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.
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.
14 * Define BITS_IN_JSAMPLE as either
15 * 8 for 8-bit sample values (the usual setting)
16 * 12 for 12-bit sample values
17 * Only 8 and 12 are legal data precisions for lossy JPEG according to the
18 * JPEG standard, and the IJG code does not support anything else!
19 * We do not support run-time selection of data precision, sorry.
22 //#define BITS_IN_JSAMPLE 8 /* use 8 or 12 */
23 #include "jBitsInJsample.h"
26 * Maximum number of components (color channels) allowed in JPEG image.
27 * To meet the letter of the JPEG spec, set this to 255. However, darn
28 * few applications need more than 4 channels (maybe 5 for CMYK + alpha
29 * mask). We recommend 10 as a reasonable compromise; use 4 if you are
30 * really short on memory. (Each allowed component costs a hundred or so
31 * bytes of storage, whether actually used in an image or not.)
34 #define MAX_COMPONENTS 10 /* maximum number of image components */
39 * You may need to change these if you have a machine with unusual data
40 * type sizes; for example, "char" not 8 bits, "short" not 16 bits,
41 * or "long" not 32 bits. We don't care whether "int" is 16 or 32 bits,
42 * but it had better be at least 16.
45 /* Representation of a single sample (pixel element value).
46 * We frequently allocate large arrays of these, so it's important to keep
47 * them small. But if you have memory to burn and access to char or short
48 * arrays is very slow on your hardware, you might want to change these.
51 #if BITS_IN_JSAMPLE == 8
52 /* JSAMPLE should be the smallest type that will hold the values 0..255.
53 * You can use a signed char by having GETJSAMPLE mask it with 0xFF.
56 #ifdef HAVE_UNSIGNED_CHAR
58 typedef unsigned char JSAMPLE;
59 #define GETJSAMPLE(value) ((int) (value))
61 #else /* not HAVE_UNSIGNED_CHAR */
64 #ifdef CHAR_IS_UNSIGNED
65 #define GETJSAMPLE(value) ((int) (value))
67 #define GETJSAMPLE(value) ((int) (value) & 0xFF)
68 #endif /* CHAR_IS_UNSIGNED */
70 #endif /* HAVE_UNSIGNED_CHAR */
72 #define MAXJSAMPLE 255
73 #define CENTERJSAMPLE 128
75 #endif /* BITS_IN_JSAMPLE == 8 */
78 #if BITS_IN_JSAMPLE == 12
79 /* JSAMPLE should be the smallest type that will hold the values 0..4095.
80 * On nearly all machines "short" will do nicely.
83 typedef short JSAMPLE;
84 #define GETJSAMPLE(value) ((int) (value))
86 #define MAXJSAMPLE 4095
87 #define CENTERJSAMPLE 2048
89 #endif /* BITS_IN_JSAMPLE == 12 */
92 /* Representation of a DCT frequency coefficient.
93 * This should be a signed value of at least 16 bits; "short" is usually OK.
94 * Again, we allocate large arrays of these, but you can change to int
95 * if you have memory to burn and "short" is really slow.
101 /* Compressed datastreams are represented as arrays of JOCTET.
102 * These must be EXACTLY 8 bits wide, at least once they are written to
103 * external storage. Note that when using the stdio data source/destination
104 * managers, this is also the data type passed to fread/fwrite.
107 #ifdef HAVE_UNSIGNED_CHAR
109 typedef unsigned char JOCTET;
110 #define GETJOCTET(value) (value)
112 #else /* not HAVE_UNSIGNED_CHAR */
115 #ifdef CHAR_IS_UNSIGNED
116 #define GETJOCTET(value) (value)
118 #define GETJOCTET(value) ((value) & 0xFF)
119 #endif /* CHAR_IS_UNSIGNED */
121 #endif /* HAVE_UNSIGNED_CHAR */
124 /* These typedefs are used for various table entries and so forth.
