src/jpeg/jmorecfg.h

   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 */