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
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.
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.)
27 #define MAX_COMPONENTS 10 /* maximum number of image components */
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.
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.
44 #if BITS_IN_JSAMPLE == 8
45 /* JSAMPLE should be the smallest type that will hold the values 0..255.
46 * You can use a signed char by having GETJSAMPLE mask it with 0xFF.
49 #ifdef HAVE_UNSIGNED_CHAR
51 typedef unsigned char JSAMPLE;
52 #define GETJSAMPLE(value) ((int)(value))
54 #else /* not HAVE_UNSIGNED_CHAR */
57 #ifdef __CHAR_UNSIGNED__
58 #define GETJSAMPLE(value) ((int)(value))
60 #define GETJSAMPLE(value) ((int)(value) & 0xFF)
61 #endif /* __CHAR_UNSIGNED__ */
63 #endif /* HAVE_UNSIGNED_CHAR */
65 #define MAXJSAMPLE 255
66 #define CENTERJSAMPLE 128
68 #endif /* BITS_IN_JSAMPLE == 8 */
71 #if BITS_IN_JSAMPLE == 12
72 /* JSAMPLE should be the smallest type that will hold the values 0..4095.
73 * On nearly all machines "short" will do nicely.
76 typedef short JSAMPLE;
77 #define GETJSAMPLE(value) ((int)(value))
79 #define MAXJSAMPLE 4095
80 #define CENTERJSAMPLE 2048
82 #endif /* BITS_IN_JSAMPLE == 12 */
85 /* Representation of a DCT frequency coefficient.
86 * This should be a signed value of at least 16 bits; "short" is usually OK.
87 * Again, we allocate large arrays of these, but you can change to int
88 * if you have memory to burn and "short" is really slow.
94 /* Compressed datastreams are represented as arrays of JOCTET.
95 * These must be EXACTLY 8 bits wide, at least once they are written to
96 * external storage. Note that when using the stdio data source/destination
97 * managers, this is also the data type passed to fread/fwrite.
100 #ifdef HAVE_UNSIGNED_CHAR
102 typedef unsigned char JOCTET;
103 #define GETJOCTET(value) (value)
105 #else /* not HAVE_UNSIGNED_CHAR */
108 #ifdef __CHAR_UNSIGNED__
109 #define GETJOCTET(value) (value)
111 #define GETJOCTET(value) ((value) & 0xFF)
112 #endif /* __CHAR_UNSIGNED__ */
114 #endif /* HAVE_UNSIGNED_CHAR */
117 /* These typedefs are used for various table entries and so forth.
118 * They must be at least as wide as specified; but making them too big
119 * won't cost a huge amount of memory, so we don't provide special
120 * extraction code like we did for JSAMPLE. (In other words, these
121 * typedefs live at a different point on the speed/space tradeoff curve.)
124 /* UINT8 must hold at least the values 0..255. */
126 #ifdef HAVE_UNSIGNED_CHAR
127 typedef unsigned char UINT8;
128 #else /* not HAVE_UNSIGNED_CHAR */
129 #ifdef __CHAR_UNSIGNED__
131 #else /* not __CHAR_UNSIGNED__ */
133 #endif /* __CHAR_UNSIGNED__ */
134 #endif /* HAVE_UNSIGNED_CHAR */
136 /* UINT16 must hold at least the values 0..65535. */
138 #ifdef HAVE_UNSIGNED_SHORT
139 typedef unsigned short UINT16;
140 #else /* not HAVE_UNSIGNED_SHORT */
141 typedef unsigned int UINT16;
142 #endif /* HAVE_UNSIGNED_SHORT */
144 /* INT16 must hold at least the values -32768..32767. */
146 #ifndef XMD_H /* X11/xmd.h correctly defines INT16 */
150 /* INT32 must hold at least signed 32-bit values.
