1 | /* |
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2 | * jmorecfg.h |
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3 | * |
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4 | * Copyright (C) 1991-1997, 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 file contains additional configuration options that customize the |
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9 | * JPEG software for special applications or support machine-dependent |
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10 | * optimizations. Most users will not need to touch this file. |
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11 | */ |
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12 | |
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13 | |
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14 | /* |
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15 | * Define BITS_IN_JSAMPLE as either |
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16 | * 8 for 8-bit sample values (the usual setting) |
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17 | * 12 for 12-bit sample values |
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18 | * Only 8 and 12 are legal data precisions for lossy JPEG according to the |
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19 | * JPEG standard, and the IJG code does not support anything else! |
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20 | * We do not support run-time selection of data precision, sorry. |
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21 | */ |
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22 | |
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23 | #define BITS_IN_JSAMPLE 8 /* use 8 or 12 */ |
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24 | |
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25 | |
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26 | /* |
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27 | * Maximum number of components (color channels) allowed in JPEG image. |
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28 | * To meet the letter of the JPEG spec, set this to 255. However, darn |
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29 | * few applications need more than 4 channels (maybe 5 for CMYK + alpha |
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30 | * mask). We recommend 10 as a reasonable compromise; use 4 if you are |
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31 | * really short on memory. (Each allowed component costs a hundred or so |
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32 | * bytes of storage, whether actually used in an image or not.) |
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33 | */ |
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34 | |
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35 | #define MAX_COMPONENTS 10 /* maximum number of image components */ |
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36 | |
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37 | |
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38 | /* |
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39 | * Basic data types. |
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40 | * You may need to change these if you have a machine with unusual data |
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41 | * type sizes; for example, "char" not 8 bits, "short" not 16 bits, |
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42 | * or "long" not 32 bits. We don't care whether "int" is 16 or 32 bits, |
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43 | * but it had better be at least 16. |
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44 | */ |
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45 | |
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46 | /* Representation of a single sample (pixel element value). |
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47 | * We frequently allocate large arrays of these, so it's important to keep |
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48 | * them small. But if you have memory to burn and access to char or short |
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49 | * arrays is very slow on your hardware, you might want to change these. |
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50 | */ |
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51 | |
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52 | #if BITS_IN_JSAMPLE == 8 |
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53 | /* JSAMPLE should be the smallest type that will hold the values 0..255. |
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54 | * You can use a signed char by having GETJSAMPLE mask it with 0xFF. |
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55 | */ |
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56 | |
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57 | typedef unsigned char JSAMPLE; |
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58 | #define GETJSAMPLE(value) ((int) (value)) |
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59 | |
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60 | #define MAXJSAMPLE 255 |
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61 | #define CENTERJSAMPLE 128 |
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62 | |
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63 | #endif /* BITS_IN_JSAMPLE == 8 */ |
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64 | |
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65 | |
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66 | #if BITS_IN_JSAMPLE == 12 |
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67 | /* JSAMPLE should be the smallest type that will hold the values 0..4095. |
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68 | * On nearly all machines "short" will do nicely. |
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69 | */ |
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70 | |
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71 | typedef short JSAMPLE; |
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72 | #define GETJSAMPLE(value) ((int) (value)) |
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73 | |
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74 | #define MAXJSAMPLE 4095 |
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75 | #define CENTERJSAMPLE 2048 |
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76 | |
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77 | #endif /* BITS_IN_JSAMPLE == 12 */ |
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78 | |
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79 | |
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80 | /* Representation of a DCT frequency coefficient. |
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81 | * This should be a signed value of at least 16 bits; "short" is usually OK. |
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82 | * Again, we allocate large arrays of these, but you can change to int |
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83 | * if you have memory to burn and "short" is really slow. |
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84 | */ |
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85 | |
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86 | typedef short JCOEF; |
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87 | |
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88 | |
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89 | /* Compressed datastreams are represented as arrays of JOCTET. |
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90 | * These must be EXACTLY 8 bits wide, at least once they are written to |
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91 | * external storage. Note that when using the stdio data source/destination |
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92 | * managers, this is also the data type passed to fread/fwrite. |
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93 | */ |
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94 | |
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95 | typedef unsigned char JOCTET; |
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96 | #define GETJOCTET(value) (value) |
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97 | |
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98 | /* These typedefs are used for various table entries and so forth. |
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99 | * They must be at least as wide as specified; but making them too big |
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100 | * won't cost a huge amount of memory, so we don't provide special |
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101 | * extraction code like we did for JSAMPLE. (In other words, these |
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102 | * typedefs live at a different point on the speed/space tradeoff curve.) |
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103 | */ |
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104 | |
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105 | /* UINT8 must hold at least the values 0..255. */ |
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106 | |
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107 | typedef unsigned char UINT8; |
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108 | |
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109 | /* UINT16 must hold at least the values 0..65535. */ |
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110 | |
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111 | typedef unsigned short UINT16; |
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112 | |
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113 | /* INT16 must hold at least the values -32768..32767. */ |
