mbed-os 6.10 versione
cmsis_dsp/TransformFunctions/arm_cfft_radix2_f32.c@1:fdd22bb7aa52, 2012-11-28 (annotated)
- Committer:
- emilmont
- Date:
- Wed Nov 28 12:30:09 2012 +0000
- Revision:
- 1:fdd22bb7aa52
- Child:
- 2:da51fb522205
DSP library code
Who changed what in which revision?
User | Revision | Line number | New contents of line |
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emilmont | 1:fdd22bb7aa52 | 1 | /* ---------------------------------------------------------------------- |
emilmont | 1:fdd22bb7aa52 | 2 | * Copyright (C) 2010 ARM Limited. All rights reserved. |
emilmont | 1:fdd22bb7aa52 | 3 | * |
emilmont | 1:fdd22bb7aa52 | 4 | * $Date: 15. February 2012 |
emilmont | 1:fdd22bb7aa52 | 5 | * $Revision: V1.1.0 |
emilmont | 1:fdd22bb7aa52 | 6 | * |
emilmont | 1:fdd22bb7aa52 | 7 | * Project: CMSIS DSP Library |
emilmont | 1:fdd22bb7aa52 | 8 | * Title: arm_cfft_radix2_f32.c |
emilmont | 1:fdd22bb7aa52 | 9 | * |
emilmont | 1:fdd22bb7aa52 | 10 | * Description: Radix-2 Decimation in Frequency CFFT & CIFFT Floating point processing function |
emilmont | 1:fdd22bb7aa52 | 11 | * |
emilmont | 1:fdd22bb7aa52 | 12 | * |
emilmont | 1:fdd22bb7aa52 | 13 | * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 |
emilmont | 1:fdd22bb7aa52 | 14 | * |
emilmont | 1:fdd22bb7aa52 | 15 | * Version 1.1.0 2012/02/15 |
emilmont | 1:fdd22bb7aa52 | 16 | * Updated with more optimizations, bug fixes and minor API changes. |
emilmont | 1:fdd22bb7aa52 | 17 | * |
emilmont | 1:fdd22bb7aa52 | 18 | * Version 1.0.3 2010/11/29 |
emilmont | 1:fdd22bb7aa52 | 19 | * Initial version |
emilmont | 1:fdd22bb7aa52 | 20 | * -------------------------------------------------------------------- */ |
emilmont | 1:fdd22bb7aa52 | 21 | |
emilmont | 1:fdd22bb7aa52 | 22 | #include "arm_math.h" |
emilmont | 1:fdd22bb7aa52 | 23 | |
emilmont | 1:fdd22bb7aa52 | 24 | /** |
emilmont | 1:fdd22bb7aa52 | 25 | * @ingroup groupTransforms |
emilmont | 1:fdd22bb7aa52 | 26 | */ |
emilmont | 1:fdd22bb7aa52 | 27 | |
emilmont | 1:fdd22bb7aa52 | 28 | /** |
emilmont | 1:fdd22bb7aa52 | 29 | * @defgroup Radix2_CFFT_CIFFT Radix-2 Complex FFT Functions |
emilmont | 1:fdd22bb7aa52 | 30 | * |
emilmont | 1:fdd22bb7aa52 | 31 | * \par |
emilmont | 1:fdd22bb7aa52 | 32 | * Complex Fast Fourier Transform(CFFT) and Complex Inverse Fast Fourier Transform(CIFFT) is an efficient algorithm to compute Discrete Fourier Transform(DFT) and Inverse Discrete Fourier Transform(IDFT). |
emilmont | 1:fdd22bb7aa52 | 33 | * Computational complexity of CFFT reduces drastically when compared to DFT. |
emilmont | 1:fdd22bb7aa52 | 34 | * \par |
emilmont | 1:fdd22bb7aa52 | 35 | * This set of functions implements CFFT/CIFFT |
emilmont | 1:fdd22bb7aa52 | 36 | * for Q15, Q31, and floating-point data types. The functions operates on in-place buffer which uses same buffer for input and output. |
emilmont | 1:fdd22bb7aa52 | 37 | * Complex input is stored in input buffer in an interleaved fashion. |
