media/libjpeg/jdct.h

   1 /*
   2  * jdct.h
   3  *
   4  * This file was part of the Independent JPEG Group's software:
   5  * Copyright (C) 1994-1996, Thomas G. Lane.
   6  * libjpeg-turbo Modifications:
   7  * Copyright (C) 2015, D. R. Commander.
   8  * For conditions of distribution and use, see the accompanying README.ijg
   9  * file.
  10  *
  11  * This include file contains common declarations for the forward and
  12  * inverse DCT modules.  These declarations are private to the DCT managers
  13  * (jcdctmgr.c, jddctmgr.c) and the individual DCT algorithms.
  14  * The individual DCT algorithms are kept in separate files to ease
  15  * machine-dependent tuning (e.g., assembly coding).
  16  */
  17
  18
  19 /*
  20  * A forward DCT routine is given a pointer to a work area of type DCTELEM[];
  21  * the DCT is to be performed in-place in that buffer.  Type DCTELEM is int
  22  * for 8-bit samples, JLONG for 12-bit samples.  (NOTE: Floating-point DCT
  23  * implementations use an array of type FAST_FLOAT, instead.)
  24  * The DCT inputs are expected to be signed (range +-CENTERJSAMPLE).
  25  * The DCT outputs are returned scaled up by a factor of 8; they therefore
  26  * have a range of +-8K for 8-bit data, +-128K for 12-bit data.  This
  27  * convention improves accuracy in integer implementations and saves some
  28  * work in floating-point ones.
  29  * Quantization of the output coefficients is done by jcdctmgr.c. This
  30  * step requires an unsigned type and also one with twice the bits.
  31  */
  32
  33 #if BITS_IN_JSAMPLE == 8
  34 #ifndef WITH_SIMD
  35 typedef int DCTELEM;            /* 16 or 32 bits is fine */
  36 typedef unsigned int UDCTELEM;
  37 typedef unsigned long long UDCTELEM2;
  38 #else
  39 typedef short DCTELEM;          /* prefer 16 bit with SIMD for parellelism */
  40 typedef unsigned short UDCTELEM;
  41 typedef unsigned int UDCTELEM2;
  42 #endif
  43 #else
  44 typedef JLONG DCTELEM;          /* must have 32 bits */
  45 typedef unsigned long long UDCTELEM2;
  46 #endif
  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_scaled_size * DCT_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 JLONG 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.  See the comments with
  83  * prepare_range_limit_table (in jdmaster.c) for more info.
  84  */
  85
  86 #define IDCT_range_limit(cinfo)  ((cinfo)->sample_range_limit + CENTERJSAMPLE)
  87
  88 #define RANGE_MASK  (MAXJSAMPLE * 4 + 3) /* 2 bits wider than legal samples */
  89
  90
  91 /* Extern declarations for the forward and inverse DCT routines. */
  92
  93 EXTERN(void) jpeg_fdct_islow(DCTELEM *data);
  94 EXTERN(void) jpeg_fdct_ifast(DCTELEM *data);
  95 EXTERN(void) jpeg_fdct_float(FAST_FLOAT *data);
  96
  97 EXTERN(void) jpeg_idct_islow(j_decompress_ptr cinfo,
  98                              jpeg_component_info *compptr, JCOEFPTR coef_block,
  99                              JSAMPARRAY output_buf, JDIMENSION output_col);
 100 EXTERN(void) jpeg_idct_ifast(j_decompress_ptr cinfo,
 101                              jpeg_component_info *compptr, JCOEFPTR coef_block,
 102                              JSAMPARRAY output_buf, JDIMENSION output_col);
 103 EXTERN(void) jpeg_idct_float(j_decompress_ptr cinfo,
 104                              jpeg_component_info *compptr, JCOEFPTR coef_block,
 105                              JSAMPARRAY output_buf, JDIMENSION output_col);
 106 EXTERN(void) jpeg_idct_7x7(j_decompress_ptr cinfo,
 107                            jpeg_component_info *compptr, JCOEFPTR coef_block,
 108                            JSAMPARRAY output_buf, JDIMENSION output_col);
 109 EXTERN(void) jpeg_idct_6x6(j_decompress_ptr cinfo,
 110                            jpeg_component_info *compptr, JCOEFPTR coef_block,
 111                            JSAMPARRAY output_buf, JDIMENSION output_col);
 112 EXTERN(void) jpeg_idct_5x5(j_decompress_ptr cinfo,
 113                            jpeg_component_info *compptr, JCOEFPTR coef_block,
 114                            JSAMPARRAY output_buf, JDIMENSION output_col);
 115 EXTERN(void) jpeg_idct_4x4(j_decompress_ptr cinfo,
 116                            jpeg_component_info *compptr, JCOEFPTR coef_block,
 117                            JSAMPARRAY output_buf, JDIMENSION output_col);
 118 EXTERN(void) jpeg_idct_3x3(j_decompress_ptr cinfo,
 119                            jpeg_component_info *compptr, JCOEFPTR coef_block,
 120                            JSAMPARRAY output_buf, JDIMENSION output_col);
 121 EXTERN(void) jpeg_idct_2x2(j_decompress_ptr cinfo,
