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* jmorecfg.h
* This file was part of the Independent JPEG Group's software:
* Copyright (C) 1991-1997, Thomas G. Lane.
* Modified 1997-2009 by Guido Vollbeding.
* libjpeg-turbo Modifications:
* Copyright (C) 2009, 2011, 2014-2015, 2018, 2020, D. R. Commander.
* For conditions of distribution and use, see the accompanying README.ijg
* file.
* This file contains additional configuration options that customize the
* JPEG software for special applications or support machine-dependent
* optimizations. Most users will not need to touch this file.
* Maximum number of components (color channels) allowed in JPEG image.
* To meet the letter of Rec. ITU-T T.81 | ISO/IEC 10918-1, set this to 255.
* However, darn few applications need more than 4 channels (maybe 5 for CMYK +
* alpha mask). We recommend 10 as a reasonable compromise; use 4 if you are
* really short on memory. (Each allowed component costs a hundred or so
* bytes of storage, whether actually used in an image or not.)
#define MAX_COMPONENTS 10 /* maximum number of image components */
* Basic data types.
* You may need to change these if you have a machine with unusual data
* type sizes; for example, "char" not 8 bits, "short" not 16 bits,
* or "long" not 32 bits. We don't care whether "int" is 16 or 32 bits,
* but it had better be at least 16.
/* Representation of a single sample (pixel element value).
* We frequently allocate large arrays of these, so it's important to keep
* them small. But if you have memory to burn and access to char or short
* arrays is very slow on your hardware, you might want to change these.
/* JSAMPLE should be the smallest type that will hold the values 0..255.
typedef unsigned char JSAMPLE;
#define GETJSAMPLE(value) ((int)(value))
#define MAXJSAMPLE 255
#endif /* BITS_IN_JSAMPLE == 8 */
/* JSAMPLE should be the smallest type that will hold the values 0..4095.
* On nearly all machines "short" will do nicely.
typedef short JSAMPLE;
#define GETJSAMPLE(value) ((int)(value))
#define MAXJSAMPLE 4095
#define CENTERJSAMPLE 2048
#endif /* BITS_IN_JSAMPLE == 12 */
/* Representation of a DCT frequency coefficient.
* This should be a signed value of at least 16 bits; "short" is usually OK.
* Again, we allocate large arrays of these, but you can change to int
* if you have memory to burn and "short" is really slow.
typedef short JCOEF;
/* Compressed datastreams are represented as arrays of JOCTET.
* These must be EXACTLY 8 bits wide, at least once they are written to
* external storage. Note that when using the stdio data source/destination
* managers, this is also the data type passed to fread/fwrite.
typedef unsigned char JOCTET;
#define GETJOCTET(value) (value)
/* These typedefs are used for various table entries and so forth.
* They must be at least as wide as specified; but making them too big
* won't cost a huge amount of memory, so we don't provide special
* extraction code like we did for JSAMPLE. (In other words, these
* typedefs live at a different point on the speed/space tradeoff curve.)
/* UINT8 must hold at least the values 0..255. */
typedef unsigned char UINT8;
/* UINT16 must hold at least the values 0..65535. */
typedef unsigned short UINT16;
#else /* not HAVE_UNSIGNED_SHORT */
typedef unsigned int UINT16;
/* INT16 must hold at least the values -32768..32767. */
#ifndef XMD_H /* X11/xmd.h correctly defines INT16 */
typedef short INT16;
/* INT32 must hold at least signed 32-bit values.
* NOTE: The INT32 typedef dates back to libjpeg v5 (1994.) Integers were
* sometimes 16-bit back then (MS-DOS), which is why INT32 is typedef'd to
* long. It also wasn't common (or at least as common) in 1994 for INT32 to be
* defined by platform headers. Since then, however, INT32 is defined in
* several other common places:
* Xmd.h (X11 header) typedefs INT32 to int on 64-bit platforms and long on
* 32-bit platforms (i.e always a 32-bit signed type.)
* basetsd.h (Win32 header) typedefs INT32 to int (always a 32-bit signed type
* on modern platforms.)
* qglobal.h (Qt header) typedefs INT32 to int (always a 32-bit signed type on
* modern platforms.)
