libs/jpeg/jdct.h

   1 /*
   2  * jdct.h
   3  *
   4  * Copyright (C) 1994-1996, Thomas G. Lane.
   5  * Modified 2002-2019 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 RANGE_CENTER
  83  * (defined in jpegint.h) is a power of 2.  See the comments with
  84  * prepare_range_limit_table (in jdmaster.c) for more info.
  85  */
  86
  87 #define RANGE_MASK  (RANGE_CENTER * 2 - 1)
  88 #define RANGE_SUBSET  (RANGE_CENTER - CENTERJSAMPLE)
  89
  90 #define IDCT_range_limit(cinfo)  ((cinfo)->sample_range_limit - RANGE_SUBSET)
  91
  92
  93 /* Short forms of external names for systems with brain-damaged linkers. */
  94
  95 #ifdef NEED_SHORT_EXTERNAL_NAMES
  96 #define jpeg_fdct_islow         jFDislow
  97 #define jpeg_fdct_ifast         jFDifast
  98 #define jpeg_fdct_float         jFDfloat
  99 #define jpeg_fdct_7x7           jFD7x7
 100 #define jpeg_fdct_6x6           jFD6x6
 101 #define jpeg_fdct_5x5           jFD5x5
 102 #define jpeg_fdct_4x4           jFD4x4
 103 #define jpeg_fdct_3x3           jFD3x3
 104 #define jpeg_fdct_2x2           jFD2x2
 105 #define jpeg_fdct_1x1           jFD1x1
 106 #define jpeg_fdct_9x9           jFD9x9
 107 #define jpeg_fdct_10x10         jFD10x10
 108 #define jpeg_fdct_11x11         jFD11x11
 109 #define jpeg_fdct_12x12         jFD12x12
 110 #define jpeg_fdct_13x13         jFD13x13
 111 #define jpeg_fdct_14x14         jFD14x14
 112 #define jpeg_fdct_15x15         jFD15x15
 113 #define jpeg_fdct_16x16         jFD16x16
 114 #define jpeg_fdct_16x8          jFD16x8
 115 #define jpeg_fdct_14x7          jFD14x7
 116 #define jpeg_fdct_12x6          jFD12x6
 117 #define jpeg_fdct_10x5          jFD10x5
 118 #define jpeg_fdct_8x4           jFD8x4
 119 #define jpeg_fdct_6x3           jFD6x3
 120 #define jpeg_fdct_4x2           jFD4x2
 121 #define jpeg_fdct_2x1           jFD2x1
 122 #define jpeg_fdct_8x16          jFD8x16
 123 #define jpeg_fdct_7x14          jFD7x14
 124 #define jpeg_fdct_6x12          jFD6x12
 125 #define jpeg_fdct_5x10          jFD5x10
 126 #define jpeg_fdct_4x8           jFD4x8
 127 #define jpeg_fdct_3x6           jFD3x6
 128 #define jpeg_fdct_2x4           jFD2x4
 129 #define jpeg_fdct_1x2           jFD1x2
 130 #define jpeg_idct_islow         jRDislow
 131 #define jpeg_idct_ifast         jRDifast
 132 #define jpeg_idct_float         jRDfloat
 133 #define jpeg_idct_7x7           jRD7x7
 134 #define jpeg_idct_6x6           jRD6x6
 135 #define jpeg_idct_5x5           jRD5x5
 136 #define jpeg_idct_4x4           jRD4x4
 137 #define jpeg_idct_3x3           jRD3x3
 138 #define jpeg_idct_2x2           jRD2x2
 139 #define jpeg_idct_1x1           jRD1x1
 140 #define jpeg_idct_9x9           jRD9x9
 141 #define jpeg_idct_10x10         jRD10x10
 142 #define jpeg_idct_11x11         jRD11x11
 143 #define jpeg_idct_12x12         jRD12x12
 144 #define jpeg_idct_13x13         jRD13x13
 145 #define jpeg_idct_14x14         jRD14x14
 146 #define jpeg_idct_15x15         jRD15x15
 147 #define jpeg_idct_16x16         jRD16x16
 148 #define jpeg_idct_16x8          jRD16x8
 149 #define jpeg_idct_14x7          jRD14x7
 150 #define jpeg_idct_12x6          jRD12x6
 151 #define jpeg_idct_10x5          jRD10x5
 152 #define jpeg_idct_8x4           jRD8x4
 153 #define jpeg_idct_6x3           jRD6x3
 154 #define jpeg_idct_4x2           jRD4x2
 155 #define jpeg_idct_2x1           jRD2x1
 156 #define jpeg_idct_8x16          jRD8x16
 157 #define jpeg_idct_7x14          jRD7x14
 158 #define jpeg_idct_6x12          jRD6x12
 159 #define jpeg_idct_5x10          jRD5x10
 160 #define jpeg_idct_4x8           jRD4x8
 161 #define jpeg_idct_3x6           jRD3x8
 162 #define jpeg_idct_2x4           jRD2x4
 163 #define jpeg_idct_1x2           jRD1x2
 164 #endif /* NEED_SHORT_EXTERNAL_NAMES */
 165
 166 /* Extern declarations for the forward and inverse DCT routines. */
 167
 168 EXTERN(void) jpeg_fdct_islow
 169     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 170 EXTERN(void) jpeg_fdct_ifast
 171     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 172 EXTERN(void) jpeg_fdct_float
 173     JPP((FAST_FLOAT * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 174 EXTERN(void) jpeg_fdct_7x7
 175     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 176 EXTERN(void) jpeg_fdct_6x6
 177     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 178 EXTERN(void) jpeg_fdct_5x5
 179     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 180 EXTERN(void) jpeg_fdct_4x4
 181     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 182 EXTERN(void) jpeg_fdct_3x3
 183     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 184 EXTERN(void) jpeg_fdct_2x2
 185     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 186 EXTERN(void) jpeg_fdct_1x1
 187     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 188 EXTERN(void) jpeg_fdct_9x9
 189     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 190 EXTERN(void) jpeg_fdct_10x10
 191     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 192 EXTERN(void) jpeg_fdct_11x11
 193     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 194 EXTERN(void) jpeg_fdct_12x12
 195     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 196 EXTERN(void) jpeg_fdct_13x13
 197     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 198 EXTERN(void) jpeg_fdct_14x14
 199     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 200 EXTERN(void) jpeg_fdct_15x15
 201     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 202 EXTERN(void) jpeg_fdct_16x16
 203     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 204 EXTERN(void) jpeg_fdct_16x8
 205     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 206 EXTERN(void) jpeg_fdct_14x7
 207     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 208 EXTERN(void) jpeg_fdct_12x6
 209     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 210 EXTERN(void) jpeg_fdct_10x5
 211     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 212 EXTERN(void) jpeg_fdct_8x4
 213     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 214 EXTERN(void) jpeg_fdct_6x3
 215     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 216 EXTERN(void) jpeg_fdct_4x2
 217     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 218 EXTERN(void) jpeg_fdct_2x1
 219     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 220 EXTERN(void) jpeg_fdct_8x16
