1 /* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_mfcc_q31.c
4 * Description: MFCC function for the q31 version
5 *
6 * $Date: 07 September 2021
7 * $Revision: V1.10.0
8 *
9 * Target Processor: Cortex-M and Cortex-A cores
10 * -------------------------------------------------------------------- */
11 /*
12 * Copyright (C) 2010-2021 ARM Limited or its affiliates. All rights reserved.
13 *
14 * SPDX-License-Identifier: Apache-2.0
15 *
16 * Licensed under the Apache License, Version 2.0 (the License); you may
17 * not use this file except in compliance with the License.
18 * You may obtain a copy of the License at
19 *
20 * www.apache.org/licenses/LICENSE-2.0
21 *
22 * Unless required by applicable law or agreed to in writing, software
23 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
24 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
25 * See the License for the specific language governing permissions and
26 * limitations under the License.
27 */
28
29
30
31 #include "dsp/transform_functions.h"
32 #include "dsp/statistics_functions.h"
33 #include "dsp/basic_math_functions.h"
34 #include "dsp/complex_math_functions.h"
35 #include "dsp/fast_math_functions.h"
36 #include "dsp/matrix_functions.h"
37
38 /* Constants for Q31 implementation */
39 #define LOG2TOLOG_Q31 0x02C5C860
40 #define MICRO_Q31 0x08637BD0
41 #define SHIFT_MELFILTER_SATURATION_Q31 10
42 /**
43 @ingroup MFCC
44 */
45
46
47
48 /**
49 @addtogroup MFCCQ31
50 @{
51 */
52
53 /**
54 @brief MFCC Q31
55 @param[in] S points to the mfcc instance structure
56 @param[in] pSrc points to the input samples in Q31
57 @param[out] pDst points to the output MFCC values in q8.23 format
58 @param[inout] pTmp points to a temporary buffer of complex
59 @return error status
60
61 @par Description
62 The number of input samples is the FFT length used
63 when initializing the instance data structure.
64
65 The temporary buffer has a 2*fft length.
66
67 The source buffer is modified by this function.
68
69 The function may saturate. If the FFT length is too
70 big and the number of MEL filters too small then the fixed
71 point computations may saturate.
72
73 */
74
arm_mfcc_q31(const arm_mfcc_instance_q31 * S,q31_t * pSrc,q31_t * pDst,q31_t * pTmp)75 ARM_DSP_ATTRIBUTE arm_status arm_mfcc_q31(
76 const arm_mfcc_instance_q31 * S,
77 q31_t *pSrc,
78 q31_t *pDst,
79 q31_t *pTmp
80 )
81 {
82 q31_t m;
83 uint32_t index;
84 uint32_t fftShift=0;
85 q31_t logExponent;
86 q63_t result;
87 arm_matrix_instance_q31 pDctMat;
88 uint32_t i;
89 uint32_t coefsPos;
90 uint32_t filterLimit;
91 q31_t *pTmp2=(q31_t*)pTmp;
92
93 arm_status status = ARM_MATH_SUCCESS;
94
95 // q31
96 arm_absmax_q31(pSrc,S->fftLen,&m,&index);
97
98 if ((m != 0) && (m != 0x7FFFFFFF))
99 {
100 q31_t quotient;
101 int16_t shift;
102
103 status = arm_divide_q31(0x7FFFFFFF,m,"ient,&shift);
104 if (status != ARM_MATH_SUCCESS)
105 {
106 return(status);
107 }
108
109 arm_scale_q31(pSrc,quotient,shift,pSrc,S->fftLen);
110 }
111
112
113 // q31
114 arm_mult_q31(pSrc,S->windowCoefs, pSrc, S->fftLen);
115
116
117 /* Compute spectrum magnitude
118 */
119 fftShift = 31 - __CLZ(S->fftLen);
120 #if defined(ARM_MFCC_CFFT_BASED)
121 /* some HW accelerator for CMSIS-DSP used in some boards
122 are only providing acceleration for CFFT.
123 With ARM_MFCC_CFFT_BASED enabled, CFFT is used and the MFCC
124 will be accelerated on those boards.
125
126 The default is to use RFFT
127 */
128 /* Convert from real to complex */
129 for(i=0; i < S->fftLen ; i++)
130 {
131 pTmp2[2*i] = pSrc[i];
132 pTmp2[2*i+1] = 0;
133 }
134 arm_cfft_q31(&(S->cfft),pTmp2,0,1);
135 #else
136 /* Default RFFT based implementation */
137 arm_rfft_q31(&(S->rfft),pSrc,pTmp2);
138 #endif
139 filterLimit = 1 + (S->fftLen >> 1);
140
141
142 // q31 - fftShift
143 arm_cmplx_mag_q31(pTmp2,pSrc,filterLimit);
144 // q30 - fftShift
145
146
147 /* Apply MEL filters */
148 coefsPos = 0;
149 for(i=0; i<S->nbMelFilters; i++)
150 {
151 arm_dot_prod_q31(pSrc+S->filterPos[i],
152 &(S->filterCoefs[coefsPos]),
153 S->filterLengths[i],
154 &result);
155
156
157 coefsPos += S->filterLengths[i];
158
159 // q16.48 - fftShift
160 result += MICRO_Q31;
161 result >>= (SHIFT_MELFILTER_SATURATION_Q31 + 18);
162 // q16.29 - fftShift - satShift
163 pTmp[i] = __SSAT(result,31) ;
164
165 }
166
167 if ((m != 0) && (m != 0x7FFFFFFF))
168 {
169 arm_scale_q31(pTmp,m,0,pTmp,S->nbMelFilters);
170 }
171
172 // q16.29 - fftShift - satShift
173 /* Compute the log */
174 arm_vlog_q31(pTmp,pTmp,S->nbMelFilters);
175
176
177 // q5.26
178
179 logExponent = fftShift + 2 + SHIFT_MELFILTER_SATURATION_Q31;
180 logExponent = logExponent * LOG2TOLOG_Q31;
181
182
183 // q5.26
184 arm_offset_q31(pTmp,logExponent,pTmp,S->nbMelFilters);
185 arm_shift_q31(pTmp,-3,pTmp,S->nbMelFilters);
186
187
188 // q8.23
189
190 pDctMat.numRows=S->nbDctOutputs;
191 pDctMat.numCols=S->nbMelFilters;
192 pDctMat.pData=(q31_t*)S->dctCoefs;
193
194 arm_mat_vec_mult_q31(&pDctMat, pTmp, pDst);
195
196 return(status);
197 }
198
199 /**
200 @} end of MFCCQ31 group
201 */
202
