mirror of https://github.com/axmolengine/axmol.git
388 lines
12 KiB
C
388 lines
12 KiB
C
/*
|
|
* 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
|
|
}
|
|
}
|