lib/main/CMSIS/DSP/Source/TransformFunctions/arm_cfft_radix2_q31.c

   1 /* ----------------------------------------------------------------------
   2  * Project:      CMSIS DSP Library
   3  * Title:        arm_cfft_radix2_q31.c
   4  * Description:  Radix-2 Decimation in Frequency CFFT & CIFFT Fixed 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 void arm_radix2_butterfly_q31(
  32   q31_t * pSrc,
  33   uint32_t fftLen,
  34   q31_t * pCoef,
  35   uint16_t twidCoefModifier);
  36
  37 void arm_radix2_butterfly_inverse_q31(
  38   q31_t * pSrc,
  39   uint32_t fftLen,
  40   q31_t * pCoef,
  41   uint16_t twidCoefModifier);
  42
  43 void arm_bitreversal_q31(
  44   q31_t * pSrc,
  45   uint32_t fftLen,
  46   uint16_t bitRevFactor,
  47   uint16_t * pBitRevTab);
  48
  49 /**
  50 * @ingroup groupTransforms
  51 */
  52
  53 /**
  54 * @addtogroup ComplexFFT
  55 * @{
  56 */
  57
  58 /**
  59 * @details
  60 * @brief Processing function for the fixed-point CFFT/CIFFT.
  61 * @deprecated Do not use this function.  It has been superseded by \ref arm_cfft_q31 and will be removed
  62 * @param[in]      *S    points to an instance of the fixed-point CFFT/CIFFT structure.
  63 * @param[in, out] *pSrc points to the complex data buffer of size <code>2*fftLen</code>. Processing occurs in-place.
  64 * @return none.
  65 */
  66
  67 void arm_cfft_radix2_q31(
  68 const arm_cfft_radix2_instance_q31 * S,
  69 q31_t * pSrc)
  70 {
  71
  72    if (S->ifftFlag == 1U)
  73    {
  74       arm_radix2_butterfly_inverse_q31(pSrc, S->fftLen,
  75       S->pTwiddle, S->twidCoefModifier);
  76    }
  77    else
  78    {
  79       arm_radix2_butterfly_q31(pSrc, S->fftLen,
  80       S->pTwiddle, S->twidCoefModifier);
  81    }
  82
  83    arm_bitreversal_q31(pSrc, S->fftLen, S->bitRevFactor, S->pBitRevTable);
  84 }
  85
  86 /**
  87 * @} end of ComplexFFT group
  88 */
  89
  90 void arm_radix2_butterfly_q31(
  91 q31_t * pSrc,
  92 uint32_t fftLen,
  93 q31_t * pCoef,
  94 uint16_t twidCoefModifier)
  95 {
  96
  97    unsigned i, j, k, l, m;
  98    unsigned n1, n2, ia;
  99    q31_t xt, yt, cosVal, sinVal;
 100    q31_t p0, p1;
 101
 102    //N = fftLen;
 103    n2 = fftLen;
 104
 105    n1 = n2;
 106    n2 = n2 >> 1;
 107    ia = 0;
 108
 109    // loop for groups
 110    for (i = 0; i < n2; i++)
 111    {
 112       cosVal = pCoef[ia * 2];
 113       sinVal = pCoef[(ia * 2) + 1];
 114       ia = ia + twidCoefModifier;
 115
 116       l = i + n2;
 117       xt = (pSrc[2 * i] >> 1U) - (pSrc[2 * l] >> 1U);
 118       pSrc[2 * i] = ((pSrc[2 * i] >> 1U) + (pSrc[2 * l] >> 1U)) >> 1U;
 119
 120       yt = (pSrc[2 * i + 1] >> 1U) - (pSrc[2 * l + 1] >> 1U);
 121       pSrc[2 * i + 1] =
 122         ((pSrc[2 * l + 1] >> 1U) + (pSrc[2 * i + 1] >> 1U)) >> 1U;
 123
 124       mult_32x32_keep32_R(p0, xt, cosVal);
 125       mult_32x32_keep32_R(p1, yt, cosVal);
 126       multAcc_32x32_keep32_R(p0, yt, sinVal);
 127       multSub_32x32_keep32_R(p1, xt, sinVal);
 128
 129       pSrc[2U * l] = p0;
 130       pSrc[2U * l + 1U] = p1;
 131
 132    }                             // groups loop end
 133
 134    twidCoefModifier <<= 1U;
 135
 136    // loop for stage
 137    for (k = fftLen / 2; k > 2; k = k >> 1)
 138    {
 139       n1 = n2;
 140       n2 = n2 >> 1;
 141       ia = 0;
 142
 143       // loop for groups
 144       for (j = 0; j < n2; j++)
 145       {
 146          cosVal = pCoef[ia * 2];
 147          sinVal = pCoef[(ia * 2) + 1];
 148          ia = ia + twidCoefModifier;
 149
 150          // loop for butterfly
 151          i = j;
 152          m = fftLen / n1;
 153          do
 154          {
 155             l = i + n2;
 156             xt = pSrc[2 * i] - pSrc[2 * l];
 157             pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) >> 1U;
 158
 159             yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
 160             pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) >> 1U;
 161
 162             mult_32x32_keep32_R(p0, xt, cosVal);
 163             mult_32x32_keep32_R(p1, yt, cosVal);
 164             multAcc_32x32_keep32_R(p0, yt, sinVal);
 165             multSub_32x32_keep32_R(p1, xt, sinVal);
 166
 167             pSrc[2U * l] = p0;
 168             pSrc[2U * l + 1U] = p1;
 169             i += n1;
 170             m--;
 171          } while ( m > 0);                   // butterfly loop end
 172
 173       }                           // groups loop end
 174
 175       twidCoefModifier <<= 1U;
 176    }                             // stages loop end
 177
 178    n1 = n2;
 179    n2 = n2 >> 1;
 180    ia = 0;
 181
 182    cosVal = pCoef[ia * 2];
