(void) jpeg_idct_4x8 329 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 330 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 331 EXTERN(void) jpeg_idct_3x6 332 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 333 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 334 EXTERN(void) jpeg_idct_2x4 335 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 336 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 337 EXTERN(void) jpeg_idct_1x2 338 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr, 339 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)); 340 341 342 /* 343 * Macros for handling fixed-point arithmetic; these are used by many 344 * but not all of the DCT/IDCT modules. 345 * 346 * All values are expected to be of type INT32. 347 * Fractional constants are scaled left by CONST_BITS bits. 348 * CONST_BITS is defined within each module using these macros, 349 * and may differ from one module to the next. 350 */ 351 352 #define ONE ((INT32) 1) 353 #define CONST_SCALE (ONE << CONST_BITS) 354 355 /* Convert a positive real constant to an integer scaled by CONST_SCALE. 356 * Caution: some C compilers fail to reduce "FIX(constant)" at compile time, 357 * thus causing a lot of useless floating-point operations at run time. 358 */ 359 360 #define FIX(x) ((INT32) ((x) * CONST_SCALE + 0.5)) 361 362 /* Descale and correctly round an INT32 value that's scaled by N bits. 363 * We assume RIGHT_SHIFT rounds towards minus infinity, so adding 364 * the fudge factor is correct for either sign of X. 365 */ 366 367 #define DESCALE(x,n) RIGHT_SHIFT((x) + (ONE << ((n)-1)), n) 368 369 /* Multiply an INT32 variable by an INT32 constant to yield an INT32 result. 370 * This macro is used only when the two inputs will actually be no more than 371 * 16 bits wide, so that a 16x16->32 bit multiply can be used instead of a 372 * full 32x32 multiply. This provides a useful speedup on many machines. 373 * Unfortunately there is no way to specify a 16x16->32 multiply portably 374 * in C, but some C compilers will do the right thing if you provide the 375 * correct combination of casts. 376 */ 377 378 #ifdef SHORTxSHORT_32 /* may work if 'int' is 32 bits */ 379 #define MULTIPLY16C16(var,const) (((INT16) (var)) * ((INT16) (const))) 380 #endif 381 #ifdef SHORTxLCONST_32 /* known to work with Microsoft C 6.0 */ 382 #define MULTIPLY16C16(var,const) (((INT16) (var)) * ((INT32) (const))) 383 #endif 384 385 #ifndef MULTIPLY16C16 /* default definition */ 386 #define MULTIPLY16C16(var,const) ((var) * (const)) 387 #endif 388 389 /* Same except both inputs are variables. */ 390 391 #ifdef SHORTxSHORT_32 /* may work if 'int' is 32 bits */ 392 #define MULTIPLY16V16(var1,var2) (((INT16) (var1)) * ((INT16) (var2))) 393 #endif 394 395 #ifndef MULTIPLY16V16 /* default definition */ 396 #define MULTIPLY16V16(var1,var2) ((var1) * (var2)) 397 #endif 398 399 /* Like RIGHT_SHIFT, but applies to a DCTELEM. 400 * We assume that int right shift is unsigned if INT32 right shift is. 401 */ 402 403 #ifdef RIGHT_SHIFT_IS_UNSIGNED 404 #define ISHIFT_TEMPS DCTELEM ishift_temp; 405 #if BITS_IN_JSAMPLE == 8 406 #define DCTELEMBITS 16 /* DCTELEM may be 16 or 32 bits */ 407 #else 408 #define DCTELEMBITS 32 /* DCTELEM must be 32 bits */ 409 #endif 410 #define IRIGHT_SHIFT(x,shft) \ 411 ((ishift_temp = (x)) < 0 ? \ 412 (ishift_temp >> (shft)) | ((~((DCTELEM) 0)) << (DCTELEMBITS-(shft))) : \ 413 (ishift_temp >> (shft))) 414 #else 415 #define ISHIFT_TEMPS 416 #define IRIGHT_SHIFT(x,shft) ((x) >> (shft)) 417 #endif 418