/*+
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 * jdct.h+
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 *+
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 * Copyright (C) 1994-1996, Thomas G. Lane.+
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 * This file is part of the Independent JPEG Group's software.+
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 * For conditions of distribution and use, see the accompanying README file.+
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 *+
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 * This include file contains common declarations for the forward and+
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 * inverse DCT modules.  These declarations are private to the DCT managers+
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 * (jcdctmgr.c, jddctmgr.c) and the individual DCT algorithms.+
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 * The individual DCT algorithms are kept in separate files to ease +
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 * machine-dependent tuning (e.g., assembly coding).+
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 */+
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+
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+
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/*+
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 * A forward DCT routine is given a pointer to a work area of type DCTELEM[];+
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 * the DCT is to be performed in-place in that buffer.  Type DCTELEM is int+
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 * for 8-bit samples, INT32 for 12-bit samples.  (NOTE: Floating-point DCT+
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 * implementations use an array of type FAST_FLOAT, instead.)+
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 * The DCT inputs are expected to be signed (range +-CENTERJSAMPLE).+
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 * The DCT outputs are returned scaled up by a factor of 8; they therefore+
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 * have a range of +-8K for 8-bit data, +-128K for 12-bit data.  This+
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 * convention improves accuracy in integer implementations and saves some+
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 * work in floating-point ones.+
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 * Quantization of the output coefficients is done by jcdctmgr.c.+
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 */+
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+
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#if BITS_IN_JSAMPLE == 8+
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typedef int DCTELEM;		/* 16 or 32 bits is fine */+
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#else+
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typedef INT32 DCTELEM;		/* must have 32 bits */+
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#endif+
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+
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typedef JMETHOD(void, forward_DCT_method_ptr, (DCTELEM * data));+
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typedef JMETHOD(void, float_DCT_method_ptr, (FAST_FLOAT * data));+
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+
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+
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/*+
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 * An inverse DCT routine is given a pointer to the input JBLOCK and a pointer+
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 * to an output sample array.  The routine must dequantize the input data as+
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 * well as perform the IDCT; for dequantization, it uses the multiplier table+
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 * pointed to by compptr->dct_table.  The output data is to be placed into the+
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 * sample array starting at a specified column.  (Any row offset needed will+
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 * be applied to the array pointer before it is passed to the IDCT code.)+
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 * Note that the number of samples emitted by the IDCT routine is+
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 * DCT_scaled_size * DCT_scaled_size.+
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 */+
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+
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/* typedef inverse_DCT_method_ptr is declared in jpegint.h */+
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+
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/*+
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 * Each IDCT routine has its own ideas about the best dct_table element type.+
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 */+
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+
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typedef MULTIPLIER ISLOW_MULT_TYPE; /* short or int, whichever is faster */+
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#if BITS_IN_JSAMPLE == 8+
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typedef MULTIPLIER IFAST_MULT_TYPE; /* 16 bits is OK, use short if faster */+
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#define IFAST_SCALE_BITS  2	/* fractional bits in scale factors */+
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#else+
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typedef INT32 IFAST_MULT_TYPE;	/* need 32 bits for scaled quantizers */+
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#define IFAST_SCALE_BITS  13	/* fractional bits in scale factors */+
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#endif+
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typedef FAST_FLOAT FLOAT_MULT_TYPE; /* preferred floating type */+
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+
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+
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/*+
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 * Each IDCT routine is responsible for range-limiting its results and+
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 * converting them to unsigned form (0..MAXJSAMPLE).  The raw outputs could+
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 * be quite far out of range if the input data is corrupt, so a bulletproof+
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 * range-limiting step is required.  We use a mask-and-table-lookup method+
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 * to do the combined operations quickly.  See the comments with+
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 * prepare_range_limit_table (in jdmaster.c) for more info.+
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 */+
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+
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#define IDCT_range_limit(cinfo)  ((cinfo)->sample_range_limit + CENTERJSAMPLE)+
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+
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#define RANGE_MASK  (MAXJSAMPLE * 4 + 3) /* 2 bits wider than legal samples */+
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+
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+
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/* Short forms of external names for systems with brain-damaged linkers. */+
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+
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#ifdef NEED_SHORT_EXTERNAL_NAMES+
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#define jpeg_fdct_islow		jFDislow+
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#define jpeg_fdct_ifast		jFDifast+
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#define jpeg_fdct_float		jFDfloat+
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#define jpeg_idct_islow		jRDislow+
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#define jpeg_idct_ifast		jRDifast+
