| [2] | 1 | /*
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| 2 | * jdct.h
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| 3 | *
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| 4 | * Copyright (C) 1994-1996, Thomas G. Lane.
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| 5 | * This file is part of the Independent JPEG Group's software.
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| 6 | * For conditions of distribution and use, see the accompanying README file.
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| 7 | *
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| 8 | * This include file contains common declarations for the forward and
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| 9 | * inverse DCT modules. These declarations are private to the DCT managers
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| 10 | * (jcdctmgr.c, jddctmgr.c) and the individual DCT algorithms.
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| 11 | * The individual DCT algorithms are kept in separate files to ease
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| 12 | * machine-dependent tuning (e.g., assembly coding).
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| 13 | */
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| 14 |
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| 15 |
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| 16 | /*
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| [846] | 17 | * A forward DCT routine is given a pointer to an input sample array and
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| 18 | * a pointer to a work area of type DCTELEM[]; the DCT is to be performed
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| 19 | * in-place in that buffer. Type DCTELEM is int for 8-bit samples, INT32
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| 20 | * for 12-bit samples. (NOTE: Floating-point DCT implementations use an
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| 21 | * array of type FAST_FLOAT, instead.)
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| 22 | * The input data is to be fetched from the sample array starting at a
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| 23 | * specified column. (Any row offset needed will be applied to the array
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| 24 | * pointer before it is passed to the FDCT code.)
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| 25 | * Note that the number of samples fetched by the FDCT routine is
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| 26 | * DCT_h_scaled_size * DCT_v_scaled_size.
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| [2] | 27 | * The DCT outputs are returned scaled up by a factor of 8; they therefore
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| 28 | * have a range of +-8K for 8-bit data, +-128K for 12-bit data. This
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| 29 | * convention improves accuracy in integer implementations and saves some
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| 30 | * work in floating-point ones.
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| 31 | * Quantization of the output coefficients is done by jcdctmgr.c.
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| 32 | */
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| 33 |
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| 34 | #if BITS_IN_JSAMPLE == 8
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| 35 | typedef int DCTELEM; /* 16 or 32 bits is fine */
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| 36 | #else
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| 37 | typedef INT32 DCTELEM; /* must have 32 bits */
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| 38 | #endif
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| 39 |
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| [846] | 40 | typedef JMETHOD(void, forward_DCT_method_ptr, (DCTELEM * data,
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| 41 | JSAMPARRAY sample_data,
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| 42 | JDIMENSION start_col));
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| 43 | typedef JMETHOD(void, float_DCT_method_ptr, (FAST_FLOAT * data,
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| 44 | JSAMPARRAY sample_data,
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| 45 | JDIMENSION start_col));
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| [2] | 46 |
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| 47 |
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| 48 | /*
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| 49 | * An inverse DCT routine is given a pointer to the input JBLOCK and a pointer
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| 50 | * to an output sample array. The routine must dequantize the input data as
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| 51 | * well as perform the IDCT; for dequantization, it uses the multiplier table
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| 52 | * pointed to by compptr->dct_table. The output data is to be placed into the
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| 53 | * sample array starting at a specified column. (Any row offset needed will
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| 54 | * be applied to the array pointer before it is passed to the IDCT code.)
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| 55 | * Note that the number of samples emitted by the IDCT routine is
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| [846] | 56 | * DCT_h_scaled_size * DCT_v_scaled_size.
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| [2] | 57 | */
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| 58 |
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| 59 | /* typedef inverse_DCT_method_ptr is declared in jpegint.h */
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| 60 |
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| 61 | /*
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| 62 | * Each IDCT routine has its own ideas about the best dct_table element type.
