jmorecfg.h (12458B)
1 /* 2 * jmorecfg.h 3 * 4 * Copyright (C) 1991-1997, Thomas G. Lane. 5 * This file is part of the Independent JPEG Group's software. 6 * For conditions of distribution and use, see the accompanying README file. 7 * 8 * This file contains additional configuration options that customize the 9 * JPEG software for special applications or support machine-dependent 10 * optimizations. Most users will not need to touch this file. 11 */ 12 13 14 /* 15 * Define BITS_IN_JSAMPLE as either 16 * 8 for 8-bit sample values (the usual setting) 17 * 12 for 12-bit sample values 18 * Only 8 and 12 are legal data precisions for lossy JPEG according to the 19 * JPEG standard, and the IJG code does not support anything else! 20 * We do not support run-time selection of data precision, sorry. 21 */ 22 23 #define BITS_IN_JSAMPLE 8 /* use 8 or 12 */ 24 25 26 /* 27 * Maximum number of components (color channels) allowed in JPEG image. 28 * To meet the letter of the JPEG spec, set this to 255. However, darn 29 * few applications need more than 4 channels (maybe 5 for CMYK + alpha 30 * mask). We recommend 10 as a reasonable compromise; use 4 if you are 31 * really short on memory. (Each allowed component costs a hundred or so 32 * bytes of storage, whether actually used in an image or not.) 33 */ 34 35 #define MAX_COMPONENTS 10 /* maximum number of image components */ 36 37 38 /* 39 * Basic data types. 40 * You may need to change these if you have a machine with unusual data 41 * type sizes; for example, "char" not 8 bits, "short" not 16 bits, 42 * or "long" not 32 bits. We don't care whether "int" is 16 or 32 bits, 43 * but it had better be at least 16. 44 */ 45 46 /* Representation of a single sample (pixel element value). 47 * We frequently allocate large arrays of these, so it's important to keep 48 * them small. But if you have memory to burn and access to char or short 49 * arrays is very slow on your hardware, you might want to change these. 50 */ 51 52 #if BITS_IN_JSAMPLE == 8 53 /* JSAMPLE should be the smallest type that will hold the values 0..255. 54 * You can use a signed char by having GETJSAMPLE mask it with 0xFF. 55 */ 56 57 #ifdef HAVE_UNSIGNED_CHAR 58 59 typedef unsigned char JSAMPLE; 60 #define GETJSAMPLE(value) ((int) (value)) 61 62 #else /* not HAVE_UNSIGNED_CHAR */ 63 64 typedef char JSAMPLE; 65 #ifdef CHAR_IS_UNSIGNED 66 #define GETJSAMPLE(value) ((int) (value)) 67 #else 68 #define GETJSAMPLE(value) ((int) (value) & 0xFF) 69 #endif /* CHAR_IS_UNSIGNED */ 70 71 #endif /* HAVE_UNSIGNED_CHAR */ 72 73 #define MAXJSAMPLE 255 74 #define CENTERJSAMPLE 128 75 76 #endif /* BITS_IN_JSAMPLE == 8 */ 77 78 79 #if BITS_IN_JSAMPLE == 12 80 /* JSAMPLE should be the smallest type that will hold the values 0..4095. 81 * On nearly all machines "short" will do nicely. 82 */ 83 84 typedef short JSAMPLE; 85 #define GETJSAMPLE(value) ((int) (value)) 86 87 #define MAXJSAMPLE 4095 88 #define CENTERJSAMPLE 2048 89 90 #endif /* BITS_IN_JSAMPLE == 12 */ 91 92 93 /* Representation of a DCT frequency coefficient. 94 * This should be a signed value of at least 16 bits; "short" is usually OK. 95 * Again, we allocate large arrays of these, but you can change to int 96 * if you have memory to burn and "short" is really slow. 97 */ 98 99 typedef short JCOEF; 100 101 102 /* Compressed datastreams are represented as arrays of JOCTET. 103 * These must be EXACTLY 8 bits wide, at least once they are written to 104 * external storage. Note that when using the stdio data source/destination 105 * managers, this is also the data type passed to fread/fwrite. 106 */ 107 108 #ifdef HAVE_UNSIGNED_CHAR 109 110 typedef unsigned char JOCTET; 111 #define GETJOCTET(value) (value) 112 113 #else /* not HAVE_UNSIGNED_CHAR */ 114 115 typedef char JOCTET; 116 #ifdef CHAR_IS_UNSIGNED 117 #define GETJOCTET(value) (value) 118 #else 119 #define GETJOCTET(value) ((value) & 0xFF) 120 #endif /* CHAR_IS_UNSIGNED */ 121 122 #endif /* HAVE_UNSIGNED_CHAR */ 123 124 125 /* These typedefs are used for various table entries and so forth. 126 * They must be at least as wide as specified; but making them too big 127 * won't cost a huge amount of memory, so we don't provide special 128 * extraction code like we did for JSAMPLE. (In other words, these 129 * typedefs live at a different point on the speed/space tradeoff curve.) 