emilmont | 1:fdd22bb7aa52 | 38 | * |
emilmont | 1:fdd22bb7aa52 | 39 | * \par |
emilmont | 1:fdd22bb7aa52 | 40 | * The functions operate on blocks of input and output data and each call to the function processes |
emilmont | 1:fdd22bb7aa52 | 41 | * <code>2*fftLen</code> samples through the transform. <code>pSrc</code> points to In-place arrays containing <code>2*fftLen</code> values. |
emilmont | 1:fdd22bb7aa52 | 42 | * \par |
emilmont | 1:fdd22bb7aa52 | 43 | * The <code>pSrc</code> points to the array of in-place buffer of size <code>2*fftLen</code> and inputs and outputs are stored in an interleaved fashion as shown below. |
emilmont | 1:fdd22bb7aa52 | 44 | * <pre> {real[0], imag[0], real[1], imag[1],..} </pre> |
emilmont | 1:fdd22bb7aa52 | 45 | * |
emilmont | 1:fdd22bb7aa52 | 46 | * \par Lengths supported by the transform: |
emilmont | 1:fdd22bb7aa52 | 47 | * \par |
emilmont | 1:fdd22bb7aa52 | 48 | * Internally, the function utilize a radix-2 decimation in frequency(DIF) algorithm |
emilmont | 1:fdd22bb7aa52 | 49 | * and the size of the FFT supported are of the lengths [16, 32, 64, 128, 256, 512, 1024, 2048, 4096]. |
emilmont | 1:fdd22bb7aa52 | 50 | * |
emilmont | 1:fdd22bb7aa52 | 51 | * |
emilmont | 1:fdd22bb7aa52 | 52 | * \par Algorithm: |
emilmont | 1:fdd22bb7aa52 | 53 | * |
emilmont | 1:fdd22bb7aa52 | 54 | * <b>Complex Fast Fourier Transform:</b> |
emilmont | 1:fdd22bb7aa52 | 55 | * \par |
emilmont | 1:fdd22bb7aa52 | 56 | * Input real and imaginary data: |
emilmont | 1:fdd22bb7aa52 | 57 | * <pre> |
emilmont | 1:fdd22bb7aa52 | 58 | * x(n) = xa + j * ya |
emilmont | 1:fdd22bb7aa52 | 59 | * x(n+N/2 ) = xb + j * yb |
emilmont | 1:fdd22bb7aa52 | 60 | * </pre> |
emilmont | 1:fdd22bb7aa52 | 61 | * where N is length of FFT |
emilmont | 1:fdd22bb7aa52 | 62 | * \par |
emilmont | 1:fdd22bb7aa52 | 63 | * Output real and imaginary data: |
emilmont | 1:fdd22bb7aa52 | 64 | * <pre> |
emilmont | 1:fdd22bb7aa52 | 65 | * X(2r) = xa'+ j * ya' |
emilmont | 1:fdd22bb7aa52 | 66 | * X(2r+1) = xb'+ j * yb' |
emilmont | 1:fdd22bb7aa52 | 67 | * </pre> |
emilmont | 1:fdd22bb7aa52 | 68 | * \par |
emilmont | 1:fdd22bb7aa52 | 69 | * Twiddle factors for radix-2 FFT: |
emilmont | 1:fdd22bb7aa52 | 70 | * <pre> |
emilmont | 1:fdd22bb7aa52 | 71 | * Wn = cosVal + j * (- sinVal) |
emilmont | 1:fdd22bb7aa52 | 72 | * </pre> |
emilmont | 1:fdd22bb7aa52 | 73 | * |
emilmont | 1:fdd22bb7aa52 | 74 | * \par |
emilmont | 1:fdd22bb7aa52 | 75 | * \image html CFFT_Radix2.gif "Radix-2 Decimation-in Frequency Complex Fast Fourier Transform" |
emilmont | 1:fdd22bb7aa52 | 76 | * |
emilmont | 1:fdd22bb7aa52 | 77 | * \par |
emilmont | 1:fdd22bb7aa52 | 78 | * Output from Radix-2 CFFT Results in Digit reversal order. Interchange middle two branches of every butterfly results in Bit reversed output. |
emilmont | 1:fdd22bb7aa52 | 79 | * \par |
emilmont | 1:fdd22bb7aa52 | 80 | * <b> Butterfly CFFT equations:</b> |
