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jmorecfg.h (12458B)
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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 */