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384 lines
12 KiB
384 lines
12 KiB
/* |
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* jddctmgr.c |
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* |
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* Copyright (C) 1994-1996, Thomas G. Lane. |
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* Modified 2002-2013 by Guido Vollbeding. |
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* This file is part of the Independent JPEG Group's software. |
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* For conditions of distribution and use, see the accompanying README file. |
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* |
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* This file contains the inverse-DCT management logic. |
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* This code selects a particular IDCT implementation to be used, |
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* and it performs related housekeeping chores. No code in this file |
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* is executed per IDCT step, only during output pass setup. |
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* |
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* Note that the IDCT routines are responsible for performing coefficient |
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* dequantization as well as the IDCT proper. This module sets up the |
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* dequantization multiplier table needed by the IDCT routine. |
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*/ |
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#define JPEG_INTERNALS |
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#include "jinclude.h" |
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#include "jpeglib.h" |
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#include "jdct.h" /* Private declarations for DCT subsystem */ |
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/* |
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* The decompressor input side (jdinput.c) saves away the appropriate |
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* quantization table for each component at the start of the first scan |
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* involving that component. (This is necessary in order to correctly |
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* decode files that reuse Q-table slots.) |
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* When we are ready to make an output pass, the saved Q-table is converted |
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* to a multiplier table that will actually be used by the IDCT routine. |
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* The multiplier table contents are IDCT-method-dependent. To support |
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* application changes in IDCT method between scans, we can remake the |
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* multiplier tables if necessary. |
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* In buffered-image mode, the first output pass may occur before any data |
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* has been seen for some components, and thus before their Q-tables have |
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* been saved away. To handle this case, multiplier tables are preset |
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* to zeroes; the result of the IDCT will be a neutral gray level. |
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*/ |
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/* Private subobject for this module */ |
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typedef struct { |
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struct jpeg_inverse_dct pub; /* public fields */ |
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/* This array contains the IDCT method code that each multiplier table |
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* is currently set up for, or -1 if it's not yet set up. |
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* The actual multiplier tables are pointed to by dct_table in the |
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* per-component comp_info structures. |
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*/ |
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int cur_method[MAX_COMPONENTS]; |
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} my_idct_controller; |
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typedef my_idct_controller * my_idct_ptr; |
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/* Allocated multiplier tables: big enough for any supported variant */ |
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typedef union { |
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ISLOW_MULT_TYPE islow_array[DCTSIZE2]; |
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#ifdef DCT_IFAST_SUPPORTED |
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IFAST_MULT_TYPE ifast_array[DCTSIZE2]; |
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#endif |
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#ifdef DCT_FLOAT_SUPPORTED |
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FLOAT_MULT_TYPE float_array[DCTSIZE2]; |
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#endif |
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} multiplier_table; |
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/* The current scaled-IDCT routines require ISLOW-style multiplier tables, |
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* so be sure to compile that code if either ISLOW or SCALING is requested. |
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*/ |
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#ifdef DCT_ISLOW_SUPPORTED |
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#define PROVIDE_ISLOW_TABLES |
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#else |
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#ifdef IDCT_SCALING_SUPPORTED |
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#define PROVIDE_ISLOW_TABLES |
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#endif |
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#endif |
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/* |
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* Prepare for an output pass. |
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* Here we select the proper IDCT routine for each component and build |
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* a matching multiplier table. |
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*/ |
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METHODDEF(void) |
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start_pass (j_decompress_ptr cinfo) |
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{ |
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my_idct_ptr idct = (my_idct_ptr) cinfo->idct; |
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int ci, i; |
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jpeg_component_info *compptr; |
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int method = 0; |
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inverse_DCT_method_ptr method_ptr = NULL; |
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JQUANT_TBL * qtbl; |
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for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; |
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ci++, compptr++) { |
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/* Select the proper IDCT routine for this component's scaling */ |
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switch ((compptr->DCT_h_scaled_size << 8) + compptr->DCT_v_scaled_size) { |
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#ifdef IDCT_SCALING_SUPPORTED |
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case ((1 << 8) + 1): |
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method_ptr = jpeg_idct_1x1; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((2 << 8) + 2): |
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method_ptr = jpeg_idct_2x2; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((3 << 8) + 3): |