emilmont | 1:fdd22bb7aa52 | 81 | * <pre> |
emilmont | 1:fdd22bb7aa52 | 82 | * xa' = xa + xb |
emilmont | 1:fdd22bb7aa52 | 83 | * ya' = ya + yb |
emilmont | 1:fdd22bb7aa52 | 84 | * xb' = (xa-xb)* cosVal + (ya-yb) * sinVal |
emilmont | 1:fdd22bb7aa52 | 85 | * yb' = (ya-yb)* cosVal - (xa-xb) * sinVal |
emilmont | 1:fdd22bb7aa52 | 86 | * </pre> |
emilmont | 1:fdd22bb7aa52 | 87 | * |
emilmont | 1:fdd22bb7aa52 | 88 | * |
emilmont | 1:fdd22bb7aa52 | 89 | * <b>Complex Inverse Fast Fourier Transform:</b> |
emilmont | 1:fdd22bb7aa52 | 90 | * \par |
emilmont | 1:fdd22bb7aa52 | 91 | * CIFFT uses same twiddle factor table as CFFT with modifications in the design equation as shown below. |
emilmont | 1:fdd22bb7aa52 | 92 | * |
emilmont | 1:fdd22bb7aa52 | 93 | * \par |
emilmont | 1:fdd22bb7aa52 | 94 | * <b> Modified Butterfly CIFFT equations:</b> |
emilmont | 1:fdd22bb7aa52 | 95 | * <pre> |
emilmont | 1:fdd22bb7aa52 | 96 | * xa' = xa + xb |
emilmont | 1:fdd22bb7aa52 | 97 | * ya' = ya + yb |
emilmont | 1:fdd22bb7aa52 | 98 | * xb' = (xa-xb)* cosVal - (ya-yb) * sinVal |
emilmont | 1:fdd22bb7aa52 | 99 | * yb' = (ya-yb)* cosVal + (xa-xb) * sinVal |
emilmont | 1:fdd22bb7aa52 | 100 | * </pre> |
emilmont | 1:fdd22bb7aa52 | 101 | * |
emilmont | 1:fdd22bb7aa52 | 102 | * \par Instance Structure |
emilmont | 1:fdd22bb7aa52 | 103 | * A separate instance structure must be defined for each Instance but the twiddle factors and bit reversal tables can be reused. |
emilmont | 1:fdd22bb7aa52 | 104 | * There are separate instance structure declarations for each of the 3 supported data types. |
emilmont | 1:fdd22bb7aa52 | 105 | * |
emilmont | 1:fdd22bb7aa52 | 106 | * \par Initialization Functions |
emilmont | 1:fdd22bb7aa52 | 107 | * There is also an associated initialization function for each data type. |
emilmont | 1:fdd22bb7aa52 | 108 | * The initialization function performs the following operations: |
emilmont | 1:fdd22bb7aa52 | 109 | * - Sets the values of the internal structure fields. |
emilmont | 1:fdd22bb7aa52 | 110 | * - Initializes twiddle factor table and bit reversal table pointers |
emilmont | 1:fdd22bb7aa52 | 111 | * \par |
emilmont | 1:fdd22bb7aa52 | 112 | * Use of the initialization function is optional. |
emilmont | 1:fdd22bb7aa52 | 113 | * However, if the initialization function is used, then the instance structure cannot be placed into a const data section. |
emilmont | 1:fdd22bb7aa52 | 114 | * To place an instance structure into a const data section, the instance structure must be manually initialized. |
emilmont | 1:fdd22bb7aa52 | 115 | * Manually initialize the instance structure as follows: |
emilmont | 1:fdd22bb7aa52 | 116 | * <pre> |
emilmont | 1:fdd22bb7aa52 | 117 | *arm_cfft_radix2_instance_f32 S = {fftLen, ifftFlag, bitReverseFlag, pTwiddle, pBitRevTable, twidCoefModifier, bitRevFactor, onebyfftLen}; |
