kc3-lang/libjpeg-turbo/src/jdct.h

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• Hash : e69dd40c
  Author :
  Date : 2024-01-23T13:26:41
  

  Reorganize source to make things easier to find
  
  - Move all libjpeg documentation, except for README.ijg, into the doc/
    subdirectory.
  
  - Move the TurboJPEG C API documentation from doc/html/ into
    doc/turbojpeg/.
  
  - Move all C source code and headers into a src/ subdirectory.
  
  - Move turbojpeg-jni.c into the java/ subdirectory.
  
  Referring to #226, there is no ideal solution to this problem.  A
  semantically ideal solution would have involved placing all source code,
  including the SIMD and Java source code, under src/ (or perhaps placing
  C library source code under lib/ and C test program source code under
  test/), all header files under include/, and all documentation under
  doc/.  However:
  
  - To me it makes more sense to have separate top-level directories for
    each language, since the SIMD extensions and the Java API are
    technically optional features.  src/ now contains only the code that
    is relevant to the core C API libraries and associated programs.
  - I didn't want to bury the java/ and simd/ directories or add a level
    of depth to them, since both directories already contain source code
    that is 3-4 levels deep.
  - I would prefer not to separate the header files from the C source
    code, because:
    1. It would be disruptive.  libjpeg and libjpeg-turbo have
       historically placed C source code and headers in the same
       directory, and people who are familiar with both projects (self
       included) are used to looking for the headers in the same directory
       as the C source code.
    2. In terms of how the headers are used internally in libjpeg-turbo,
       the distinction between public and private headers is a bit fuzzy.
  - It didn't make sense to separate the test source code from the library
    source code, since there is not a clear distinction in some cases.
    (For instance, the IJG image I/O functions are used by cjpeg and djpeg
    as well as by the TurboJPEG API.)
  
  This solution is minimally disruptive, since it keeps all C source code
  and headers together and keeps java/ and simd/ as top-level directories.
  It is a bit awkward, because java/ and simd/ technically contain source
  code, even though they are not under src/.  However, other solutions
  would have been more awkward for different reasons.
  
  Closes #226
  

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• src/jdct.h

• /*
   * jdct.h
   *
   * This file was part of the Independent JPEG Group's software:
   * Copyright (C) 1994-1996, Thomas G. Lane.
   * libjpeg-turbo Modifications:
   * Copyright (C) 2015, 2022, D. R. Commander.
   * For conditions of distribution and use, see the accompanying README.ijg
   * file.
   *
   * This include file contains common declarations for the forward and
   * inverse DCT modules.  These declarations are private to the DCT managers
   * (jcdctmgr.c, jddctmgr.c) and the individual DCT algorithms.
   * The individual DCT algorithms are kept in separate files to ease
   * machine-dependent tuning (e.g., assembly coding).
   */
  
  #include "jsamplecomp.h"
  
  
  /*
   * A forward DCT routine is given a pointer to a work area of type DCTELEM[];
   * the DCT is to be performed in-place in that buffer.  Type DCTELEM is int
   * for 8-bit samples, JLONG for 12-bit samples.  (NOTE: Floating-point DCT
   * implementations use an array of type FAST_FLOAT, instead.)
   * The DCT inputs are expected to be signed (range +-_CENTERJSAMPLE).
   * The DCT outputs are returned scaled up by a factor of 8; they therefore
   * have a range of +-8K for 8-bit data, +-128K for 12-bit data.  This
   * convention improves accuracy in integer implementations and saves some
   * work in floating-point ones.
   * Quantization of the output coefficients is done by jcdctmgr.c. This
   * step requires an unsigned type and also one with twice the bits.
   */
  
  #if BITS_IN_JSAMPLE == 8
  #ifndef WITH_SIMD
  typedef int DCTELEM;            /* 16 or 32 bits is fine */
  typedef unsigned int UDCTELEM;
  typedef unsigned long long UDCTELEM2;
  #else
  typedef short DCTELEM;          /* prefer 16 bit with SIMD for parellelism */
  typedef unsigned short UDCTELEM;
  typedef unsigned int UDCTELEM2;
  #endif
  #else
  typedef JLONG DCTELEM;          /* must have 32 bits */
  typedef unsigned long long UDCTELEM2;
  #endif
  
  
  /*
   * An inverse DCT routine is given a pointer to the input JBLOCK and a pointer
   * to an output sample array.  The routine must dequantize the input data as
   * well as perform the IDCT; for dequantization, it uses the multiplier table
   * pointed to by compptr->dct_table.  The output data is to be placed into the
   * sample array starting at a specified column.  (Any row offset needed will
   * be applied to the array pointer before it is passed to the IDCT code.)
   * Note that the number of samples emitted by the IDCT routine is
   * DCT_scaled_size * DCT_scaled_size.
   */
  
