1/*
2 * jmorecfg.h
3 *
4 * This file was part of the Independent JPEG Group's software:
5 * Copyright (C) 1991-1997, Thomas G. Lane.
6 * Modified 1997-2009 by Guido Vollbeding.
7 * libjpeg-turbo Modifications:
8 * Copyright (C) 2009, 2011, 2014-2015, 2018, 2020, D. R. Commander.
9 * For conditions of distribution and use, see the accompanying README.ijg
10 * file.
11 *
12 * This file contains additional configuration options that customize the
13 * JPEG software for special applications or support machine-dependent
14 * optimizations. Most users will not need to touch this file.
15 */
16
17
18/*
19 * Maximum number of components (color channels) allowed in JPEG image.
20 * To meet the letter of Rec. ITU-T T.81 | ISO/IEC 10918-1, set this to 255.
21 * However, darn few applications need more than 4 channels (maybe 5 for CMYK +
22 * alpha mask). We recommend 10 as a reasonable compromise; use 4 if you are
23 * really short on memory. (Each allowed component costs a hundred or so
24 * bytes of storage, whether actually used in an image or not.)
25 */
26
27#define MAX_COMPONENTS 10 /* maximum number of image components */
28
29
30/*
31 * Basic data types.
32 * You may need to change these if you have a machine with unusual data
33 * type sizes; for example, "char" not 8 bits, "short" not 16 bits,
34 * or "long" not 32 bits. We don't care whether "int" is 16 or 32 bits,
35 * but it had better be at least 16.
36 */
37
38/* Representation of a single sample (pixel element value).
39 * We frequently allocate large arrays of these, so it's important to keep
40 * them small. But if you have memory to burn and access to char or short
41 * arrays is very slow on your hardware, you might want to change these.
42 */
43
44#if BITS_IN_JSAMPLE == 8
45/* JSAMPLE should be the smallest type that will hold the values 0..255.
46 */
47
48typedef unsigned char JSAMPLE;
49#define GETJSAMPLE(value) ((int)(value))
50
51#define MAXJSAMPLE 255
52#define CENTERJSAMPLE 128
53
54#endif /* BITS_IN_JSAMPLE == 8 */
55
56
57#if BITS_IN_JSAMPLE == 12
58/* JSAMPLE should be the smallest type that will hold the values 0..4095.
59 * On nearly all machines "short" will do nicely.
60 */
61
62typedef short JSAMPLE;
63#define GETJSAMPLE(value) ((int)(value))
64
65#define MAXJSAMPLE 4095
66#define CENTERJSAMPLE 2048
67
68#endif /* BITS_IN_JSAMPLE == 12 */
69
70
71/* Representation of a DCT frequency coefficient.
72 * This should be a signed value of at least 16 bits; "short" is usually OK.
73 * Again, we allocate large arrays of these, but you can change to int
74 * if you have memory to burn and "short" is really slow.
75 */
76
77typedef short JCOEF;
78
79
80/* Compressed datastreams are represented as arrays of JOCTET.
81 * These must be EXACTLY 8 bits wide, at least once they are written to
82 * external storage. Note that when using the stdio data source/destination
83 * managers, this is also the data type passed to fread/fwrite.
84 */
85
86typedef unsigned char JOCTET;
87#define GETJOCTET(value) (value)
88
89
90/* These typedefs are used for various table entries and so forth.
91 * They must be at least as wide as specified; but making them too big
92 * won't cost a huge amount of memory, so we don't provide special
93 * extraction code like we did for JSAMPLE. (In other words, these
94 * typedefs live at a different point on the speed/space tradeoff curve.)
95 */
96
97/* UINT8 must hold at least the values 0..255. */
98
99typedef unsigned char UINT8;
100
101/* UINT16 must hold at least the values 0..65535. */
102
103#ifdef HAVE_UNSIGNED_SHORT
104typedef unsigned short UINT16;
105#else /* not HAVE_UNSIGNED_SHORT */
106typedef unsigned int UINT16;
107#endif /* HAVE_UNSIGNED_SHORT */
108
109/* INT16 must hold at least the values -32768..32767. */
110
111#ifndef XMD_H /* X11/xmd.h correctly defines INT16 */
112typedef short INT16;
113#endif
114
115/* INT32 must hold at least signed 32-bit values.
