1 /* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_rfft_f32.c
4 * Description: RFFT & RIFFT Floating point process function
5 *
6 * $Date: 23 April 2021
7 * $Revision: V1.9.0
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 #include "dsp/transform_functions.h"
30
31 /* ----------------------------------------------------------------------
32 * Internal functions prototypes
33 * -------------------------------------------------------------------- */
34
35 extern void arm_radix4_butterfly_f32(
36 float32_t * pSrc,
37 uint16_t fftLen,
38 const float32_t * pCoef,
39 uint16_t twidCoefModifier);
40
41 extern void arm_radix4_butterfly_inverse_f32(
42 float32_t * pSrc,
43 uint16_t fftLen,
44 const float32_t * pCoef,
45 uint16_t twidCoefModifier,
46 float32_t onebyfftLen);
47
48 extern void arm_bitreversal_f32(
49 float32_t * pSrc,
50 uint16_t fftSize,
51 uint16_t bitRevFactor,
52 const uint16_t * pBitRevTab);
53
54 void arm_split_rfft_f32(
55 float32_t * pSrc,
56 uint32_t fftLen,
57 const float32_t * pATable,
58 const float32_t * pBTable,
59 float32_t * pDst,
60 uint32_t modifier);
61
62 void arm_split_rifft_f32(
63 float32_t * pSrc,
64 uint32_t fftLen,
65 const float32_t * pATable,
66 const float32_t * pBTable,
67 float32_t * pDst,
68 uint32_t modifier);
69
70
71
72 /**
73 @addtogroup DeprecatedRealFFT
74 @{
75 */
76
77 /**
78 @brief Processing function for the floating-point RFFT/RIFFT.
79 Source buffer is modified by this function.
80
81 @deprecated Do not use this function. It has been superceded by \ref arm_rfft_fast_f32 and will be removed in the future.
82 @param[in] S points to an instance of the floating-point RFFT/RIFFT structure
83 @param[in] pSrc points to the input buffer
84 @param[out] pDst points to the output buffer
85
86 */
87
arm_rfft_f32(const arm_rfft_instance_f32 * S,float32_t * pSrc,float32_t * pDst)88 void arm_rfft_f32(
89 const arm_rfft_instance_f32 * S,
90 float32_t * pSrc,
91 float32_t * pDst)
92 {
93 const arm_cfft_radix4_instance_f32 *S_CFFT = S->pCfft;
94
95 /* Calculation of Real IFFT of input */
96 if (S->ifftFlagR == 1U)
97 {
98 /* Real IFFT core process */
99 arm_split_rifft_f32 (pSrc, S->fftLenBy2, S->pTwiddleAReal, S->pTwiddleBReal, pDst, S->twidCoefRModifier);
100
101
102 /* Complex radix-4 IFFT process */
103 arm_radix4_butterfly_inverse_f32 (pDst, S_CFFT->fftLen, S_CFFT->pTwiddle, S_CFFT->twidCoefModifier, S_CFFT->onebyfftLen);
104
105 /* Bit reversal process */
106 if (S->bitReverseFlagR == 1U)
107 {
108 arm_bitreversal_f32 (pDst, S_CFFT->fftLen, S_CFFT->bitRevFactor, S_CFFT->pBitRevTable);
109 }
110 }
111 else
112 {
113 /* Calculation of RFFT of input */
114
115 /* Complex radix-4 FFT process */
116 arm_radix4_butterfly_f32 (pSrc, S_CFFT->fftLen, S_CFFT->pTwiddle, S_CFFT->twidCoefModifier);
117