emilmont | 1:fdd22bb7aa52 | 118 | *arm_cfft_radix2_instance_q31 S = {fftLen, ifftFlag, bitReverseFlag, pTwiddle, pBitRevTable, twidCoefModifier, bitRevFactor}; |
emilmont | 1:fdd22bb7aa52 | 119 | *arm_cfft_radix2_instance_q15 S = {fftLen, ifftFlag, bitReverseFlag, pTwiddle, pBitRevTable, twidCoefModifier, bitRevFactor}; |
emilmont | 1:fdd22bb7aa52 | 120 | * </pre> |
emilmont | 1:fdd22bb7aa52 | 121 | * \par |
emilmont | 1:fdd22bb7aa52 | 122 | * where <code>fftLen</code> length of CFFT/CIFFT; <code>ifftFlag</code> Flag for selection of CFFT or CIFFT(Set ifftFlag to calculate CIFFT otherwise calculates CFFT); |
emilmont | 1:fdd22bb7aa52 | 123 | * <code>bitReverseFlag</code> Flag for selection of output order(Set bitReverseFlag to output in normal order otherwise output in bit reversed order); |
emilmont | 1:fdd22bb7aa52 | 124 | * <code>pTwiddle</code>points to array of twiddle coefficients; <code>pBitRevTable</code> points to the array of bit reversal table. |
emilmont | 1:fdd22bb7aa52 | 125 | * <code>twidCoefModifier</code> modifier for twiddle factor table which supports all FFT lengths with same table; |
emilmont | 1:fdd22bb7aa52 | 126 | * <code>pBitRevTable</code> modifier for bit reversal table which supports all FFT lengths with same table. |
emilmont | 1:fdd22bb7aa52 | 127 | * <code>onebyfftLen</code> value of 1/fftLen to calculate CIFFT; |
emilmont | 1:fdd22bb7aa52 | 128 | * |
emilmont | 1:fdd22bb7aa52 | 129 | * \par Fixed-Point Behavior |
emilmont | 1:fdd22bb7aa52 | 130 | * Care must be taken when using the fixed-point versions of the CFFT/CIFFT function. |
emilmont | 1:fdd22bb7aa52 | 131 | * Refer to the function specific documentation below for usage guidelines. |
emilmont | 1:fdd22bb7aa52 | 132 | */ |
emilmont | 1:fdd22bb7aa52 | 133 | |
emilmont | 1:fdd22bb7aa52 | 134 | |
emilmont | 1:fdd22bb7aa52 | 135 | /** |
emilmont | 1:fdd22bb7aa52 | 136 | * @addtogroup Radix2_CFFT_CIFFT |
emilmont | 1:fdd22bb7aa52 | 137 | * @{ |
emilmont | 1:fdd22bb7aa52 | 138 | */ |
emilmont | 1:fdd22bb7aa52 | 139 | |
emilmont | 1:fdd22bb7aa52 | 140 | /** |
emilmont | 1:fdd22bb7aa52 | 141 | * @details |
emilmont | 1:fdd22bb7aa52 | 142 | * @brief Processing function for the floating-point Radix-2 CFFT/CIFFT. |
emilmont | 1:fdd22bb7aa52 | 143 | * @param[in] *S points to an instance of the floating-point Radix-2 CFFT/CIFFT structure. |
emilmont | 1:fdd22bb7aa52 | 144 | * @param[in, out] *pSrc points to the complex data buffer of size <code>2*fftLen</code>. Processing occurs in-place. |
emilmont | 1:fdd22bb7aa52 | 145 | * @return none. |
emilmont | 1:fdd22bb7aa52 | 146 | */ |
emilmont | 1:fdd22bb7aa52 | 147 | |
emilmont | 1:fdd22bb7aa52 | 148 | void arm_cfft_radix2_f32( |
emilmont | 1:fdd22bb7aa52 | 149 | const arm_cfft_radix2_instance_f32 * S, |
emilmont | 1:fdd22bb7aa52 | 150 | float32_t * pSrc) |
emilmont | 1:fdd22bb7aa52 | 151 | { |
emilmont | 1:fdd22bb7aa52 | 152 | |
emilmont | 1:fdd22bb7aa52 | 153 | if(S->ifftFlag == 1u) |