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#define jpeg_idct_float		jRDfloat+
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#define jpeg_idct_4x4		jRD4x4+
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#define jpeg_idct_2x2		jRD2x2+
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#define jpeg_idct_1x1		jRD1x1+
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#endif /* NEED_SHORT_EXTERNAL_NAMES */+
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+
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/* Extern declarations for the forward and inverse DCT routines. */+
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+
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EXTERN(void) jpeg_fdct_islow JPP((DCTELEM * data));+
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EXTERN(void) jpeg_fdct_ifast JPP((DCTELEM * data));+
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EXTERN(void) jpeg_fdct_float JPP((FAST_FLOAT * data));+
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+
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EXTERN(void) jpeg_idct_islow+
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    JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,+
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	 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));+
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EXTERN(void) jpeg_idct_ifast+
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    JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,+
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	 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));+
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EXTERN(void) jpeg_idct_float+
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    JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,+
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	 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));+
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EXTERN(void) jpeg_idct_4x4+
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    JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,+
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	 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));+
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EXTERN(void) jpeg_idct_2x2+
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    JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,+
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	 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));+
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EXTERN(void) jpeg_idct_1x1+
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    JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,+
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	 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));+
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+
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+
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/*+
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 * Macros for handling fixed-point arithmetic; these are used by many+
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 * but not all of the DCT/IDCT modules.+
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 *+
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 * All values are expected to be of type INT32.+
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 * Fractional constants are scaled left by CONST_BITS bits.+
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 * CONST_BITS is defined within each module using these macros,+
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 * and may differ from one module to the next.+
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 */+
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+
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#define ONE	((INT32) 1)+
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#define CONST_SCALE (ONE << CONST_BITS)+
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+
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/* Convert a positive real constant to an integer scaled by CONST_SCALE.+
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 * Caution: some C compilers fail to reduce "FIX(constant)" at compile time,+
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 * thus causing a lot of useless floating-point operations at run time.+
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 */+
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+
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#define FIX(x)	((INT32) ((x) * CONST_SCALE + 0.5))+
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+
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/* Descale and correctly round an INT32 value that's scaled by N bits.+
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 * We assume RIGHT_SHIFT rounds towards minus infinity, so adding+
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 * the fudge factor is correct for either sign of X.+
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 */+
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+
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#define DESCALE(x,n)  RIGHT_SHIFT((x) + (ONE << ((n)-1)), n)+
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+
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/* Multiply an INT32 variable by an INT32 constant to yield an INT32 result.+
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 * This macro is used only when the two inputs will actually be no more than+
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 * 16 bits wide, so that a 16x16->32 bit multiply can be used instead of a+
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 * full 32x32 multiply.  This provides a useful speedup on many machines.+
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 * Unfortunately there is no way to specify a 16x16->32 multiply portably+
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 * in C, but some C compilers will do the right thing if you provide the+
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 * correct combination of casts.+
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 */+
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+
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#ifdef SHORTxSHORT_32		/* may work if 'int' is 32 bits */+
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#define MULTIPLY16C16(var,const)  (((INT16) (var)) * ((INT16) (const)))+
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#endif+
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#ifdef SHORTxLCONST_32		/* known to work with Microsoft C 6.0 */+
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#define MULTIPLY16C16(var,const)  (((INT16) (var)) * ((INT32) (const)))+
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#endif+
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+
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#ifndef MULTIPLY16C16		/* default definition */+
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#define MULTIPLY16C16(var,const)  ((var) * (const))+
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#endif+
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+
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/* Same except both inputs are variables. */+
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+
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#ifdef SHORTxSHORT_32		/* may work if 'int' is 32 bits */+
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#define MULTIPLY16V16(var1,var2)  (((INT16) (var1)) * ((INT16) (var2)))+
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#endif+
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+
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#ifndef MULTIPLY16V16		/* default definition */+
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#define MULTIPLY16V16(var1,var2)  ((var1) * (var2))+
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#endif+
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