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| 63 | */
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| 64 |
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| 65 | typedef MULTIPLIER ISLOW_MULT_TYPE; /* short or int, whichever is faster */
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| 66 | #if BITS_IN_JSAMPLE == 8
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| 67 | typedef MULTIPLIER IFAST_MULT_TYPE; /* 16 bits is OK, use short if faster */
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| 68 | #define IFAST_SCALE_BITS 2 /* fractional bits in scale factors */
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| 69 | #else
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| 70 | typedef INT32 IFAST_MULT_TYPE; /* need 32 bits for scaled quantizers */
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| 71 | #define IFAST_SCALE_BITS 13 /* fractional bits in scale factors */
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| 72 | #endif
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| 73 | typedef FAST_FLOAT FLOAT_MULT_TYPE; /* preferred floating type */
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| 74 |
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| 75 |
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| 76 | /*
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| 77 | * Each IDCT routine is responsible for range-limiting its results and
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| 78 | * converting them to unsigned form (0..MAXJSAMPLE). The raw outputs could
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| 79 | * be quite far out of range if the input data is corrupt, so a bulletproof
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| 80 | * range-limiting step is required. We use a mask-and-table-lookup method
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| 81 | * to do the combined operations quickly. See the comments with
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| 82 | * prepare_range_limit_table (in jdmaster.c) for more info.
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| 83 | */
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| 84 |
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| 85 | #define IDCT_range_limit(cinfo) ((cinfo)->sample_range_limit + CENTERJSAMPLE)
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| 86 |
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| 87 | #define RANGE_MASK (MAXJSAMPLE * 4 + 3) /* 2 bits wider than legal samples */
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| 88 |
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| 89 |
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| 90 | /* Short forms of external names for systems with brain-damaged linkers. */
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| 91 |
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| 92 | #ifdef NEED_SHORT_EXTERNAL_NAMES
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| 93 | #define jpeg_fdct_islow jFDislow
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| 94 | #define jpeg_fdct_ifast jFDifast
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| 95 | #define jpeg_fdct_float jFDfloat
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| [846] | 96 | #define jpeg_fdct_7x7 jFD7x7
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| 97 | #define jpeg_fdct_6x6 jFD6x6
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| 98 | #define jpeg_fdct_5x5 jFD5x5
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| 99 | #define jpeg_fdct_4x4 jFD4x4
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| 100 | #define jpeg_fdct_3x3 jFD3x3
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| 101 | #define jpeg_fdct_2x2 jFD2x2
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| 102 | #define jpeg_fdct_1x1 jFD1x1
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| 103 | #define jpeg_fdct_9x9 jFD9x9
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| 104 | #define jpeg_fdct_10x10 jFD10x10
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| 105 | #define jpeg_fdct_11x11 jFD11x11
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| 106 | #define jpeg_fdct_12x12 jFD12x12
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| 107 | #define jpeg_fdct_13x13 jFD13x13
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| 108 | #define jpeg_fdct_14x14 jFD14x14
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| 109 | #define jpeg_fdct_15x15 jFD15x15
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| 110 | #define jpeg_fdct_16x16 jFD16x16
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| 111 | #define jpeg_fdct_16x8 jFD16x8
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| 112 | #define jpeg_fdct_14x7 jFD14x7
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| 113 | #define jpeg_fdct_12x6 jFD12x6
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| 114 | #define jpeg_fdct_10x5 jFD10x5
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| 115 | #define jpeg_fdct_8x4 jFD8x4
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| 116 | #define jpeg_fdct_6x3 jFD6x3
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| 117 | #define jpeg_fdct_4x2 jFD4x2
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| 118 | #define jpeg_fdct_2x1 jFD2x1
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| 119 | #define jpeg_fdct_8x16 jFD8x16
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| 120 | #define jpeg_fdct_7x14 jFD7x14
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| 121 | #define jpeg_fdct_6x12 jFD6x12
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| 122 | #define jpeg_fdct_5x10 jFD5x10
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| 123 | #define jpeg_fdct_4x8 jFD4x8
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| 124 | #define jpeg_fdct_3x6 jFD3x6
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| 125 | #define jpeg_fdct_2x4 jFD2x4
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| 126 | #define jpeg_fdct_1x2 jFD1x2
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| [2] | 127 | #define jpeg_idct_islow jRDislow
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| 128 | #define jpeg_idct_ifast jRDifast
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| 129 | #define jpeg_idct_float jRDfloat
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| [846] | 130 | #define jpeg_idct_7x7 jRD7x7
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| 131 | #define jpeg_idct_6x6 jRD6x6
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| 132 | #define jpeg_idct_5x5 jRD5x5
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| [2] | 133 | #define jpeg_idct_4x4 jRD4x4
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| [846] | 134 | #define jpeg_idct_3x3 jRD3x3
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| [2] | 135 | #define jpeg_idct_2x2 jRD2x2
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| 136 | #define jpeg_idct_1x1 jRD1x1
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| [846] | 137 | #define jpeg_idct_9x9 jRD9x9
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| 138 | #define jpeg_idct_10x10 jRD10x10
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| 139 | #define jpeg_idct_11x11 jRD11x11
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| 140 | #define jpeg_idct_12x12 jRD12x12
