1 /* 2 * jmorecfg.h 3 * 4 * Copyright (C) 1991-1997, Thomas G. Lane. 5 * Modified 1997-2012 by Guido Vollbeding. 6 * This file is part of the Independent JPEG Group's software. 7 * For conditions of distribution and use, see the accompanying README file. 8 * 9 * This file contains additional configuration options that customize the 10 * JPEG software for special applications or support machine-dependent 11 * optimizations. Most users will not need to touch this file. 12 */ 13 14 15 /* 16 * Define BITS_IN_JSAMPLE as either 17 * 8 for 8-bit sample values (the usual setting) 18 * 12 for 12-bit sample values 19 * Only 8 and 12 are legal data precisions for lossy JPEG according to the 20 * JPEG standard, and the IJG code does not support anything else! 21 * We do not support run-time selection of data precision, sorry. 22 */ 23 24 #define BITS_IN_JSAMPLE 8 /* use 8 or 12 */ 25 26 27 /* 28 * Maximum number of components (color channels) allowed in JPEG image. 29 * To meet the letter of the JPEG spec, set this to 255. However, darn 30 * few applications need more than 4 channels (maybe 5 for CMYK + alpha 31 * mask). We recommend 10 as a reasonable compromise; use 4 if you are 32 * really short on memory. (Each allowed component costs a hundred or so 33 * bytes of storage, whether actually used in an image or not.) 34 */ 35 36 #define MAX_COMPONENTS 10 /* maximum number of image components */ 37 38 39 /* 40 * Basic data types. 41 * You may need to change these if you have a machine with unusual data 42 * type sizes; for example, "char" not 8 bits, "short" not 16 bits, 43 * or "long" not 32 bits. We don't care whether "int" is 16 or 32 bits, 44 * but it had better be at least 16. 45 */ 46 47 /* Representation of a single sample (pixel element value). 48 * We frequently allocate large arrays of these, so it's important to keep 49 * them small. But if you have memory to burn and access to char or short 50 * arrays is very slow on your hardware, you might want to change these. 51 */ 52 53 #if BITS_IN_JSAMPLE == 8 54 /* JSAMPLE should be the smallest type that will hold the values 0..255. 55 * You can use a signed char by having GETJSAMPLE mask it with 0xFF. 56 */ 57 58 #ifdef HAVE_UNSIGNED_CHAR 59 60 typedef unsigned char JSAMPLE; 61 #define GETJSAMPLE(value) ((int) (value)) 62 63 #else /* not HAVE_UNSIGNED_CHAR */ 64 65 typedef char JSAMPLE; 66 #ifdef CHAR_IS_UNSIGNED 67 #define GETJSAMPLE(value) ((int) (value)) 68 #else 69 #define GETJSAMPLE(value) ((int) (value) & 0xFF) 70 #endif /* CHAR_IS_UNSIGNED */ 71 72 #endif /* HAVE_UNSIGNED_CHAR */ 73 74 #define MAXJSAMPLE 255 75 #define CENTERJSAMPLE 128 76 77 #endif /* BITS_IN_JSAMPLE == 8 */ 78 79 80 #if BITS_IN_JSAMPLE == 12 81 /* JSAMPLE should be the smallest type that will hold the values 0..4095. 82 * On nearly all machines "short" will do nicely. 83 */ 84 85 typedef short JSAMPLE; 86 #define GETJSAMPLE(value) ((int) (value)) 87 88 #define MAXJSAMPLE 4095 89 #define CENTERJSAMPLE 2048 90 91 #endif /* BITS_IN_JSAMPLE == 12 */ 92 93 94 /* Representation of a DCT frequency coefficient. 95 * This should be a signed value of at least 16 bits; "short" is usually OK. 96 * Again, we allocate large arrays of these, but you can change to int 97 * if you have memory to burn and "short" is really slow. 98 */ 99 100 typedef short JCOEF; 101 102 103 /* Compressed datastreams are represented as arrays of JOCTET. 104 * These must be EXACTLY 8 bits wide, at least once they are written to 105 * external storage. Note that when using the stdio data source/destination 106 * managers, this is also the data type passed to fread/fwrite. 