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af618ffe093de6563fc61355d4d28f2038ec6e9e
mozjpeg/jmorecfg.h
DRC af618ffe09 Clean up the lossless JPEG feature 
- Rename jpeg_simple_lossless() to jpeg_enable_lossless() and modify the
  function so that it stores the lossless parameters directly in the Ss
  and Al fields of jpeg_compress_struct rather than using a scan script.

- Move the cjpeg -lossless switch into "Switches for advanced users".

- Document the libjpeg API and run-time features that are unavailable in
  lossless mode, and ensure that all parameters, functions, and switches
  related to unavailable features are ignored or generate errors in
  lossless mode.

- Defer any action that depends on whether lossless mode is enabled
  until jpeg_start_compress()/jpeg_start_decompress() is called.

- Document the purpose of the point transform value.

- "Codec" stands for coder/decoder, so it is a bit awkward to say
  "lossless compression codec" and "lossless decompression codec".
  Use "lossless compressor" and "lossless decompressor" instead.

- Restore backward API/ABI compatibility with libjpeg v6b:

  * Move the new 'lossless' field from the exposed jpeg_compress_struct
    and jpeg_decompress_struct structures into the opaque
    jpeg_comp_master and jpeg_decomp_master structures, and allocate the
    master structures in the body of jpeg_create_compress() and
    jpeg_create_decompress().

  * Remove the new 'process' field from jpeg_compress_struct and
    jpeg_decompress_struct and replace it with the old
    'progressive_mode' field and the new 'lossless' field.

  * Remove the new 'data_unit' field from jpeg_compress_struct and
    jpeg_decompress_struct and replace it with a locally-computed
    data unit variable.

  * Restore the names of macros and fields that refer to DCT blocks, and
    document that they have a different meaning in lossless mode.  (Most
    of them aren't very meaningful in lossless mode anyhow.)

  * Remove the new alloc_darray() method from jpeg_memory_mgr and
    replace it with an internal macro that wraps the alloc_sarray()
    method.

  * Move the JDIFF* data types from jpeglib.h and jmorecfg.h into
    jpegint.h.

  * Remove the new 'codec' field from jpeg_compress_struct and
    jpeg_decompress_struct and instead reuse the existing internal
    coefficient control, forward/inverse DCT, and entropy
    encoding/decoding structures for lossless compression/decompression.

  * Repurpose existing error codes rather than introducing new ones.
    (The new JERR_BAD_RESTART and JWRN_MUST_DOWNSCALE codes remain,
    although JWRN_MUST_DOWNSCALE will probably be removed in
    libjpeg-turbo, since we have a different way of handling multiple
    data precisions.)

- Automatically enable lossless mode when a scan script with parameters
  that are only valid for lossless mode is detected, and document the
  use of scan scripts to generate lossless JPEG images.

- Move the sequential and shared Huffman routines back into jchuff.c and
  jdhuff.c, and document that those routines are shared with jclhuff.c
  and jdlhuff.c as well as with jcphuff.c and jdphuff.c.

- Move MAX_DIFF_BITS from jchuff.h into jclhuff.c, the only place where
  it is used.

- Move the predictor and scaler code into jclossls.c and jdlossls.c.

- Streamline register usage in the [un]differencers (inspired by similar
  optimizations in the color [de]converters.)

- Restructure the logic in a few places to reduce duplicated code.

- Ensure that all lossless-specific code is guarded by
  C_LOSSLESS_SUPPORTED or D_LOSSLESS_SUPPORTED and that the library can
  be built successfully if either or both of those macros is undefined.

- Remove all short forms of external names introduced by the lossless
  JPEG patch.  (These will not be needed by libjpeg-turbo, so there is
  no use cleaning them up.)

