    /*
     * 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 short 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((long) qtbl->quantval[i],
    				  (long) 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
      }
    }