107 */ 108 109 #ifdef HAVE_UNSIGNED_CHAR 110 111 typedef unsigned char JOCTET; 112 #define GETJOCTET(value) (value) 113 114 #else /* not HAVE_UNSIGNED_CHAR */ 115 116 typedef char JOCTET; 117 #ifdef CHAR_IS_UNSIGNED 118 #define GETJOCTET(value) (value) 119 #else 120 #define GETJOCTET(value) ((value) & 0xFF) 121 #endif /* CHAR_IS_UNSIGNED */ 122 123 #endif /* HAVE_UNSIGNED_CHAR */ 124 125 126 /* These typedefs are used for various table entries and so forth. 127 * They must be at least as wide as specified; but making them too big 128 * won't cost a huge amount of memory, so we don't provide special 129 * extraction code like we did for JSAMPLE. (In other words, these 130 * typedefs live at a different point on the speed/space tradeoff curve.) 131 */ 132 133 /* UINT8 must hold at least the values 0..255. */ 134 135 #ifdef HAVE_UNSIGNED_CHAR 136 typedef unsigned char UINT8; 137 #else /* not HAVE_UNSIGNED_CHAR */ 138 #ifdef CHAR_IS_UNSIGNED 139 typedef char UINT8; 140 #else /* not CHAR_IS_UNSIGNED */ 141 typedef short UINT8; 142 #endif /* CHAR_IS_UNSIGNED */ 143 #endif /* HAVE_UNSIGNED_CHAR */ 144 145 /* UINT16 must hold at least the values 0..65535. */ 146 147 #ifdef HAVE_UNSIGNED_SHORT 148 typedef unsigned short UINT16; 149 #else /* not HAVE_UNSIGNED_SHORT */ 150 typedef unsigned int UINT16; 151 #endif /* HAVE_UNSIGNED_SHORT */ 152 153 /* INT16 must hold at least the values -32768..32767. */ 154 155 #ifndef XMD_H /* X11/xmd.h correctly defines INT16 */ 156 typedef short INT16; 157 #endif 158 159 /* INT32 must hold at least signed 32-bit values. */ 160 161 #ifndef XMD_H /* X11/xmd.h correctly defines INT32 */ 162 #ifndef _BASETSD_H_ /* Microsoft defines it in basetsd.h */ 163 #ifndef _BASETSD_H /* MinGW is slightly different */ 164 #ifndef QGLOBAL_H /* Qt defines it in qglobal.h */ 165 typedef long INT32; 166 #endif 167 #endif 168 #endif 169 #endif 170 171 /* Datatype used for image dimensions. The JPEG standard only supports 172 * images up to 64K*64K due to 16-bit fields in SOF markers. Therefore 173 * "unsigned int" is sufficient on all machines. However, if you need to 174 * handle larger images and you don't mind deviating from the spec, you 175 * can change this datatype. 176 */ 177 178 typedef unsigned int JDIMENSION; 179 180 #define JPEG_MAX_DIMENSION 65500L /* a tad under 64K to prevent overflows */ 181 182 183 /* These macros are used in all function definitions and extern declarations. 184 * You could modify them if you need to change function linkage conventions; 185 * in particular, you'll need to do that to make the library a Windows DLL. 186 * Another application is to make all functions global for use with debuggers 187 * or code profilers that require it. 188 */ 189 190 /* a function called through method pointers: */ 191 #define METHODDEF(type) static type 192 /* a function used only in its module: */ 193 #define LOCAL(type) static type 194 /* a function referenced thru EXTERNs: */ 195 #define GLOBAL(type) type 196 /* a reference to a GLOBAL function: */ 197 #define EXTERN(type) extern type 198 199 200 /* This macro is used to declare a "method", that is, a function pointer. 201 * We want to supply prototype parameters if the compiler can cope. 202 * Note that the arglist parameter must be parenthesized! 203 * Again, you can customize this if you need special linkage keywords. 204 */ 205 206 #ifdef HAVE_PROTOTYPES 207 #define JMETHOD(type,methodname,arglist) type (*methodname) arglist 208 #else 209 #define JMETHOD(type,methodname,arglist) type (*methodname) () 210 #endif 211 212 213 /* The noreturn type identifier is used to declare functions 214 * which cannot return. 