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