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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 */