emilmont | 1:fdd22bb7aa52 | 154 | { |
emilmont | 1:fdd22bb7aa52 | 155 | /* Complex IFFT radix-2 */ |
emilmont | 1:fdd22bb7aa52 | 156 | arm_radix2_butterfly_inverse_f32(pSrc, S->fftLen, S->pTwiddle, |
emilmont | 1:fdd22bb7aa52 | 157 | S->twidCoefModifier, S->onebyfftLen); |
emilmont | 1:fdd22bb7aa52 | 158 | } |
emilmont | 1:fdd22bb7aa52 | 159 | else |
emilmont | 1:fdd22bb7aa52 | 160 | { |
emilmont | 1:fdd22bb7aa52 | 161 | /* Complex FFT radix-2 */ |
emilmont | 1:fdd22bb7aa52 | 162 | arm_radix2_butterfly_f32(pSrc, S->fftLen, S->pTwiddle, |
emilmont | 1:fdd22bb7aa52 | 163 | S->twidCoefModifier); |
emilmont | 1:fdd22bb7aa52 | 164 | } |
emilmont | 1:fdd22bb7aa52 | 165 | |
emilmont | 1:fdd22bb7aa52 | 166 | if(S->bitReverseFlag == 1u) |
emilmont | 1:fdd22bb7aa52 | 167 | { |
emilmont | 1:fdd22bb7aa52 | 168 | /* Bit Reversal */ |
emilmont | 1:fdd22bb7aa52 | 169 | arm_bitreversal_f32(pSrc, S->fftLen, S->bitRevFactor, S->pBitRevTable); |
emilmont | 1:fdd22bb7aa52 | 170 | } |
emilmont | 1:fdd22bb7aa52 | 171 | |
emilmont | 1:fdd22bb7aa52 | 172 | } |
emilmont | 1:fdd22bb7aa52 | 173 | |
emilmont | 1:fdd22bb7aa52 | 174 | |
emilmont | 1:fdd22bb7aa52 | 175 | /** |
emilmont | 1:fdd22bb7aa52 | 176 | * @} end of Radix2_CFFT_CIFFT group |
emilmont | 1:fdd22bb7aa52 | 177 | */ |
emilmont | 1:fdd22bb7aa52 | 178 | |
emilmont | 1:fdd22bb7aa52 | 179 | |
emilmont | 1:fdd22bb7aa52 | 180 | |
emilmont | 1:fdd22bb7aa52 | 181 | /* ---------------------------------------------------------------------- |
emilmont | 1:fdd22bb7aa52 | 182 | ** Internal helper function used by the FFTs |
emilmont | 1:fdd22bb7aa52 | 183 | ** ------------------------------------------------------------------- */ |
emilmont | 1:fdd22bb7aa52 | 184 | |
emilmont | 1:fdd22bb7aa52 | 185 | /* |
emilmont | 1:fdd22bb7aa52 | 186 | * @brief Core function for the floating-point CFFT butterfly process. |
emilmont | 1:fdd22bb7aa52 | 187 | * @param[in, out] *pSrc points to the in-place buffer of floating-point data type. |
emilmont | 1:fdd22bb7aa52 | 188 | * @param[in] fftLen length of the FFT. |
emilmont | 1:fdd22bb7aa52 | 189 | * @param[in] *pCoef points to the twiddle coefficient buffer. |
emilmont | 1:fdd22bb7aa52 | 190 | * @param[in] twidCoefModifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table. |
emilmont | 1:fdd22bb7aa52 | 191 | * @return none. |
emilmont | 1:fdd22bb7aa52 | 192 | */ |
emilmont | 1:fdd22bb7aa52 | 193 | |
emilmont | 1:fdd22bb7aa52 | 194 | void arm_radix2_butterfly_f32( |
emilmont | 1:fdd22bb7aa52 | 195 | float32_t * pSrc, |
emilmont | 1:fdd22bb7aa52 | 196 | uint32_t fftLen, |
emilmont | 1:fdd22bb7aa52 | 197 | float32_t * pCoef, |
emilmont | 1:fdd22bb7aa52 | 198 | uint16_t twidCoefModifier) |
emilmont | 1:fdd22bb7aa52 | 199 | { |
emilmont | 1:fdd22bb7aa52 | 200 | |
emilmont | 1:fdd22bb7aa52 | 201 | int i, j, k, l; |
emilmont | 1:fdd22bb7aa52 | 202 | int n1, n2, ia; |
emilmont | 1:fdd22bb7aa52 | 203 | float32_t xt, yt, cosVal, sinVal; |