130 */ 131 132 /* UINT8 must hold at least the values 0..255. */ 133 134 #ifdef HAVE_UNSIGNED_CHAR 135 typedef unsigned char UINT8; 136 #else /* not HAVE_UNSIGNED_CHAR */ 137 #ifdef CHAR_IS_UNSIGNED 138 typedef char UINT8; 139 #else /* not CHAR_IS_UNSIGNED */ 140 typedef short UINT8; 141 #endif /* CHAR_IS_UNSIGNED */ 142 #endif /* HAVE_UNSIGNED_CHAR */ 143 144 /* UINT16 must hold at least the values 0..65535. */ 145 146 #ifdef HAVE_UNSIGNED_SHORT 147 typedef unsigned short UINT16; 148 #else /* not HAVE_UNSIGNED_SHORT */ 149 typedef unsigned int UINT16; 150 #endif /* HAVE_UNSIGNED_SHORT */ 151 152 /* INT16 must hold at least the values -32768..32767. */ 153 154 #ifndef XMD_H /* X11/xmd.h correctly defines INT16 */ 155 typedef short INT16; 156 #endif 157 158 /* INT32 must hold at least signed 32-bit values. */ 159 160 #ifndef XMD_H /* X11/xmd.h correctly defines INT32 */ 161 typedef long INT32; 162 #endif 163 164 /* Datatype used for image dimensions. The JPEG standard only supports 165 * images up to 64K*64K due to 16-bit fields in SOF markers. Therefore 166 * "unsigned int" is sufficient on all machines. However, if you need to 167 * handle larger images and you don't mind deviating from the spec, you 168 * can change this datatype. 169 */ 170 171 typedef unsigned int JDIMENSION; 172 173 #define JPEG_MAX_DIMENSION 65500L /* a tad under 64K to prevent overflows */ 174 175 176 /* These macros are used in all function definitions and extern declarations. 177 * You could modify them if you need to change function linkage conventions; 178 * in particular, you'll need to do that to make the library a Windows DLL. 179 * Another application is to make all functions global for use with debuggers 180 * or code profilers that require it. 181 */ 182 183 /* a function called through method pointers: */ 184 #define METHODDEF(type) static type 185 /* a function used only in its module: */ 186 #define LOCAL(type) static type 187 /* a function referenced thru EXTERNs: */ 188 #define GLOBAL(type) type 189 /* a reference to a GLOBAL function: */ 190 #define EXTERN(type) extern type 191 192 193 /* This macro is used to declare a "method", that is, a function pointer. 194 * We want to supply prototype parameters if the compiler can cope. 195 * Note that the arglist parameter must be parenthesized! 196 * Again, you can customize this if you need special linkage keywords. 197 */ 198 199 #ifdef HAVE_PROTOTYPES 200 #define JMETHOD(type,methodname,arglist) type (*methodname) arglist 201 #else 202 #define JMETHOD(type,methodname,arglist) type (*methodname) () 203 #endif 204 205 206 /* Here is the pseudo-keyword for declaring pointers that must be "far" 207 * on 80x86 machines. Most of the specialized coding for 80x86 is handled 208 * by just saying "FAR *" where such a pointer is needed. In a few places 209 * explicit coding is needed; see uses of the NEED_FAR_POINTERS symbol. 210 */ 211 212 #ifdef NEED_FAR_POINTERS 213 #define FAR far 214 #else 215 #define FAR 216 #endif 217 218 219 /* 220 * On a few systems, type boolean and/or its values FALSE, TRUE may appear 221 * in standard header files. Or you may have conflicts with application- 222 * specific header files that you want to include together with these files. 223 * Defining HAVE_BOOLEAN before including jpeglib.h should make it work. 224 */ 225 226 #ifndef HAVE_BOOLEAN 227 typedef int boolean; 228 #endif 229 #ifndef FALSE /* in case these macros already exist */ 230 #define FALSE 0 /* values of boolean */ 231 #endif 232 #ifndef TRUE 233 #define TRUE 1 234 #endif 235 236 237 /* 238 * The remaining options affect code selection within the JPEG library, 239 * but they don't need to be visible to most applications using the library. 240 * To minimize application namespace pollution, the symbols won't be 241 * defined unless JPEG_INTERNALS or JPEG_INTERNAL_OPTIONS has been defined. 242 */ 243 244 #ifdef JPEG_INTERNALS 245 #define JPEG_INTERNAL_OPTIONS 246 #endif 247 248 #ifdef JPEG_INTERNAL_OPTIONS 249 250 251 /* 252 * These defines indicate whether to include various optional functions. 253 * Undefining some of these symbols will produce a smaller but less capable 254 * library. Note that you can leave certain source files out of the 255 * compilation/linking process if you've #undef'd the corresponding symbols. 256 * (You may HAVE to do that if your compiler doesn't like null source files.) 