jmorecfg.h revision 989630f70cf1af69ebfefca8910d1647bf189712
1/* 2 * jmorecfg.h 3 * 4 * Copyright (C) 1991-1997, Thomas G. Lane. 5 * Modified 1997-2009 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 60typedef unsigned char JSAMPLE; 61#define GETJSAMPLE(value) ((int) (value)) 62 63#else /* not HAVE_UNSIGNED_CHAR */ 64 65typedef 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 85typedef 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 100typedef 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 111typedef unsigned char JOCTET; 112#define GETJOCTET(value) (value) 113 114#else /* not HAVE_UNSIGNED_CHAR */ 115 116typedef 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 136typedef unsigned char UINT8; 137#else /* not HAVE_UNSIGNED_CHAR */ 138#ifdef CHAR_IS_UNSIGNED 139typedef char UINT8; 140#else /* not CHAR_IS_UNSIGNED */ 141typedef 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 148typedef unsigned short UINT16; 149#else /* not HAVE_UNSIGNED_SHORT */ 150typedef 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 */ 156typedef 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 */ 165typedef 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 178typedef 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/* Here is the pseudo-keyword for declaring pointers that must be "far" 214 * on 80x86 machines. Most of the specialized coding for 80x86 is handled 215 * by just saying "FAR *" where such a pointer is needed. In a few places 216 * explicit coding is needed; see uses of the NEED_FAR_POINTERS symbol. 217 */ 218 219#ifndef FAR 220#ifdef NEED_FAR_POINTERS 221#define FAR far 222#else 223#define FAR 224#endif 225#endif 226 227 228/* 229 * On a few systems, type boolean and/or its values FALSE, TRUE may appear 230 * in standard header files. Or you may have conflicts with application- 231 * specific header files that you want to include together with these files. 232 * Defining HAVE_BOOLEAN before including jpeglib.h should make it work. 233 */ 234 235#ifndef HAVE_BOOLEAN 236typedef int boolean; 237#endif 238#ifndef FALSE /* in case these macros already exist */ 239#define FALSE 0 /* values of boolean */ 240#endif 241#ifndef TRUE 242#define TRUE 1 243#endif 244 245 246/* 247 * The remaining options affect code selection within the JPEG library, 248 * but they don't need to be visible to most applications using the library. 249 * To minimize application namespace pollution, the symbols won't be 250 * defined unless JPEG_INTERNALS or JPEG_INTERNAL_OPTIONS has been defined. 251 */ 252 253#ifdef JPEG_INTERNALS 254#define JPEG_INTERNAL_OPTIONS 255#endif 256 257#ifdef JPEG_INTERNAL_OPTIONS 258 259 260/* 261 * These defines indicate whether to include various optional functions. 262 * Undefining some of these symbols will produce a smaller but less capable 263 * library. Note that you can leave certain source files out of the 264 * compilation/linking process if you've #undef'd the corresponding symbols. 265 * (You may HAVE to do that if your compiler doesn't like null source files.) 266 */ 267 268/* Capability options common to encoder and decoder: */ 269 270#define DCT_ISLOW_SUPPORTED /* slow but accurate integer algorithm */ 271#define DCT_IFAST_SUPPORTED /* faster, less accurate integer method */ 272#define DCT_FLOAT_SUPPORTED /* floating-point: accurate, fast on fast HW */ 273 274/* Encoder capability options: */ 275 276#define C_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */ 277#define C_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */ 278#define C_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/ 279#define DCT_SCALING_SUPPORTED /* Input rescaling via DCT? (Requires DCT_ISLOW)*/ 280#define ENTROPY_OPT_SUPPORTED /* Optimization of entropy coding parms? */ 281/* Note: if you selected 12-bit data precision, it is dangerous to turn off 282 * ENTROPY_OPT_SUPPORTED. The standard Huffman tables are only good for 8-bit 283 * precision, so jchuff.c normally uses entropy optimization to compute 284 * usable tables for higher precision. If you don't want to do optimization, 285 * you'll have to supply different default Huffman tables. 