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/*
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darco |
56a656 |
* jddctmgr.c
|
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darco |
56a656 |
*
|
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darco |
56a656 |
* Copyright (C) 1994-1996, Thomas G. Lane.
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56a656 |
* This file is part of the Independent JPEG Group's software.
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56a656 |
* For conditions of distribution and use, see the accompanying README file.
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darco |
56a656 |
*
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56a656 |
* This file contains the inverse-DCT management logic.
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56a656 |
* This code selects a particular IDCT implementation to be used,
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darco |
56a656 |
* and it performs related housekeeping chores. No code in this file
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|
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56a656 |
* is executed per IDCT step, only during output pass setup.
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darco |
56a656 |
*
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56a656 |
* Note that the IDCT routines are responsible for performing coefficient
|
|
darco |
56a656 |
* dequantization as well as the IDCT proper. This module sets up the
|
|
darco |
56a656 |
* dequantization multiplier table needed by the IDCT routine.
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darco |
56a656 |
*/
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56a656 |
|
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darco |
56a656 |
#define JPEG_INTERNALS
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56a656 |
#include "jinclude.h"
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56a656 |
#include "jpeglib.h"
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darco |
56a656 |
#include "jdct.h" /* Private declarations for DCT subsystem */
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56a656 |
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56a656 |
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56a656 |
/*
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56a656 |
* The decompressor input side (jdinput.c) saves away the appropriate
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56a656 |
* quantization table for each component at the start of the first scan
|
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darco |
56a656 |
* involving that component. (This is necessary in order to correctly
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56a656 |
* decode files that reuse Q-table slots.)
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56a656 |
* When we are ready to make an output pass, the saved Q-table is converted
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56a656 |
* to a multiplier table that will actually be used by the IDCT routine.
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56a656 |
* The multiplier table contents are IDCT-method-dependent. To support
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56a656 |
* application changes in IDCT method between scans, we can remake the
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* multiplier tables if necessary.
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* In buffered-image mode, the first output pass may occur before any data
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* has been seen for some components, and thus before their Q-tables have
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56a656 |
* been saved away. To handle this case, multiplier tables are preset
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56a656 |
* to zeroes; the result of the IDCT will be a neutral gray level.
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56a656 |
*/
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darco |
56a656 |
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darco |
56a656 |
|
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/* Private subobject for this module */
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typedef struct {
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56a656 |
struct jpeg_inverse_dct pub; /* public fields */
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56a656 |
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/* This array contains the IDCT method code that each multiplier table
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* is currently set up for, or -1 if it's not yet set up.
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* The actual multiplier tables are pointed to by dct_table in the
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56a656 |
* per-component comp_info structures.
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56a656 |
*/
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int cur_method[MAX_COMPONENTS];
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} my_idct_controller;
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56a656 |
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typedef my_idct_controller * my_idct_ptr;
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56a656 |
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56a656 |
|
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darco |
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/* Allocated multiplier tables: big enough for any supported variant */
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56a656 |
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darco |
56a656 |
typedef union {
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56a656 |
ISLOW_MULT_TYPE islow_array[DCTSIZE2];
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56a656 |
#ifdef DCT_IFAST_SUPPORTED
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56a656 |
IFAST_MULT_TYPE ifast_array[DCTSIZE2];
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56a656 |
#endif
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56a656 |
#ifdef DCT_FLOAT_SUPPORTED
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56a656 |
FLOAT_MULT_TYPE float_array[DCTSIZE2];
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56a656 |
#endif
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56a656 |
} multiplier_table;
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|
darco |
56a656 |
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darco |
56a656 |
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56a656 |
/* The current scaled-IDCT routines require ISLOW-style multiplier tables,
|
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56a656 |
* so be sure to compile that code if either ISLOW or SCALING is requested.
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56a656 |
*/
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56a656 |
#ifdef DCT_ISLOW_SUPPORTED
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56a656 |
#define PROVIDE_ISLOW_TABLES
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56a656 |
#else
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darco |
56a656 |
#ifdef IDCT_SCALING_SUPPORTED
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56a656 |
#define PROVIDE_ISLOW_TABLES
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darco |
56a656 |
#endif
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darco |
56a656 |
#endif
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darco |
56a656 |
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darco |
56a656 |
|
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darco |
56a656 |
/*
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* Prepare for an output pass.