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114 | |
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115 | #ifndef XMD_H /* X11/xmd.h correctly defines INT16 */ |
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116 | typedef short INT16; |
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117 | #endif |
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118 | |
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119 | /* INT32 must hold at least signed 32-bit values. */ |
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120 | |
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121 | #ifndef XMD_H |
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122 | typedef int INT32; |
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123 | #endif |
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124 | |
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125 | /* Datatype used for image dimensions. The JPEG standard only supports |
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126 | * images up to 64K*64K due to 16-bit fields in SOF markers. Therefore |
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127 | * "unsigned int" is sufficient on all machines. However, if you need to |
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128 | * handle larger images and you don't mind deviating from the spec, you |
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129 | * can change this datatype. |
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130 | */ |
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131 | |
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132 | typedef unsigned int JDIMENSION; |
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133 | |
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134 | #define JPEG_MAX_DIMENSION 65500L /* a tad under 64K to prevent overflows */ |
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135 | |
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136 | |
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137 | /* These macros are used in all function definitions and extern declarations. |
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138 | * You could modify them if you need to change function linkage conventions; |
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139 | * in particular, you'll need to do that to make the library a Windows DLL. |
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140 | * Another application is to make all functions global for use with debuggers |
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141 | * or code profilers that require it. |
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142 | */ |
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143 | |
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144 | /* a function called through method pointers: */ |
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145 | #define METHODDEF(type) static type |
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146 | /* a function used only in its module: */ |
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147 | #define LOCAL(type) static type |
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148 | /* a function referenced thru EXTERNs: */ |
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149 | #define GLOBAL(type) type |
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150 | /* a reference to a GLOBAL function: */ |
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151 | #define EXTERN(type) extern type |
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152 | |
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153 | |
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154 | /* This macro is used to declare a "method", that is, a function pointer. |
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155 | * We want to supply prototype parameters if the compiler can cope. |
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156 | * Note that the arglist parameter must be parenthesized! |
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157 | * Again, you can customize this if you need special linkage keywords. |
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158 | */ |
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159 | |
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160 | #define JMETHOD(type,methodname,arglist) type (*methodname) arglist |
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161 | |
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162 | /* Here is the pseudo-keyword for declaring pointers that must be "far" |
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163 | * on 80x86 machines. Most of the specialized coding for 80x86 is handled |
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164 | * by just saying "FAR *" where such a pointer is needed. In a few places |
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165 | * explicit coding is needed; see uses of the NEED_FAR_POINTERS symbol. |
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166 | */ |
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167 | |
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168 | #undef FAR |
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169 | #define FAR |
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170 | |
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171 | |
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172 | /* |
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173 | * On a few systems, type boolean and/or its values FALSE, TRUE may appear |
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174 | * in standard header files. Or you may have conflicts with application- |
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175 | * specific header files that you want to include together with these files. |
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176 | * Defining HAVE_BOOLEAN before including jpeglib.h should make it work. |
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177 | */ |
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178 | |
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179 | #ifndef HAVE_BOOLEAN |
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180 | typedef char boolean; |
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181 | #endif |
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182 | #ifndef FALSE /* in case these macros already exist */ |
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183 | #define FALSE 0 /* values of boolean */ |
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184 | #endif |
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185 | #ifndef TRUE |
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186 | #define TRUE 1 |
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187 | #endif |
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188 | |
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189 | |
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190 | /* |
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191 | * The remaining options affect code selection within the JPEG library, |
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192 | * but they don't need to be visible to most applications using the library. |
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193 | * To minimize application namespace pollution, the symbols won't be |
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194 | * defined unless JPEG_INTERNALS or JPEG_INTERNAL_OPTIONS has been defined. |
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195 | */ |
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196 | |
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197 | #ifdef JPEG_INTERNALS |
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198 | #define JPEG_INTERNAL_OPTIONS |
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199 | #endif |
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200 | |
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201 | #ifdef JPEG_INTERNAL_OPTIONS |
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202 | |
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203 | |
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204 | /* |
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205 | * These defines indicate whether to include various optional functions. |
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206 | * Undefining some of these symbols will produce a smaller but less capable |
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207 | * library. Note that you can leave certain source files out of the |
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208 | * compilation/linking process if you've #undef'd the corresponding symbols. |
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209 | * (You may HAVE to do that if your compiler doesn't like null source files.) |
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210 | */ |
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211 | |
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212 | /* Arithmetic coding is unsupported for legal reasons. Complaints to IBM. */ |
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213 | |
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214 | /* Capability options common to encoder and decoder: */ |
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215 | |
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216 | #define DCT_ISLOW_SUPPORTED /* slow but accurate integer algorithm */ |
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217 | #define DCT_IFAST_SUPPORTED /* faster, less accurate integer method */ |
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218 | #define DCT_FLOAT_SUPPORTED /* floating-point: accurate, fast on fast HW */ |
