workbench/libs/jpeg/jdct.h

   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