* This is a recipe for conflict, since "long" and "int" aren't always
* compatible types. Since the definition of INT32 has technically been part
* of the libjpeg API for more than 20 years, we can't remove it, but we do not
* use it internally any longer. We instead define a separate type (JLONG)
* for internal use, which ensures that internal behavior will always be the
* same regardless of any external headers that may be included.
#ifndef XMD_H /* X11/xmd.h correctly defines INT32 */
#ifndef _BASETSD_H_ /* Microsoft defines it in basetsd.h */
#ifndef _BASETSD_H /* MinGW is slightly different */
#ifndef QGLOBAL_H /* Qt defines it in qglobal.h */
typedef long INT32;
/* Datatype used for image dimensions. The JPEG standard only supports
* images up to 64K*64K due to 16-bit fields in SOF markers. Therefore
* "unsigned int" is sufficient on all machines. However, if you need to
* handle larger images and you don't mind deviating from the spec, you
* can change this datatype. (Note that changing this datatype will
* potentially require modifying the SIMD code. The x86-64 SIMD extensions,
* in particular, assume a 32-bit JDIMENSION.)
typedef unsigned int JDIMENSION;
#define JPEG_MAX_DIMENSION 65500L /* a tad under 64K to prevent overflows */
/* These macros are used in all function definitions and extern declarations.
* You could modify them if you need to change function linkage conventions;
* in particular, you'll need to do that to make the library a Windows DLL.
* Another application is to make all functions global for use with debuggers
* or code profilers that require it.
/* a function called through method pointers: */
#define METHODDEF(type) static type
/* a function used only in its module: */
#define LOCAL(type) static type
/* a function referenced thru EXTERNs: */
#define GLOBAL(type) type
/* a reference to a GLOBAL function: */
#define EXTERN(type) extern type
/* Originally, this macro was used as a way of defining function prototypes
* for both modern compilers as well as older compilers that did not support
* prototype parameters. libjpeg-turbo has never supported these older,
* non-ANSI compilers, but the macro is still included because there is some
* software out there that uses it.
#define JMETHOD(type, methodname, arglist) type (*methodname) arglist
/* libjpeg-turbo no longer supports platforms that have far symbols (MS-DOS),
* but again, some software relies on this macro.
#undef FAR
#define FAR
* On a few systems, type boolean and/or its values FALSE, TRUE may appear
* in standard header files. Or you may have conflicts with application-
* specific header files that you want to include together with these files.
* Defining HAVE_BOOLEAN before including jpeglib.h should make it work.
typedef int boolean;
#ifndef FALSE /* in case these macros already exist */
#define FALSE 0 /* values of boolean */
#ifndef TRUE
#define TRUE 1
* The remaining options affect code selection within the JPEG library,
* but they don't need to be visible to most applications using the library.
* To minimize application namespace pollution, the symbols won't be
* defined unless JPEG_INTERNALS or JPEG_INTERNAL_OPTIONS has been defined.
* These defines indicate whether to include various optional functions.
* Undefining some of these symbols will produce a smaller but less capable
* library. Note that you can leave certain source files out of the
* compilation/linking process if you've #undef'd the corresponding symbols.
* (You may HAVE to do that if your compiler doesn't like null source files.)
/* Capability options common to encoder and decoder: */
#define DCT_ISLOW_SUPPORTED /* accurate integer method */
#define DCT_IFAST_SUPPORTED /* less accurate int method [legacy feature] */
#define DCT_FLOAT_SUPPORTED /* floating-point method [legacy feature] */
/* Encoder capability options: */
#define C_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */
#define C_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/
#define ENTROPY_OPT_SUPPORTED /* Optimization of entropy coding parms? */
/* Note: if you selected 12-bit data precision, it is dangerous to turn off
* ENTROPY_OPT_SUPPORTED. The standard Huffman tables are only good for 8-bit
* precision, so jchuff.c normally uses entropy optimization to compute
* usable tables for higher precision. If you don't want to do optimization,
* you'll have to supply different default Huffman tables.
* The exact same statements apply for progressive JPEG: the default tables
* don't work for progressive mode. (This may get fixed, however.)
