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/*
 * jcdctmgr.c
 *
 * Copyright (C) 1994-1996, Thomas G. Lane.
 * Modified 2003-2013 by Guido Vollbeding.
 * 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[MAX_COMPONENTS];

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

typedef my_fdct_controller * my_fdct_ptr;


/* The allocated post-DCT divisor tables -- big enough for any
 * supported variant and not identical to the quant table entries,
 * because of scaling (especially for an unnormalized DCT) --
 * are pointed to by dct_table in the per-component comp_info
 * structures.  Each table is given in normal array order.
 */

typedef union {
  DCTELEM int_array[DCTSIZE2];
#ifdef DCT_FLOAT_SUPPORTED
  FAST_FLOAT float_array[DCTSIZE2];
#endif
} divisor_table;


/* The current scaled-DCT routines require ISLOW-style divisor tables,
 * so be sure to compile that code if either ISLOW or SCALING is requested.
 */
#ifdef DCT_ISLOW_SUPPORTED
#define PROVIDE_ISLOW_TABLES
#else
#ifdef DCT_SCALING_SUPPORTED
#define PROVIDE_ISLOW_TABLES
#endif
#endif


/*
 * 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[compptr->component_index];
  DCTELEM * divisors = (DCTELEM *) compptr->dct_table;
  DCTELEM workspace[DCTSIZE2];	/* work area for FDCT subroutine */