116 *
117 * NOTE: The INT32 typedef dates back to libjpeg v5 (1994.) Integers were
118 * sometimes 16-bit back then (MS-DOS), which is why INT32 is typedef'd to
119 * long. It also wasn't common (or at least as common) in 1994 for INT32 to be
120 * defined by platform headers. Since then, however, INT32 is defined in
121 * several other common places:
122 *
123 * Xmd.h (X11 header) typedefs INT32 to int on 64-bit platforms and long on
124 * 32-bit platforms (i.e always a 32-bit signed type.)
125 *
126 * basetsd.h (Win32 header) typedefs INT32 to int (always a 32-bit signed type
127 * on modern platforms.)
128 *
129 * qglobal.h (Qt header) typedefs INT32 to int (always a 32-bit signed type on
130 * modern platforms.)
131 *
132 * This is a recipe for conflict, since "long" and "int" aren't always
133 * compatible types. Since the definition of INT32 has technically been part
134 * of the libjpeg API for more than 20 years, we can't remove it, but we do not
135 * use it internally any longer. We instead define a separate type (JLONG)
136 * for internal use, which ensures that internal behavior will always be the
137 * same regardless of any external headers that may be included.
138 */
139
140#ifndef XMD_H /* X11/xmd.h correctly defines INT32 */
141#ifndef _BASETSD_H_ /* Microsoft defines it in basetsd.h */
142#ifndef _BASETSD_H /* MinGW is slightly different */
143#ifndef QGLOBAL_H /* Qt defines it in qglobal.h */
144typedef long INT32;
145#endif
146#endif
147#endif
148#endif
149
150/* Datatype used for image dimensions. The JPEG standard only supports
151 * images up to 64K*64K due to 16-bit fields in SOF markers. Therefore
152 * "unsigned int" is sufficient on all machines. However, if you need to
153 * handle larger images and you don't mind deviating from the spec, you
154 * can change this datatype. (Note that changing this datatype will
155 * potentially require modifying the SIMD code. The x86-64 SIMD extensions,
156 * in particular, assume a 32-bit JDIMENSION.)
157 */
158
159typedef unsigned int JDIMENSION;
160
161#define JPEG_MAX_DIMENSION 65500L /* a tad under 64K to prevent overflows */
162
163
164/* These macros are used in all function definitions and extern declarations.
165 * You could modify them if you need to change function linkage conventions;
166 * in particular, you'll need to do that to make the library a Windows DLL.
167 * Another application is to make all functions global for use with debuggers
168 * or code profilers that require it.
169 */
170
171/* a function called through method pointers: */
172#define METHODDEF(type) static type
173/* a function used only in its module: */
174#define LOCAL(type) static type
175/* a function referenced thru EXTERNs: */
176#define GLOBAL(type) type
177/* a reference to a GLOBAL function: */
178#define EXTERN(type) extern type
179
180
181/* Originally, this macro was used as a way of defining function prototypes
182 * for both modern compilers as well as older compilers that did not support
183 * prototype parameters. libjpeg-turbo has never supported these older,
184 * non-ANSI compilers, but the macro is still included because there is some
185 * software out there that uses it.
186 */
187
188#define JMETHOD(type, methodname, arglist) type (*methodname) arglist
189
190
191/* libjpeg-turbo no longer supports platforms that have far symbols (MS-DOS),
192 * but again, some software relies on this macro.
193 */
194
195#undef FAR
196#define FAR
197
198
199/*
200 * On a few systems, type boolean and/or its values FALSE, TRUE may appear
201 * in standard header files. Or you may have conflicts with application-
202 * specific header files that you want to include together with these files.
203 * Defining HAVE_BOOLEAN before including jpeglib.h should make it work.
204 */
205
206#ifndef HAVE_BOOLEAN
207typedef int boolean;
208#endif
209#ifndef FALSE /* in case these macros already exist */
210#define FALSE 0 /* values of boolean */
211#endif
212#ifndef TRUE
213#define TRUE 1
214#endif
215
216
217/*
218 * The remaining options affect code selection within the JPEG library,
219 * but they don't need to be visible to most applications using the library.
220 * To minimize application namespace pollution, the symbols won't be
221 * defined unless JPEG_INTERNALS or JPEG_INTERNAL_OPTIONS has been defined.
