208 lines
5.0 KiB
C
208 lines
5.0 KiB
C
/* ----------------------------------------------------------------------
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* Project: CMSIS DSP Library
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* Title: arm_mfcc_q31.c
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* Description: MFCC function for the q31 version
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*
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* $Date: 07 September 2021
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* $Revision: V1.10.0
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*
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* Target Processor: Cortex-M and Cortex-A cores
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* -------------------------------------------------------------------- */
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/*
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* Copyright (C) 2010-2021 ARM Limited or its affiliates. All rights reserved.
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the License); you may
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* 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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* 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, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "dsp/transform_functions.h"
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#include "dsp/statistics_functions.h"
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#include "dsp/basic_math_functions.h"
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#include "dsp/complex_math_functions.h"
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#include "dsp/fast_math_functions.h"
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#include "dsp/matrix_functions.h"
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/* Constants for Q31 implementation */
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#define LOG2TOLOG_Q31 0x02C5C860
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#define MICRO_Q31 0x08637BD0
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#define SHIFT_MELFILTER_SATURATION_Q31 10
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/**
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@ingroup groupTransforms
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*/
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/**
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@defgroup MFCC MFCC
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MFCC Transform
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There are separate functions for floating-point, Q31, and Q31 data types.
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*/
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/**
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@addtogroup MFCC
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@{
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*/
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/**
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@brief MFCC Q31
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@param[in] S points to the mfcc instance structure
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@param[in] pSrc points to the input samples in Q31
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@param[out] pDst points to the output MFCC values in q8.23 format
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@param[inout] pTmp points to a temporary buffer of complex
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@return none
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@par Description
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The number of input samples is the FFT length used
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when initializing the instance data structure.
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The temporary buffer has a 2*fft length.
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The source buffer is modified by this function.
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The function may saturate. If the FFT length is too
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big and the number of MEL filters too small then the fixed
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point computations may saturate.
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*/
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arm_status arm_mfcc_q31(
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const arm_mfcc_instance_q31 * S,
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q31_t *pSrc,
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q31_t *pDst,
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q31_t *pTmp
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)
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{
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q31_t m;
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uint32_t index;
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uint32_t fftShift=0;
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q31_t logExponent;
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q63_t result;
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arm_matrix_instance_q31 pDctMat;
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uint32_t i;
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uint32_t coefsPos;
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uint32_t filterLimit;
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q31_t *pTmp2=(q31_t*)pTmp;
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arm_status status = ARM_MATH_SUCCESS;
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// q31
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arm_absmax_q31(pSrc,S->fftLen,&m,&index);
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if (m !=0)
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{
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q31_t quotient;
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int16_t shift;
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status = arm_divide_q31(0x7FFFFFFF,m,"ient,&shift);
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if (status != ARM_MATH_SUCCESS)
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{
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return(status);
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}
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arm_scale_q31(pSrc,quotient,shift,pSrc,S->fftLen);
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}
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// q31
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arm_mult_q31(pSrc,S->windowCoefs, pSrc, S->fftLen);
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/* Compute spectrum magnitude
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*/
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fftShift = 31 - __CLZ(S->fftLen);
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#if defined(ARM_MFCC_CFFT_BASED)
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/* some HW accelerator for CMSIS-DSP used in some boards
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are only providing acceleration for CFFT.
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With ARM_MFCC_CFFT_BASED enabled, CFFT is used and the MFCC
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will be accelerated on those boards.
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The default is to use RFFT
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*/
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/* Convert from real to complex */
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for(i=0; i < S->fftLen ; i++)
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{
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pTmp2[2*i] = pSrc[i];
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pTmp2[2*i+1] = 0;
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}
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arm_cfft_q31(&(S->cfft),pTmp2,0,1);
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#else
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/* Default RFFT based implementation */
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arm_rfft_q31(&(S->rfft),pSrc,pTmp2);
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#endif
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filterLimit = 1 + (S->fftLen >> 1);
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// q31 - fftShift
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arm_cmplx_mag_q31(pTmp2,pSrc,filterLimit);
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// q30 - fftShift
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/* Apply MEL filters */
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coefsPos = 0;
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for(i=0; i<S->nbMelFilters; i++)
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{
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arm_dot_prod_q31(pSrc+S->filterPos[i],
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&(S->filterCoefs[coefsPos]),
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S->filterLengths[i],
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&result);
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coefsPos += S->filterLengths[i];
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// q16.48 - fftShift
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result += MICRO_Q31;
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result >>= (SHIFT_MELFILTER_SATURATION_Q31 + 18);
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// q16.29 - fftShift - satShift
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pTmp[i] = __SSAT(result,31) ;
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}
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// q16.29 - fftShift - satShift
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/* Compute the log */
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arm_vlog_q31(pTmp,pTmp,S->nbMelFilters);
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// q5.26
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logExponent = fftShift + 2 + SHIFT_MELFILTER_SATURATION_Q31;
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logExponent = logExponent * LOG2TOLOG_Q31;
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// q5.26
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arm_offset_q31(pTmp,logExponent,pTmp,S->nbMelFilters);
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arm_shift_q31(pTmp,-3,pTmp,S->nbMelFilters);
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// q8.23
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pDctMat.numRows=S->nbDctOutputs;
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pDctMat.numCols=S->nbMelFilters;
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pDctMat.pData=(q31_t*)S->dctCoefs;
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arm_mat_vec_mult_q31(&pDctMat, pTmp, pDst);
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return(status);
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}
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/**
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@} end of MFCC group
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*/
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