/*

* jddctmgr.c

*

* Copyright (C) 1994-1996, Thomas G. Lane.

* Modified 2002-2010 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 inverse-DCT management logic.

* This code selects a particular IDCT implementation to be used,

* and it performs related housekeeping chores. No code in this file

* is executed per IDCT step, only during output pass setup.

*

* Note that the IDCT routines are responsible for performing coefficient

* dequantization as well as the IDCT proper. This module sets up the

* dequantization multiplier table needed by the IDCT routine.

*/

#define JPEG_INTERNALS

#include "jinclude.h"

#include "jpeglib.h"

#include "jdct.h" /* Private declarations for DCT subsystem */

/*

* The decompressor input side (jdinput.c) saves away the appropriate

* quantization table for each component at the start of the first scan

* involving that component. (This is necessary in order to correctly

* decode files that reuse Q-table slots.)

* When we are ready to make an output pass, the saved Q-table is converted

* to a multiplier table that will actually be used by the IDCT routine.

* The multiplier table contents are IDCT-method-dependent. To support

* application changes in IDCT method between scans, we can remake the

* multiplier tables if necessary.

* In buffered-image mode, the first output pass may occur before any data

* has been seen for some components, and thus before their Q-tables have

* been saved away. To handle this case, multiplier tables are preset

* to zeroes; the result of the IDCT will be a neutral gray level.

*/

/* Private subobject for this module */

typedef struct {

struct jpeg_inverse_dct pub; /* public fields */

/* This array contains the IDCT method code that each multiplier table

* is currently set up for, or -1 if it's not yet set up.

* The actual multiplier tables are pointed to by dct_table in the

* per-component comp_info structures.

*/

int cur_method[MAX_COMPONENTS];

} my_idct_controller;

typedef my_idct_controller * my_idct_ptr;

/* Allocated multiplier tables: big enough for any supported variant */

typedef union {

ISLOW_MULT_TYPE islow_array[DCTSIZE2];

#ifdef DCT_IFAST_SUPPORTED

IFAST_MULT_TYPE ifast_array[DCTSIZE2];

#endif

#ifdef DCT_FLOAT_SUPPORTED

FLOAT_MULT_TYPE float_array[DCTSIZE2];

#endif

} multiplier_table;

/* The current scaled-IDCT routines require ISLOW-style multiplier 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 IDCT_SCALING_SUPPORTED

#define PROVIDE_ISLOW_TABLES

#endif

#endif

/*

* Prepare for an output pass.

* Here we select the proper IDCT routine for each component and build

* a matching multiplier table.

*/

METHODDEF(void)

start_pass (j_decompress_ptr cinfo)

{

my_idct_ptr idct = (my_idct_ptr) cinfo->idct;

int ci, i;

jpeg_component_info *compptr;

int method = 0;

inverse_DCT_method_ptr method_ptr = NULL;

JQUANT_TBL * qtbl;

for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;

ci++, compptr++) {

/* Select the proper IDCT routine for this component's scaling */

switch ((compptr->DCT_h_scaled_size << 8) + compptr->DCT_v_scaled_size) {

#ifdef IDCT_SCALING_SUPPORTED

case ((1 << 8) + 1):

method_ptr = jpeg_idct_1x1;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((2 << 8) + 2):

method_ptr = jpeg_idct_2x2;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((3 << 8) + 3):

method_ptr = jpeg_idct_3x3;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((4 << 8) + 4):

method_ptr = jpeg_idct_4x4;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((5 << 8) + 5):

method_ptr = jpeg_idct_5x5;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((6 << 8) + 6):

method_ptr = jpeg_idct_6x6;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((7 << 8) + 7):

method_ptr = jpeg_idct_7x7;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((9 << 8) + 9):

method_ptr = jpeg_idct_9x9;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((10 << 8) + 10):

method_ptr = jpeg_idct_10x10;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((11 << 8) + 11):

method_ptr = jpeg_idct_11x11;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((12 << 8) + 12):

method_ptr = jpeg_idct_12x12;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((13 << 8) + 13):

method_ptr = jpeg_idct_13x13;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((14 << 8) + 14):

method_ptr = jpeg_idct_14x14;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((15 << 8) + 15):

method_ptr = jpeg_idct_15x15;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((16 << 8) + 16):

method_ptr = jpeg_idct_16x16;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((16 << 8) + 8):

method_ptr = jpeg_idct_16x8;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((14 << 8) + 7):

method_ptr = jpeg_idct_14x7;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((12 << 8) + 6):

method_ptr = jpeg_idct_12x6;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((10 << 8) + 5):

method_ptr = jpeg_idct_10x5;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((8 << 8) + 4):

method_ptr = jpeg_idct_8x4;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((6 << 8) + 3):