222 */
223
224#ifdef JPEG_INTERNALS
225#define JPEG_INTERNAL_OPTIONS
226#endif
227
228#ifdef JPEG_INTERNAL_OPTIONS
229
230
231/*
232 * These defines indicate whether to include various optional functions.
233 * Undefining some of these symbols will produce a smaller but less capable
234 * library. Note that you can leave certain source files out of the
235 * compilation/linking process if you've #undef'd the corresponding symbols.
236 * (You may HAVE to do that if your compiler doesn't like null source files.)
237 */
238
239/* Capability options common to encoder and decoder: */
240
241#define DCT_ISLOW_SUPPORTED /* accurate integer method */
242#define DCT_IFAST_SUPPORTED /* less accurate int method [legacy feature] */
243#define DCT_FLOAT_SUPPORTED /* floating-point method [legacy feature] */
244
245/* Encoder capability options: */
246
247#define C_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */
248#define C_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/
249#define ENTROPY_OPT_SUPPORTED /* Optimization of entropy coding parms? */
250/* Note: if you selected 12-bit data precision, it is dangerous to turn off
251 * ENTROPY_OPT_SUPPORTED. The standard Huffman tables are only good for 8-bit
252 * precision, so jchuff.c normally uses entropy optimization to compute
253 * usable tables for higher precision. If you don't want to do optimization,
254 * you'll have to supply different default Huffman tables.
255 * The exact same statements apply for progressive JPEG: the default tables
256 * don't work for progressive mode. (This may get fixed, however.)
257 */
258#define INPUT_SMOOTHING_SUPPORTED /* Input image smoothing option? */
259
260/* Decoder capability options: */
261
262#define D_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */
263#define D_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/
264#define SAVE_MARKERS_SUPPORTED /* jpeg_save_markers() needed? */
265#define BLOCK_SMOOTHING_SUPPORTED /* Block smoothing? (Progressive only) */
266#define IDCT_SCALING_SUPPORTED /* Output rescaling via IDCT? */
267#undef UPSAMPLE_SCALING_SUPPORTED /* Output rescaling at upsample stage? */
268#define UPSAMPLE_MERGING_SUPPORTED /* Fast path for sloppy upsampling? */
269#define QUANT_1PASS_SUPPORTED /* 1-pass color quantization? */
270#define QUANT_2PASS_SUPPORTED /* 2-pass color quantization? */
271
272/* more capability options later, no doubt */
273
274
275/*
276 * The RGB_RED, RGB_GREEN, RGB_BLUE, and RGB_PIXELSIZE macros are a vestigial
277 * feature of libjpeg. The idea was that, if an application developer needed
278 * to compress from/decompress to a BGR/BGRX/RGBX/XBGR/XRGB buffer, they could
279 * change these macros, rebuild libjpeg, and link their application statically
280 * with it. In reality, few people ever did this, because there were some
281 * severe restrictions involved (cjpeg and djpeg no longer worked properly,
282 * compressing/decompressing RGB JPEGs no longer worked properly, and the color
283 * quantizer wouldn't work with pixel sizes other than 3.) Furthermore, since
284 * all of the O/S-supplied versions of libjpeg were built with the default
285 * values of RGB_RED, RGB_GREEN, RGB_BLUE, and RGB_PIXELSIZE, many applications
286 * have come to regard these values as immutable.
287 *
288 * The libjpeg-turbo colorspace extensions provide a much cleaner way of
289 * compressing from/decompressing to buffers with arbitrary component orders
290 * and pixel sizes. Thus, we do not support changing the values of RGB_RED,
291 * RGB_GREEN, RGB_BLUE, or RGB_PIXELSIZE. In addition to the restrictions
292 * listed above, changing these values will also break the SIMD extensions and
293 * the regression tests.