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| 141 | #define jpeg_idct_13x13 jRD13x13
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| 142 | #define jpeg_idct_14x14 jRD14x14
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| 143 | #define jpeg_idct_15x15 jRD15x15
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| 144 | #define jpeg_idct_16x16 jRD16x16
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| 145 | #define jpeg_idct_16x8 jRD16x8
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| 146 | #define jpeg_idct_14x7 jRD14x7
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| 147 | #define jpeg_idct_12x6 jRD12x6
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| 148 | #define jpeg_idct_10x5 jRD10x5
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| 149 | #define jpeg_idct_8x4 jRD8x4
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| 150 | #define jpeg_idct_6x3 jRD6x3
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| 151 | #define jpeg_idct_4x2 jRD4x2
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| 152 | #define jpeg_idct_2x1 jRD2x1
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| 153 | #define jpeg_idct_8x16 jRD8x16
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| 154 | #define jpeg_idct_7x14 jRD7x14
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| 155 | #define jpeg_idct_6x12 jRD6x12
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| 156 | #define jpeg_idct_5x10 jRD5x10
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| 157 | #define jpeg_idct_4x8 jRD4x8
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| 158 | #define jpeg_idct_3x6 jRD3x8
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| 159 | #define jpeg_idct_2x4 jRD2x4
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| 160 | #define jpeg_idct_1x2 jRD1x2
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| [2] | 161 | #endif /* NEED_SHORT_EXTERNAL_NAMES */
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| 162 |
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| 163 | /* Extern declarations for the forward and inverse DCT routines. */
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| 164 |
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| [846] | 165 | EXTERN(void) jpeg_fdct_islow
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| 166 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 167 | EXTERN(void) jpeg_fdct_ifast
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| 168 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 169 | EXTERN(void) jpeg_fdct_float
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| 170 | JPP((FAST_FLOAT * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 171 | EXTERN(void) jpeg_fdct_7x7
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| 172 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 173 | EXTERN(void) jpeg_fdct_6x6
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| 174 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 175 | EXTERN(void) jpeg_fdct_5x5
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| 176 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 177 | EXTERN(void) jpeg_fdct_4x4
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| 178 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 179 | EXTERN(void) jpeg_fdct_3x3
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| 180 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 181 | EXTERN(void) jpeg_fdct_2x2
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| 182 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 183 | EXTERN(void) jpeg_fdct_1x1
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| 184 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 185 | EXTERN(void) jpeg_fdct_9x9
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| 186 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 187 | EXTERN(void) jpeg_fdct_10x10
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| 188 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 189 | EXTERN(void) jpeg_fdct_11x11
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| 190 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 191 | EXTERN(void) jpeg_fdct_12x12
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| 192 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 193 | EXTERN(void) jpeg_fdct_13x13
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| 194 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 195 | EXTERN(void) jpeg_fdct_14x14
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| 196 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 197 | EXTERN(void) jpeg_fdct_15x15
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| 198 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 199 | EXTERN(void) jpeg_fdct_16x16
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| 200 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 201 | EXTERN(void) jpeg_fdct_16x8
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| 202 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 203 | EXTERN(void) jpeg_fdct_14x7
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| 204 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 205 | EXTERN(void) jpeg_fdct_12x6
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| 206 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 207 | EXTERN(void) jpeg_fdct_10x5
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| 208 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 209 | EXTERN(void) jpeg_fdct_8x4
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| 210 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 211 | EXTERN(void) jpeg_fdct_6x3
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| 212 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 213 | EXTERN(void) jpeg_fdct_4x2
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| 214 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 215 | EXTERN(void) jpeg_fdct_2x1
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| 216 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 217 | EXTERN(void) jpeg_fdct_8x16
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| 218 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 219 | EXTERN(void) jpeg_fdct_7x14
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| 220 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 221 | EXTERN(void) jpeg_fdct_6x12
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| 222 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 223 | EXTERN(void) jpeg_fdct_5x10
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| 224 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 225 | EXTERN(void) jpeg_fdct_4x8
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| 226 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 227 | EXTERN(void) jpeg_fdct_3x6
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| 228 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 229 | EXTERN(void) jpeg_fdct_2x4
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| 230 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| 231 | EXTERN(void) jpeg_fdct_1x2
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| 232 | JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
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| [2] | 233 |
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| 234 | EXTERN(void) jpeg_idct_islow