257 */ 258 259 /* Arithmetic coding is unsupported for legal reasons. Complaints to IBM. */ 260 261 /* Capability options common to encoder and decoder: */ 262 263 #define DCT_ISLOW_SUPPORTED /* slow but accurate integer algorithm */ 264 #define DCT_IFAST_SUPPORTED /* faster, less accurate integer method */ 265 #define DCT_FLOAT_SUPPORTED /* floating-point: accurate, fast on fast HW */ 266 267 /* Encoder capability options: */ 268 269 #undef C_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */ 270 #define C_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */ 271 #define C_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/ 272 #define ENTROPY_OPT_SUPPORTED /* Optimization of entropy coding parms? */ 273 /* Note: if you selected 12-bit data precision, it is dangerous to turn off 274 * ENTROPY_OPT_SUPPORTED. The standard Huffman tables are only good for 8-bit 275 * precision, so jchuff.c normally uses entropy optimization to compute 276 * usable tables for higher precision. If you don't want to do optimization, 277 * you'll have to supply different default Huffman tables. 278 * The exact same statements apply for progressive JPEG: the default tables 279 * don't work for progressive mode. (This may get fixed, however.) 280 */ 281 #define INPUT_SMOOTHING_SUPPORTED /* Input image smoothing option? */ 282 283 /* Decoder capability options: */ 284 285 #undef D_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */ 286 #define D_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */ 287 #define D_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/ 288 #define SAVE_MARKERS_SUPPORTED /* jpeg_save_markers() needed? */ 289 #define BLOCK_SMOOTHING_SUPPORTED /* Block smoothing? (Progressive only) */ 290 #define IDCT_SCALING_SUPPORTED /* Output rescaling via IDCT? */ 291 #undef UPSAMPLE_SCALING_SUPPORTED /* Output rescaling at upsample stage? */ 292 #define UPSAMPLE_MERGING_SUPPORTED /* Fast path for sloppy upsampling? */ 293 #define QUANT_1PASS_SUPPORTED /* 1-pass color quantization? */ 294 #define QUANT_2PASS_SUPPORTED /* 2-pass color quantization? */ 295 296 /* more capability options later, no doubt */ 297 298 299 /* 300 * Ordering of RGB data in scanlines passed to or from the application. 301 * If your application wants to deal with data in the order B,G,R, just 302 * change these macros. You can also deal with formats such as R,G,B,X 303 * (one extra byte per pixel) by changing RGB_PIXELSIZE. Note that changing 304 * the offsets will also change the order in which colormap data is organized. 305 * RESTRICTIONS: 306 * 1. The sample applications cjpeg,djpeg do NOT support modified RGB formats. 307 * 2. These macros only affect RGB<=>YCbCr color conversion, so they are not 308 * useful if you are using JPEG color spaces other than YCbCr or grayscale. 309 * 3. The color quantizer modules will not behave desirably if RGB_PIXELSIZE 310 * is not 3 (they don't understand about dummy color components!). So you 311 * can't use color quantization if you change that value. 312 */ 313 314 #define RGB_RED 0 /* Offset of Red in an RGB scanline element */ 315 #define RGB_GREEN 1 /* Offset of Green */ 316 #define RGB_BLUE 2 /* Offset of Blue */ 317 #define RGB_PIXELSIZE 3 /* JSAMPLEs per RGB scanline element */ 318 319 320 /* Definitions for speed-related optimizations. */ 321 322 323 /* If your compiler supports inline functions, define INLINE 324 * as the inline keyword; otherwise define it as empty. 325 */ 326 327 #ifndef INLINE 328 #ifdef __GNUC__ /* for instance, GNU C knows about inline */ 329 #define INLINE __inline__ 330 #endif 331 #ifndef INLINE 332 #define INLINE /* default is to define it as empty */ 333 #endif 334 #endif 335 336 337 /* On some machines (notably 68000 series) "int" is 32 bits, but multiplying 338 * two 16-bit shorts is faster than multiplying two ints. Define MULTIPLIER 339 * as short on such a machine. MULTIPLIER must be at least 16 bits wide. 340 */ 341 342 #ifndef MULTIPLIER 343 #define MULTIPLIER int /* type for fastest integer multiply */ 344 #endif 345 346 347 /* FAST_FLOAT should be either float or double, whichever is done faster 348 * by your compiler. (Note that this type is only used in the floating point 349 * DCT routines, so it only matters if you've defined DCT_FLOAT_SUPPORTED.) 350 * Typically, float is faster in ANSI C compilers, while double is faster in 351 * pre-ANSI compilers (because they insist on converting to double anyway). 352 * The code below therefore chooses float if we have ANSI-style prototypes. 353 */ 354 355 #ifndef FAST_FLOAT 356 #ifdef HAVE_PROTOTYPES 357 #define FAST_FLOAT float 358 #else 359 #define FAST_FLOAT double 360 #endif 361 #endif 362 363 #endif /* JPEG_INTERNAL_OPTIONS */