/*
 * jddctmgr.c
 *
 * This file was part of the Independent JPEG Group's software:
 * Copyright (C) 1994-1996, Thomas G. Lane.
 * Modified 2002-2010 by Guido Vollbeding.
 * libjpeg-turbo Modifications:
 * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
 * Copyright (C) 2010, 2015, D. R. Commander.
 * Copyright (C) 2013, MIPS Technologies, Inc., California.
 * For conditions of distribution and use, see the accompanying README.ijg
 * 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 */
#include "jsimddct.h"
#include "jpegcomp.h"


/*
 * 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_scaled_size) {
#ifdef IDCT_SCALING_SUPPORTED
			case 1:
				method_ptr = jpeg_idct_1x1;
				method = JDCT_ISLOW;      /* jidctred uses islow-style table */
				break;
			case 2:
				if (jsimd_can_idct_2x2())
					method_ptr = jsimd_idct_2x2;
				else
					method_ptr = jpeg_idct_2x2;
				method = JDCT_ISLOW;      /* jidctred uses islow-style table */
				break;
			case 3:
				method_ptr = jpeg_idct_3x3;
				method = JDCT_ISLOW;      /* jidctint uses islow-style table */
				break;
			case 4:
				if (jsimd_can_idct_4x4())
					method_ptr = jsimd_idct_4x4;
				else
					method_ptr = jpeg_idct_4x4;
				method = JDCT_ISLOW;      /* jidctred uses islow-style table */
				break;
			case 5:
				method_ptr = jpeg_idct_5x5;
				method = JDCT_ISLOW;      /* jidctint uses islow-style table */
				break;
			case 6:
#if defined(__mips__)
				if (jsimd_can_idct_6x6())
				  method_ptr = jsimd_idct_6x6;
				else
#endif
				method_ptr = jpeg_idct_6x6;
				method = JDCT_ISLOW;      /* jidctint uses islow-style table */
				break;
			case 7:
				method_ptr = jpeg_idct_7x7;
				method = JDCT_ISLOW;      /* jidctint uses islow-style table */
				break;
#endif
			case DCTSIZE:
				switch (cinfo->dct_method) {
#ifdef DCT_ISLOW_SUPPORTED
					case JDCT_ISLOW:
						if (jsimd_can_idct_islow())
							method_ptr = jsimd_idct_islow;
						else
							method_ptr = jpeg_idct_islow;
						method = JDCT_ISLOW;
						break;
#endif
#ifdef DCT_IFAST_SUPPORTED
					case JDCT_IFAST:
						if (jsimd_can_idct_ifast())
							method_ptr = jsimd_idct_ifast;
						else
							method_ptr = jpeg_idct_ifast;
						method = JDCT_IFAST;
						break;
#endif
#ifdef DCT_FLOAT_SUPPORTED
					case JDCT_FLOAT:
						if (jsimd_can_idct_float())
							method_ptr = jsimd_idct_float;
						else
							method_ptr = jpeg_idct_float;
						method = JDCT_FLOAT;
						break;
#endif
					default:
						ERREXIT(cinfo, JERR_NOT_COMPILED);
						break;
				}
				break;
#ifdef IDCT_SCALING_SUPPORTED
			case 9:
				method_ptr = jpeg_idct_9x9;
				method = JDCT_ISLOW;      /* jidctint uses islow-style table */
				break;
			case 10:
				method_ptr = jpeg_idct_10x10;
				method = JDCT_ISLOW;      /* jidctint uses islow-style table */
				break;
			case 11:
				method_ptr = jpeg_idct_11x11;
				method = JDCT_ISLOW;      /* jidctint uses islow-style table */
				break;
			case 12:
#if defined(__mips__)
				if (jsimd_can_idct_12x12())
				  method_ptr = jsimd_idct_12x12;
				else
#endif
				method_ptr = jpeg_idct_12x12;
				method = JDCT_ISLOW;      /* jidctint uses islow-style table */
				break;
			case 13:
				method_ptr = jpeg_idct_13x13;
				method = JDCT_ISLOW;      /* jidctint uses islow-style table */
				break;
			case 14:
				method_ptr = jpeg_idct_14x14;
				method = JDCT_ISLOW;      /* jidctint uses islow-style table */
				break;
			case 15:
				method_ptr = jpeg_idct_15x15;
				method = JDCT_ISLOW;      /* jidctint uses islow-style table */
				break;
			case 16:
				method_ptr = jpeg_idct_16x16;
				method = JDCT_ISLOW;      /* jidctint uses islow-style table */
				break;
#endif
			default:
				ERREXIT1(cinfo, JERR_BAD_DCTSIZE, compptr->_DCT_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((JLONG) qtbl->quantval[i],
							                      (JLONG) 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
				 */
				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]);
						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;
	}
}
