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