152 * NOTE: The INT32 typedef dates back to libjpeg v5 (1994.) Integers were
153 * sometimes 16-bit back then (MS-DOS), which is why INT32 is typedef'd to
154 * long. It also wasn't common (or at least as common) in 1994 for INT32 to be
155 * defined by platform headers. Since then, however, INT32 is defined in
156 * several other common places:
158 * Xmd.h (X11 header) typedefs INT32 to int on 64-bit platforms and long on
159 * 32-bit platforms (i.e always a 32-bit signed type.)
161 * basetsd.h (Win32 header) typedefs INT32 to int (always a 32-bit signed type
162 * on modern platforms.)
164 * qglobal.h (Qt header) typedefs INT32 to int (always a 32-bit signed type on
167 * This is a recipe for conflict, since "long" and "int" aren't always
168 * compatible types. Since the definition of INT32 has technically been part
169 * of the libjpeg API for more than 20 years, we can't remove it, but we do not
170 * use it internally any longer. We instead define a separate type (JLONG)
171 * for internal use, which ensures that internal behavior will always be the
172 * same regardless of any external headers that may be included.
175 #ifndef XMD_H /* X11/xmd.h correctly defines INT32 */
176 #ifndef _BASETSD_H_ /* Microsoft defines it in basetsd.h */
177 #ifndef _BASETSD_H /* MinGW is slightly different */
178 #ifndef QGLOBAL_H /* Qt defines it in qglobal.h */
185 /* Datatype used for image dimensions. The JPEG standard only supports
186 * images up to 64K*64K due to 16-bit fields in SOF markers. Therefore
187 * "unsigned int" is sufficient on all machines. However, if you need to
188 * handle larger images and you don't mind deviating from the spec, you
189 * can change this datatype. (Note that changing this datatype will
190 * potentially require modifying the SIMD code. The x86-64 SIMD extensions,
191 * in particular, assume a 32-bit JDIMENSION.)
194 typedef unsigned int JDIMENSION;
196 #define JPEG_MAX_DIMENSION 65500L /* a tad under 64K to prevent overflows */
199 /* These macros are used in all function definitions and extern declarations.
200 * You could modify them if you need to change function linkage conventions;
201 * in particular, you'll need to do that to make the library a Windows DLL.
202 * Another application is to make all functions global for use with debuggers
203 * or code profilers that require it.
206 /* a function called through method pointers: */
207 #define METHODDEF(type) static type
208 /* a function used only in its module: */
209 #define LOCAL(type) static type
210 /* a function referenced thru EXTERNs: */
211 #define GLOBAL(type) type
212 /* a reference to a GLOBAL function: */
213 #define EXTERN(type) extern type
216 /* Originally, this macro was used as a way of defining function prototypes
217 * for both modern compilers as well as older compilers that did not support
218 * prototype parameters. libjpeg-turbo has never supported these older,
219 * non-ANSI compilers, but the macro is still included because there is some
220 * software out there that uses it.
223 #define JMETHOD(type, methodname, arglist) type (*methodname) arglist
226 /* libjpeg-turbo no longer supports platforms that have far symbols (MS-DOS),
227 * but again, some software relies on this macro.
235 * On a few systems, type boolean and/or its values FALSE, TRUE may appear
236 * in standard header files. Or you may have conflicts with application-
237 * specific header files that you want to include together with these files.
238 * Defining HAVE_BOOLEAN before including jpeglib.h should make it work.
244 #ifndef FALSE /* in case these macros already exist */
245 #define FALSE 0 /* values of boolean */
253 * The remaining options affect code selection within the JPEG library,
254 * but they don't need to be visible to most applications using the library.
255 * To minimize application namespace pollution, the symbols won't be
256 * defined unless JPEG_INTERNALS or JPEG_INTERNAL_OPTIONS has been defined.
259 #ifdef JPEG_INTERNALS
260 #define JPEG_INTERNAL_OPTIONS
263 #ifdef JPEG_INTERNAL_OPTIONS
267 * These defines indicate whether to include various optional functions.