  /* typedef inverse_DCT_method_ptr is declared in jpegint.h */
  
  /*
   * Each IDCT routine has its own ideas about the best dct_table element type.
   */
  
  typedef MULTIPLIER ISLOW_MULT_TYPE;  /* short or int, whichever is faster */
  #if BITS_IN_JSAMPLE == 8
  typedef MULTIPLIER IFAST_MULT_TYPE;  /* 16 bits is OK, use short if faster */
  #define IFAST_SCALE_BITS  2          /* fractional bits in scale factors */
  #else
  typedef JLONG IFAST_MULT_TYPE;       /* need 32 bits for scaled quantizers */
  #define IFAST_SCALE_BITS  13         /* fractional bits in scale factors */
  #endif
  typedef FAST_FLOAT FLOAT_MULT_TYPE;  /* preferred floating type */
  
  
  /*
   * Each IDCT routine is responsible for range-limiting its results and
   * converting them to unsigned form (0.._MAXJSAMPLE).  The raw outputs could
   * be quite far out of range if the input data is corrupt, so a bulletproof
   * range-limiting step is required.  We use a mask-and-table-lookup method
   * to do the combined operations quickly.  See the comments with
   * prepare_range_limit_table (in jdmaster.c) for more info.
   */
  
  #define IDCT_range_limit(cinfo) \
    ((_JSAMPLE *)((cinfo)->sample_range_limit) + _CENTERJSAMPLE)
  
  #define RANGE_MASK  (_MAXJSAMPLE * 4 + 3) /* 2 bits wider than legal samples */
  
  
  /* Extern declarations for the forward and inverse DCT routines. */
  
  EXTERN(void) _jpeg_fdct_islow(DCTELEM *data);
  EXTERN(void) _jpeg_fdct_ifast(DCTELEM *data);
  EXTERN(void) jpeg_fdct_float(FAST_FLOAT *data);
  
  EXTERN(void) _jpeg_idct_islow(j_decompress_ptr cinfo,
                                jpeg_component_info *compptr,
                                JCOEFPTR coef_block, _JSAMPARRAY output_buf,
                                JDIMENSION output_col);
  EXTERN(void) _jpeg_idct_ifast(j_decompress_ptr cinfo,
                                jpeg_component_info *compptr,
                                JCOEFPTR coef_block, _JSAMPARRAY output_buf,
                                JDIMENSION output_col);
  EXTERN(void) _jpeg_idct_float(j_decompress_ptr cinfo,
                                jpeg_component_info *compptr,
                                JCOEFPTR coef_block, _JSAMPARRAY output_buf,
                                JDIMENSION output_col);
  EXTERN(void) _jpeg_idct_7x7(j_decompress_ptr cinfo,
                              jpeg_component_info *compptr, JCOEFPTR coef_block,
                              _JSAMPARRAY output_buf, JDIMENSION output_col);
  EXTERN(void) _jpeg_idct_6x6(j_decompress_ptr cinfo,
                              jpeg_component_info *compptr, JCOEFPTR coef_block,
                              _JSAMPARRAY output_buf, JDIMENSION output_col);
  EXTERN(void) _jpeg_idct_5x5(j_decompress_ptr cinfo,
                              jpeg_component_info *compptr, JCOEFPTR coef_block,
                              _JSAMPARRAY output_buf, JDIMENSION output_col);
  EXTERN(void) _jpeg_idct_4x4(j_decompress_ptr cinfo,
                              jpeg_component_info *compptr, JCOEFPTR coef_block,
                              _JSAMPARRAY output_buf, JDIMENSION output_col);
  EXTERN(void) _jpeg_idct_3x3(j_decompress_ptr cinfo,
                              jpeg_component_info *compptr, JCOEFPTR coef_block,
                              _JSAMPARRAY output_buf, JDIMENSION output_col);
  EXTERN(void) _jpeg_idct_2x2(j_decompress_ptr cinfo,
                              jpeg_component_info *compptr, JCOEFPTR coef_block,
                              _JSAMPARRAY output_buf, JDIMENSION output_col);
  EXTERN(void) _jpeg_idct_1x1(j_decompress_ptr cinfo,
                              jpeg_component_info *compptr, JCOEFPTR coef_block,
                              _JSAMPARRAY output_buf, JDIMENSION output_col);
  EXTERN(void) _jpeg_idct_9x9(j_decompress_ptr cinfo,
                              jpeg_component_info *compptr, JCOEFPTR coef_block,
                              _JSAMPARRAY output_buf, JDIMENSION output_col);
  EXTERN(void) _jpeg_idct_10x10(j_decompress_ptr cinfo,
                                jpeg_component_info *compptr,
                                JCOEFPTR coef_block, _JSAMPARRAY output_buf,
                                JDIMENSION output_col);
  EXTERN(void) _jpeg_idct_11x11(j_decompress_ptr cinfo,
                                jpeg_component_info *compptr,
                                JCOEFPTR coef_block, _JSAMPARRAY output_buf,
                                JDIMENSION output_col);
  EXTERN(void) _jpeg_idct_12x12(j_decompress_ptr cinfo,
                                jpeg_component_info *compptr,
                                JCOEFPTR coef_block, _JSAMPARRAY output_buf,
                                JDIMENSION output_col);
  EXTERN(void) _jpeg_idct_13x13(j_decompress_ptr cinfo,
                                jpeg_component_info *compptr,
                                JCOEFPTR coef_block, _JSAMPARRAY output_buf,
                                JDIMENSION output_col);
  EXTERN(void) _jpeg_idct_14x14(j_decompress_ptr cinfo,
                                jpeg_component_info *compptr,
                                JCOEFPTR coef_block, _JSAMPARRAY output_buf,
                                JDIMENSION output_col);
  EXTERN(void) _jpeg_idct_15x15(j_decompress_ptr cinfo,
                                jpeg_component_info *compptr,
                                JCOEFPTR coef_block, _JSAMPARRAY output_buf,
                                JDIMENSION output_col);
  EXTERN(void) _jpeg_idct_16x16(j_decompress_ptr cinfo,
                                jpeg_component_info *compptr,
                                JCOEFPTR coef_block, _JSAMPARRAY output_buf,
                                JDIMENSION output_col);
  
