third_party/libjpeg/jcdctmgr.c - mojo-tools - Git at Google

 /*
  * jcdctmgr.c
  *
  * Copyright (C) 1994-1996, 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.
    */
   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;
   DCTELEM * dtbl;

   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[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 */
 	  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[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[i] *
 		       aanscalefactor[row] * aanscalefactor[col] * 8.0)));
 	    i++;
 	  }
 	}
       }
       break;
 #endif
     default:
       ERREXIT(cinfo, JERR_NOT_COMPILED);
       break;
     }
   }
 }


 /*
  * 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;
       }
     }
   }
 }


 #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
   }
 }
	/*
	* jcdctmgr.c
	*
	* Copyright (C) 1994-1996, 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.
	*/
	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;
	DCTELEM * dtbl;

	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[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(kPI/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 */
	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[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(kPI/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[i] *
	aanscalefactor[row] * aanscalefactor[col] * 8.0)));
	i++;
	}
	}
	}
	break;
	#endif
	default:
	ERREXIT(cinfo, JERR_NOT_COMPILED);
	break;
	}
	}
	}


	/*
	* 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;
	}
	}
	}
	}


	#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
	}
	}