jdct.h - third_party/libjpeg-turbo - Git at Google

 /*
  * 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, 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).
  */


 /*
  * 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)  ((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
	/*
	* 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, 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).
	*/


	/*
	* 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) ((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