268 * Undefining some of these symbols will produce a smaller but less capable
269 * library. Note that you can leave certain source files out of the
270 * compilation/linking process if you've #undef'd the corresponding symbols.
271 * (You may HAVE to do that if your compiler doesn't like null source files.)
274 /* Capability options common to encoder and decoder: */
276 #define DCT_ISLOW_SUPPORTED /* accurate integer method */
277 #define DCT_IFAST_SUPPORTED /* less accurate int method [legacy feature] */
278 #define DCT_FLOAT_SUPPORTED /* floating-point method [legacy feature] */
280 /* Encoder capability options: */
282 #define C_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */
283 #define C_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/
284 #define ENTROPY_OPT_SUPPORTED /* Optimization of entropy coding parms? */
285 /* Note: if you selected 12-bit data precision, it is dangerous to turn off
286 * ENTROPY_OPT_SUPPORTED. The standard Huffman tables are only good for 8-bit
287 * precision, so jchuff.c normally uses entropy optimization to compute
288 * usable tables for higher precision. If you don't want to do optimization,
289 * you'll have to supply different default Huffman tables.
290 * The exact same statements apply for progressive JPEG: the default tables
291 * don't work for progressive mode. (This may get fixed, however.)
293 #define INPUT_SMOOTHING_SUPPORTED /* Input image smoothing option? */
295 /* Decoder capability options: */
297 #define D_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */
298 #define D_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/
299 #define SAVE_MARKERS_SUPPORTED /* jpeg_save_markers() needed? */
300 #define BLOCK_SMOOTHING_SUPPORTED /* Block smoothing? (Progressive only) */
301 #define IDCT_SCALING_SUPPORTED /* Output rescaling via IDCT? */
302 #undef UPSAMPLE_SCALING_SUPPORTED /* Output rescaling at upsample stage? */
303 #define UPSAMPLE_MERGING_SUPPORTED /* Fast path for sloppy upsampling? */
304 #define QUANT_1PASS_SUPPORTED /* 1-pass color quantization? */
305 #define QUANT_2PASS_SUPPORTED /* 2-pass color quantization? */
307 /* more capability options later, no doubt */
311 * The RGB_RED, RGB_GREEN, RGB_BLUE, and RGB_PIXELSIZE macros are a vestigial
312 * feature of libjpeg. The idea was that, if an application developer needed
313 * to compress from/decompress to a BGR/BGRX/RGBX/XBGR/XRGB buffer, they could
314 * change these macros, rebuild libjpeg, and link their application statically
315 * with it. In reality, few people ever did this, because there were some
316 * severe restrictions involved (cjpeg and djpeg no longer worked properly,
317 * compressing/decompressing RGB JPEGs no longer worked properly, and the color
318 * quantizer wouldn't work with pixel sizes other than 3.) Furthermore, since
319 * all of the O/S-supplied versions of libjpeg were built with the default
320 * values of RGB_RED, RGB_GREEN, RGB_BLUE, and RGB_PIXELSIZE, many applications
321 * have come to regard these values as immutable.
323 * The libjpeg-turbo colorspace extensions provide a much cleaner way of
324 * compressing from/decompressing to buffers with arbitrary component orders
325 * and pixel sizes. Thus, we do not support changing the values of RGB_RED,
326 * RGB_GREEN, RGB_BLUE, or RGB_PIXELSIZE. In addition to the restrictions
327 * listed above, changing these values will also break the SIMD extensions and
328 * the regression tests.
