/*
 * jcdctmgr.c
 *
 * Copyright (C) 1994-1995, Thomas G. Lane.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file contains the forward-DCT management logic.
 * This code selects a particular DCT implementation to be used,
 * and it performs related housekeeping chores including coefficient
 * quantization.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
#include "jdct.h"        /* Private declarations for DCT subsystem */


/* Private subobject for this module */

typedef struct {
	struct jpeg_forward_dct pub; /* public fields */

	/* Pointer to the DCT routine actually in use */
	forward_DCT_method_ptr do_dct;

	/* The actual post-DCT divisors --- not identical to the quant table
	 * entries, because of scaling (especially for an unnormalized DCT).
	 * Each table is given in normal array order; note that this must
	 * be converted from the zigzag order of the quantization tables.
	 */
	DCTELEM * divisors[NUM_QUANT_TBLS];

#ifdef DCT_FLOAT_SUPPORTED
	/* Same as above for the floating-point case. */
	float_DCT_method_ptr do_float_dct;
	FAST_FLOAT * float_divisors[NUM_QUANT_TBLS];
#endif
} my_fdct_controller;

typedef my_fdct_controller * my_fdct_ptr;


/*
 * Initialize for a processing pass.
 * Verify that all referenced Q-tables are present, and set up
 * the divisor table for each one.
 * In the current implementation, DCT of all components is done during
 * the first pass, even if only some components will be output in the
 * first scan.  Hence all components should be examined here.
 */

METHODDEF void
start_pass_fdctmgr( j_compress_ptr cinfo ) {
	my_fdct_ptr fdct = (my_fdct_ptr) cinfo->fdct;
	int ci, qtblno, i;
	jpeg_component_info *compptr;
	JQUANT_TBL * qtbl;
#ifdef DCT_ISLOW_SUPPORTED
	DCTELEM * dtbl;
#endif

	for ( ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
		  ci++, compptr++ ) {
		qtblno = compptr->quant_tbl_no;
		/* Make sure specified quantization table is present */
		if ( qtblno < 0 || qtblno >= NUM_QUANT_TBLS ||
			 cinfo->quant_tbl_ptrs[qtblno] == NULL ) {
			ERREXIT1( cinfo, JERR_NO_QUANT_TABLE, qtblno );
		}
		qtbl = cinfo->quant_tbl_ptrs[qtblno];
		/* Compute divisors for this quant table */
		/* We may do this more than once for same table, but it's not a big deal */
		switch ( cinfo->dct_method ) {
#ifdef DCT_ISLOW_SUPPORTED
		case JDCT_ISLOW:
			/* For LL&M IDCT method, divisors are equal to raw quantization
			 * coefficients multiplied by 8 (to counteract scaling).
			 */
			if ( fdct->divisors[qtblno] == NULL ) {
				fdct->divisors[qtblno] = ( DCTELEM * )
										 ( *cinfo->mem->alloc_small )( (j_common_ptr) cinfo, JPOOL_IMAGE,
																	   DCTSIZE2 * SIZEOF( DCTELEM ) );
			}
			dtbl = fdct->divisors[qtblno];
			for ( i = 0; i < DCTSIZE2; i++ ) {
				dtbl[i] = ( (DCTELEM) qtbl->quantval[jpeg_zigzag_order[i]] ) << 3;
			}
			break;
#endif
#ifdef DCT_IFAST_SUPPORTED
		case JDCT_IFAST:
		{
			/* For AA&N IDCT method, divisors are equal to quantization
			 * coefficients scaled by scalefactor[row]*scalefactor[col], where
			 *   scalefactor[0] = 1
			 *   scalefactor[k] = cos(k*PI/16) * sqrt(2)    for k=1..7
			 * We apply a further scale factor of 8.
			 */
#define CONST_BITS 14
			static const INT16 aanscales[DCTSIZE2] = {
				/* precomputed values scaled up by 14 bits: in natural order */
				16384, 22725, 21407, 19266, 16384, 12873,  8867,  4520,
				22725, 31521, 29692, 26722, 22725, 17855, 12299,  6270,
				21407, 29692, 27969, 25172, 21407, 16819, 11585,  5906,
				19266, 26722, 25172, 22654, 19266, 15137, 10426,  5315,
				16384, 22725, 21407, 19266, 16384, 12873,  8867,  4520,
				12873, 17855, 16819, 15137, 12873, 10114,  6967,  3552,
				8867, 12299, 11585, 10426,  8867,  6967,  4799,  2446,
				4520,  6270,  5906,  5315,  4520,  3552,  2446,  1247
			};
			SHIFT_TEMPS