125 * They must be at least as wide as specified; but making them too big
126 * won't cost a huge amount of memory, so we don't provide special
127 * extraction code like we did for JSAMPLE. (In other words, these
128 * typedefs live at a different point on the speed/space tradeoff curve.)
131 /* UINT8 must hold at least the values 0..255. */
133 #ifdef HAVE_UNSIGNED_CHAR
134 typedef unsigned char UINT8;
135 #else /* not HAVE_UNSIGNED_CHAR */
136 #ifdef CHAR_IS_UNSIGNED
138 #else /* not CHAR_IS_UNSIGNED */
140 #endif /* CHAR_IS_UNSIGNED */
141 #endif /* HAVE_UNSIGNED_CHAR */
143 /* UINT16 must hold at least the values 0..65535. */
145 #ifdef HAVE_UNSIGNED_SHORT
146 typedef unsigned short UINT16;
147 #else /* not HAVE_UNSIGNED_SHORT */
148 typedef unsigned int UINT16;
149 #endif /* HAVE_UNSIGNED_SHORT */
151 /* INT16 must hold at least the values -32768..32767. */
153 #ifndef XMD_H /* X11/xmd.h correctly defines INT16 */
157 /* INT32 must hold at least signed 32-bit values. */
159 #ifndef XMD_H /* X11/xmd.h correctly defines INT32 */
163 /* Datatype used for image dimensions. The JPEG standard only supports
164 * images up to 64K*64K due to 16-bit fields in SOF markers. Therefore
165 * "unsigned int" is sufficient on all machines. However, if you need to
166 * handle larger images and you don't mind deviating from the spec, you
167 * can change this datatype.
170 typedef unsigned int JDIMENSION;
172 #define JPEG_MAX_DIMENSION 65500L /* a tad under 64K to prevent overflows */
175 /* These macros are used in all function definitions and extern declarations.
176 * You could modify them if you need to change function linkage conventions;
177 * in particular, you'll need to do that to make the library a Windows DLL.
178 * Another application is to make all functions global for use with debuggers
179 * or code profilers that require it.
182 /* a function called through method pointers: */
183 #define METHODDEF(type) static type
184 /* a function used only in its module: */
185 #define LOCAL(type) static type
186 /* a function referenced thru EXTERNs: */
188 #define GLOBAL(type) __declspec( dllexport ) type
190 #define GLOBAL(type) type
192 /* a reference to a GLOBAL function: */
194 #define EXTERN(type) extern __declspec( dllexport ) type
196 #define EXTERN(type) extern type
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.
206 #ifdef HAVE_PROTOTYPES
207 #define JMETHOD(type,methodname,arglist) type (*methodname) arglist
209 #define JMETHOD(type,methodname,arglist) type (*methodname) ()
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.
219 #ifdef NEED_FAR_POINTERS
227 * On a few systems, type boolean and/or its values FALSE, TRUE may appear
228 * in standard header files. Or you may have conflicts with application-
229 * specific header files that you want to include together with these files.
230 * Defining HAVE_BOOLEAN before including jpeglib.h should make it work.
236 #ifndef FALSE /* in case these macros already exist */
237 #define FALSE 0 /* values of boolean */
245 * The remaining options affect code selection within the JPEG library,
246 * but they don't need to be visible to most applications using the library.
247 * To minimize application namespace pollution, the symbols won't be
248 * defined unless JPEG_INTERNALS or JPEG_INTERNAL_OPTIONS has been defined.
251 #ifdef JPEG_INTERNALS
252 #define JPEG_INTERNAL_OPTIONS
255 #ifdef JPEG_INTERNAL_OPTIONS
259 * These defines indicate whether to include various optional functions.
260 * Undefining some of these symbols will produce a smaller but less capable
261 * library. Note that you can leave certain source files out of the
262 * compilation/linking process if you've #undef'd the corresponding symbols.
263 * (You may HAVE to do that if your compiler doesn't like null source files.)