 183    sinVal = pCoef[(ia * 2) + 1];
 184    ia = ia + twidCoefModifier;
 185
 186    // loop for butterfly
 187    for (i = 0; i < fftLen; i += n1)
 188    {
 189       l = i + n2;
 190       xt = pSrc[2 * i] - pSrc[2 * l];
 191       pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);
 192
 193       yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
 194       pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);
 195
 196       pSrc[2U * l] = xt;
 197
 198       pSrc[2U * l + 1U] = yt;
 199
 200       i += n1;
 201       l = i + n2;
 202
 203       xt = pSrc[2 * i] - pSrc[2 * l];
 204       pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);
 205
 206       yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
 207       pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);
 208
 209       pSrc[2U * l] = xt;
 210
 211       pSrc[2U * l + 1U] = yt;
 212
 213    }                             // butterfly loop end
 214
 215 }
 216
 217
 218 void arm_radix2_butterfly_inverse_q31(
 219 q31_t * pSrc,
 220 uint32_t fftLen,
 221 q31_t * pCoef,
 222 uint16_t twidCoefModifier)
 223 {
 224
 225    unsigned i, j, k, l;
 226    unsigned n1, n2, ia;
 227    q31_t xt, yt, cosVal, sinVal;
 228    q31_t p0, p1;
 229
 230    //N = fftLen;
 231    n2 = fftLen;
 232
 233    n1 = n2;
 234    n2 = n2 >> 1;
 235    ia = 0;
 236
 237    // loop for groups
 238    for (i = 0; i < n2; i++)
 239    {
 240       cosVal = pCoef[ia * 2];
 241       sinVal = pCoef[(ia * 2) + 1];
 242       ia = ia + twidCoefModifier;
 243
 244       l = i + n2;
 245       xt = (pSrc[2 * i] >> 1U) - (pSrc[2 * l] >> 1U);
 246       pSrc[2 * i] = ((pSrc[2 * i] >> 1U) + (pSrc[2 * l] >> 1U)) >> 1U;
 247
 248       yt = (pSrc[2 * i + 1] >> 1U) - (pSrc[2 * l + 1] >> 1U);
 249       pSrc[2 * i + 1] =
 250         ((pSrc[2 * l + 1] >> 1U) + (pSrc[2 * i + 1] >> 1U)) >> 1U;
 251
 252       mult_32x32_keep32_R(p0, xt, cosVal);
 253       mult_32x32_keep32_R(p1, yt, cosVal);
 254       multSub_32x32_keep32_R(p0, yt, sinVal);
 255       multAcc_32x32_keep32_R(p1, xt, sinVal);
 256
 257       pSrc[2U * l] = p0;
 258       pSrc[2U * l + 1U] = p1;
 259    }                             // groups loop end
 260
 261    twidCoefModifier = twidCoefModifier << 1U;
 262
 263    // loop for stage
 264    for (k = fftLen / 2; k > 2; k = k >> 1)
 265    {
 266       n1 = n2;
 267       n2 = n2 >> 1;
 268       ia = 0;
 269
 270       // loop for groups
 271       for (j = 0; j < n2; j++)
 272       {
 273          cosVal = pCoef[ia * 2];
 274          sinVal = pCoef[(ia * 2) + 1];
 275          ia = ia + twidCoefModifier;
 276
 277          // loop for butterfly
 278          for (i = j; i < fftLen; i += n1)
 279          {
 280             l = i + n2;
 281             xt = pSrc[2 * i] - pSrc[2 * l];
 282             pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) >> 1U;
 283
 284             yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
 285             pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) >> 1U;
 286
 287             mult_32x32_keep32_R(p0, xt, cosVal);
 288             mult_32x32_keep32_R(p1, yt, cosVal);
 289             multSub_32x32_keep32_R(p0, yt, sinVal);
 290             multAcc_32x32_keep32_R(p1, xt, sinVal);
 291
 292             pSrc[2U * l] = p0;
 293             pSrc[2U * l + 1U] = p1;
 294          }                         // butterfly loop end
 295
 296       }                           // groups loop end
 297
 298       twidCoefModifier = twidCoefModifier << 1U;
 299    }                             // stages loop end
 300
 301    n1 = n2;
 302    n2 = n2 >> 1;
 303    ia = 0;
 304
 305    cosVal = pCoef[ia * 2];
 306    sinVal = pCoef[(ia * 2) + 1];
 307    ia = ia + twidCoefModifier;
 308
 309    // loop for butterfly
 310    for (i = 0; i < fftLen; i += n1)
 311    {
 312       l = i + n2;
 313       xt = pSrc[2 * i] - pSrc[2 * l];
 314       pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);
 315
 316       yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
 317       pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);
 318
 319       pSrc[2U * l] = xt;
 320
 321       pSrc[2U * l + 1U] = yt;
 322
 323       i += n1;
 324       l = i + n2;
 325
 326       xt = pSrc[2 * i] - pSrc[2 * l];
 327       pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);
 328
 329       yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
 330       pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);
 331
 332       pSrc[2U * l] = xt;
 333
 334       pSrc[2U * l + 1U] = yt;
 335
 336    }                             // butterfly loop end
 337
 338 }