331 #define RGB_RED 0 /* Offset of Red in an RGB scanline element */
332 #define RGB_GREEN 1 /* Offset of Green */
333 #define RGB_BLUE 2 /* Offset of Blue */
334 #define RGB_PIXELSIZE 3 /* JSAMPLEs per RGB scanline element */
336 #define JPEG_NUMCS 17
338 #define EXT_RGB_RED 0
339 #define EXT_RGB_GREEN 1
340 #define EXT_RGB_BLUE 2
341 #define EXT_RGB_PIXELSIZE 3
343 #define EXT_RGBX_RED 0
344 #define EXT_RGBX_GREEN 1
345 #define EXT_RGBX_BLUE 2
346 #define EXT_RGBX_PIXELSIZE 4
348 #define EXT_BGR_RED 2
349 #define EXT_BGR_GREEN 1
350 #define EXT_BGR_BLUE 0
351 #define EXT_BGR_PIXELSIZE 3
353 #define EXT_BGRX_RED 2
354 #define EXT_BGRX_GREEN 1
355 #define EXT_BGRX_BLUE 0
356 #define EXT_BGRX_PIXELSIZE 4
358 #define EXT_XBGR_RED 3
359 #define EXT_XBGR_GREEN 2
360 #define EXT_XBGR_BLUE 1
361 #define EXT_XBGR_PIXELSIZE 4
363 #define EXT_XRGB_RED 1
364 #define EXT_XRGB_GREEN 2
365 #define EXT_XRGB_BLUE 3
366 #define EXT_XRGB_PIXELSIZE 4
368 static const int rgb_red[JPEG_NUMCS] = {
369 -1, -1, RGB_RED, -1, -1, -1, EXT_RGB_RED, EXT_RGBX_RED,
370 EXT_BGR_RED, EXT_BGRX_RED, EXT_XBGR_RED, EXT_XRGB_RED,
371 EXT_RGBX_RED, EXT_BGRX_RED, EXT_XBGR_RED, EXT_XRGB_RED,
375 static const int rgb_green[JPEG_NUMCS] = {
376 -1, -1, RGB_GREEN, -1, -1, -1, EXT_RGB_GREEN, EXT_RGBX_GREEN,
377 EXT_BGR_GREEN, EXT_BGRX_GREEN, EXT_XBGR_GREEN, EXT_XRGB_GREEN,
378 EXT_RGBX_GREEN, EXT_BGRX_GREEN, EXT_XBGR_GREEN, EXT_XRGB_GREEN,
382 static const int rgb_blue[JPEG_NUMCS] = {
383 -1, -1, RGB_BLUE, -1, -1, -1, EXT_RGB_BLUE, EXT_RGBX_BLUE,
384 EXT_BGR_BLUE, EXT_BGRX_BLUE, EXT_XBGR_BLUE, EXT_XRGB_BLUE,
385 EXT_RGBX_BLUE, EXT_BGRX_BLUE, EXT_XBGR_BLUE, EXT_XRGB_BLUE,
389 static const int rgb_pixelsize[JPEG_NUMCS] = {
390 -1, -1, RGB_PIXELSIZE, -1, -1, -1, EXT_RGB_PIXELSIZE, EXT_RGBX_PIXELSIZE,
391 EXT_BGR_PIXELSIZE, EXT_BGRX_PIXELSIZE, EXT_XBGR_PIXELSIZE, EXT_XRGB_PIXELSIZE,
392 EXT_RGBX_PIXELSIZE, EXT_BGRX_PIXELSIZE, EXT_XBGR_PIXELSIZE, EXT_XRGB_PIXELSIZE,
396 /* Definitions for speed-related optimizations. */
398 /* On some machines (notably 68000 series) "int" is 32 bits, but multiplying
399 * two 16-bit shorts is faster than multiplying two ints. Define MULTIPLIER
400 * as short on such a machine. MULTIPLIER must be at least 16 bits wide.
405 #define MULTIPLIER int /* type for fastest integer multiply */
407 #define MULTIPLIER short /* prefer 16-bit with SIMD for parellelism */
412 /* FAST_FLOAT should be either float or double, whichever is done faster
413 * by your compiler. (Note that this type is only used in the floating point
414 * DCT routines, so it only matters if you've defined DCT_FLOAT_SUPPORTED.)
418 #define FAST_FLOAT float
421 #endif /* JPEG_INTERNAL_OPTIONS */