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+/*
+ * 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;
+ }
+}
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