294 */
295
296#define RGB_RED 0 /* Offset of Red in an RGB scanline element */
297#define RGB_GREEN 1 /* Offset of Green */
298#define RGB_BLUE 2 /* Offset of Blue */
299#define RGB_PIXELSIZE 3 /* JSAMPLEs per RGB scanline element */
300
301#define JPEG_NUMCS 17
302
303#define EXT_RGB_RED 0
304#define EXT_RGB_GREEN 1
305#define EXT_RGB_BLUE 2
306#define EXT_RGB_PIXELSIZE 3
307
308#define EXT_RGBX_RED 0
309#define EXT_RGBX_GREEN 1
310#define EXT_RGBX_BLUE 2
311#define EXT_RGBX_PIXELSIZE 4
312
313#define EXT_BGR_RED 2
314#define EXT_BGR_GREEN 1
315#define EXT_BGR_BLUE 0
316#define EXT_BGR_PIXELSIZE 3
317
318#define EXT_BGRX_RED 2
319#define EXT_BGRX_GREEN 1
320#define EXT_BGRX_BLUE 0
321#define EXT_BGRX_PIXELSIZE 4
322
323#define EXT_XBGR_RED 3
324#define EXT_XBGR_GREEN 2
325#define EXT_XBGR_BLUE 1
326#define EXT_XBGR_PIXELSIZE 4
327
328#define EXT_XRGB_RED 1
329#define EXT_XRGB_GREEN 2
330#define EXT_XRGB_BLUE 3
331#define EXT_XRGB_PIXELSIZE 4
332
333static const int rgb_red[JPEG_NUMCS] = {
334 -1, -1, RGB_RED, -1, -1, -1, EXT_RGB_RED, EXT_RGBX_RED,
335 EXT_BGR_RED, EXT_BGRX_RED, EXT_XBGR_RED, EXT_XRGB_RED,
336 EXT_RGBX_RED, EXT_BGRX_RED, EXT_XBGR_RED, EXT_XRGB_RED,
337 -1
338};
339
340static const int rgb_green[JPEG_NUMCS] = {
341 -1, -1, RGB_GREEN, -1, -1, -1, EXT_RGB_GREEN, EXT_RGBX_GREEN,
342 EXT_BGR_GREEN, EXT_BGRX_GREEN, EXT_XBGR_GREEN, EXT_XRGB_GREEN,
343 EXT_RGBX_GREEN, EXT_BGRX_GREEN, EXT_XBGR_GREEN, EXT_XRGB_GREEN,
344 -1
345};
346
347static const int rgb_blue[JPEG_NUMCS] = {
348 -1, -1, RGB_BLUE, -1, -1, -1, EXT_RGB_BLUE, EXT_RGBX_BLUE,
349 EXT_BGR_BLUE, EXT_BGRX_BLUE, EXT_XBGR_BLUE, EXT_XRGB_BLUE,
350 EXT_RGBX_BLUE, EXT_BGRX_BLUE, EXT_XBGR_BLUE, EXT_XRGB_BLUE,
351 -1
352};
353
354static const int rgb_pixelsize[JPEG_NUMCS] = {
355 -1, -1, RGB_PIXELSIZE, -1, -1, -1, EXT_RGB_PIXELSIZE, EXT_RGBX_PIXELSIZE,
356 EXT_BGR_PIXELSIZE, EXT_BGRX_PIXELSIZE, EXT_XBGR_PIXELSIZE, EXT_XRGB_PIXELSIZE,
357 EXT_RGBX_PIXELSIZE, EXT_BGRX_PIXELSIZE, EXT_XBGR_PIXELSIZE, EXT_XRGB_PIXELSIZE,
358 -1
359};
360
361/* Definitions for speed-related optimizations. */
362
363/* On some machines (notably 68000 series) "int" is 32 bits, but multiplying
364 * two 16-bit shorts is faster than multiplying two ints. Define MULTIPLIER
365 * as short on such a machine. MULTIPLIER must be at least 16 bits wide.
366 */
367
368#ifndef MULTIPLIER
369#ifndef WITH_SIMD
370#define MULTIPLIER int /* type for fastest integer multiply */
371#else
372#define MULTIPLIER short /* prefer 16-bit with SIMD for parellelism */
373#endif
374#endif
375
376
377/* FAST_FLOAT should be either float or double, whichever is done faster
378 * by your compiler. (Note that this type is only used in the floating point
379 * DCT routines, so it only matters if you've defined DCT_FLOAT_SUPPORTED.)
380 */
381
382#ifndef FAST_FLOAT
383#define FAST_FLOAT float
384#endif
385
386#endif /* JPEG_INTERNAL_OPTIONS */
387

source code of include/jmorecfg.h