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method_ptr = jpeg_idct_3x3; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((4 << 8) + 4): |
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method_ptr = jpeg_idct_4x4; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((5 << 8) + 5): |
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method_ptr = jpeg_idct_5x5; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((6 << 8) + 6): |
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method_ptr = jpeg_idct_6x6; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((7 << 8) + 7): |
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method_ptr = jpeg_idct_7x7; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((9 << 8) + 9): |
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method_ptr = jpeg_idct_9x9; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((10 << 8) + 10): |
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method_ptr = jpeg_idct_10x10; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((11 << 8) + 11): |
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method_ptr = jpeg_idct_11x11; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((12 << 8) + 12): |
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method_ptr = jpeg_idct_12x12; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((13 << 8) + 13): |
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method_ptr = jpeg_idct_13x13; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((14 << 8) + 14): |
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method_ptr = jpeg_idct_14x14; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((15 << 8) + 15): |
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method_ptr = jpeg_idct_15x15; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((16 << 8) + 16): |
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method_ptr = jpeg_idct_16x16; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((16 << 8) + 8): |
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method_ptr = jpeg_idct_16x8; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((14 << 8) + 7): |
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method_ptr = jpeg_idct_14x7; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((12 << 8) + 6): |
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method_ptr = jpeg_idct_12x6; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((10 << 8) + 5): |
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method_ptr = jpeg_idct_10x5; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((8 << 8) + 4): |
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method_ptr = jpeg_idct_8x4; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((6 << 8) + 3): |
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method_ptr = jpeg_idct_6x3; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((4 << 8) + 2): |
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method_ptr = jpeg_idct_4x2; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((2 << 8) + 1): |
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method_ptr = jpeg_idct_2x1; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((8 << 8) + 16): |
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method_ptr = jpeg_idct_8x16; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((7 << 8) + 14): |
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method_ptr = jpeg_idct_7x14; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((6 << 8) + 12): |
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method_ptr = jpeg_idct_6x12; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((5 << 8) + 10): |
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method_ptr = jpeg_idct_5x10; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((4 << 8) + 8): |
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method_ptr = jpeg_idct_4x8; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((3 << 8) + 6): |
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method_ptr = jpeg_idct_3x6; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((2 << 8) + 4): |
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method_ptr = jpeg_idct_2x4; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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case ((1 << 8) + 2): |
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method_ptr = jpeg_idct_1x2; |
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method = JDCT_ISLOW; /* jidctint uses islow-style table */ |
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break; |
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#endif |
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case ((DCTSIZE << 8) + DCTSIZE): |
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switch (cinfo->dct_method) { |
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#ifdef DCT_ISLOW_SUPPORTED |
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case JDCT_ISLOW: |
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method_ptr = jpeg_idct_islow; |
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method = JDCT_ISLOW; |
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break; |
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#endif |
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#ifdef DCT_IFAST_SUPPORTED |
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case JDCT_IFAST: |
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method_ptr = jpeg_idct_ifast; |
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method = JDCT_IFAST; |
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break; |
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#endif |
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#ifdef DCT_FLOAT_SUPPORTED |
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case JDCT_FLOAT: |
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method_ptr = jpeg_idct_float; |
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method = JDCT_FLOAT; |
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break; |
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#endif |
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default: |
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ERREXIT(cinfo, JERR_NOT_COMPILED); |
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break; |
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} |
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break; |
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default: |
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ERREXIT2(cinfo, JERR_BAD_DCTSIZE, |
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compptr->DCT_h_scaled_size, compptr->DCT_v_scaled_size); |
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break; |
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} |
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idct->pub.inverse_DCT[ci] = method_ptr; |
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/* Create multiplier table from quant table. |
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* However, we can skip this if the component is uninteresting |
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* or if we already built the table. Also, if no quant table |
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* has yet been saved for the component, we leave the |
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* multiplier table all-zero; we'll be reading zeroes from the |
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* coefficient controller's buffer anyway. |
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*/ |
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if (! compptr->component_needed || idct->cur_method[ci] == method) |
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continue; |
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qtbl = compptr->quant_table; |
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if (qtbl == NULL) /* happens if no data yet for component */ |
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continue; |
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idct->cur_method[ci] = method; |
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switch (method) { |
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#ifdef PROVIDE_ISLOW_TABLES |
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case JDCT_ISLOW: |
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{ |
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/* For LL&M IDCT method, multipliers are equal to raw quantization |