			if ( fdct->divisors[qtblno] == NULL ) {
				fdct->divisors[qtblno] = ( DCTELEM * )
										 ( *cinfo->mem->alloc_small )( (j_common_ptr) cinfo, JPOOL_IMAGE,
																	   DCTSIZE2 * SIZEOF( DCTELEM ) );
			}
			dtbl = fdct->divisors[qtblno];
			for ( i = 0; i < DCTSIZE2; i++ ) {
				dtbl[i] = (DCTELEM)
						  DESCALE( MULTIPLY16V16( (INT32) qtbl->quantval[jpeg_zigzag_order[i]],
												  (INT32) aanscales[i] ),
								   CONST_BITS - 3 );
			}
		}
		break;
#endif
#ifdef DCT_FLOAT_SUPPORTED
		case JDCT_FLOAT:
		{
			/* For float AA&N IDCT method, divisors are equal to quantization
			 * coefficients scaled by scalefactor[row]*scalefactor[col], where
			 *   scalefactor[0] = 1
			 *   scalefactor[k] = cos(k*PI/16) * sqrt(2)    for k=1..7
			 * We apply a further scale factor of 8.
			 * What's actually stored is 1/divisor so that the inner loop can
			 * use a multiplication rather than a division.
			 */
			FAST_FLOAT * fdtbl;
			int row, col;
			static const double aanscalefactor[DCTSIZE] = {
				1.0, 1.387039845, 1.306562965, 1.175875602,
				1.0, 0.785694958, 0.541196100, 0.275899379
			};

			if ( fdct->float_divisors[qtblno] == NULL ) {
				fdct->float_divisors[qtblno] = ( FAST_FLOAT * )
											   ( *cinfo->mem->alloc_small )( (j_common_ptr) cinfo, JPOOL_IMAGE,
																			 DCTSIZE2 * SIZEOF( FAST_FLOAT ) );
			}
			fdtbl = fdct->float_divisors[qtblno];
			i = 0;
			for ( row = 0; row < DCTSIZE; row++ ) {
				for ( col = 0; col < DCTSIZE; col++ ) {
					fdtbl[i] = (FAST_FLOAT)
					  ( 1.0 / ( ( (double) qtbl->quantval[jpeg_zigzag_order[i]] *
								  aanscalefactor[row] * aanscalefactor[col] * 8.0 ) ) );
					i++;
				}
			}
		}
		break;
#endif
		default:
			ERREXIT( cinfo, JERR_NOT_COMPILED );
			break;
		}
	}
}

// TTimo unused
#if 0
/*
 * Perform forward DCT on one or more blocks of a component.
 *
 * The input samples are taken from the sample_data[] array starting at
 * position start_row/start_col, and moving to the right for any additional
 * blocks. The quantized coefficients are returned in coef_blocks[].
 */

METHODDEF void
forward_DCT( j_compress_ptr cinfo, jpeg_component_info * compptr,
			 JSAMPARRAY sample_data, JBLOCKROW coef_blocks,
			 JDIMENSION start_row, JDIMENSION start_col,
			 JDIMENSION num_blocks ) {
/* This version is used for integer DCT implementations. */
/* This routine is heavily used, so it's worth coding it tightly. */
	my_fdct_ptr fdct = (my_fdct_ptr) cinfo->fdct;
	forward_DCT_method_ptr do_dct = fdct->do_dct;
	DCTELEM * divisors = fdct->divisors[compptr->quant_tbl_no];
	DCTELEM workspace[DCTSIZE2]; /* work area for FDCT subroutine */
	JDIMENSION bi;

	sample_data += start_row; /* fold in the vertical offset once */

	for ( bi = 0; bi < num_blocks; bi++, start_col += DCTSIZE ) {
		/* Load data into workspace, applying unsigned->signed conversion */
		{ register DCTELEM *workspaceptr;
		  register JSAMPROW elemptr;
		  register int elemr;