215 * Compilers can thus create more optimized code and perform 216 * better checks for warnings and errors. 217 * Static analyzer tools can make improved inferences about 218 * execution paths and are prevented from giving false alerts. 219 * 220 * Unfortunately, the proposed specifications of corresponding 221 * extensions in the Dec 2011 ISO C standard revision (C11), 222 * GCC, MSVC, etc. are not viable. 223 * Thus we introduce a user defined type to declare noreturn 224 * functions at least for clarity. A proper compiler would 225 * have a suitable noreturn type to match in place of void. 226 */ 227 228 #ifndef HAVE_NORETURN_T 229 typedef void noreturn_t; 230 #endif 231 232 233 /* Here is the pseudo-keyword for declaring pointers that must be "far" 234 * on 80x86 machines. Most of the specialized coding for 80x86 is handled 235 * by just saying "FAR *" where such a pointer is needed. In a few places 236 * explicit coding is needed; see uses of the NEED_FAR_POINTERS symbol. 237 */ 238 239 #ifndef FAR 240 #ifdef NEED_FAR_POINTERS 241 #define FAR far 242 #else 243 #define FAR 244 #endif 245 #endif 246 247 248 /* 249 * On a few systems, type boolean and/or its values FALSE, TRUE may appear 250 * in standard header files. Or you may have conflicts with application- 251 * specific header files that you want to include together with these files. 252 * Defining HAVE_BOOLEAN before including jpeglib.h should make it work. 253 */ 254 255 #ifdef HAVE_BOOLEAN 256 #ifndef FALSE /* in case these macros already exist */ 257 #define FALSE 0 /* values of boolean */ 258 #endif 259 #ifndef TRUE 260 #define TRUE 1 261 #endif 262 #else 263 typedef enum { FALSE = 0, TRUE = 1 } boolean; 264 #endif 265 266 267 /* 268 * The remaining options affect code selection within the JPEG library, 269 * but they don't need to be visible to most applications using the library. 270 * To minimize application namespace pollution, the symbols won't be 271 * defined unless JPEG_INTERNALS or JPEG_INTERNAL_OPTIONS has been defined. 272 */ 273 274 #ifdef JPEG_INTERNALS 275 #define JPEG_INTERNAL_OPTIONS 276 #endif 277 278 #ifdef JPEG_INTERNAL_OPTIONS 279 280 281 /* 282 * These defines indicate whether to include various optional functions. 283 * Undefining some of these symbols will produce a smaller but less capable 284 * library. Note that you can leave certain source files out of the 285 * compilation/linking process if you've #undef'd the corresponding symbols. 286 * (You may HAVE to do that if your compiler doesn't like null source files.) 287 */ 288 289 /* Capability options common to encoder and decoder: */ 290 291 #define DCT_ISLOW_SUPPORTED /* slow but accurate integer algorithm */ 292 #define DCT_IFAST_SUPPORTED /* faster, less accurate integer method */ 293 #define DCT_FLOAT_SUPPORTED /* floating-point: accurate, fast on fast HW */ 294 295 /* Encoder capability options: */ 296 297 #define C_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */ 298 #define C_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */ 299 #define C_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/ 300 #define DCT_SCALING_SUPPORTED /* Input rescaling via DCT? (Requires DCT_ISLOW)*/ 301 #define ENTROPY_OPT_SUPPORTED /* Optimization of entropy coding parms? */ 302 /* Note: if you selected 12-bit data precision, it is dangerous to turn off 303 * ENTROPY_OPT_SUPPORTED. The standard Huffman tables are only good for 8-bit 304 * precision, so jchuff.c normally uses entropy optimization to compute 305 * usable tables for higher precision. If you don't want to do optimization, 306 * you'll have to supply different default Huffman tables. 