pvmp3_mdct_6.cpp
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/* ------------------------------------------------------------------
* Copyright (C) 1998-2009 PacketVideo
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied.
* See the License for the specific language governing permissions
* and limitations under the License.
* -------------------------------------------------------------------
*/
/*
------------------------------------------------------------------------------
PacketVideo Corp.
MP3 Decoder Library
Filename: mdct_18.cpp
Date: 09/21/2007
------------------------------------------------------------------------------
REVISION HISTORY
Description:
------------------------------------------------------------------------------
INPUT AND OUTPUT DEFINITIONS
Input
int32 vec[], input vector of length 6
int32 *history input for overlap and add, vector updated with
next overlap and add values
Returns
none mdct computation in-place
------------------------------------------------------------------------------
FUNCTION DESCRIPTION
Returns the mdct of length 6 of the input vector, as well as the overlap
vector for next iteration ( on history[])
------------------------------------------------------------------------------
REQUIREMENTS
------------------------------------------------------------------------------
REFERENCES
------------------------------------------------------------------------------
PSEUDO-CODE
------------------------------------------------------------------------------
*/
/*----------------------------------------------------------------------------
; INCLUDES
----------------------------------------------------------------------------*/
#include "pv_mp3dec_fxd_op.h"
#include "pvmp3_mdct_6.h"
/*----------------------------------------------------------------------------
; MACROS
; Define module specific macros here
----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------
; DEFINES
; Include all pre-processor statements here. Include conditional
; compile variables also.
----------------------------------------------------------------------------*/
#define QFORMAT 29
#define Qfmt29(a) (int32)(a*((int32)1<<QFORMAT) + (a>=0?0.5F:-0.5F))
/*----------------------------------------------------------------------------
; LOCAL FUNCTION DEFINITIONS
; Function Prototype declaration
----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------
; LOCAL STORE/BUFFER/POINTER DEFINITIONS
; Variable declaration - defined here and used outside this module
----------------------------------------------------------------------------*/
/*
* (1./(2*cos((pi/(2*N))*(2*i+1)))), N = 12, i = [0:N/2-1]
*/
const int32 cosTerms_1_ov_cos_phi_N6[6] =
{
Qfmt29(0.50431448029008f), Qfmt29(0.54119610014620f),
Qfmt29(0.63023620700513f), Qfmt29(0.82133981585229f),
Qfmt29(1.30656296487638f), Qfmt29(3.83064878777019f)
};
/*----------------------------------------------------------------------------
; EXTERNAL FUNCTION REFERENCES
; Declare functions defined elsewhere and referenced in this module
----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------
; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES
; Declare variables used in this module but defined elsewhere
----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------
; FUNCTION CODE
----------------------------------------------------------------------------*/
void pvmp3_mdct_6(int32 vec[], int32 *history)
{
int32 i;
int32 tmp;
int32 tmp1;
int32 tmp2;
int32 *pt_vec = vec;
int32 *pt_vec_o = vec;
const int32 *pt_cos = cosTerms_1_ov_cos_phi_N6;
for (i = 2; i != 0; i--)
{
tmp = *(pt_vec++);
tmp1 = *(pt_vec++);
tmp2 = *(pt_vec++);
*(pt_vec_o++) = fxp_mul32_Q29(tmp, *(pt_cos++));
*(pt_vec_o++) = fxp_mul32_Q29(tmp1, *(pt_cos++));
*(pt_vec_o++) = fxp_mul32_Q29(tmp2, *(pt_cos++));
}
pvmp3_dct_6(vec); // Even terms
tmp = -(vec[0] + vec[1]);
history[3] = tmp;
history[2] = tmp;
tmp = -(vec[1] + vec[2]);
vec[0] = vec[3] + vec[4];
vec[1] = vec[4] + vec[5];
history[4] = tmp;
history[1] = tmp;
tmp = -(vec[2] + vec[3]);
vec[4] = -vec[1];
history[5] = tmp;
history[0] = tmp;
vec[2] = vec[5];
vec[3] = -vec[5];
vec[5] = -vec[0];
}