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Diffstat (limited to 'code/jpeg-6b/jcdctmgr.c')
| -rw-r--r-- | code/jpeg-6b/jcdctmgr.c | 389 |
1 files changed, 389 insertions, 0 deletions
diff --git a/code/jpeg-6b/jcdctmgr.c b/code/jpeg-6b/jcdctmgr.c new file mode 100644 index 0000000..94d5cda --- /dev/null +++ b/code/jpeg-6b/jcdctmgr.c @@ -0,0 +1,389 @@ +/* + * 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; + + 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; + } + } +} + + +/* code/jpeg-6b/jcdctmgr.c:184: warning: ‘forward_DCT’ defined but not used */ +#if 0 +/* + * 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; + } + } + } +} +#endif + + +#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 + } +} |