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这个确实不错,准备测试下。
- /* ----------------------------------------------------------------------
- * Project: CMSIS DSP Library
- * Title: arm_cfft_f64.c
- * Description: Combined Radix Decimation in Frequency CFFT Double Precision Floating point processing function
- *
- * $Date: 29. November 2019
- * $Revision: V1.0.0
- *
- * Target Processor: Cortex-M cores
- * -------------------------------------------------------------------- */
- /*
- * Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved.
- *
- * SPDX-License-Identifier: Apache-2.0
- *
- * Licensed under the Apache License, Version 2.0 (the License); you may
- * not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an AS IS BASIS, WITHOUT
- * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
- #include "arm_math.h"
- #include "arm_common_tables.h"
- extern void arm_radix4_butterfly_f64(
- float64_t * pSrc,
- uint16_t fftLen,
- const float64_t * pCoef,
- uint16_t twidCoefModifier);
- extern void arm_bitreversal_64(
- uint64_t * pSrc,
- const uint16_t bitRevLen,
- const uint16_t * pBitRevTable);
- /**
- * @} end of ComplexFFT group
- */
- /* ----------------------------------------------------------------------
- * Internal helper function used by the FFTs
- * ---------------------------------------------------------------------- */
- /*
- * @brief Core function for the Double Precision floating-point CFFT butterfly process.
- * @param[in, out] *pSrc points to the in-place buffer of F64 data type.
- * @param[in] fftLen length of the FFT.
- * @param[in] *pCoef points to the twiddle coefficient buffer.
- * @param[in] twidCoefModifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table.
- * @return none.
- */
- void arm_radix4_butterfly_f64(
- float64_t * pSrc,
- uint16_t fftLen,
- const float64_t * pCoef,
- uint16_t twidCoefModifier)
- {
- float64_t co1, co2, co3, si1, si2, si3;
- uint32_t ia1, ia2, ia3;
- uint32_t i0, i1, i2, i3;
- uint32_t n1, n2, j, k;
- float64_t t1, t2, r1, r2, s1, s2;
- /* Initializations for the fft calculation */
- n2 = fftLen;
- n1 = n2;
- for (k = fftLen; k > 1U; k >>= 2U)
- {
- /* Initializations for the fft calculation */
- n1 = n2;
- n2 >>= 2U;
- ia1 = 0U;
- /* FFT Calculation */
- j = 0;
- do
- {
- /* index calculation for the coefficients */
- ia2 = ia1 + ia1;
- ia3 = ia2 + ia1;
- co1 = pCoef[ia1 * 2U];
- si1 = pCoef[(ia1 * 2U) + 1U];
- co2 = pCoef[ia2 * 2U];
- si2 = pCoef[(ia2 * 2U) + 1U];
- co3 = pCoef[ia3 * 2U];
- si3 = pCoef[(ia3 * 2U) + 1U];
- /* Twiddle coefficients index modifier */
- ia1 = ia1 + twidCoefModifier;
- i0 = j;
- do
- {
- /* index calculation for the input as, */
- /* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */
- i1 = i0 + n2;
- i2 = i1 + n2;
- i3 = i2 + n2;
- /* xa + xc */
- r1 = pSrc[(2U * i0)] + pSrc[(2U * i2)];
- /* xa - xc */
- r2 = pSrc[(2U * i0)] - pSrc[(2U * i2)];
- /* ya + yc */
- s1 = pSrc[(2U * i0) + 1U] + pSrc[(2U * i2) + 1U];
- /* ya - yc */
- s2 = pSrc[(2U * i0) + 1U] - pSrc[(2U * i2) + 1U];
- /* xb + xd */
- t1 = pSrc[2U * i1] + pSrc[2U * i3];
- /* xa' = xa + xb + xc + xd */
- pSrc[2U * i0] = r1 + t1;
- /* xa + xc -(xb + xd) */
- r1 = r1 - t1;
- /* yb + yd */
- t2 = pSrc[(2U * i1) + 1U] + pSrc[(2U * i3) + 1U];
- /* ya' = ya + yb + yc + yd */
- pSrc[(2U * i0) + 1U] = s1 + t2;
- /* (ya + yc) - (yb + yd) */
- s1 = s1 - t2;
- /* (yb - yd) */
- t1 = pSrc[(2U * i1) + 1U] - pSrc[(2U * i3) + 1U];
- /* (xb - xd) */
- t2 = pSrc[2U * i1] - pSrc[2U * i3];
- /* xc' = (xa-xb+xc-xd)co2 + (ya-yb+yc-yd)(si2) */
- pSrc[2U * i1] = (r1 * co2) + (s1 * si2);
- /* yc' = (ya-yb+yc-yd)co2 - (xa-xb+xc-xd)(si2) */
- pSrc[(2U * i1) + 1U] = (s1 * co2) - (r1 * si2);
- /* (xa - xc) + (yb - yd) */
- r1 = r2 + t1;
- /* (xa - xc) - (yb - yd) */
- r2 = r2 - t1;
- /* (ya - yc) - (xb - xd) */
- s1 = s2 - t2;
- /* (ya - yc) + (xb - xd) */
- s2 = s2 + t2;
- /* xb' = (xa+yb-xc-yd)co1 + (ya-xb-yc+xd)(si1) */
- pSrc[2U * i2] = (r1 * co1) + (s1 * si1);
- /* yb' = (ya-xb-yc+xd)co1 - (xa+yb-xc-yd)(si1) */
- pSrc[(2U * i2) + 1U] = (s1 * co1) - (r1 * si1);
- /* xd' = (xa-yb-xc+yd)co3 + (ya+xb-yc-xd)(si3) */
- pSrc[2U * i3] = (r2 * co3) + (s2 * si3);
- /* yd' = (ya+xb-yc-xd)co3 - (xa-yb-xc+yd)(si3) */
- pSrc[(2U * i3) + 1U] = (s2 * co3) - (r2 * si3);
- i0 += n1;
- } while ( i0 < fftLen);
- j++;
- } while (j <= (n2 - 1U));
- twidCoefModifier <<= 2U;
- }
- }
- /*
- * @brief Core function for the Double Precision floating-point CFFT butterfly process.