 221     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 222 EXTERN(void) jpeg_fdct_7x14
 223     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 224 EXTERN(void) jpeg_fdct_6x12
 225     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 226 EXTERN(void) jpeg_fdct_5x10
 227     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 228 EXTERN(void) jpeg_fdct_4x8
 229     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 230 EXTERN(void) jpeg_fdct_3x6
 231     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 232 EXTERN(void) jpeg_fdct_2x4
 233     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 234 EXTERN(void) jpeg_fdct_1x2
 235     JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
 236
 237 EXTERN(void) jpeg_idct_islow
 238     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 239          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 240 EXTERN(void) jpeg_idct_ifast
 241     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 242          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 243 EXTERN(void) jpeg_idct_float
 244     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 245          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 246 EXTERN(void) jpeg_idct_7x7
 247     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 248          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 249 EXTERN(void) jpeg_idct_6x6
 250     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 251          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 252 EXTERN(void) jpeg_idct_5x5
 253     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 254          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 255 EXTERN(void) jpeg_idct_4x4
 256     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 257          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 258 EXTERN(void) jpeg_idct_3x3
 259     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 260          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 261 EXTERN(void) jpeg_idct_2x2
 262     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 263          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 264 EXTERN(void) jpeg_idct_1x1
 265     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 266          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 267 EXTERN(void) jpeg_idct_9x9
 268     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 269          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 270 EXTERN(void) jpeg_idct_10x10
 271     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 272          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 273 EXTERN(void) jpeg_idct_11x11
 274     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 275          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 276 EXTERN(void) jpeg_idct_12x12
 277     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 278          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 279 EXTERN(void) jpeg_idct_13x13
 280     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 281          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 282 EXTERN(void) jpeg_idct_14x14
 283     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 284          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 285 EXTERN(void) jpeg_idct_15x15
 286     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 287          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 288 EXTERN(void) jpeg_idct_16x16
 289     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 290          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 291 EXTERN(void) jpeg_idct_16x8
 292     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 293          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 294 EXTERN(void) jpeg_idct_14x7
 295     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 296          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 297 EXTERN(void) jpeg_idct_12x6
 298     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 299          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 300 EXTERN(void) jpeg_idct_10x5
 301     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 302          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 303 EXTERN(void) jpeg_idct_8x4
 304     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 305          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 306 EXTERN(void) jpeg_idct_6x3
 307     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 308          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 309 EXTERN(void) jpeg_idct_4x2
 310     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 311          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 312 EXTERN(void) jpeg_idct_2x1
 313     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 314          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 315 EXTERN(void) jpeg_idct_8x16
 316     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 317          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 318 EXTERN(void) jpeg_idct_7x14
 319     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 320          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 321 EXTERN(void) jpeg_idct_6x12
 322     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 323          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 324 EXTERN(void) jpeg_idct_5x10
 325     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 326          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 327 EXTERN(void) jpeg_idct_4x8
 328     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 329          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 330 EXTERN(void) jpeg_idct_3x6
 331     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 332          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 333 EXTERN(void) jpeg_idct_2x4
 334     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 335          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 336 EXTERN(void) jpeg_idct_1x2
 337     JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
 338          JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
 339
 340
 341 /*
 342  * Macros for handling fixed-point arithmetic; these are used by many
 343  * but not all of the DCT/IDCT modules.