#define INPUT_SMOOTHING_SUPPORTED /* Input image smoothing option? */
/* Decoder capability options: */
#define D_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */
#define D_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/
#define SAVE_MARKERS_SUPPORTED /* jpeg_save_markers() needed? */
#define BLOCK_SMOOTHING_SUPPORTED /* Block smoothing? (Progressive only) */
#define IDCT_SCALING_SUPPORTED /* Output rescaling via IDCT? */
#undef UPSAMPLE_SCALING_SUPPORTED /* Output rescaling at upsample stage? */
#define UPSAMPLE_MERGING_SUPPORTED /* Fast path for sloppy upsampling? */
#define QUANT_1PASS_SUPPORTED /* 1-pass color quantization? */
#define QUANT_2PASS_SUPPORTED /* 2-pass color quantization? */
/* more capability options later, no doubt */
* The RGB_RED, RGB_GREEN, RGB_BLUE, and RGB_PIXELSIZE macros are a vestigial
* feature of libjpeg. The idea was that, if an application developer needed
* to compress from/decompress to a BGR/BGRX/RGBX/XBGR/XRGB buffer, they could
* change these macros, rebuild libjpeg, and link their application statically
* with it. In reality, few people ever did this, because there were some
* severe restrictions involved (cjpeg and djpeg no longer worked properly,
* compressing/decompressing RGB JPEGs no longer worked properly, and the color
* quantizer wouldn't work with pixel sizes other than 3.) Furthermore, since
* all of the O/S-supplied versions of libjpeg were built with the default
* values of RGB_RED, RGB_GREEN, RGB_BLUE, and RGB_PIXELSIZE, many applications
* have come to regard these values as immutable.
* The libjpeg-turbo colorspace extensions provide a much cleaner way of
* compressing from/decompressing to buffers with arbitrary component orders
* and pixel sizes. Thus, we do not support changing the values of RGB_RED,
* RGB_GREEN, RGB_BLUE, or RGB_PIXELSIZE. In addition to the restrictions
* listed above, changing these values will also break the SIMD extensions and
* the regression tests.
#define RGB_RED 0 /* Offset of Red in an RGB scanline element */
#define RGB_GREEN 1 /* Offset of Green */
#define RGB_BLUE 2 /* Offset of Blue */
#define RGB_PIXELSIZE 3 /* JSAMPLEs per RGB scanline element */
#define JPEG_NUMCS 17
#define EXT_RGB_RED 0
#define EXT_RGB_GREEN 1
#define EXT_RGB_BLUE 2
#define EXT_RGBX_RED 0
#define EXT_RGBX_GREEN 1
#define EXT_RGBX_BLUE 2
#define EXT_BGR_RED 2
#define EXT_BGR_GREEN 1
#define EXT_BGR_BLUE 0
#define EXT_BGRX_RED 2
#define EXT_BGRX_GREEN 1
#define EXT_BGRX_BLUE 0
#define EXT_XBGR_RED 3
#define EXT_XBGR_GREEN 2
#define EXT_XBGR_BLUE 1
#define EXT_XRGB_RED 1
#define EXT_XRGB_GREEN 2
#define EXT_XRGB_BLUE 3
static const int rgb_red[JPEG_NUMCS] = {
-1, -1, RGB_RED, -1, -1, -1, EXT_RGB_RED, EXT_RGBX_RED,
static const int rgb_green[JPEG_NUMCS] = {
static const int rgb_blue[JPEG_NUMCS] = {
-1, -1, RGB_BLUE, -1, -1, -1, EXT_RGB_BLUE, EXT_RGBX_BLUE,
static const int rgb_pixelsize[JPEG_NUMCS] = {
/* Definitions for speed-related optimizations. */
/* On some machines (notably 68000 series) "int" is 32 bits, but multiplying
* two 16-bit shorts is faster than multiplying two ints. Define MULTIPLIER
* as short on such a machine. MULTIPLIER must be at least 16 bits wide.
#ifndef WITH_SIMD
#define MULTIPLIER int /* type for fastest integer multiply */
#define MULTIPLIER short /* prefer 16-bit with SIMD for parellelism */
/* FAST_FLOAT should be either float or double, whichever is done faster
* by your compiler. (Note that this type is only used in the floating point
* DCT routines, so it only matters if you've defined DCT_FLOAT_SUPPORTED.)
#ifndef FAST_FLOAT
#define FAST_FLOAT float