118 /* Bit reversal process */
119 if (S->bitReverseFlagR == 1U)
120 {
121 arm_bitreversal_f32 (pSrc, S_CFFT->fftLen, S_CFFT->bitRevFactor, S_CFFT->pBitRevTable);
122 }
123
124 /* Real FFT core process */
125 arm_split_rfft_f32 (pSrc, S->fftLenBy2, S->pTwiddleAReal, S->pTwiddleBReal, pDst, S->twidCoefRModifier);
126 }
127
128 }
129
130 /**
131 @} end of DeprecatedRealFFT group
132 */
133
134 /**
135 @brief Core Real FFT process
136 @param[in] pSrc points to input buffer
137 @param[in] fftLen length of FFT
138 @param[in] pATable points to twiddle Coef A buffer
139 @param[in] pBTable points to twiddle Coef B buffer
140 @param[out] pDst points to output buffer
141 @param[in] modifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table
142 */
143
arm_split_rfft_f32(float32_t * pSrc,uint32_t fftLen,const float32_t * pATable,const float32_t * pBTable,float32_t * pDst,uint32_t modifier)144 void arm_split_rfft_f32(
145 float32_t * pSrc,
146 uint32_t fftLen,
147 const float32_t * pATable,
148 const float32_t * pBTable,
149 float32_t * pDst,
150 uint32_t modifier)
151 {
152 uint32_t i; /* Loop Counter */
153 float32_t outR, outI; /* Temporary variables for output */
154 const float32_t *pCoefA, *pCoefB; /* Temporary pointers for twiddle factors */
155 float32_t CoefA1, CoefA2, CoefB1; /* Temporary variables for twiddle coefficients */
156 float32_t *pDst1 = &pDst[2], *pDst2 = &pDst[(4U * fftLen) - 1U]; /* temp pointers for output buffer */
157 float32_t *pSrc1 = &pSrc[2], *pSrc2 = &pSrc[(2U * fftLen) - 1U]; /* temp pointers for input buffer */
158
159 /* Init coefficient pointers */
160 pCoefA = &pATable[modifier * 2];
161 pCoefB = &pBTable[modifier * 2];
162
163 i = fftLen - 1U;
164
165 while (i > 0U)
166 {
167 /*
168 outR = ( pSrc[2 * i] * pATable[2 * i]
169 - pSrc[2 * i + 1] * pATable[2 * i + 1]
170 + pSrc[2 * n - 2 * i] * pBTable[2 * i]
171 + pSrc[2 * n - 2 * i + 1] * pBTable[2 * i + 1]);
172
173 outI = ( pIn[2 * i + 1] * pATable[2 * i]
174 + pIn[2 * i] * pATable[2 * i + 1]
175 + pIn[2 * n - 2 * i] * pBTable[2 * i + 1]
176 - pIn[2 * n - 2 * i + 1] * pBTable[2 * i]);
177 */
178
179 /* read pATable[2 * i] */
180 CoefA1 = *pCoefA++;
181 /* pATable[2 * i + 1] */
182 CoefA2 = *pCoefA;
183
184 /* pSrc[2 * i] * pATable[2 * i] */
185 outR = *pSrc1 * CoefA1;
186 /* pSrc[2 * i] * CoefA2 */
187 outI = *pSrc1++ * CoefA2;
188
189 /* (pSrc[2 * i + 1] + pSrc[2 * fftLen - 2 * i + 1]) * CoefA2 */
190 outR -= (*pSrc1 + *pSrc2) * CoefA2;
191 /* pSrc[2 * i + 1] * CoefA1 */
192 outI += *pSrc1++ * CoefA1;
193
194 CoefB1 = *pCoefB;
195
196 /* pSrc[2 * fftLen - 2 * i + 1] * CoefB1 */
197 outI -= *pSrc2-- * CoefB1;
198 /* pSrc[2 * fftLen - 2 * i] * CoefA2 */
199 outI -= *pSrc2 * CoefA2;
200
201 /* pSrc[2 * fftLen - 2 * i] * CoefB1 */
202 outR += *pSrc2-- * CoefB1;
203
204 /* write output */