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| 235 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 236 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 237 | EXTERN(void) jpeg_idct_ifast
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| 238 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 239 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 240 | EXTERN(void) jpeg_idct_float
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| 241 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 242 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| [846] | 243 | EXTERN(void) jpeg_idct_7x7
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| 244 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 245 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 246 | EXTERN(void) jpeg_idct_6x6
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| 247 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 248 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 249 | EXTERN(void) jpeg_idct_5x5
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| 250 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 251 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| [2] | 252 | EXTERN(void) jpeg_idct_4x4
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| 253 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 254 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| [846] | 255 | EXTERN(void) jpeg_idct_3x3
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| 256 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 257 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| [2] | 258 | EXTERN(void) jpeg_idct_2x2
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| 259 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 260 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 261 | EXTERN(void) jpeg_idct_1x1
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| 262 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 263 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| [846] | 264 | EXTERN(void) jpeg_idct_9x9
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| 265 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 266 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 267 | EXTERN(void) jpeg_idct_10x10
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| 268 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 269 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 270 | EXTERN(void) jpeg_idct_11x11
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| 271 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 272 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 273 | EXTERN(void) jpeg_idct_12x12
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| 274 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 275 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 276 | EXTERN(void) jpeg_idct_13x13
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| 277 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 278 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 279 | EXTERN(void) jpeg_idct_14x14
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| 280 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 281 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 282 | EXTERN(void) jpeg_idct_15x15
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| 283 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 284 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 285 | EXTERN(void) jpeg_idct_16x16
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| 286 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 287 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 288 | EXTERN(void) jpeg_idct_16x8
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| 289 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 290 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 291 | EXTERN(void) jpeg_idct_14x7
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| 292 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 293 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 294 | EXTERN(void) jpeg_idct_12x6
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| 295 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 296 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 297 | EXTERN(void) jpeg_idct_10x5
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| 298 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 299 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 300 | EXTERN(void) jpeg_idct_8x4
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| 301 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 302 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 303 | EXTERN(void) jpeg_idct_6x3
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| 304 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 305 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 306 | EXTERN(void) jpeg_idct_4x2
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| 307 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 308 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 309 | EXTERN(void) jpeg_idct_2x1
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| 310 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 311 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 312 | EXTERN(void) jpeg_idct_8x16
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| 313 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 314 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 315 | EXTERN(void) jpeg_idct_7x14
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| 316 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 317 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 318 | EXTERN(void) jpeg_idct_6x12
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| 319 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 320 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 321 | EXTERN(void) jpeg_idct_5x10
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| 322 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 323 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 324 | EXTERN(void) jpeg_idct_4x8
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| 325 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 326 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 327 | EXTERN(void) jpeg_idct_3x6
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| 328 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 329 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 330 | EXTERN(void) jpeg_idct_2x4
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| 331 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 332 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| 333 | EXTERN(void) jpeg_idct_1x2
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| 334 | JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
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| 335 | JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
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| [2] | 336 |
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| 337 |
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| 338 | /*
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| 339 | * Macros for handling fixed-point arithmetic; these are used by many
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| 340 | * but not all of the DCT/IDCT modules.