 344  *
 345  * All values are expected to be of type INT32.
 346  * Fractional constants are scaled left by CONST_BITS bits.
 347  * CONST_BITS is defined within each module using these macros,
 348  * and may differ from one module to the next.
 349  */
 350
 351 #define ONE     ((INT32) 1)
 352 #define CONST_SCALE (ONE << CONST_BITS)
 353
 354 /* Convert a positive real constant to an integer scaled by CONST_SCALE.
 355  * Caution: some C compilers fail to reduce "FIX(constant)" at compile time,
 356  * thus causing a lot of useless floating-point operations at run time.
 357  */
 358
 359 #define FIX(x)  ((INT32) ((x) * CONST_SCALE + 0.5))
 360
 361 /* Multiply an INT32 variable by an INT32 constant to yield an INT32 result.
 362  * This macro is used only when the two inputs will actually be no more than
 363  * 16 bits wide, so that a 16x16->32 bit multiply can be used instead of a
 364  * full 32x32 multiply.  This provides a useful speedup on many machines.
 365  * Unfortunately there is no way to specify a 16x16->32 multiply portably
 366  * in C, but some C compilers will do the right thing if you provide the
 367  * correct combination of casts.
 368  */
 369
 370 #ifdef SHORTxSHORT_32           /* may work if 'int' is 32 bits */
 371 #define MULTIPLY16C16(var,const)  (((INT16) (var)) * ((INT16) (const)))
 372 #endif
 373 #ifdef SHORTxLCONST_32          /* known to work with Microsoft C 6.0 */
 374 #define MULTIPLY16C16(var,const)  (((INT16) (var)) * ((INT32) (const)))
 375 #endif
 376
 377 #ifndef MULTIPLY16C16           /* default definition */
 378 #define MULTIPLY16C16(var,const)  ((var) * (const))
 379 #endif
 380
 381 /* Same except both inputs are variables. */
 382
 383 #ifdef SHORTxSHORT_32           /* may work if 'int' is 32 bits */
 384 #define MULTIPLY16V16(var1,var2)  (((INT16) (var1)) * ((INT16) (var2)))
 385 #endif
 386
 387 #ifndef MULTIPLY16V16           /* default definition */
 388 #define MULTIPLY16V16(var1,var2)  ((var1) * (var2))
 389 #endif
 390
 391 /* Like RIGHT_SHIFT, but applies to a DCTELEM.
 392  * We assume that int right shift is unsigned if INT32 right shift is.
 393  */
 394
 395 #ifdef RIGHT_SHIFT_IS_UNSIGNED
 396 #define ISHIFT_TEMPS    DCTELEM ishift_temp;
 397 #if BITS_IN_JSAMPLE == 8
 398 #define DCTELEMBITS  16         /* DCTELEM may be 16 or 32 bits */
 399 #else
 400 #define DCTELEMBITS  32         /* DCTELEM must be 32 bits */
 401 #endif
 402 #define IRIGHT_SHIFT(x,shft)  \
 403     ((ishift_temp = (x)) < 0 ? \
 404      (ishift_temp >> (shft)) | ((~((DCTELEM) 0)) << (DCTELEMBITS-(shft))) : \
 405      (ishift_temp >> (shft)))
 406 #else
 407 #define ISHIFT_TEMPS
 408 #define IRIGHT_SHIFT(x,shft)    ((x) >> (shft))
 409 #endif