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* coefficients, but are stored as ints to ensure access efficiency. |
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*/ |
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ISLOW_MULT_TYPE * ismtbl = (ISLOW_MULT_TYPE *) compptr->dct_table; |
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for (i = 0; i < DCTSIZE2; i++) { |
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ismtbl[i] = (ISLOW_MULT_TYPE) qtbl->quantval[i]; |
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} |
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} |
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break; |
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#endif |
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#ifdef DCT_IFAST_SUPPORTED |
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case JDCT_IFAST: |
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{ |
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/* For AA&N IDCT method, multipliers are equal to quantization |
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* coefficients scaled by scalefactor[row]*scalefactor[col], where |
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* scalefactor[0] = 1 |
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* scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7 |
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* For integer operation, the multiplier table is to be scaled by |
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* IFAST_SCALE_BITS. |
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*/ |
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IFAST_MULT_TYPE * ifmtbl = (IFAST_MULT_TYPE *) compptr->dct_table; |
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#define CONST_BITS 14 |
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static const INT16 aanscales[DCTSIZE2] = { |
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/* precomputed values scaled up by 14 bits */ |
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16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520, |
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22725, 31521, 29692, 26722, 22725, 17855, 12299, 6270, |
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21407, 29692, 27969, 25172, 21407, 16819, 11585, 5906, |
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19266, 26722, 25172, 22654, 19266, 15137, 10426, 5315, |
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16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520, |
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12873, 17855, 16819, 15137, 12873, 10114, 6967, 3552, |
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8867, 12299, 11585, 10426, 8867, 6967, 4799, 2446, |
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4520, 6270, 5906, 5315, 4520, 3552, 2446, 1247 |
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}; |
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SHIFT_TEMPS |
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for (i = 0; i < DCTSIZE2; i++) { |
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ifmtbl[i] = (IFAST_MULT_TYPE) |
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DESCALE(MULTIPLY16V16((INT32) qtbl->quantval[i], |
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(INT32) aanscales[i]), |
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CONST_BITS-IFAST_SCALE_BITS); |
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} |
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} |
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break; |
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#endif |
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#ifdef DCT_FLOAT_SUPPORTED |
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case JDCT_FLOAT: |
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{ |
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/* For float AA&N IDCT method, multipliers are equal to quantization |
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* coefficients scaled by scalefactor[row]*scalefactor[col], where |
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* scalefactor[0] = 1 |
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* scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7 |
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* We apply a further scale factor of 1/8. |
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*/ |
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FLOAT_MULT_TYPE * fmtbl = (FLOAT_MULT_TYPE *) compptr->dct_table; |
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int row, col; |
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static const double aanscalefactor[DCTSIZE] = { |
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1.0, 1.387039845, 1.306562965, 1.175875602, |
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1.0, 0.785694958, 0.541196100, 0.275899379 |
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}; |
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i = 0; |
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for (row = 0; row < DCTSIZE; row++) { |
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for (col = 0; col < DCTSIZE; col++) { |
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fmtbl[i] = (FLOAT_MULT_TYPE) |
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((double) qtbl->quantval[i] * |
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aanscalefactor[row] * aanscalefactor[col] * 0.125); |
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i++; |
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} |
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} |
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} |
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break; |
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#endif |
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default: |
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ERREXIT(cinfo, JERR_NOT_COMPILED); |
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break; |
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} |
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} |
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} |
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/* |
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* Initialize IDCT manager. |
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*/ |
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GLOBAL(void) |
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jinit_inverse_dct (j_decompress_ptr cinfo) |
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{ |
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my_idct_ptr idct; |
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int ci; |
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jpeg_component_info *compptr; |
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idct = (my_idct_ptr) |
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(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
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SIZEOF(my_idct_controller)); |
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cinfo->idct = &idct->pub; |
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idct->pub.start_pass = start_pass; |
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for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; |
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ci++, compptr++) { |
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/* Allocate and pre-zero a multiplier table for each component */ |
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compptr->dct_table = |
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(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
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SIZEOF(multiplier_table)); |
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MEMZERO(compptr->dct_table, SIZEOF(multiplier_table)); |
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/* Mark multiplier table not yet set up for any method */ |
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idct->cur_method[ci] = -1; |
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} |
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}
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