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| 341 | *
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| 342 | * All values are expected to be of type INT32.
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| 343 | * Fractional constants are scaled left by CONST_BITS bits.
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| 344 | * CONST_BITS is defined within each module using these macros,
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| 345 | * and may differ from one module to the next.
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| 346 | */
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| 347 |
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| 348 | #define ONE ((INT32) 1)
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| 349 | #define CONST_SCALE (ONE << CONST_BITS)
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| 350 |
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| 351 | /* Convert a positive real constant to an integer scaled by CONST_SCALE.
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| 352 | * Caution: some C compilers fail to reduce "FIX(constant)" at compile time,
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| 353 | * thus causing a lot of useless floating-point operations at run time.
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| 354 | */
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| 355 |
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| 356 | #define FIX(x) ((INT32) ((x) * CONST_SCALE + 0.5))
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| 357 |
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| 358 | /* Descale and correctly round an INT32 value that's scaled by N bits.
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| 359 | * We assume RIGHT_SHIFT rounds towards minus infinity, so adding
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| 360 | * the fudge factor is correct for either sign of X.
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| 361 | */
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| 362 |
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| 363 | #define DESCALE(x,n) RIGHT_SHIFT((x) + (ONE << ((n)-1)), n)
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| 364 |
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| 365 | /* Multiply an INT32 variable by an INT32 constant to yield an INT32 result.
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| 366 | * This macro is used only when the two inputs will actually be no more than
|
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| 367 | * 16 bits wide, so that a 16x16->32 bit multiply can be used instead of a
|
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| 368 | * full 32x32 multiply. This provides a useful speedup on many machines.
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| 369 | * Unfortunately there is no way to specify a 16x16->32 multiply portably
|
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| 370 | * in C, but some C compilers will do the right thing if you provide the
|
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| 371 | * correct combination of casts.
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| 372 | */
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| 373 |
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| 374 | #ifdef SHORTxSHORT_32 /* may work if 'int' is 32 bits */
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| 375 | #define MULTIPLY16C16(var,const) (((INT16) (var)) * ((INT16) (const)))
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| 376 | #endif
|
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| 377 | #ifdef SHORTxLCONST_32 /* known to work with Microsoft C 6.0 */
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| 378 | #define MULTIPLY16C16(var,const) (((INT16) (var)) * ((INT32) (const)))
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| 379 | #endif
|
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| 380 |
|
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| 381 | #ifndef MULTIPLY16C16 /* default definition */
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| 382 | #define MULTIPLY16C16(var,const) ((var) * (const))
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| 383 | #endif
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| 384 |
|
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| 385 | /* Same except both inputs are variables. */
|
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| 386 |
|
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| 387 | #ifdef SHORTxSHORT_32 /* may work if 'int' is 32 bits */
|
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| 388 | #define MULTIPLY16V16(var1,var2) (((INT16) (var1)) * ((INT16) (var2)))
|
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| 389 | #endif
|
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| 390 |
|
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| 391 | #ifndef MULTIPLY16V16 /* default definition */
|
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| 392 | #define MULTIPLY16V16(var1,var2) ((var1) * (var2))
|
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| 393 | #endif
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