205 *pDst1++ = outR;
206 *pDst1++ = outI;
207
208 /* write complex conjugate output */
209 *pDst2-- = -outI;
210 *pDst2-- = outR;
211
212 /* update coefficient pointer */
213 pCoefB = pCoefB + (modifier * 2U);
214 pCoefA = pCoefA + ((modifier * 2U) - 1U);
215
216 i--;
217
218 }
219
220 pDst[2U * fftLen] = pSrc[0] - pSrc[1];
221 pDst[(2U * fftLen) + 1U] = 0.0f;
222
223 pDst[0] = pSrc[0] + pSrc[1];
224 pDst[1] = 0.0f;
225
226 }
227
228
229 /**
230 @brief Core Real IFFT process
231 @param[in] pSrc points to input buffer
232 @param[in] fftLen length of FFT
233 @param[in] pATable points to twiddle Coef A buffer
234 @param[in] pBTable points to twiddle Coef B buffer
235 @param[out] pDst points to output buffer
236 @param[in] modifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table
237 */
238
arm_split_rifft_f32(float32_t * pSrc,uint32_t fftLen,const float32_t * pATable,const float32_t * pBTable,float32_t * pDst,uint32_t modifier)239 void arm_split_rifft_f32(
240 float32_t * pSrc,
241 uint32_t fftLen,
242 const float32_t * pATable,
243 const float32_t * pBTable,
244 float32_t * pDst,
245 uint32_t modifier)
246 {
247 float32_t outR, outI; /* Temporary variables for output */
248 const float32_t *pCoefA, *pCoefB; /* Temporary pointers for twiddle factors */
249 float32_t CoefA1, CoefA2, CoefB1; /* Temporary variables for twiddle coefficients */
250 float32_t *pSrc1 = &pSrc[0], *pSrc2 = &pSrc[(2U * fftLen) + 1U];
251
252 pCoefA = &pATable[0];
253 pCoefB = &pBTable[0];
254
255 while (fftLen > 0U)
256 {
257 /*
258 outR = ( pIn[2 * i] * pATable[2 * i]
259 + pIn[2 * i + 1] * pATable[2 * i + 1]
260 + pIn[2 * n - 2 * i] * pBTable[2 * i]
261 - pIn[2 * n - 2 * i + 1] * pBTable[2 * i + 1]);
262
263 outI = ( pIn[2 * i + 1] * pATable[2 * i]
264 - pIn[2 * i] * pATable[2 * i + 1]
265 - pIn[2 * n - 2 * i] * pBTable[2 * i + 1]
266 - pIn[2 * n - 2 * i + 1] * pBTable[2 * i]);
267 */
268
269 CoefA1 = *pCoefA++;
270 CoefA2 = *pCoefA;
271
272 /* outR = (pSrc[2 * i] * CoefA1 */
273 outR = *pSrc1 * CoefA1;
274
275 /* - pSrc[2 * i] * CoefA2 */
276 outI = -(*pSrc1++) * CoefA2;
277
278 /* (pSrc[2 * i + 1] + pSrc[2 * fftLen - 2 * i + 1]) * CoefA2 */
279 outR += (*pSrc1 + *pSrc2) * CoefA2;
280
281 /* pSrc[2 * i + 1] * CoefA1 */
282 outI += (*pSrc1++) * CoefA1;
283
284 CoefB1 = *pCoefB;
285
286 /* - pSrc[2 * fftLen - 2 * i + 1] * CoefB1 */
287 outI -= *pSrc2-- * CoefB1;
288
289 /* pSrc[2 * fftLen - 2 * i] * CoefB1 */
290 outR += *pSrc2 * CoefB1;
291
292 /* pSrc[2 * fftLen - 2 * i] * CoefA2 */
293 outI += *pSrc2-- * CoefA2;
294
295 /* write output */
296 *pDst++ = outR;
297 *pDst++ = outI;
298
299 /* update coefficient pointer */
300 pCoefB = pCoefB + (modifier * 2);
301 pCoefA = pCoefA + (modifier * 2 - 1);
302
303 /* Decrement loop count */
304 fftLen--;
305 }
306
307 }
308
