+++ /dev/null
-/*
- * 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
- }
-}
projects / opencv / blobdiff