286 * The exact same statements apply for progressive JPEG: the default tables 287 * don't work for progressive mode. (This may get fixed, however.) 288 */ 289#define INPUT_SMOOTHING_SUPPORTED /* Input image smoothing option? */ 290 291/* Decoder capability options: */ 292 293#define D_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */ 294#define D_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */ 295#define D_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/ 296#define IDCT_SCALING_SUPPORTED /* Output rescaling via IDCT? */ 297#define SAVE_MARKERS_SUPPORTED /* jpeg_save_markers() needed? */ 298#define BLOCK_SMOOTHING_SUPPORTED /* Block smoothing? (Progressive only) */ 299#undef UPSAMPLE_SCALING_SUPPORTED /* Output rescaling at upsample stage? */ 300#define UPSAMPLE_MERGING_SUPPORTED /* Fast path for sloppy upsampling? */ 301#define QUANT_1PASS_SUPPORTED /* 1-pass color quantization? */ 302#define QUANT_2PASS_SUPPORTED /* 2-pass color quantization? */ 303 304/* more capability options later, no doubt */ 305 306 307/* 308 * Ordering of RGB data in scanlines passed to or from the application. 309 * If your application wants to deal with data in the order B,G,R, just 310 * change these macros. You can also deal with formats such as R,G,B,X 311 * (one extra byte per pixel) by changing RGB_PIXELSIZE. Note that changing 312 * the offsets will also change the order in which colormap data is organized. 313 * RESTRICTIONS: 314 * 1. The sample applications cjpeg,djpeg do NOT support modified RGB formats. 315 * 2. These macros only affect RGB<=>YCbCr color conversion, so they are not 316 * useful if you are using JPEG color spaces other than YCbCr or grayscale. 317 * 3. The color quantizer modules will not behave desirably if RGB_PIXELSIZE 318 * is not 3 (they don't understand about dummy color components!). So you 319 * can't use color quantization if you change that value. 320 */ 321 322#define RGB_RED 0 /* Offset of Red in an RGB scanline element */ 323#define RGB_GREEN 1 /* Offset of Green */ 324#define RGB_BLUE 2 /* Offset of Blue */ 325#define RGB_PIXELSIZE 3 /* JSAMPLEs per RGB scanline element */ 326 327 328/* Definitions for speed-related optimizations. */ 329 330 331/* If your compiler supports inline functions, define INLINE 332 * as the inline keyword; otherwise define it as empty. 333 */ 334 335#ifndef INLINE 336#ifdef __GNUC__ /* for instance, GNU C knows about inline */ 337#define INLINE __inline__ 338#endif 339#ifndef INLINE 340#define INLINE /* default is to define it as empty */ 341#endif 342#endif 343 344 345/* On some machines (notably 68000 series) "int" is 32 bits, but multiplying 346 * two 16-bit shorts is faster than multiplying two ints. Define MULTIPLIER 347 * as short on such a machine. MULTIPLIER must be at least 16 bits wide. 348 */ 349 350#ifndef MULTIPLIER 351#define MULTIPLIER int /* type for fastest integer multiply */ 352#endif 353 354 355/* FAST_FLOAT should be either float or double, whichever is done faster 356 * by your compiler. (Note that this type is only used in the floating point 357 * DCT routines, so it only matters if you've defined DCT_FLOAT_SUPPORTED.) 358 * Typically, float is faster in ANSI C compilers, while double is faster in 359 * pre-ANSI compilers (because they insist on converting to double anyway). 360 * The code below therefore chooses float if we have ANSI-style prototypes. 361 */ 362 363#ifndef FAST_FLOAT 364#ifdef HAVE_PROTOTYPES 365#define FAST_FLOAT float 366#else 367#define FAST_FLOAT double 368#endif 369#endif 370 371#endif /* JPEG_INTERNAL_OPTIONS */ 372