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56a656 |
* Here we select the proper IDCT routine for each component and build
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|
darco |
56a656 |
* a matching multiplier table.
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|
darco |
56a656 |
*/
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darco |
56a656 |
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darco |
56a656 |
METHODDEF(void)
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start_pass (j_decompress_ptr cinfo)
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|
darco |
56a656 |
{
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|
darco |
56a656 |
my_idct_ptr idct = (my_idct_ptr) cinfo->idct;
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|
darco |
56a656 |
int ci, i;
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|
darco |
56a656 |
jpeg_component_info *compptr;
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|
darco |
56a656 |
int method = 0;
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darco |
56a656 |
inverse_DCT_method_ptr method_ptr = NULL;
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|
darco |
56a656 |
JQUANT_TBL * qtbl;
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|
darco |
56a656 |
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|
darco |
56a656 |
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
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|
darco |
56a656 |
ci++, compptr++) {
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|
darco |
56a656 |
/* Select the proper IDCT routine for this component's scaling */
|
|
darco |
56a656 |
switch (compptr->DCT_scaled_size) {
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|
darco |
56a656 |
#ifdef IDCT_SCALING_SUPPORTED
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|
darco |
56a656 |
case 1:
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|
darco |
56a656 |
method_ptr = jpeg_idct_1x1;
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|
darco |
56a656 |
method = JDCT_ISLOW; /* jidctred uses islow-style table */
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|
darco |
56a656 |
break;
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|
darco |
56a656 |
case 2:
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|
darco |
56a656 |
method_ptr = jpeg_idct_2x2;
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|
darco |
56a656 |
method = JDCT_ISLOW; /* jidctred uses islow-style table */
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|
darco |
56a656 |
break;
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|
darco |
56a656 |
case 4:
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darco |
56a656 |
method_ptr = jpeg_idct_4x4;
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darco |
56a656 |
method = JDCT_ISLOW; /* jidctred uses islow-style table */
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darco |
56a656 |
break;
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darco |
56a656 |
#endif
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darco |
56a656 |
case DCTSIZE:
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|
darco |
56a656 |
switch (cinfo->dct_method) {
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|
darco |
56a656 |
#ifdef DCT_ISLOW_SUPPORTED
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|
darco |
56a656 |
case JDCT_ISLOW:
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|
darco |
56a656 |
method_ptr = jpeg_idct_islow;
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|
darco |
56a656 |
method = JDCT_ISLOW;
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|
darco |
56a656 |
break;
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|
darco |
56a656 |
#endif
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|
darco |
56a656 |
#ifdef DCT_IFAST_SUPPORTED
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|
darco |
56a656 |
case JDCT_IFAST:
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|
darco |
56a656 |
method_ptr = jpeg_idct_ifast;
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|
darco |
56a656 |
method = JDCT_IFAST;
|
|
darco |
56a656 |
break;
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|
darco |
56a656 |
#endif
|
|
darco |
56a656 |
#ifdef DCT_FLOAT_SUPPORTED
|
|
darco |
56a656 |
case JDCT_FLOAT:
|
|
darco |
56a656 |
method_ptr = jpeg_idct_float;
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|
darco |
56a656 |
method = JDCT_FLOAT;
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darco |
56a656 |
break;
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darco |
56a656 |
#endif
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darco |
56a656 |
default:
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darco |
56a656 |
ERREXIT(cinfo, JERR_NOT_COMPILED);
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darco |
56a656 |
break;
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darco |
56a656 |
}
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darco |
56a656 |
break;
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darco |
56a656 |
default:
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darco |
56a656 |
ERREXIT1(cinfo, JERR_BAD_DCTSIZE, compptr->DCT_scaled_size);
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darco |
56a656 |
break;
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darco |
56a656 |
}
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56a656 |
idct->pub.inverse_DCT[ci] = method_ptr;
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darco |
56a656 |
/* Create multiplier table from quant table.
