ref: 2c23de27d5006e969106fad672399fafe6464845
dir: /DoConfig/fltk/jpeg/jcdctmgr.c/
/* * 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 */ JDIMENSION bi; sample_data += start_row; /* fold in the vertical offset once */ for (bi = 0; bi < num_blocks; bi++, start_col += compptr->DCT_h_scaled_size) { /* Perform the DCT */ (*do_dct) (workspace, sample_data, start_col); /* 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[compptr->component_index]; FAST_FLOAT * divisors = (FAST_FLOAT *) compptr->dct_table; 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 += compptr->DCT_h_scaled_size) { /* Perform the DCT */ (*do_dct) (workspace, sample_data, start_col); /* 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 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; int method = 0; JQUANT_TBL * qtbl; DCTELEM * dtbl; for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; ci++, compptr++) { /* Select the proper DCT routine for this component's scaling */ switch ((compptr->DCT_h_scaled_size << 8) + compptr->DCT_v_scaled_size) { #ifdef DCT_SCALING_SUPPORTED case ((1 << 8) + 1): fdct->do_dct[ci] = jpeg_fdct_1x1; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((2 << 8) + 2): fdct->do_dct[ci] = jpeg_fdct_2x2; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((3 << 8) + 3): fdct->do_dct[ci] = jpeg_fdct_3x3; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((4 << 8) + 4): fdct->do_dct[ci] = jpeg_fdct_4x4; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((5 << 8) + 5): fdct->do_dct[ci] = jpeg_fdct_5x5; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((6 << 8) + 6): fdct->do_dct[ci] = jpeg_fdct_6x6; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((7 << 8) + 7): fdct->do_dct[ci] = jpeg_fdct_7x7; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((9 << 8) + 9): fdct->do_dct[ci] = jpeg_fdct_9x9; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((10 << 8) + 10): fdct->do_dct[ci] = jpeg_fdct_10x10; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((11 << 8) + 11): fdct->do_dct[ci] = jpeg_fdct_11x11; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((12 << 8) + 12): fdct->do_dct[ci] = jpeg_fdct_12x12; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((13 << 8) + 13): fdct->do_dct[ci] = jpeg_fdct_13x13; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((14 << 8) + 14): fdct->do_dct[ci] = jpeg_fdct_14x14; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((15 << 8) + 15): fdct->do_dct[ci] = jpeg_fdct_15x15; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((16 << 8) + 16): fdct->do_dct[ci] = jpeg_fdct_16x16; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((16 << 8) + 8): fdct->do_dct[ci] = jpeg_fdct_16x8; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((14 << 8) + 7): fdct->do_dct[ci] = jpeg_fdct_14x7; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((12 << 8) + 6): fdct->do_dct[ci] = jpeg_fdct_12x6; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((10 << 8) + 5): fdct->do_dct[ci] = jpeg_fdct_10x5; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((8 << 8) + 4): fdct->do_dct[ci] = jpeg_fdct_8x4; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((6 << 8) + 3): fdct->do_dct[ci] = jpeg_fdct_6x3; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((4 << 8) + 2): fdct->do_dct[ci] = jpeg_fdct_4x2; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((2 << 8) + 1): fdct->do_dct[ci] = jpeg_fdct_2x1; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((8 << 8) + 16): fdct->do_dct[ci] = jpeg_fdct_8x16; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((7 << 8) + 14): fdct->do_dct[ci] = jpeg_fdct_7x14; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((6 << 8) + 12): fdct->do_dct[ci] = jpeg_fdct_6x12; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((5 << 8) + 10): fdct->do_dct[ci] = jpeg_fdct_5x10; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((4 << 8) + 8): fdct->do_dct[ci] = jpeg_fdct_4x8; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((3 << 8) + 6): fdct->do_dct[ci] = jpeg_fdct_3x6; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((2 << 8) + 4): fdct->do_dct[ci] = jpeg_fdct_2x4; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; case ((1 << 8) + 2): fdct->do_dct[ci] = jpeg_fdct_1x2; method = JDCT_ISLOW; /* jfdctint uses islow-style table */ break; #endif case ((DCTSIZE << 8) + DCTSIZE): switch (cinfo->dct_method) { #ifdef DCT_ISLOW_SUPPORTED case JDCT_ISLOW: fdct->do_dct[ci] = jpeg_fdct_islow; method = JDCT_ISLOW; break; #endif #ifdef DCT_IFAST_SUPPORTED case JDCT_IFAST: fdct->do_dct[ci] = jpeg_fdct_ifast; method = JDCT_IFAST; break; #endif #ifdef DCT_FLOAT_SUPPORTED case JDCT_FLOAT: fdct->do_float_dct[ci] = jpeg_fdct_float; method = JDCT_FLOAT; break; #endif default: ERREXIT(cinfo, JERR_NOT_COMPILED); break; } break; default: ERREXIT2(cinfo, JERR_BAD_DCTSIZE, compptr->DCT_h_scaled_size, compptr->DCT_v_scaled_size); break; } 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]; /* Create divisor table from quant table */ switch (method) { #ifdef PROVIDE_ISLOW_TABLES case JDCT_ISLOW: /* For LL&M IDCT method, divisors are equal to raw quantization * coefficients multiplied by 8 (to counteract scaling). */ dtbl = (DCTELEM *) compptr->dct_table; for (i = 0; i < DCTSIZE2; i++) { dtbl[i] = ((DCTELEM) qtbl->quantval[i]) << (compptr->component_needed ? 4 : 3); } fdct->pub.forward_DCT[ci] = forward_DCT; 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 dtbl = (DCTELEM *) compptr->dct_table; for (i = 0; i < DCTSIZE2; i++) { dtbl[i] = (DCTELEM) DESCALE(MULTIPLY16V16((INT32) qtbl->quantval[i], (INT32) aanscales[i]), compptr->component_needed ? CONST_BITS-4 : CONST_BITS-3); } } fdct->pub.forward_DCT[ci] = forward_DCT; 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 = (FAST_FLOAT *) 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++) { fdtbl[i] = (FAST_FLOAT) (1.0 / ((double) qtbl->quantval[i] * aanscalefactor[row] * aanscalefactor[col] * (compptr->component_needed ? 16.0 : 8.0))); i++; } } } fdct->pub.forward_DCT[ci] = forward_DCT_float; break; #endif default: ERREXIT(cinfo, JERR_NOT_COMPILED); break; } } } /* * Initialize FDCT manager. */ GLOBAL(void) jinit_forward_dct (j_compress_ptr cinfo) { my_fdct_ptr fdct; int ci; jpeg_component_info *compptr; fdct = (my_fdct_ptr) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, SIZEOF(my_fdct_controller)); cinfo->fdct = &fdct->pub; fdct->pub.start_pass = start_pass_fdctmgr; for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; ci++, compptr++) { /* Allocate a divisor table for each component */ compptr->dct_table = (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, SIZEOF(divisor_table)); } }