lib/main/CMSIS/DSP/Source/TransformFunctions/arm_cfft_radix8_f32.c

   1 /* ----------------------------------------------------------------------
   2  * Project:      CMSIS DSP Library
   3  * Title:        arm_cfft_radix8_f32.c
   4  * Description:  Radix-8 Decimation in Frequency CFFT & CIFFT Floating point processing function
   5  *
   6  * $Date:        27. January 2017
   7  * $Revision:    V.1.5.1
   8  *
   9  * Target Processor: Cortex-M cores
  10  * -------------------------------------------------------------------- */
  11 /*
  12  * Copyright (C) 2010-2017 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 "arm_math.h"
  30
  31
  32 /* ----------------------------------------------------------------------
  33  * Internal helper function used by the FFTs
  34  * -------------------------------------------------------------------- */
  35
  36 /*
  37 * @brief  Core function for the floating-point CFFT butterfly process.
  38 * @param[in, out] *pSrc            points to the in-place buffer of floating-point data type.
  39 * @param[in]      fftLen           length of the FFT.
  40 * @param[in]      *pCoef           points to the twiddle coefficient buffer.
  41 * @param[in]      twidCoefModifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table.
  42 * @return none.
  43 */
  44
  45 void arm_radix8_butterfly_f32(
  46 float32_t * pSrc,
  47 uint16_t fftLen,
  48 const float32_t * pCoef,
  49 uint16_t twidCoefModifier)
  50 {
  51    uint32_t ia1, ia2, ia3, ia4, ia5, ia6, ia7;
  52    uint32_t i1, i2, i3, i4, i5, i6, i7, i8;
  53    uint32_t id;
  54    uint32_t n1, n2, j;
  55
  56    float32_t r1, r2, r3, r4, r5, r6, r7, r8;
  57    float32_t t1, t2;
  58    float32_t s1, s2, s3, s4, s5, s6, s7, s8;
  59    float32_t p1, p2, p3, p4;
  60    float32_t co2, co3, co4, co5, co6, co7, co8;
  61    float32_t si2, si3, si4, si5, si6, si7, si8;
  62    const float32_t C81 = 0.70710678118f;
  63
  64    n2 = fftLen;
  65
  66    do
  67    {
  68       n1 = n2;
  69       n2 = n2 >> 3;
  70       i1 = 0;
  71
  72       do
  73       {
  74          i2 = i1 + n2;
  75          i3 = i2 + n2;
  76          i4 = i3 + n2;
  77          i5 = i4 + n2;
  78          i6 = i5 + n2;
  79          i7 = i6 + n2;
  80          i8 = i7 + n2;
  81          r1 = pSrc[2 * i1] + pSrc[2 * i5];
  82          r5 = pSrc[2 * i1] - pSrc[2 * i5];
  83          r2 = pSrc[2 * i2] + pSrc[2 * i6];
  84          r6 = pSrc[2 * i2] - pSrc[2 * i6];
  85          r3 = pSrc[2 * i3] + pSrc[2 * i7];
  86          r7 = pSrc[2 * i3] - pSrc[2 * i7];
  87          r4 = pSrc[2 * i4] + pSrc[2 * i8];
  88          r8 = pSrc[2 * i4] - pSrc[2 * i8];
  89          t1 = r1 - r3;
  90          r1 = r1 + r3;
  91          r3 = r2 - r4;
  92          r2 = r2 + r4;
  93          pSrc[2 * i1] = r1 + r2;
  94          pSrc[2 * i5] = r1 - r2;
  95          r1 = pSrc[2 * i1 + 1] + pSrc[2 * i5 + 1];
  96          s5 = pSrc[2 * i1 + 1] - pSrc[2 * i5 + 1];
  97          r2 = pSrc[2 * i2 + 1] + pSrc[2 * i6 + 1];
  98          s6 = pSrc[2 * i2 + 1] - pSrc[2 * i6 + 1];
  99          s3 = pSrc[2 * i3 + 1] + pSrc[2 * i7 + 1];
 100          s7 = pSrc[2 * i3 + 1] - pSrc[2 * i7 + 1];