  
  /*
   * Macros for handling fixed-point arithmetic; these are used by many
   * but not all of the DCT/IDCT modules.
   *
   * All values are expected to be of type JLONG.
   * Fractional constants are scaled left by CONST_BITS bits.
   * CONST_BITS is defined within each module using these macros,
   * and may differ from one module to the next.
   */
  
  #define ONE          ((JLONG)1)
  #define CONST_SCALE  (ONE << CONST_BITS)
  
  /* Convert a positive real constant to an integer scaled by CONST_SCALE.
   * Caution: some C compilers fail to reduce "FIX(constant)" at compile time,
   * thus causing a lot of useless floating-point operations at run time.
   */
  
  #define FIX(x)  ((JLONG)((x) * CONST_SCALE + 0.5))
  
  /* Descale and correctly round a JLONG value that's scaled by N bits.
   * We assume RIGHT_SHIFT rounds towards minus infinity, so adding
   * the fudge factor is correct for either sign of X.
   */
  
  #define DESCALE(x, n)  RIGHT_SHIFT((x) + (ONE << ((n) - 1)), n)
  
  /* Multiply a JLONG variable by a JLONG constant to yield a JLONG result.
   * This macro is used only when the two inputs will actually be no more than
   * 16 bits wide, so that a 16x16->32 bit multiply can be used instead of a
   * full 32x32 multiply.  This provides a useful speedup on many machines.
   * Unfortunately there is no way to specify a 16x16->32 multiply portably
   * in C, but some C compilers will do the right thing if you provide the
   * correct combination of casts.
   */
  
  #ifdef SHORTxSHORT_32           /* may work if 'int' is 32 bits */
  #define MULTIPLY16C16(var, const)  (((INT16)(var)) * ((INT16)(const)))
  #endif
  #ifdef SHORTxLCONST_32          /* known to work with Microsoft C 6.0 */
  #define MULTIPLY16C16(var, const)  (((INT16)(var)) * ((JLONG)(const)))
  #endif
  
  #ifndef MULTIPLY16C16           /* default definition */
  #define MULTIPLY16C16(var, const)  ((var) * (const))
  #endif
  
  /* Same except both inputs are variables. */
  
  #ifdef SHORTxSHORT_32           /* may work if 'int' is 32 bits */
  #define MULTIPLY16V16(var1, var2)  (((INT16)(var1)) * ((INT16)(var2)))
  #endif
  
  #ifndef MULTIPLY16V16           /* default definition */
  #define MULTIPLY16V16(var1, var2)  ((var1) * (var2))
  #endif
  

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