1 /* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_mfcc_q15.c
4 * Description: MFCC function for the q15 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 Q15 implementation */
39 #define LOG2TOLOG_Q15 0x02C5C860
40 #define MICRO_Q15 0x00000219
41 #define SHIFT_MELFILTER_SATURATION_Q15 10
42 /**
43 @ingroup MFCC
44 */
45
46
47
48 /**
49 @addtogroup MFCCQ15
50 @{
51 */
52
53 /**
54 @brief MFCC Q15
55 @param[in] S points to the mfcc instance structure
56 @param[in] pSrc points to the input samples in Q15
57 @param[out] pDst points to the output MFCC values in q8.7 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 */
arm_mfcc_q15(const arm_mfcc_instance_q15 * S,q15_t * pSrc,q15_t * pDst,q31_t * pTmp)74 ARM_DSP_ATTRIBUTE arm_status arm_mfcc_q15(
75 const arm_mfcc_instance_q15 * S,
76 q15_t *pSrc,
77 q15_t *pDst,
78 q31_t *pTmp
79 )
80 {
81 q15_t m;
82 uint32_t index;
83 uint32_t fftShift=0;
84 q31_t logExponent;
85 q63_t result;
86 arm_matrix_instance_q15 pDctMat;
87 uint32_t i;
88 uint32_t coefsPos;
89 uint32_t filterLimit;
90 q15_t *pTmp2=(q15_t*)pTmp;
91
92 arm_status status = ARM_MATH_SUCCESS;
93
94 // q15
95 arm_absmax_q15(pSrc,S->fftLen,&m,&index);
96
97 if ((m != 0) && (m != 0x7FFF))
98 {
99 q15_t quotient;
100 int16_t shift;
101
102 status = arm_divide_q15(0x7FFF,m,"ient,&shift);
103 if (status != ARM_MATH_SUCCESS)
104 {
105 return(status);
106 }
107
108 arm_scale_q15(pSrc,quotient,shift,pSrc,S->fftLen);
109 }
110
111
112 // q15
113 arm_mult_q15(pSrc,S->windowCoefs, pSrc, S->fftLen);
114
115
116 /* Compute spectrum magnitude
117 */
118 fftShift = 31 - __CLZ(S->fftLen);
119 #if defined(ARM_MFCC_CFFT_BASED)
120 /* some HW accelerator for CMSIS-DSP used in some boards
121 are only providing acceleration for CFFT.
122 With ARM_MFCC_CFFT_BASED enabled, CFFT is used and the MFCC
123 will be accelerated on those boards.
124
125 The default is to use RFFT
126 */
127 /* Convert from real to complex */
128 for(i=0; i < S->fftLen ; i++)
129 {
130 pTmp2[2*i] = pSrc[i];
131 pTmp2[2*i+1] = 0;
132 }
133 arm_cfft_q15(&(S->cfft),pTmp2,0,1);
134 #else
135 /* Default RFFT based implementation */
136 arm_rfft_q15(&(S->rfft),pSrc,pTmp2);
137 #endif
138 filterLimit = 1 + (S->fftLen >> 1);
139
140
141 // q15 - fftShift
142 arm_cmplx_mag_q15(pTmp2,pSrc,filterLimit);
143 // q14 - fftShift
144
145 /* Apply MEL filters */
146 coefsPos = 0;
147 for(i=0; i<S->nbMelFilters; i++)
148 {
149 arm_dot_prod_q15(pSrc+S->filterPos[i],
150 &(S->filterCoefs[coefsPos]),
151 S->filterLengths[i],
152 &result);
153
154 coefsPos += S->filterLengths[i];
155
156 // q34.29 - fftShift
157 result += MICRO_Q15;
158 result >>= SHIFT_MELFILTER_SATURATION_Q15;
159 // q34.29 - fftShift - satShift
160 pTmp[i] = __SSAT(result,31) ;
161
162 }
163
164 if ((m != 0) && (m != 0x7FFF))
165 {
166 arm_scale_q31(pTmp,m<<16,0,pTmp,S->nbMelFilters);
167 }
168
169 // q34.29 - fftShift - satShift
170 /* Compute the log */
171 arm_vlog_q31(pTmp,pTmp,S->nbMelFilters);
172
173
174 // q5.26
175
176 logExponent = fftShift + 2 + SHIFT_MELFILTER_SATURATION_Q15;
177 logExponent = logExponent * LOG2TOLOG_Q15;
178
179
180 // q8.26
181 arm_offset_q31(pTmp,logExponent,pTmp,S->nbMelFilters);
182 arm_shift_q31(pTmp,-19,pTmp,S->nbMelFilters);
183 for(i=0; i<S->nbMelFilters; i++)
184 {
185 pSrc[i] = __SSAT((q15_t)pTmp[i],16);
186 }
187
188 // q8.7
189
190 pDctMat.numRows=S->nbDctOutputs;
191 pDctMat.numCols=S->nbMelFilters;
192 pDctMat.pData=(q15_t*)S->dctCoefs;
193
194 arm_mat_vec_mult_q15(&pDctMat, pSrc, pDst);
195
196 return(status);
197 }
198
199 /**
200 @} end of MFCCQ15 group
201 */
202
