221 lines
6.4 KiB
C
221 lines
6.4 KiB
C
/*
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* g722_1 - a library for the G.722.1 and Annex C codecs
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*
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* dct4.c
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*
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* Adapted by Steve Underwood <steveu@coppice.org> from the reference
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* code supplied with ITU G.722.1, which is:
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*
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* © 2004 Polycom, Inc.
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* All rights reserved.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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*
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* $Id: dct4.c,v 1.8 2008/09/29 16:09:26 steveu Exp $
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*/
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#if defined(HAVE_CONFIG_H)
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#include <config.h>
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#endif
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#include <inttypes.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <math.h>
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#include <memory.h>
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#include "g722_1/g722_1.h"
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#include "defs.h"
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#if !defined(G722_1_USE_FIXED_POINT)
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typedef struct
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{
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float cosine;
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float minus_sine;
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} cos_msin_t;
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#include "dct4.h"
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static const cos_msin_t *cos_msin_table[] =
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{
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cos_msin_5,
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cos_msin_10,
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cos_msin_20,
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cos_msin_40,
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cos_msin_80,
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cos_msin_160,
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cos_msin_320,
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cos_msin_640
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};
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/*********************************************************************************
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Description: Discrete Cosine Transform, Type IV
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*********************************************************************************/
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void dct_type_iv(float input[], float output[], int dct_length)
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{
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float buffer_a[MAX_DCT_LENGTH];
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float buffer_b[MAX_DCT_LENGTH];
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float buffer_c[MAX_DCT_LENGTH];
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float *in_ptr;
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float *in_ptr_low;
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float *in_ptr_high;
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float *next_in_base;
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float *out_ptr_low;
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float *out_ptr_high;
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float *next_out_base;
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float *out_buffer;
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float *in_buffer;
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float *buffer_swap;
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float *fptr0;
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const float *fptr2;
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const float *core_a;
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float in_val_low;
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float in_val_high;
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float cos_even;
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float cos_odd;
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float msin_even;
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float msin_odd;
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float sum;
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const cos_msin_t **table_ptr_ptr;
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const cos_msin_t *cos_msin_ptr;
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int set_span;
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int set_count;
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int set_count_log;
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int pairs_left;
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int sets_left;
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int i;
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int k;
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int dct_length_log;
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if (dct_length == MAX_DCT_LENGTH)
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{
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core_a = max_dct_core_a;
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dct_length_log = MAX_DCT_LENGTH_LOG;
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}
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else
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{
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core_a = dct_core_a;
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dct_length_log = DCT_LENGTH_LOG;
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}
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/* Do the sum/difference butterflies, the first part of
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converting one N-point transform into N/2 two-point
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transforms, where N = 1 << dct_length_log. */
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in_buffer = input;
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out_buffer = buffer_a;
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for (set_count_log = 0; set_count_log <= dct_length_log - 2; set_count_log++)
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{
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/* Initialization for the loop over sets at the current size */
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set_span = dct_length >> set_count_log;
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set_count = 1 << set_count_log;
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in_ptr = in_buffer;
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next_out_base = out_buffer;
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/* Loop over all the sets of this size */
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for (sets_left = set_count; sets_left > 0; sets_left--)
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{
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/* Set up output pointers for the current set */
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out_ptr_low = next_out_base;
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next_out_base += set_span;
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out_ptr_high = next_out_base;
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/* Loop over all the butterflies in the current set */
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do
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{
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in_val_low = *in_ptr++;
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in_val_high = *in_ptr++;
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*out_ptr_low++ = in_val_low + in_val_high;
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*--out_ptr_high = in_val_low - in_val_high;
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}
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while (out_ptr_low < out_ptr_high);
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}
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/* Decide which buffers to use as input and output next time.
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Except for the first time (when the input buffer is the
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subroutine input) we just alternate the local buffers. */
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in_buffer = out_buffer;
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if (out_buffer == buffer_a)
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out_buffer = buffer_b;
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else
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out_buffer = buffer_a;
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}
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/* Do dct_size/10 ten-point transforms */
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fptr0 = in_buffer;
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buffer_swap = buffer_c;
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for (pairs_left = 1 << (dct_length_log - 1); pairs_left > 0; pairs_left--)
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{
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fptr2 = core_a;
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for (k = 0; k < CORE_SIZE; k++)
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{
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sum = 0;
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for (i = 0; i < CORE_SIZE; i++)
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sum += fptr0[i]*fptr2[i];
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fptr2 += CORE_SIZE;
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buffer_swap[k] = sum;
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}
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fptr0 += CORE_SIZE;
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buffer_swap += CORE_SIZE;
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}
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memcpy(in_buffer, buffer_c, dct_length*sizeof(float));
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table_ptr_ptr = cos_msin_table;
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/* Perform rotation butterflies */
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for (set_count_log = dct_length_log - 2; set_count_log >= 0; set_count_log--)
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{
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/* Initialization for the loop over sets at the current size */
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set_span = dct_length >> set_count_log;
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set_count = 1 << set_count_log;
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next_in_base = in_buffer;
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if (set_count_log == 0)
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next_out_base = output;
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else
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next_out_base = out_buffer;
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++table_ptr_ptr;
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/* Loop over all the sets of this size */
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for (sets_left = set_count; sets_left > 0; sets_left--)
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{
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/* Set up the pointers for the current set */
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in_ptr_low = next_in_base;
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in_ptr_high = in_ptr_low + (set_span >> 1);
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next_in_base += set_span;
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out_ptr_low = next_out_base;
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next_out_base += set_span;
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out_ptr_high = next_out_base;
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cos_msin_ptr = *table_ptr_ptr;
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/* Loop over all the butterfly pairs in the current set */
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do
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{
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cos_even = (*cos_msin_ptr).cosine;
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msin_even = (*cos_msin_ptr++).minus_sine;
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*out_ptr_low++ = cos_even * *in_ptr_low - msin_even * *in_ptr_high;
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*--out_ptr_high = msin_even * *in_ptr_low++ + cos_even * *in_ptr_high++;
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cos_odd = (*cos_msin_ptr).cosine;
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msin_odd = (*cos_msin_ptr++).minus_sine;
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*out_ptr_low++ = cos_odd * *in_ptr_low + msin_odd * *in_ptr_high;
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*--out_ptr_high = msin_odd * *in_ptr_low++ - cos_odd * *in_ptr_high++;
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}
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while (out_ptr_low < out_ptr_high);
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}
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/* Swap input and output buffers for next time */
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buffer_swap = in_buffer;
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in_buffer = out_buffer;
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out_buffer = buffer_swap;
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}
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}
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/*- End of function --------------------------------------------------------*/
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#endif
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/*- End of file ------------------------------------------------------------*/
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