- Various wordsmithing, formatting, and punctuation tweaks

- Eliminate various compiler warnings.
2022-11-16 11:27:18 -06:00

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/*
* jmorecfg.h
*
* This file was part of the Independent JPEG Group's software:
* Copyright (C) 1991-1997, Thomas G. Lane.
* Lossless JPEG Modifications:
* Copyright (C) 1999, Ken Murchison.
* For conditions of distribution and use, see the accompanying README 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.
*/
/*
* Define BITS_IN_JSAMPLE as either
* 8 for 8-bit sample values (the usual setting)
* 12 for 12-bit sample values
* Only 8 and 12 are legal data precisions for lossy JPEG according to the
* JPEG standard, and the IJG code does not support anything else!
* We do not support run-time selection of data precision, sorry.
*/
#define BITS_IN_JSAMPLE 8 /* use 8 or 12 */
/*
* Maximum number of components (color channels) allowed in JPEG image.
* To meet the letter of the JPEG spec, 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.
*/
#if BITS_IN_JSAMPLE == 8
/* JSAMPLE should be the smallest type that will hold the values 0..255.
* You can use a signed char by having GETJSAMPLE mask it with 0xFF.
*/
#ifdef HAVE_UNSIGNED_CHAR
typedef unsigned char JSAMPLE;
#define GETJSAMPLE(value) ((int) (value))
#else /* not HAVE_UNSIGNED_CHAR */
typedef char JSAMPLE;
#ifdef CHAR_IS_UNSIGNED
#define GETJSAMPLE(value) ((int) (value))
#else
#define GETJSAMPLE(value) ((int) (value) & 0xFF)
#endif /* CHAR_IS_UNSIGNED */
#endif /* HAVE_UNSIGNED_CHAR */
#define MAXJSAMPLE 255
#define CENTERJSAMPLE 128
#endif /* BITS_IN_JSAMPLE == 8 */
#if BITS_IN_JSAMPLE == 12
/* 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 */
#if BITS_IN_JSAMPLE == 16
/* JSAMPLE should be the smallest type that will hold the values 0..65535.
* You can use a signed short by having GETJSAMPLE mask it with 0xFFFF.
*/
#ifdef HAVE_UNSIGNED_SHORT
typedef unsigned short JSAMPLE;
#define GETJSAMPLE(value) ((int) (value))
#else /* not HAVE_UNSIGNED_SHORT */
typedef short JSAMPLE;
#ifdef SHORT_IS_UNSIGNED
#define GETJSAMPLE(value) ((int) (value))
#else
#define GETJSAMPLE(value) ((int) (value) & 0xFFFF)
#endif /* SHORT_IS_UNSIGNED */
#endif /* HAVE_UNSIGNED_SHORT */
#define MAXJSAMPLE 65535
#define CENTERJSAMPLE 32768
#endif /* BITS_IN_JSAMPLE == 16 */
/* 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.
*/
#ifdef HAVE_UNSIGNED_CHAR
typedef unsigned char JOCTET;
#define GETJOCTET(value) (value)
#else /* not HAVE_UNSIGNED_CHAR */
typedef char JOCTET;
#ifdef CHAR_IS_UNSIGNED
#define GETJOCTET(value) (value)
#else
#define GETJOCTET(value) ((value) & 0xFF)
#endif /* CHAR_IS_UNSIGNED */
#endif /* HAVE_UNSIGNED_CHAR */
/* 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. */
#ifdef HAVE_UNSIGNED_CHAR
typedef unsigned char UINT8;
#else /* not HAVE_UNSIGNED_CHAR */
#ifdef CHAR_IS_UNSIGNED
typedef char UINT8;
#else /* not CHAR_IS_UNSIGNED */
typedef short UINT8;
#endif /* CHAR_IS_UNSIGNED */
#endif /* HAVE_UNSIGNED_CHAR */
/* UINT16 must hold at least the values 0..65535. */
#ifdef HAVE_UNSIGNED_SHORT
typedef unsigned short UINT16;
#else /* not HAVE_UNSIGNED_SHORT */
typedef unsigned int UINT16;
#endif /* HAVE_UNSIGNED_SHORT */
/* INT16 must hold at least the values -32768..32767. */
#ifndef XMD_H /* X11/xmd.h correctly defines INT16 */
typedef short INT16;
#endif
/* INT32 must hold at least signed 32-bit values. */
#ifndef XMD_H /* X11/xmd.h correctly defines INT32 */
typedef long INT32;
#endif
/* 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.
*/
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
/* This macro is used to declare a "method", that is, a function pointer.
* We want to supply prototype parameters if the compiler can cope.
* Note that the arglist parameter must be parenthesized!
* Again, you can customize this if you need special linkage keywords.
*/
#ifdef HAVE_PROTOTYPES
#define JMETHOD(type,methodname,arglist) type (*methodname) arglist
#else