		  workspaceptr = workspace;
		  for ( elemr = 0; elemr < DCTSIZE; elemr++ ) {
			  elemptr = sample_data[elemr] + start_col;
#if DCTSIZE == 8        /* unroll the inner loop */
			  *workspaceptr++ = GETJSAMPLE( *elemptr++ ) - CENTERJSAMPLE;
			  *workspaceptr++ = GETJSAMPLE( *elemptr++ ) - CENTERJSAMPLE;
			  *workspaceptr++ = GETJSAMPLE( *elemptr++ ) - CENTERJSAMPLE;
			  *workspaceptr++ = GETJSAMPLE( *elemptr++ ) - CENTERJSAMPLE;
			  *workspaceptr++ = GETJSAMPLE( *elemptr++ ) - CENTERJSAMPLE;
			  *workspaceptr++ = GETJSAMPLE( *elemptr++ ) - CENTERJSAMPLE;
			  *workspaceptr++ = GETJSAMPLE( *elemptr++ ) - CENTERJSAMPLE;
			  *workspaceptr++ = GETJSAMPLE( *elemptr++ ) - CENTERJSAMPLE;
#else
			  { register int elemc;
			for ( elemc = DCTSIZE; elemc > 0; elemc-- ) {
				*workspaceptr++ = GETJSAMPLE( *elemptr++ ) - CENTERJSAMPLE;
			}}
#endif
		  }}

		/* Perform the DCT */
		( *do_dct )( workspace );

		/* Quantize/descale the coefficients, and store into coef_blocks[] */
		{ register DCTELEM temp, qval;
		  register int i;
		  register JCOEFPTR output_ptr = coef_blocks[bi];

		  for ( i = 0; i < DCTSIZE2; i++ ) {
			  qval = divisors[i];
			  temp = workspace[i];
			  /* Divide the coefficient value by qval, ensuring proper rounding.
			   * Since C does not specify the direction of rounding for negative
			   * quotients, we have to force the dividend positive for portability.
			   *
			   * In most files, at least half of the output values will be zero
			   * (at default quantization settings, more like three-quarters...)
			   * so we should ensure that this case is fast.  On many machines,
			   * a comparison is enough cheaper than a divide to make a special test
			   * a win.  Since both inputs will be nonnegative, we need only test
			   * for a < b to discover whether a/b is 0.
			   * If your machine's division is fast enough, define FAST_DIVIDE.
			   */
#ifdef FAST_DIVIDE
#define DIVIDE_BY( a,b )  a /= b
#else
#define DIVIDE_BY( a,b )  if ( a >= b ) {a /= b; \
} else a = 0
#endif
			  if ( temp < 0 ) {
				  temp = -temp;
				  temp += qval >> 1; /* for rounding */
				  DIVIDE_BY( temp, qval );
				  temp = -temp;
			  } else {
				  temp += qval >> 1; /* for rounding */
				  DIVIDE_BY( temp, qval );
			  }
			  output_ptr[i] = (JCOEF) temp;
		  }}
	}
}
#endif

#ifdef DCT_FLOAT_SUPPORTED

METHODDEF void
forward_DCT_float( j_compress_ptr cinfo, jpeg_component_info * compptr,
				   JSAMPARRAY sample_data, JBLOCKROW coef_blocks,
				   JDIMENSION start_row, JDIMENSION start_col,
				   JDIMENSION num_blocks ) {
/* This version is used for floating-point DCT implementations. */
/* This routine is heavily used, so it's worth coding it tightly. */
	my_fdct_ptr fdct = (my_fdct_ptr) cinfo->fdct;
	float_DCT_method_ptr do_dct = fdct->do_float_dct;
	FAST_FLOAT * divisors = fdct->float_divisors[compptr->quant_tbl_no];
	FAST_FLOAT workspace[DCTSIZE2]; /* work area for FDCT subroutine */
	JDIMENSION bi;

	sample_data += start_row; /* fold in the vertical offset once */

	for ( bi = 0; bi < num_blocks; bi++, start_col += DCTSIZE ) {
		/* Load data into workspace, applying unsigned->signed conversion */
		{ register FAST_FLOAT *workspaceptr;
		  register JSAMPROW elemptr;
		  register int elemr;