 101          r4 = pSrc[2 * i4 + 1] + pSrc[2 * i8 + 1];
 102          s8 = pSrc[2 * i4 + 1] - pSrc[2 * i8 + 1];
 103          t2 = r1 - s3;
 104          r1 = r1 + s3;
 105          s3 = r2 - r4;
 106          r2 = r2 + r4;
 107          pSrc[2 * i1 + 1] = r1 + r2;
 108          pSrc[2 * i5 + 1] = r1 - r2;
 109          pSrc[2 * i3]     = t1 + s3;
 110          pSrc[2 * i7]     = t1 - s3;
 111          pSrc[2 * i3 + 1] = t2 - r3;
 112          pSrc[2 * i7 + 1] = t2 + r3;
 113          r1 = (r6 - r8) * C81;
 114          r6 = (r6 + r8) * C81;
 115          r2 = (s6 - s8) * C81;
 116          s6 = (s6 + s8) * C81;
 117          t1 = r5 - r1;
 118          r5 = r5 + r1;
 119          r8 = r7 - r6;
 120          r7 = r7 + r6;
 121          t2 = s5 - r2;
 122          s5 = s5 + r2;
 123          s8 = s7 - s6;
 124          s7 = s7 + s6;
 125          pSrc[2 * i2]     = r5 + s7;
 126          pSrc[2 * i8]     = r5 - s7;
 127          pSrc[2 * i6]     = t1 + s8;
 128          pSrc[2 * i4]     = t1 - s8;
 129          pSrc[2 * i2 + 1] = s5 - r7;
 130          pSrc[2 * i8 + 1] = s5 + r7;
 131          pSrc[2 * i6 + 1] = t2 - r8;
 132          pSrc[2 * i4 + 1] = t2 + r8;
 133
 134          i1 += n1;
 135       } while (i1 < fftLen);
 136
 137       if (n2 < 8)
 138          break;
 139
 140       ia1 = 0;
 141       j = 1;
 142
 143       do
 144       {
 145          /*  index calculation for the coefficients */
 146          id  = ia1 + twidCoefModifier;
 147          ia1 = id;
 148          ia2 = ia1 + id;
 149          ia3 = ia2 + id;
 150          ia4 = ia3 + id;
 151          ia5 = ia4 + id;
 152          ia6 = ia5 + id;
 153          ia7 = ia6 + id;
 154
 155          co2 = pCoef[2 * ia1];
 156          co3 = pCoef[2 * ia2];
 157          co4 = pCoef[2 * ia3];
 158          co5 = pCoef[2 * ia4];
 159          co6 = pCoef[2 * ia5];
 160          co7 = pCoef[2 * ia6];
 161          co8 = pCoef[2 * ia7];
 162          si2 = pCoef[2 * ia1 + 1];
 163          si3 = pCoef[2 * ia2 + 1];
 164          si4 = pCoef[2 * ia3 + 1];
 165          si5 = pCoef[2 * ia4 + 1];
 166          si6 = pCoef[2 * ia5 + 1];
 167          si7 = pCoef[2 * ia6 + 1];
 168          si8 = pCoef[2 * ia7 + 1];
 169
 170          i1 = j;
 171
 172          do
 173          {
 174             /*  index calculation for the input */
 175             i2 = i1 + n2;
 176             i3 = i2 + n2;
 177             i4 = i3 + n2;
 178             i5 = i4 + n2;
 179             i6 = i5 + n2;
 180             i7 = i6 + n2;
 181             i8 = i7 + n2;
 182             r1 = pSrc[2 * i1] + pSrc[2 * i5];
 183             r5 = pSrc[2 * i1] - pSrc[2 * i5];
 184             r2 = pSrc[2 * i2] + pSrc[2 * i6];
 185             r6 = pSrc[2 * i2] - pSrc[2 * i6];
 186             r3 = pSrc[2 * i3] + pSrc[2 * i7];
 187             r7 = pSrc[2 * i3] - pSrc[2 * i7];
 188             r4 = pSrc[2 * i4] + pSrc[2 * i8];
 189             r8 = pSrc[2 * i4] - pSrc[2 * i8];
 190             t1 = r1 - r3;
 191             r1 = r1 + r3;
 192             r3 = r2 - r4;
 193             r2 = r2 + r4;
 194             pSrc[2 * i1] = r1 + r2;
 195             r2 = r1 - r2;
