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
60 @return none
61
62 @par Description
63 The number of input samples is the FFT length used
64 when initializing the instance data structure.
65
66 The temporary buffer has a 2*fft length.
67
68 The source buffer is modified by this function.
69
70 The function may saturate. If the FFT length is too
71 big and the number of MEL filters too small then the fixed
72 point computations may saturate.
73
74 */
75
arm_mfcc_q31(const arm_mfcc_instance_q31 * S,q31_t * pSrc,q31_t * pDst,q31_t * pTmp)76 arm_status arm_mfcc_q31(
77 const arm_mfcc_instance_q31 * S,
78 q31_t *pSrc,
79 q31_t *pDst,
80 q31_t *pTmp
81 )
82 {
83 q31_t m;
84 uint32_t index;
85 uint32_t fftShift=0;
86 q31_t logExponent;
87 q63_t result;
88 arm_matrix_instance_q31 pDctMat;
89 uint32_t i;
90 uint32_t coefsPos;
91 uint32_t filterLimit;
92 q31_t *pTmp2=(q31_t*)pTmp;
93
94 arm_status status = ARM_MATH_SUCCESS;
95
96 // q31
97 arm_absmax_q31(pSrc,S->fftLen,&m,&index);
98
99 if ((m != 0) && (m != 0x7FFFFFFF))
100 {
101 q31_t quotient;
102 int16_t shift;
103
104 status = arm_divide_q31(0x7FFFFFFF,m,"ient,&shift);
105 if (status != ARM_MATH_SUCCESS)
106 {
107 return(status);
108 }
109
110 arm_scale_q31(pSrc,quotient,shift,pSrc,S->fftLen);
111 }
112
113
114 // q31
115 arm_mult_q31(pSrc,S->windowCoefs, pSrc, S->fftLen);
116
117
118 /* Compute spectrum magnitude
119 */
120 fftShift = 31 - __CLZ(S->fftLen);
121 #if defined(ARM_MFCC_CFFT_BASED)
122 /* some HW accelerator for CMSIS-DSP used in some boards
123 are only providing acceleration for CFFT.
124 With ARM_MFCC_CFFT_BASED enabled, CFFT is used and the MFCC
125 will be accelerated on those boards.
126
127 The default is to use RFFT
128 */
129 /* Convert from real to complex */
130 for(i=0; i < S->fftLen ; i++)
131 {
132 pTmp2[2*i] = pSrc[i];
133 pTmp2[2*i+1] = 0;
134 }
135 arm_cfft_q31(&(S->cfft),pTmp2,0,1);
136 #else
137 /* Default RFFT based implementation */
138 arm_rfft_q31(&(S->rfft),pSrc,pTmp2);
139 #endif
140 filterLimit = 1 + (S->fftLen >> 1);
141
142
143 // q31 - fftShift
144 arm_cmplx_mag_q31(pTmp2,pSrc,filterLimit);
145 // q30 - fftShift
146
147
148 /* Apply MEL filters */
149 coefsPos = 0;
150 for(i=0; i<S->nbMelFilters; i++)
151 {
152 arm_dot_prod_q31(pSrc+S->filterPos[i],
153 &(S->filterCoefs[coefsPos]),
154 S->filterLengths[i],
155 &result);
156
157
158 coefsPos += S->filterLengths[i];
159
160 // q16.48 - fftShift
161 result += MICRO_Q31;
162 result >>= (SHIFT_MELFILTER_SATURATION_Q31 + 18);
163 // q16.29 - fftShift - satShift
164 pTmp[i] = __SSAT(result,31) ;
165
166 }
167
168 if ((m != 0) && (m != 0x7FFFFFFF))
169 {
170 arm_scale_q31(pTmp,m,0,pTmp,S->nbMelFilters);
171 }
172
173 // q16.29 - fftShift - satShift
174 /* Compute the log */
175 arm_vlog_q31(pTmp,pTmp,S->nbMelFilters);
176
177
178 // q5.26
179
180 logExponent = fftShift + 2 + SHIFT_MELFILTER_SATURATION_Q31;
181 logExponent = logExponent * LOG2TOLOG_Q31;
182
183
184 // q5.26
185 arm_offset_q31(pTmp,logExponent,pTmp,S->nbMelFilters);
186 arm_shift_q31(pTmp,-3,pTmp,S->nbMelFilters);
187
188
189 // q8.23
190
191 pDctMat.numRows=S->nbDctOutputs;
192 pDctMat.numCols=S->nbMelFilters;
193 pDctMat.pData=(q31_t*)S->dctCoefs;
194
195 arm_mat_vec_mult_q31(&pDctMat, pTmp, pDst);
196
197 return(status);
198 }
199
200 /**
201 @} end of MFCCQ31 group
202 */
203