266 /* Arithmetic coding is unsupported for legal reasons. Complaints to IBM. */
268 /* Capability options common to encoder and decoder: */
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 */
274 /* Encoder capability options: */
276 #undef 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 ENTROPY_OPT_SUPPORTED /* Optimization of entropy coding parms? */
280 /* Note: if you selected 12-bit data precision, it is dangerous to turn off
281 * ENTROPY_OPT_SUPPORTED. The standard Huffman tables are only good for 8-bit
282 * precision, so jchuff.c normally uses entropy optimization to compute
283 * usable tables for higher precision. If you don't want to do optimization,
284 * you'll have to supply different default Huffman tables.
285 * The exact same statements apply for progressive JPEG: the default tables
286 * don't work for progressive mode. (This may get fixed, however.)
288 #define INPUT_SMOOTHING_SUPPORTED /* Input image smoothing option? */
290 /* Decoder capability options: */
292 #undef D_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */
293 #define D_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */
294 #define D_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/
295 #define SAVE_MARKERS_SUPPORTED /* jpeg_save_markers() needed? */
296 #define BLOCK_SMOOTHING_SUPPORTED /* Block smoothing? (Progressive only) */
297 #define IDCT_SCALING_SUPPORTED /* Output rescaling via IDCT? */
298 #undef UPSAMPLE_SCALING_SUPPORTED /* Output rescaling at upsample stage? */
299 #define UPSAMPLE_MERGING_SUPPORTED /* Fast path for sloppy upsampling? */
300 #define QUANT_1PASS_SUPPORTED /* 1-pass color quantization? */
301 #define QUANT_2PASS_SUPPORTED /* 2-pass color quantization? */
303 /* more capability options later, no doubt */
307 * Ordering of RGB data in scanlines passed to or from the application.
308 * If your application wants to deal with data in the order B,G,R, just
309 * change these macros. You can also deal with formats such as R,G,B,X
310 * (one extra byte per pixel) by changing RGB_PIXELSIZE. Note that changing
311 * the offsets will also change the order in which colormap data is organized.
313 * 1. The sample applications cjpeg,djpeg do NOT support modified RGB formats.
314 * 2. These macros only affect RGB<=>YCbCr color conversion, so they are not
315 * useful if you are using JPEG color spaces other than YCbCr or grayscale.
316 * 3. The color quantizer modules will not behave desirably if RGB_PIXELSIZE
317 * is not 3 (they don't understand about dummy color components!). So you
318 * can't use color quantization if you change that value.
321 #define RGB_RED 0 /* Offset of Red in an RGB scanline element */
322 #define RGB_GREEN 1 /* Offset of Green */
323 #define RGB_BLUE 2 /* Offset of Blue */
324 #define RGB_PIXELSIZE 3 /* JSAMPLEs per RGB scanline element */
327 /* Definitions for speed-related optimizations. */
330 /* If your compiler supports inline functions, define INLINE
331 * as the inline keyword; otherwise define it as empty.
335 #ifdef __GNUC__ /* for instance, GNU C knows about inline */
336 #define INLINE __inline__
339 #define INLINE /* default is to define it as empty */
344 /* On some machines (notably 68000 series) "int" is 32 bits, but multiplying
345 * two 16-bit shorts is faster than multiplying two ints. Define MULTIPLIER
346 * as short on such a machine. MULTIPLIER must be at least 16 bits wide.
350 #define MULTIPLIER int /* type for fastest integer multiply */
354 /* FAST_FLOAT should be either float or double, whichever is done faster
355 * by your compiler. (Note that this type is only used in the floating point
356 * DCT routines, so it only matters if you've defined DCT_FLOAT_SUPPORTED.)
357 * Typically, float is faster in ANSI C compilers, while double is faster in
358 * pre-ANSI compilers (because they insist on converting to double anyway).
359 * The code below therefore chooses float if we have ANSI-style prototypes.
363 #ifdef HAVE_PROTOTYPES
364 #define FAST_FLOAT float
366 #define FAST_FLOAT double
370 #endif /* JPEG_INTERNAL_OPTIONS */