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219 | |
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220 | /* Encoder capability options: */ |
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221 | |
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222 | #undef C_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */ |
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223 | #define C_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */ |
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224 | #define C_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/ |
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225 | #define ENTROPY_OPT_SUPPORTED /* Optimization of entropy coding parms? */ |
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226 | /* Note: if you selected 12-bit data precision, it is dangerous to turn off |
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227 | * ENTROPY_OPT_SUPPORTED. The standard Huffman tables are only good for 8-bit |
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228 | * precision, so jchuff.c normally uses entropy optimization to compute |
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229 | * usable tables for higher precision. If you don't want to do optimization, |
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230 | * you'll have to supply different default Huffman tables. |
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231 | * The exact same statements apply for progressive JPEG: the default tables |
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232 | * don't work for progressive mode. (This may get fixed, however.) |
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233 | */ |
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234 | #define INPUT_SMOOTHING_SUPPORTED /* Input image smoothing option? */ |
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235 | |
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236 | /* Decoder capability options: */ |
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237 | |
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238 | #undef D_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */ |
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239 | #define D_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */ |
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240 | #define D_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/ |
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241 | #define SAVE_MARKERS_SUPPORTED /* jpeg_save_markers() needed? */ |
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242 | #define BLOCK_SMOOTHING_SUPPORTED /* Block smoothing? (Progressive only) */ |
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243 | #define IDCT_SCALING_SUPPORTED /* Output rescaling via IDCT? */ |
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244 | #undef UPSAMPLE_SCALING_SUPPORTED /* Output rescaling at upsample stage? */ |
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245 | #define UPSAMPLE_MERGING_SUPPORTED /* Fast path for sloppy upsampling? */ |
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246 | #define QUANT_1PASS_SUPPORTED /* 1-pass color quantization? */ |
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247 | #define QUANT_2PASS_SUPPORTED /* 2-pass color quantization? */ |
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248 | |
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249 | /* more capability options later, no doubt */ |
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250 | |
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251 | |
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252 | /* |
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253 | * Ordering of RGB data in scanlines passed to or from the application. |
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254 | * If your application wants to deal with data in the order B,G,R, just |
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255 | * change these macros. You can also deal with formats such as R,G,B,X |
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256 | * (one extra byte per pixel) by changing RGB_PIXELSIZE. Note that changing |
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257 | * the offsets will also change the order in which colormap data is organized. |
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258 | * RESTRICTIONS: |
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259 | * 1. The sample applications cjpeg,djpeg do NOT support modified RGB formats. |
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260 | * 2. These macros only affect RGB<=>YCbCr color conversion, so they are not |
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261 | * useful if you are using JPEG color spaces other than YCbCr or grayscale. |
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262 | * 3. The color quantizer modules will not behave desirably if RGB_PIXELSIZE |
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263 | * is not 3 (they don't understand about dummy color components!). So you |
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264 | * can't use color quantization if you change that value. |
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265 | */ |
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266 | |
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267 | #define RGB_RED 0 /* Offset of Red in an RGB scanline element */ |
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268 | #define RGB_GREEN 1 /* Offset of Green */ |
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269 | #define RGB_BLUE 2 /* Offset of Blue */ |
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270 | #define RGB_PIXELSIZE 3 /* JSAMPLEs per RGB scanline element */ |
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271 | |
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272 | |
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273 | /* Definitions for speed-related optimizations. */ |
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274 | |
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275 | |
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276 | /* If your compiler supports inline functions, define INLINE |
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277 | * as the inline keyword; otherwise define it as empty. |
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278 | */ |
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279 | |
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280 | #ifndef INLINE |
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281 | #ifdef __GNUC__ /* for instance, GNU C knows about inline */ |
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282 | #define INLINE __inline__ |
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283 | #endif |
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284 | #ifndef INLINE |
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285 | #define INLINE /* default is to define it as empty */ |
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286 | #endif |
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287 | #endif |
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288 | |
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289 | |
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290 | /* On some machines (notably 68000 series) "int" is 32 bits, but multiplying |
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291 | * two 16-bit shorts is faster than multiplying two ints. Define MULTIPLIER |
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292 | * as short on such a machine. MULTIPLIER must be at least 16 bits wide. |
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293 | */ |
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294 | |
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295 | #ifndef MULTIPLIER |
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296 | #define MULTIPLIER int /* type for fastest integer multiply */ |
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297 | #endif |
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298 | |
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299 | |
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300 | /* FAST_FLOAT should be either float or double, whichever is done faster |
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301 | * by your compiler. (Note that this type is only used in the floating point |
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302 | * DCT routines, so it only matters if you've defined DCT_FLOAT_SUPPORTED.) |
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303 | * Typically, float is faster in ANSI C compilers, while double is faster in |
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304 | * pre-ANSI compilers (because they insist on converting to double anyway). |
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305 | * The code below therefore chooses float if we have ANSI-style prototypes. |
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306 | */ |
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307 | |
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308 | #ifndef FAST_FLOAT |
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309 | #ifdef HAVE_PROTOTYPES |
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310 | #define FAST_FLOAT float |
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311 | #else |
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312 | #define FAST_FLOAT double |
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313 | #endif |
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314 | #endif |
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315 | |
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316 | #endif /* JPEG_INTERNAL_OPTIONS */ |
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