jmorecfg.h revision bc79e0680a45d1ca330d690dae0340c8e17ab5e3
1/* 2 * jmorecfg.h 3 * 4 * Copyright (C) 1991-1995, 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 59typedef unsigned char JSAMPLE; 60#define GETJSAMPLE(value) ((int) (value)) 61 62#else /* not HAVE_UNSIGNED_CHAR */ 63 64typedef 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 84typedef 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 99typedef 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 110typedef unsigned char JOCTET; 111#define GETJOCTET(value) (value) 112 113#else /* not HAVE_UNSIGNED_CHAR */ 114 115typedef 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 135typedef unsigned char UINT8; 136#else /* not HAVE_UNSIGNED_CHAR */ 137#ifdef CHAR_IS_UNSIGNED 138typedef char UINT8; 139#else /* not CHAR_IS_UNSIGNED */ 140typedef 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 147typedef unsigned short UINT16; 148#else /* not HAVE_UNSIGNED_SHORT */ 149typedef 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 */ 155typedef 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 */ 161typedef 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 171typedef unsigned int JDIMENSION; 172 173#define JPEG_MAX_DIMENSION 65500L /* a tad under 64K to prevent overflows */ 174 175 176/* These defines are used in all function definitions and extern declarations. 177 * You could modify them if you need to change function linkage conventions. 178 * Another application is to make all functions global for use with debuggers 179 * or code profilers that require it. 180 */ 181 182#define METHODDEF static /* a function called through method pointers */ 183#define LOCAL static /* a function used only in its module */ 184#define GLOBAL /* a function referenced thru EXTERNs */ 185#define EXTERN extern /* a reference to a GLOBAL function */ 186 187 188/* Here is the pseudo-keyword for declaring pointers that must be "far" 189 * on 80x86 machines. Most of the specialized coding for 80x86 is handled 190 * by just saying "FAR *" where such a pointer is needed. In a few places 191 * explicit coding is needed; see uses of the NEED_FAR_POINTERS symbol. 192 */ 193 194#ifdef NEED_FAR_POINTERS 195#define FAR far 196#else 197#define FAR 198#endif 199 200 201/* 202 * On a few systems, type boolean and/or its values FALSE, TRUE may appear 203 * in standard header files. Or you may have conflicts with application- 204 * specific header files that you want to include together with these files. 205 * Defining HAVE_BOOLEAN before including jpeglib.h should make it work. 206 */ 207 208#ifndef HAVE_BOOLEAN 209typedef int boolean; 210#endif 211#ifndef FALSE /* in case these macros already exist */ 212#define FALSE 0 /* values of boolean */ 213#endif 214#ifndef TRUE 215#define TRUE 1 216#endif 217 218 219/* 220 * The remaining options affect code selection within the JPEG library, 221 * but they don't need to be visible to most applications using the library. 222 * To minimize application namespace pollution, the symbols won't be 223 * defined unless JPEG_INTERNALS or JPEG_INTERNAL_OPTIONS has been defined. 224 */ 225 226#ifdef JPEG_INTERNALS 227#define JPEG_INTERNAL_OPTIONS 228#endif 229 230#ifdef JPEG_INTERNAL_OPTIONS 231 232 233/* 234 * These defines indicate whether to include various optional functions. 235 * Undefining some of these symbols will produce a smaller but less capable 236 * library. Note that you can leave certain source files out of the 237 * compilation/linking process if you've #undef'd the corresponding symbols. 238 * (You may HAVE to do that if your compiler doesn't like null source files.) 