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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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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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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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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34 #if BITS_IN_JSAMPLE == 8
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35 typedef int DCTELEM; /* 16 or 32 bits is fine */
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37 typedef INT32 DCTELEM; /* must have 32 bits */
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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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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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56 * DCT_h_scaled_size * DCT_v_scaled_size.
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59 /* typedef inverse_DCT_method_ptr is declared in jpegint.h */
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62 * Each IDCT routine has its own ideas about the best dct_table element type.
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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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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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73 typedef FAST_FLOAT FLOAT_MULT_TYPE; /* preferred floating type */
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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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85 #define IDCT_range_limit(cinfo) ((cinfo)->sample_range_limit + CENTERJSAMPLE)
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87 #define RANGE_MASK (MAXJSAMPLE * 4 + 3) /* 2 bits wider than legal samples */
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90 /* Short forms of external names for systems with brain-damaged linkers. */
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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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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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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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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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133 #define jpeg_idct_4x4 jRD4x4
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134 #define jpeg_idct_3x3 jRD3x3
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135 #define jpeg_idct_2x2 jRD2x2
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136 #define jpeg_idct_1x1 jRD1x1
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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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161 #endif /* NEED_SHORT_EXTERNAL_NAMES */
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163 /* Extern declarations for the forward and inverse DCT routines. */
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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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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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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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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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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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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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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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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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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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348 #define ONE ((INT32) 1)
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349 #define CONST_SCALE (ONE << CONST_BITS)
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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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356 #define FIX(x) ((INT32) ((x) * CONST_SCALE + 0.5))
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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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363 #define DESCALE(x,n) RIGHT_SHIFT((x) + (ONE << ((n)-1)), n)
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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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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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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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381 #ifndef MULTIPLY16C16 /* default definition */
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382 #define MULTIPLY16C16(var,const) ((var) * (const))
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385 /* Same except both inputs are variables. */
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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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391 #ifndef MULTIPLY16V16 /* default definition */
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392 #define MULTIPLY16V16(var1,var2) ((var1) * (var2))
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