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jmorecfg.h
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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 #undef FAR
214 #define FAR far
215 #else
216 #undef FAR
217 #define FAR
218 #endif
219 
220 
221 /*
222  * On a few systems, type boolean and/or its values FALSE, TRUE may appear
223  * in standard header files. Or you may have conflicts with application-
224  * specific header files that you want to include together with these files.
225  * Defining HAVE_BOOLEAN before including jpeglib.h should make it work.
226  */
227 
228 #ifndef HAVE_BOOLEAN
229 typedef char boolean;
230 #endif
231 #ifndef FALSE /* in case these macros already exist */
232 #define FALSE 0 /* values of boolean */
233 #endif
234 #ifndef TRUE
235 #define TRUE 1
236 #endif
237 
238 
239 /*
240  * The remaining options affect code selection within the JPEG library,
241  * but they don't need to be visible to most applications using the library.
242  * To minimize application namespace pollution, the symbols won't be
243  * defined unless JPEG_INTERNALS or JPEG_INTERNAL_OPTIONS has been defined.
244  */
245 
246 #ifdef JPEG_INTERNALS
247 #define JPEG_INTERNAL_OPTIONS
248 #endif
249 
250 #ifdef JPEG_INTERNAL_OPTIONS
251 
252 
253 /*
254  * These defines indicate whether to include various optional functions.
255  * Undefining some of these symbols will produce a smaller but less capable
256  * library. Note that you can leave certain source files out of the
257  * compilation/linking process if you've #undef'd the corresponding symbols.
258  * (You may HAVE to do that if your compiler doesn't like null source files.)
259  */
260 
261 /* Arithmetic coding is unsupported for legal reasons. Complaints to IBM. */
262 
263 /* Capability options common to encoder and decoder: */
264 
265 #define DCT_ISLOW_SUPPORTED /* slow but accurate integer algorithm */
266 #define DCT_IFAST_SUPPORTED /* faster, less accurate integer method */
267 #define DCT_FLOAT_SUPPORTED /* floating-point: accurate, fast on fast HW */
268 
269 /* Encoder capability options: */
270 
271 #undef C_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */
272 #define C_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */
273 #define C_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/
274 #define ENTROPY_OPT_SUPPORTED /* Optimization of entropy coding parms? */
275 /* Note: if you selected 12-bit data precision, it is dangerous to turn off
276  * ENTROPY_OPT_SUPPORTED. The standard Huffman tables are only good for 8-bit
277  * precision, so jchuff.c normally uses entropy optimization to compute
278  * usable tables for higher precision. If you don't want to do optimization,
279  * you'll have to supply different default Huffman tables.
280  * The exact same statements apply for progressive JPEG: the default tables
281  * don't work for progressive mode. (This may get fixed, however.)
282  */
283 #define INPUT_SMOOTHING_SUPPORTED /* Input image smoothing option? */
284 
285 /* Decoder capability options: */
286 
287 #undef D_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */
288 #define D_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */
289 #define D_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/
290 #define SAVE_MARKERS_SUPPORTED /* jpeg_save_markers() needed? */
291 #define BLOCK_SMOOTHING_SUPPORTED /* Block smoothing? (Progressive only) */
292 #define IDCT_SCALING_SUPPORTED /* Output rescaling via IDCT? */
293 #undef UPSAMPLE_SCALING_SUPPORTED /* Output rescaling at upsample stage? */
294 #define UPSAMPLE_MERGING_SUPPORTED /* Fast path for sloppy upsampling? */
295 #define QUANT_1PASS_SUPPORTED /* 1-pass color quantization? */
296 #define QUANT_2PASS_SUPPORTED /* 2-pass color quantization? */
297 
298 /* more capability options later, no doubt */
299 
300 
301 /*
302  * Ordering of RGB data in scanlines passed to or from the application.
303  * If your application wants to deal with data in the order B,G,R, just
304  * change these macros. You can also deal with formats such as R,G,B,X
305  * (one extra byte per pixel) by changing RGB_PIXELSIZE. Note that changing
306  * the offsets will also change the order in which colormap data is organized.
307  * RESTRICTIONS:
308  * 1. The sample applications cjpeg,djpeg do NOT support modified RGB formats.
309  * 2. These macros only affect RGB<=>YCbCr color conversion, so they are not
310  * useful if you are using JPEG color spaces other than YCbCr or grayscale.
311  * 3. The color quantizer modules will not behave desirably if RGB_PIXELSIZE
312  * is not 3 (they don't understand about dummy color components!). So you
313  * can't use color quantization if you change that value.
314  */
315 
316 #define RGB_RED 0 /* Offset of Red in an RGB scanline element */
317 #define RGB_GREEN 1 /* Offset of Green */
318 #define RGB_BLUE 2 /* Offset of Blue */
319 #define RGB_PIXELSIZE 3 /* JSAMPLEs per RGB scanline element */
320 
321 
322 /* Definitions for speed-related optimizations. */
323 
324 
325 /* If your compiler supports inline functions, define INLINE
326  * as the inline keyword; otherwise define it as empty.
327  */
328 
329 #ifndef INLINE
330 #ifdef __GNUC__ /* for instance, GNU C knows about inline */
331 #define INLINE __inline__
332 #endif
333 #ifndef INLINE
334 #define INLINE /* default is to define it as empty */
335 #endif
336 #endif
337 
338 
339 /* On some machines (notably 68000 series) "int" is 32 bits, but multiplying
340  * two 16-bit shorts is faster than multiplying two ints. Define MULTIPLIER
341  * as short on such a machine. MULTIPLIER must be at least 16 bits wide.
342  */
343 
344 #ifndef MULTIPLIER
345 #define MULTIPLIER int /* type for fastest integer multiply */
346 #endif
347 
348 
349 /* FAST_FLOAT should be either float or double, whichever is done faster
350  * by your compiler. (Note that this type is only used in the floating point
351  * DCT routines, so it only matters if you've defined DCT_FLOAT_SUPPORTED.)
352  * Typically, float is faster in ANSI C compilers, while double is faster in
353  * pre-ANSI compilers (because they insist on converting to double anyway).
354  * The code below therefore chooses float if we have ANSI-style prototypes.
355  */
356 
357 #ifndef FAST_FLOAT
358 #ifdef HAVE_PROTOTYPES
359 #define FAST_FLOAT float
360 #else
361 #define FAST_FLOAT double
362 #endif
363 #endif
364 
365 #endif /* JPEG_INTERNAL_OPTIONS */
unsigned int JDIMENSION
Definition: jmorecfg.h:171
long INT32
Definition: jmorecfg.h:161
char boolean
Definition: jmorecfg.h:229
char JOCTET
Definition: jmorecfg.h:115
char JSAMPLE
Definition: jmorecfg.h:64
short INT16
Definition: jmorecfg.h:155
unsigned int UINT16
Definition: jmorecfg.h:149
short UINT8
Definition: jmorecfg.h:140
short JCOEF
Definition: jmorecfg.h:99