307 * The exact same statements apply for progressive JPEG: the default tables 308 * don't work for progressive mode. (This may get fixed, however.) 309 */ 310 #define INPUT_SMOOTHING_SUPPORTED /* Input image smoothing option? */ 311 312 /* Decoder capability options: */ 313 314 #define D_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */ 315 #define D_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */ 316 #define D_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/ 317 #define IDCT_SCALING_SUPPORTED /* Output rescaling via IDCT? */ 318 #define SAVE_MARKERS_SUPPORTED /* jpeg_save_markers() needed? */ 319 #define BLOCK_SMOOTHING_SUPPORTED /* Block smoothing? (Progressive only) */ 320 #undef UPSAMPLE_SCALING_SUPPORTED /* Output rescaling at upsample stage? */ 321 #define UPSAMPLE_MERGING_SUPPORTED /* Fast path for sloppy upsampling? */ 322 #define QUANT_1PASS_SUPPORTED /* 1-pass color quantization? */ 323 #define QUANT_2PASS_SUPPORTED /* 2-pass color quantization? */ 324 325 /* more capability options later, no doubt */ 326 327 328 /* 329 * Ordering of RGB data in scanlines passed to or from the application. 330 * If your application wants to deal with data in the order B,G,R, just 331 * change these macros. You can also deal with formats such as R,G,B,X 332 * (one extra byte per pixel) by changing RGB_PIXELSIZE. Note that changing 333 * the offsets will also change the order in which colormap data is organized. 334 * RESTRICTIONS: 335 * 1. The sample applications cjpeg,djpeg do NOT support modified RGB formats. 336 * 2. The color quantizer modules will not behave desirably if RGB_PIXELSIZE 337 * is not 3 (they don't understand about dummy color components!). So you 338 * can't use color quantization if you change that value. 339 */ 340 341 #define RGB_RED 0 /* Offset of Red in an RGB scanline element */ 342 #define RGB_GREEN 1 /* Offset of Green */ 343 #define RGB_BLUE 2 /* Offset of Blue */ 344 #define RGB_PIXELSIZE 3 /* JSAMPLEs per RGB scanline element */ 345 346 347 /* Definitions for speed-related optimizations. */ 348 349 350 /* If your compiler supports inline functions, define INLINE 351 * as the inline keyword; otherwise define it as empty. 352 */ 353 354 #ifndef INLINE 355 #ifdef __GNUC__ /* for instance, GNU C knows about inline */ 356 #define INLINE __inline__ 357 #endif 358 #ifndef INLINE 359 #define INLINE /* default is to define it as empty */ 360 #endif 361 #endif 362 363 364 /* On some machines (notably 68000 series) "int" is 32 bits, but multiplying 365 * two 16-bit shorts is faster than multiplying two ints. Define MULTIPLIER 366 * as short on such a machine. MULTIPLIER must be at least 16 bits wide. 367 */ 368 369 #ifndef MULTIPLIER 370 #define MULTIPLIER int /* type for fastest integer multiply */ 371 #endif 372 373 374 /* FAST_FLOAT should be either float or double, whichever is done faster 375 * by your compiler. (Note that this type is only used in the floating point 376 * DCT routines, so it only matters if you've defined DCT_FLOAT_SUPPORTED.) 377 * Typically, float is faster in ANSI C compilers, while double is faster in 378 * pre-ANSI compilers (because they insist on converting to double anyway). 379 * The code below therefore chooses float if we have ANSI-style prototypes. 380 */ 381 382 #ifndef FAST_FLOAT 383 #ifdef HAVE_PROTOTYPES 384 #define FAST_FLOAT float 385 #else 386 #define FAST_FLOAT double 387 #endif 388 #endif 389 390 #endif /* JPEG_INTERNAL_OPTIONS */ 391