239 */ 240 241/* Arithmetic coding is unsupported for legal reasons. Complaints to IBM. */ 242 243/* Capability options common to encoder and decoder: */ 244 245#define DCT_ISLOW_SUPPORTED /* slow but accurate integer algorithm */ 246#define DCT_IFAST_SUPPORTED /* faster, less accurate integer method */ 247#define DCT_FLOAT_SUPPORTED /* floating-point: accurate, fast on fast HW */ 248 249/* Encoder capability options: */ 250 251#undef C_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */ 252#define C_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */ 253#define C_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/ 254#define ENTROPY_OPT_SUPPORTED /* Optimization of entropy coding parms? */ 255/* Note: if you selected 12-bit data precision, it is dangerous to turn off 256 * ENTROPY_OPT_SUPPORTED. The standard Huffman tables are only good for 8-bit 257 * precision, so jchuff.c normally uses entropy optimization to compute 258 * usable tables for higher precision. If you don't want to do optimization, 259 * you'll have to supply different default Huffman tables. 260 * The exact same statements apply for progressive JPEG: the default tables 261 * don't work for progressive mode. (This may get fixed, however.) 262 */ 263#define INPUT_SMOOTHING_SUPPORTED /* Input image smoothing option? */ 264 265/* Decoder capability options: */ 266 267#undef D_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */ 268#define D_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */ 269#define D_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/ 270#define BLOCK_SMOOTHING_SUPPORTED /* Block smoothing? (Progressive only) */ 271#define IDCT_SCALING_SUPPORTED /* Output rescaling via IDCT? */ 272#undef UPSAMPLE_SCALING_SUPPORTED /* Output rescaling at upsample stage? */ 273#define UPSAMPLE_MERGING_SUPPORTED /* Fast path for sloppy upsampling? */ 274#define QUANT_1PASS_SUPPORTED /* 1-pass color quantization? */ 275#define QUANT_2PASS_SUPPORTED /* 2-pass color quantization? */ 276 277/* more capability options later, no doubt */ 278 279 280/* 281 * Ordering of RGB data in scanlines passed to or from the application. 282 * If your application wants to deal with data in the order B,G,R, just 283 * change these macros. You can also deal with formats such as R,G,B,X 284 * (one extra byte per pixel) by changing RGB_PIXELSIZE. Note that changing 285 * the offsets will also change the order in which colormap data is organized. 286 * RESTRICTIONS: 287 * 1. The sample applications cjpeg,djpeg do NOT support modified RGB formats. 288 * 2. These macros only affect RGB<=>YCbCr color conversion, so they are not 289 * useful if you are using JPEG color spaces other than YCbCr or grayscale. 290 * 3. The color quantizer modules will not behave desirably if RGB_PIXELSIZE 291 * is not 3 (they don't understand about dummy color components!). So you 292 * can't use color quantization if you change that value. 293 */ 294 295#define RGB_RED 0 /* Offset of Red in an RGB scanline element */ 296#define RGB_GREEN 1 /* Offset of Green */ 297#define RGB_BLUE 2 /* Offset of Blue */ 298#define RGB_PIXELSIZE 3 /* JSAMPLEs per RGB scanline element */ 299 300 301/* Definitions for speed-related optimizations. */ 302 303 304/* If your compiler supports inline functions, define INLINE 305 * as the inline keyword; otherwise define it as empty. 306 */ 307 308#ifndef INLINE 309#ifdef __GNUC__ /* for instance, GNU C knows about inline */ 310#define INLINE __inline__ 311#endif 312#ifndef INLINE 313#define INLINE /* default is to define it as empty */ 314#endif 315#endif 316 317 318/* On some machines (notably 68000 series) "int" is 32 bits, but multiplying 319 * two 16-bit shorts is faster than multiplying two ints. Define MULTIPLIER 320 * as short on such a machine. MULTIPLIER must be at least 16 bits wide. 321 */ 322 323#ifndef MULTIPLIER 324#define MULTIPLIER int /* type for fastest integer multiply */ 325#endif 326 327 328/* FAST_FLOAT should be either float or double, whichever is done faster 329 * by your compiler. (Note that this type is only used in the floating point 330 * DCT routines, so it only matters if you've defined DCT_FLOAT_SUPPORTED.) 331 * Typically, float is faster in ANSI C compilers, while double is faster in 332 * pre-ANSI compilers (because they insist on converting to double anyway). 333 * The code below therefore chooses float if we have ANSI-style prototypes. 334 */ 335 336#ifndef FAST_FLOAT 337#ifdef HAVE_PROTOTYPES 338#define FAST_FLOAT float 339#else 340#define FAST_FLOAT double 341#endif 342#endif 343 344#endif /* JPEG_INTERNAL_OPTIONS */ 345