/*

* 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[MAX_COMPONENTS];

/* 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[MAX_COMPONENTS];

FAST_FLOAT * float_divisors[NUM_QUANT_TBLS];

#endif

} my_fdct_controller;

typedef my_fdct_controller * my_fdct_ptr;

/* 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 = 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 += 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 = 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 += 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];

/* Compute divisors for this quant table */

/* We may do this more than once for same table, but it's not a big deal */

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).

*/

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;

}

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

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);

}

}

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;

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++;

}

}

}

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 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;

/* 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

}

}