- * @param[in, out] *pSrc points to the in-place buffer of F64 data type.
- * @param[in] fftLen length of the FFT.
- * @param[in] *pCoef points to the twiddle coefficient buffer.
- * @param[in] twidCoefModifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table.
- * @return none.
- */
- void arm_cfft_radix4by2_f64(
- float64_t * pSrc,
- uint32_t fftLen,
- const float64_t * pCoef)
- {
- uint32_t i, l;
- uint32_t n2, ia;
- float64_t xt, yt, cosVal, sinVal;
- float64_t p0, p1,p2,p3,a0,a1;
- n2 = fftLen >> 1;
- ia = 0;
- for (i = 0; i < n2; i++)
- {
- cosVal = pCoef[2*ia];
- sinVal = pCoef[2*ia + 1];
- ia++;
- l = i + n2;
- /* Butterfly implementation */
- a0 = pSrc[2 * i] + pSrc[2 * l];
- xt = pSrc[2 * i] - pSrc[2 * l];
- yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
- a1 = pSrc[2 * l + 1] + pSrc[2 * i + 1];
- p0 = xt * cosVal;
- p1 = yt * sinVal;
- p2 = yt * cosVal;
- p3 = xt * sinVal;
- pSrc[2 * i] = a0;
- pSrc[2 * i + 1] = a1;
- pSrc[2 * l] = p0 + p1;
- pSrc[2 * l + 1] = p2 - p3;
- }
- // first col
- arm_radix4_butterfly_f64( pSrc, n2, (float64_t*)pCoef, 2U);
- // second col
- arm_radix4_butterfly_f64( pSrc + fftLen, n2, (float64_t*)pCoef, 2U);
- }
- /**
- @addtogroup ComplexFFT
- @{
- */
- /**
- @brief Processing function for the Double Precision floating-point complex FFT.
- @param[in] S points to an instance of the Double Precision floating-point CFFT structure
- @param[in,out] p1 points to the complex data buffer of size <code>2*fftLen</code>. Processing occurs in-place
- @param[in] ifftFlag flag that selects transform direction
- - value = 0: forward transform
- - value = 1: inverse transform
- @param[in] bitReverseFlag flag that enables / disables bit reversal of output
- - value = 0: disables bit reversal of output
- - value = 1: enables bit reversal of output
- @return none
- */
- void arm_cfft_f64(
- const arm_cfft_instance_f64 * S,
- float64_t * p1,
- uint8_t ifftFlag,
- uint8_t bitReverseFlag)
- {
- uint32_t L = S->fftLen, l;
- float64_t invL, * pSrc;
- if (ifftFlag == 1U)
- {
- /* Conjugate input data */
- pSrc = p1 + 1;
- for(l=0; l<L; l++)
- {
- *pSrc = -*pSrc;
- pSrc += 2;
- }
- }
- switch (L)
- {
- case 16:
- case 64:
- case 256:
- case 1024:
- case 4096:
- arm_radix4_butterfly_f64 (p1, L, (float64_t*)S->pTwiddle, 1U);
- break;
- case 32:
- case 128:
- case 512:
- case 2048:
- arm_cfft_radix4by2_f64 ( p1, L, (float64_t*)S->pTwiddle);
- break;
- }
- if ( bitReverseFlag )
- arm_bitreversal_64((uint64_t*)p1, S->bitRevLength,S->pBitRevTable);
- if (ifftFlag == 1U)
- {
- invL = 1.0 / (float64_t)L;
- /* Conjugate and scale output data */
- pSrc = p1;
- for(l=0; l<L; l++)
- {
- *pSrc++ *= invL ;
- *pSrc = -(*pSrc) * invL;
- pSrc++;
- }
- }
- }
- /**
- @} end of ComplexFFT group
- */
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