#define JMETHOD(type,methodname,arglist) type (*methodname) ()
#endif
/* Here is the pseudo-keyword for declaring pointers that must be "far"
* on 80x86 machines. Most of the specialized coding for 80x86 is handled
* by just saying "FAR *" where such a pointer is needed. In a few places
* explicit coding is needed; see uses of the NEED_FAR_POINTERS symbol.
*/
#ifdef NEED_FAR_POINTERS
#define FAR far
#else
#define FAR
#endif
/*
* 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.
*/
#ifndef HAVE_BOOLEAN
typedef int boolean;
#endif
#ifndef FALSE /* in case these macros already exist */
#define FALSE 0 /* values of boolean */
#endif
#ifndef TRUE
#define TRUE 1
#endif
/*
* 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.
*/
#ifdef JPEG_INTERNALS
#define JPEG_INTERNAL_OPTIONS
#endif
#ifdef JPEG_INTERNAL_OPTIONS
/*
* 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.)
*/
/* Arithmetic coding is unsupported for legal reasons. Complaints to IBM. */
/* Capability options common to encoder and decoder: */
#define DCT_ISLOW_SUPPORTED /* slow but accurate integer algorithm */
#define DCT_IFAST_SUPPORTED /* faster, less accurate integer method */
#define DCT_FLOAT_SUPPORTED /* floating-point: accurate, fast on fast HW */
/* Encoder capability options: */
#undef C_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */
#define C_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */
#define C_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/
#define C_LOSSLESS_SUPPORTED /* Lossless JPEG? */
#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 and lossless JPEG:
* the default tables don't work for progressive mode or lossless mode.
* (This may get fixed, however.)
*/
#define INPUT_SMOOTHING_SUPPORTED /* Input image smoothing option? */
/* Decoder capability options: */
#undef D_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */
#define D_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */
#define D_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/
#define D_LOSSLESS_SUPPORTED /* Lossless JPEG? */
#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 */
/*
* Ordering of RGB data in scanlines passed to or from the application.
* If your application wants to deal with data in the order B,G,R, just
* change these macros. You can also deal with formats such as R,G,B,X
* (one extra byte per pixel) by changing RGB_PIXELSIZE. Note that changing
* the offsets will also change the order in which colormap data is organized.
* RESTRICTIONS:
* 1. The sample applications cjpeg,djpeg do NOT support modified RGB formats.
* 2. These macros only affect RGB<=>YCbCr color conversion, so they are not
* useful if you are using JPEG color spaces other than YCbCr or grayscale.
* 3. The color quantizer modules will not behave desirably if RGB_PIXELSIZE
* is not 3 (they don't understand about dummy color components!). So you
* can't use color quantization if you change that value.
*/
#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 */
/* Definitions for speed-related optimizations. */
/* If your compiler supports inline functions, define INLINE
* as the inline keyword; otherwise define it as empty.
*/
#ifndef INLINE
#ifdef __GNUC__ /* for instance, GNU C knows about inline */
#define INLINE __inline__
#endif
#ifndef INLINE
#define INLINE /* default is to define it as empty */
#endif
#endif
/* 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 MULTIPLIER
#define MULTIPLIER int /* type for fastest integer multiply */
#endif
/* 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.)
* Typically, float is faster in ANSI C compilers, while double is faster in
* pre-ANSI compilers (because they insist on converting to double anyway).
* The code below therefore chooses float if we have ANSI-style prototypes.
*/
#ifndef FAST_FLOAT
#ifdef HAVE_PROTOTYPES
#define FAST_FLOAT float
#else
#define FAST_FLOAT double
#endif
#endif
#endif /* JPEG_INTERNAL_OPTIONS */
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