 196             s1 = pSrc[2 * i1 + 1] + pSrc[2 * i5 + 1];
 197             s5 = pSrc[2 * i1 + 1] - pSrc[2 * i5 + 1];
 198             s2 = pSrc[2 * i2 + 1] + pSrc[2 * i6 + 1];
 199             s6 = pSrc[2 * i2 + 1] - pSrc[2 * i6 + 1];
 200             s3 = pSrc[2 * i3 + 1] + pSrc[2 * i7 + 1];
 201             s7 = pSrc[2 * i3 + 1] - pSrc[2 * i7 + 1];
 202             s4 = pSrc[2 * i4 + 1] + pSrc[2 * i8 + 1];
 203             s8 = pSrc[2 * i4 + 1] - pSrc[2 * i8 + 1];
 204             t2 = s1 - s3;
 205             s1 = s1 + s3;
 206             s3 = s2 - s4;
 207             s2 = s2 + s4;
 208             r1 = t1 + s3;
 209             t1 = t1 - s3;
 210             pSrc[2 * i1 + 1] = s1 + s2;
 211             s2 = s1 - s2;
 212             s1 = t2 - r3;
 213             t2 = t2 + r3;
 214             p1 = co5 * r2;
 215             p2 = si5 * s2;
 216             p3 = co5 * s2;
 217             p4 = si5 * r2;
 218             pSrc[2 * i5]     = p1 + p2;
 219             pSrc[2 * i5 + 1] = p3 - p4;
 220             p1 = co3 * r1;
 221             p2 = si3 * s1;
 222             p3 = co3 * s1;
 223             p4 = si3 * r1;
 224             pSrc[2 * i3]     = p1 + p2;
 225             pSrc[2 * i3 + 1] = p3 - p4;
 226             p1 = co7 * t1;
 227             p2 = si7 * t2;
 228             p3 = co7 * t2;
 229             p4 = si7 * t1;
 230             pSrc[2 * i7]     = p1 + p2;
 231             pSrc[2 * i7 + 1] = p3 - p4;
 232             r1 = (r6 - r8) * C81;
 233             r6 = (r6 + r8) * C81;
 234             s1 = (s6 - s8) * C81;
 235             s6 = (s6 + s8) * C81;
 236             t1 = r5 - r1;
 237             r5 = r5 + r1;
 238             r8 = r7 - r6;
 239             r7 = r7 + r6;
 240             t2 = s5 - s1;
 241             s5 = s5 + s1;
 242             s8 = s7 - s6;
 243             s7 = s7 + s6;
 244             r1 = r5 + s7;
 245             r5 = r5 - s7;
 246             r6 = t1 + s8;
 247             t1 = t1 - s8;
 248             s1 = s5 - r7;
 249             s5 = s5 + r7;
 250             s6 = t2 - r8;
 251             t2 = t2 + r8;
 252             p1 = co2 * r1;
 253             p2 = si2 * s1;
 254             p3 = co2 * s1;
 255             p4 = si2 * r1;
 256             pSrc[2 * i2]     = p1 + p2;
 257             pSrc[2 * i2 + 1] = p3 - p4;
 258             p1 = co8 * r5;
 259             p2 = si8 * s5;
 260             p3 = co8 * s5;
 261             p4 = si8 * r5;
 262             pSrc[2 * i8]     = p1 + p2;
 263             pSrc[2 * i8 + 1] = p3 - p4;
 264             p1 = co6 * r6;
 265             p2 = si6 * s6;
 266             p3 = co6 * s6;
 267             p4 = si6 * r6;
 268             pSrc[2 * i6]     = p1 + p2;
 269             pSrc[2 * i6 + 1] = p3 - p4;
 270             p1 = co4 * t1;
 271             p2 = si4 * t2;
 272             p3 = co4 * t2;
 273             p4 = si4 * t1;
 274             pSrc[2 * i4]     = p1 + p2;
 275             pSrc[2 * i4 + 1] = p3 - p4;
 276
 277             i1 += n1;
 278          } while (i1 < fftLen);
 279
 280          j++;
 281       } while (j < n2);
 282
 283       twidCoefModifier <<= 3;
 284    } while (n2 > 7);
 285 }