 122                            jpeg_component_info *compptr, JCOEFPTR coef_block,
 123                            JSAMPARRAY output_buf, JDIMENSION output_col);
 124 EXTERN(void) jpeg_idct_1x1(j_decompress_ptr cinfo,
 125                            jpeg_component_info *compptr, JCOEFPTR coef_block,
 126                            JSAMPARRAY output_buf, JDIMENSION output_col);
 127 EXTERN(void) jpeg_idct_9x9(j_decompress_ptr cinfo,
 128                            jpeg_component_info *compptr, JCOEFPTR coef_block,
 129                            JSAMPARRAY output_buf, JDIMENSION output_col);
 130 EXTERN(void) jpeg_idct_10x10(j_decompress_ptr cinfo,
 131                              jpeg_component_info *compptr, JCOEFPTR coef_block,
 132                              JSAMPARRAY output_buf, JDIMENSION output_col);
 133 EXTERN(void) jpeg_idct_11x11(j_decompress_ptr cinfo,
 134                              jpeg_component_info *compptr, JCOEFPTR coef_block,
 135                              JSAMPARRAY output_buf, JDIMENSION output_col);
 136 EXTERN(void) jpeg_idct_12x12(j_decompress_ptr cinfo,
 137                              jpeg_component_info *compptr, JCOEFPTR coef_block,
 138                              JSAMPARRAY output_buf, JDIMENSION output_col);
 139 EXTERN(void) jpeg_idct_13x13(j_decompress_ptr cinfo,
 140                              jpeg_component_info *compptr, JCOEFPTR coef_block,
 141                              JSAMPARRAY output_buf, JDIMENSION output_col);
 142 EXTERN(void) jpeg_idct_14x14(j_decompress_ptr cinfo,
 143                              jpeg_component_info *compptr, JCOEFPTR coef_block,
 144                              JSAMPARRAY output_buf, JDIMENSION output_col);
 145 EXTERN(void) jpeg_idct_15x15(j_decompress_ptr cinfo,
 146                              jpeg_component_info *compptr, JCOEFPTR coef_block,
 147                              JSAMPARRAY output_buf, JDIMENSION output_col);
 148 EXTERN(void) jpeg_idct_16x16(j_decompress_ptr cinfo,
 149                              jpeg_component_info *compptr, JCOEFPTR coef_block,
 150                              JSAMPARRAY output_buf, JDIMENSION output_col);
 151
 152
 153 /*
 154  * Macros for handling fixed-point arithmetic; these are used by many
 155  * but not all of the DCT/IDCT modules.
 156  *
 157  * All values are expected to be of type JLONG.
 158  * Fractional constants are scaled left by CONST_BITS bits.
 159  * CONST_BITS is defined within each module using these macros,
 160  * and may differ from one module to the next.
 161  */
 162
 163 #define ONE          ((JLONG)1)
 164 #define CONST_SCALE  (ONE << CONST_BITS)
 165
 166 /* Convert a positive real constant to an integer scaled by CONST_SCALE.
 167  * Caution: some C compilers fail to reduce "FIX(constant)" at compile time,
 168  * thus causing a lot of useless floating-point operations at run time.
 169  */
 170
 171 #define FIX(x)  ((JLONG)((x) * CONST_SCALE + 0.5))
 172
 173 /* Descale and correctly round a JLONG value that's scaled by N bits.
 174  * We assume RIGHT_SHIFT rounds towards minus infinity, so adding
 175  * the fudge factor is correct for either sign of X.
 176  */
 177
 178 #define DESCALE(x, n)  RIGHT_SHIFT((x) + (ONE << ((n) - 1)), n)
 179
 180 /* Multiply a JLONG variable by a JLONG constant to yield a JLONG result.
 181  * This macro is used only when the two inputs will actually be no more than
 182  * 16 bits wide, so that a 16x16->32 bit multiply can be used instead of a
 183  * full 32x32 multiply.  This provides a useful speedup on many machines.
 184  * Unfortunately there is no way to specify a 16x16->32 multiply portably
 185  * in C, but some C compilers will do the right thing if you provide the
 186  * correct combination of casts.
 187  */
 188
 189 #ifdef SHORTxSHORT_32           /* may work if 'int' is 32 bits */
 190 #define MULTIPLY16C16(var, const)  (((INT16)(var)) * ((INT16)(const)))
 191 #endif
 192 #ifdef SHORTxLCONST_32          /* known to work with Microsoft C 6.0 */
 193 #define MULTIPLY16C16(var, const)  (((INT16)(var)) * ((JLONG)(const)))
 194 #endif
 195
 196 #ifndef MULTIPLY16C16           /* default definition */
 197 #define MULTIPLY16C16(var, const)  ((var) * (const))
 198 #endif
 199
 200 /* Same except both inputs are variables. */
 201
 202 #ifdef SHORTxSHORT_32           /* may work if 'int' is 32 bits */
 203 #define MULTIPLY16V16(var1, var2)  (((INT16)(var1)) * ((INT16)(var2)))
 204 #endif
 205
 206 #ifndef MULTIPLY16V16           /* default definition */
 207 #define MULTIPLY16V16(var1, var2)  ((var1) * (var2))
 208 #endif