		  workspaceptr = workspace;
		  for ( elemr = 0; elemr < DCTSIZE; elemr++ ) {
			  elemptr = sample_data[elemr] + start_col;
#if DCTSIZE == 8        /* unroll the inner loop */
			  *workspaceptr++ = (FAST_FLOAT)( GETJSAMPLE( *elemptr++ ) - CENTERJSAMPLE );
			  *workspaceptr++ = (FAST_FLOAT)( GETJSAMPLE( *elemptr++ ) - CENTERJSAMPLE );
			  *workspaceptr++ = (FAST_FLOAT)( GETJSAMPLE( *elemptr++ ) - CENTERJSAMPLE );
			  *workspaceptr++ = (FAST_FLOAT)( GETJSAMPLE( *elemptr++ ) - CENTERJSAMPLE );
			  *workspaceptr++ = (FAST_FLOAT)( GETJSAMPLE( *elemptr++ ) - CENTERJSAMPLE );
			  *workspaceptr++ = (FAST_FLOAT)( GETJSAMPLE( *elemptr++ ) - CENTERJSAMPLE );
			  *workspaceptr++ = (FAST_FLOAT)( GETJSAMPLE( *elemptr++ ) - CENTERJSAMPLE );
			  *workspaceptr++ = (FAST_FLOAT)( GETJSAMPLE( *elemptr++ ) - CENTERJSAMPLE );
#else
			  { register int elemc;
			for ( elemc = DCTSIZE; elemc > 0; elemc-- ) {
				*workspaceptr++ = (FAST_FLOAT)
					  ( GETJSAMPLE( *elemptr++ ) - CENTERJSAMPLE );
			}}
#endif
		  }}

		/* Perform the DCT */
		( *do_dct )( workspace );

		/* Quantize/descale the coefficients, and store into coef_blocks[] */
		{ register FAST_FLOAT temp;
		  register int i;
		  register JCOEFPTR output_ptr = coef_blocks[bi];

		  for ( i = 0; i < DCTSIZE2; i++ ) {
			  /* Apply the quantization and scaling factor */
			  temp = workspace[i] * divisors[i];
			  /* Round to nearest integer.
			   * Since C does not specify the direction of rounding for negative
			   * quotients, we have to force the dividend positive for portability.
			   * The maximum coefficient size is +-16K (for 12-bit data), so this
			   * code should work for either 16-bit or 32-bit ints.
			   */
			  output_ptr[i] = (JCOEF) ( (int) ( temp + (FAST_FLOAT) 16384.5 ) - 16384 );
		  }}
	}
}

#endif /* DCT_FLOAT_SUPPORTED */


/*
 * Initialize FDCT manager.
 */

GLOBAL void
jinit_forward_dct( j_compress_ptr cinfo ) {
	my_fdct_ptr fdct;
	int i;

	fdct = (my_fdct_ptr)
				( *cinfo->mem->alloc_small ) ( (j_common_ptr) cinfo, JPOOL_IMAGE,
											   SIZEOF( my_fdct_controller ) );
	cinfo->fdct = (struct jpeg_forward_dct *) fdct;
	fdct->pub.start_pass = start_pass_fdctmgr;

	switch ( cinfo->dct_method ) {
#ifdef DCT_ISLOW_SUPPORTED
	case JDCT_ISLOW:
		fdct->pub.forward_DCT = forward_DCT;
		fdct->do_dct = jpeg_fdct_islow;
		break;
#endif
#ifdef DCT_IFAST_SUPPORTED
	case JDCT_IFAST:
		fdct->pub.forward_DCT = forward_DCT;
		fdct->do_dct = jpeg_fdct_ifast;
		break;
#endif
#ifdef DCT_FLOAT_SUPPORTED
	case JDCT_FLOAT:
		fdct->pub.forward_DCT = forward_DCT_float;
		fdct->do_float_dct = jpeg_fdct_float;
		break;
#endif
	default:
		ERREXIT( cinfo, JERR_NOT_COMPILED );
		break;
	}

	/* Mark divisor tables unallocated */
	for ( i = 0; i < NUM_QUANT_TBLS; i++ ) {
		fdct->divisors[i] = NULL;
#ifdef DCT_FLOAT_SUPPORTED
		fdct->float_divisors[i] = NULL;
#endif
	}
}