method_ptr = jpeg_idct_6x3;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((4 << 8) + 2):

method_ptr = jpeg_idct_4x2;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((2 << 8) + 1):

method_ptr = jpeg_idct_2x1;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((8 << 8) + 16):

method_ptr = jpeg_idct_8x16;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((7 << 8) + 14):

method_ptr = jpeg_idct_7x14;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((6 << 8) + 12):

method_ptr = jpeg_idct_6x12;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((5 << 8) + 10):

method_ptr = jpeg_idct_5x10;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((4 << 8) + 8):

method_ptr = jpeg_idct_4x8;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((3 << 8) + 6):

method_ptr = jpeg_idct_3x6;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((2 << 8) + 4):

method_ptr = jpeg_idct_2x4;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

case ((1 << 8) + 2):

method_ptr = jpeg_idct_1x2;

method = JDCT_ISLOW; /* jidctint uses islow-style table */

break;

#endif

case ((DCTSIZE << 8) + DCTSIZE):

switch (cinfo->dct_method) {

#ifdef DCT_ISLOW_SUPPORTED

case JDCT_ISLOW:

method_ptr = jpeg_idct_islow;

method = JDCT_ISLOW;

break;

#endif

#ifdef DCT_IFAST_SUPPORTED

case JDCT_IFAST:

method_ptr = jpeg_idct_ifast;

method = JDCT_IFAST;

break;

#endif

#ifdef DCT_FLOAT_SUPPORTED

case JDCT_FLOAT:

method_ptr = jpeg_idct_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;

}

idct->pub.inverse_DCT[ci] = method_ptr;

/* Create multiplier table from quant table.

* However, we can skip this if the component is uninteresting

* or if we already built the table. Also, if no quant table

* has yet been saved for the component, we leave the

* multiplier table all-zero; we'll be reading zeroes from the

* coefficient controller's buffer anyway.

*/

if (! compptr->component_needed || idct->cur_method[ci] == method)

continue;

qtbl = compptr->quant_table;

if (qtbl == NULL) /* happens if no data yet for component */

continue;

idct->cur_method[ci] = method;

switch (method) {

#ifdef PROVIDE_ISLOW_TABLES

case JDCT_ISLOW:

{

/* For LL&M IDCT method, multipliers are equal to raw quantization

* coefficients, but are stored as ints to ensure access efficiency.

*/

ISLOW_MULT_TYPE * ismtbl = (ISLOW_MULT_TYPE *) compptr->dct_table;

for (i = 0; i < DCTSIZE2; i++) {

ismtbl[i] = (ISLOW_MULT_TYPE) qtbl->quantval[i];

}

}

break;

#endif

#ifdef DCT_IFAST_SUPPORTED

case JDCT_IFAST:

{

/* For AA&N IDCT method, multipliers 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

* For integer operation, the multiplier table is to be scaled by

* IFAST_SCALE_BITS.

*/

IFAST_MULT_TYPE * ifmtbl = (IFAST_MULT_TYPE *) compptr->dct_table;

#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

for (i = 0; i < DCTSIZE2; i++) {

ifmtbl[i] = (IFAST_MULT_TYPE)

DESCALE(MULTIPLY16V16((INT32) qtbl->quantval[i],

(INT32) aanscales[i]),

CONST_BITS-IFAST_SCALE_BITS);

}

}

break;

#endif

#ifdef DCT_FLOAT_SUPPORTED

case JDCT_FLOAT:

{

/* For float AA&N IDCT method, multipliers 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 1/8.

*/

FLOAT_MULT_TYPE * fmtbl = (FLOAT_MULT_TYPE *) 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++) {

fmtbl[i] = (FLOAT_MULT_TYPE)

((double) qtbl->quantval[i] *

aanscalefactor[row] * aanscalefactor[col] * 0.125);

i++;

}

}

}

break;

#endif

default:

ERREXIT(cinfo, JERR_NOT_COMPILED);

break;

}

}

}

/*

* Initialize IDCT manager.

*/

GLOBAL(void)

jinit_inverse_dct (j_decompress_ptr cinfo)

{

my_idct_ptr idct;

int ci;

jpeg_component_info *compptr;

idct = (my_idct_ptr)

(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,

SIZEOF(my_idct_controller));

cinfo->idct = (struct jpeg_inverse_dct *) idct;

idct->pub.start_pass = start_pass;

for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;

ci++, compptr++) {

/* Allocate and pre-zero a multiplier table for each component */

compptr->dct_table =

(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,

SIZEOF(multiplier_table));

MEMZERO(compptr->dct_table, SIZEOF(multiplier_table));

/* Mark multiplier table not yet set up for any method */

idct->cur_method[ci] = -1;

}

}