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darco |
56a656 |
* However, we can skip this if the component is uninteresting
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darco |
56a656 |
* or if we already built the table. Also, if no quant table
|
|
darco |
56a656 |
* has yet been saved for the component, we leave the
|
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darco |
56a656 |
* multiplier table all-zero; we'll be reading zeroes from the
|
|
darco |
56a656 |
* coefficient controller's buffer anyway.
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darco |
56a656 |
*/
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darco |
56a656 |
if (! compptr->component_needed || idct->cur_method[ci] == method)
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darco |
56a656 |
continue;
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|
darco |
56a656 |
qtbl = compptr->quant_table;
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darco |
56a656 |
if (qtbl == NULL) /* happens if no data yet for component */
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darco |
56a656 |
continue;
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|
darco |
56a656 |
idct->cur_method[ci] = method;
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|
darco |
56a656 |
switch (method) {
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|
darco |
56a656 |
#ifdef PROVIDE_ISLOW_TABLES
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|
darco |
56a656 |
case JDCT_ISLOW:
|
|
darco |
56a656 |
{
|
|
darco |
56a656 |
/* For LL&M IDCT method, multipliers are equal to raw quantization
|
|
darco |
56a656 |
* coefficients, but are stored as ints to ensure access efficiency.
|
|
darco |
56a656 |
*/
|
|
darco |
56a656 |
ISLOW_MULT_TYPE * ismtbl = (ISLOW_MULT_TYPE *) compptr->dct_table;
|
|
darco |
56a656 |
for (i = 0; i < DCTSIZE2; i++) {
|
|
darco |
56a656 |
ismtbl[i] = (ISLOW_MULT_TYPE) qtbl->quantval[i];
|
|
darco |
56a656 |
}
|
|
darco |
56a656 |
}
|
|
darco |
56a656 |
break;
|
|
darco |
56a656 |
#endif
|
|
darco |
56a656 |
#ifdef DCT_IFAST_SUPPORTED
|
|
darco |
56a656 |
case JDCT_IFAST:
|
|
darco |
56a656 |
{
|
|
darco |
56a656 |
/* For AA&N IDCT method, multipliers are equal to quantization
|
|
darco |
56a656 |
* coefficients scaled by scalefactor[row]*scalefactor[col], where
|
|
darco |
56a656 |
* scalefactor[0] = 1
|
|
darco |
56a656 |
* scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7
|
|
darco |
56a656 |
* For integer operation, the multiplier table is to be scaled by
|
|
darco |
56a656 |
* IFAST_SCALE_BITS.
|
|
darco |
56a656 |
*/
|
|
darco |
56a656 |
IFAST_MULT_TYPE * ifmtbl = (IFAST_MULT_TYPE *) compptr->dct_table;
|
|
darco |
56a656 |
#define CONST_BITS 14
|
|
darco |
56a656 |
static const INT16 aanscales[DCTSIZE2] = {
|
|
darco |
56a656 |
/* precomputed values scaled up by 14 bits */
|
|
darco |
56a656 |
16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520,
|
|
darco |
56a656 |
22725, 31521, 29692, 26722, 22725, 17855, 12299, 6270,
|
|
darco |
56a656 |
21407, 29692, 27969, 25172, 21407, 16819, 11585, 5906,
|
|
darco |
56a656 |
19266, 26722, 25172, 22654, 19266, 15137, 10426, 5315,
|
|
darco |
56a656 |
16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520,
|
|
darco |
56a656 |
12873, 17855, 16819, 15137, 12873, 10114, 6967, 3552,
|
|
darco |
56a656 |
8867, 12299, 11585, 10426, 8867, 6967, 4799, 2446,
|
|
darco |
56a656 |
4520, 6270, 5906, 5315, 4520, 3552, 2446, 1247
|
|
darco |
56a656 |
};
|
|
darco |
56a656 |
SHIFT_TEMPS
|
|
darco |
56a656 |
|
|
darco |
56a656 |
for (i = 0; i < DCTSIZE2; i++) {
|
|
darco |
56a656 |
ifmtbl[i] = (IFAST_MULT_TYPE)
|
|
darco |
56a656 |
DESCALE(MULTIPLY16V16((INT32) qtbl->quantval[i],
|
|
darco |
56a656 |
(INT32) aanscales[i]),
|
|
darco |
56a656 |
CONST_BITS-IFAST_SCALE_BITS);
|
|
darco |
56a656 |
}
|
|
darco |
56a656 |
}
|
|
darco |
56a656 |
break;
|
|
darco |
56a656 |
#endif
|
|
darco |
56a656 |
#ifdef DCT_FLOAT_SUPPORTED
|
|
darco |
56a656 |
case JDCT_FLOAT:
|
|
darco |
56a656 |
{
|
|
darco |
56a656 |
/* For float AA&N IDCT method, multipliers are equal to quantization
|
|
darco |
56a656 |
* coefficients scaled by scalefactor[row]*scalefactor[col], where
|
|
darco |
56a656 |
* scalefactor[0] = 1
|
|
darco |
56a656 |
* scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7
|
|
darco |
56a656 |
*/
|
|
darco |
56a656 |
FLOAT_MULT_TYPE * fmtbl = (FLOAT_MULT_TYPE *) compptr->dct_table;
|
|
darco |
56a656 |
int row, col;
|
|
darco |
56a656 |
static const double aanscalefactor[DCTSIZE] = {
|
|
darco |
56a656 |
1.0, 1.387039845, 1.306562965, 1.175875602,
|
|
darco |
56a656 |
1.0, 0.785694958, 0.541196100, 0.275899379
|
|
darco |
56a656 |
};
|
|
darco |
56a656 |
|
|
darco |
56a656 |
i = 0;
|
|
darco |
56a656 |
for (row = 0; row < DCTSIZE; row++) {
|
|
darco |
56a656 |
for (col = 0; col < DCTSIZE; col++) {
|
|
darco |
56a656 |
fmtbl[i] = (FLOAT_MULT_TYPE)
|
|
darco |
56a656 |
((double) qtbl->quantval[i] *
|
|
darco |
56a656 |
aanscalefactor[row] * aanscalefactor[col]);
|
|
darco |
56a656 |
i++;
|
|
darco |
56a656 |
}
|
|
darco |
56a656 |
}
|
|
darco |
56a656 |
}
|
|
darco |
56a656 |
break;
|
|
darco |
56a656 |
#endif
|
|
darco |
56a656 |
default:
|
|
darco |
56a656 |
ERREXIT(cinfo, JERR_NOT_COMPILED);
|
|
darco |
56a656 |
break;
|
|
darco |
56a656 |
}
|
|
darco |
56a656 |
}
|
|
darco |
56a656 |
}
|
|
darco |
56a656 |
|
|
darco |
56a656 |
|
|
darco |
56a656 |
/*
|
|
darco |
56a656 |
* Initialize IDCT manager.
|
|
darco |
56a656 |
*/
|
|
darco |
56a656 |
|
|
darco |
56a656 |
GLOBAL(void)
|
|
darco |
56a656 |
jinit_inverse_dct (j_decompress_ptr cinfo)
|
|
darco |
56a656 |
{
|
|
darco |
56a656 |
my_idct_ptr idct;
|
|
darco |
56a656 |
int ci;
|
|
darco |
56a656 |
jpeg_component_info *compptr;
|
|
darco |
56a656 |
|
|
darco |
56a656 |
idct = (my_idct_ptr)
|
|
darco |
56a656 |
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
|
|
darco |
56a656 |
SIZEOF(my_idct_controller));
|
|
darco |
56a656 |
cinfo->idct = (struct jpeg_inverse_dct *) idct;
|
|
darco |
56a656 |
idct->pub.start_pass = start_pass;
|
|
darco |
56a656 |
|
|
darco |
56a656 |
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
|
|
darco |
56a656 |
ci++, compptr++) {
|
|
darco |
56a656 |
/* Allocate and pre-zero a multiplier table for each component */
|
|
darco |
56a656 |
compptr->dct_table =
|
|
darco |
56a656 |
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
|
|
darco |
56a656 |
SIZEOF(multiplier_table));
|
|
darco |
56a656 |
MEMZERO(compptr->dct_table, SIZEOF(multiplier_table));
|
|
darco |
56a656 |
/* Mark multiplier table not yet set up for any method */
|
|
darco |
56a656 |
idct->cur_method[ci] = -1;
|
|
darco |
56a656 |
}
|
|
darco |
56a656 |
}
|