emilmont | 1:fdd22bb7aa52 | 204 | |
emilmont | 1:fdd22bb7aa52 | 205 | #ifndef ARM_MATH_CM0 |
emilmont | 1:fdd22bb7aa52 | 206 | |
emilmont | 1:fdd22bb7aa52 | 207 | /* Initializations for the first stage */ |
emilmont | 1:fdd22bb7aa52 | 208 | n2 = fftLen; |
emilmont | 1:fdd22bb7aa52 | 209 | |
emilmont | 1:fdd22bb7aa52 | 210 | n1 = n2; |
emilmont | 1:fdd22bb7aa52 | 211 | n2 = n2 >> 1; |
emilmont | 1:fdd22bb7aa52 | 212 | ia = 0; |
emilmont | 1:fdd22bb7aa52 | 213 | |
emilmont | 1:fdd22bb7aa52 | 214 | // loop for groups |
emilmont | 1:fdd22bb7aa52 | 215 | for (i = 0; i < n2; i++) |
emilmont | 1:fdd22bb7aa52 | 216 | { |
emilmont | 1:fdd22bb7aa52 | 217 | cosVal = pCoef[ia * 2]; |
emilmont | 1:fdd22bb7aa52 | 218 | sinVal = pCoef[(ia * 2) + 1]; |
emilmont | 1:fdd22bb7aa52 | 219 | |
emilmont | 1:fdd22bb7aa52 | 220 | /* Twiddle coefficients index modifier */ |
emilmont | 1:fdd22bb7aa52 | 221 | ia = ia + twidCoefModifier; |
emilmont | 1:fdd22bb7aa52 | 222 | |
emilmont | 1:fdd22bb7aa52 | 223 | /* index calculation for the input as, */ |
emilmont | 1:fdd22bb7aa52 | 224 | /* pSrc[i + 0], pSrc[i + fftLen/1] */ |
emilmont | 1:fdd22bb7aa52 | 225 | l = i + n2; |
emilmont | 1:fdd22bb7aa52 | 226 | |
emilmont | 1:fdd22bb7aa52 | 227 | /* Butterfly implementation */ |
emilmont | 1:fdd22bb7aa52 | 228 | xt = pSrc[2 * i] - pSrc[2 * l]; |
emilmont | 1:fdd22bb7aa52 | 229 | pSrc[2 * i] = pSrc[2 * i] + pSrc[2 * l]; |
emilmont | 1:fdd22bb7aa52 | 230 | |
emilmont | 1:fdd22bb7aa52 | 231 | yt = pSrc[2 * i + 1] - pSrc[2 * l + 1]; |
emilmont | 1:fdd22bb7aa52 | 232 | pSrc[2 * i + 1] = pSrc[2 * l + 1] + pSrc[2 * i + 1]; |
emilmont | 1:fdd22bb7aa52 | 233 | |
emilmont | 1:fdd22bb7aa52 | 234 | pSrc[2u * l] = xt * cosVal + yt * sinVal; |
emilmont | 1:fdd22bb7aa52 | 235 | |
emilmont | 1:fdd22bb7aa52 | 236 | pSrc[2u * l + 1u] = yt * cosVal - xt * sinVal; |
emilmont | 1:fdd22bb7aa52 | 237 | |
emilmont | 1:fdd22bb7aa52 | 238 | } // groups loop end |
emilmont | 1:fdd22bb7aa52 | 239 | |
emilmont | 1:fdd22bb7aa52 | 240 | twidCoefModifier = twidCoefModifier << 1u; |
emilmont | 1:fdd22bb7aa52 | 241 | |
emilmont | 1:fdd22bb7aa52 | 242 | // loop for stage |
emilmont | 1:fdd22bb7aa52 | 243 | for (k = fftLen / 2; k > 2; k = k >> 1) |
emilmont | 1:fdd22bb7aa52 | 244 | { |
emilmont | 1:fdd22bb7aa52 | 245 | n1 = n2; |
emilmont | 1:fdd22bb7aa52 | 246 | n2 = n2 >> 1; |
emilmont | 1:fdd22bb7aa52 | 247 | ia = 0; |
emilmont | 1:fdd22bb7aa52 | 248 | |
emilmont | 1:fdd22bb7aa52 | 249 | // loop for groups |
emilmont | 1:fdd22bb7aa52 | 250 | for (j = 0; j < n2; j++) |
emilmont | 1:fdd22bb7aa52 | 251 | { |
emilmont | 1:fdd22bb7aa52 | 252 | cosVal = pCoef[ia * 2]; |
emilmont | 1:fdd22bb7aa52 | 253 | sinVal = pCoef[(ia * 2) + 1]; |
emilmont | 1:fdd22bb7aa52 | 254 | ia = ia + twidCoefModifier; |
emilmont | 1:fdd22bb7aa52 | 255 | |
emilmont | 1:fdd22bb7aa52 | 256 | // loop for butterfly |
emilmont | 1:fdd22bb7aa52 | 257 | for (i = j; i < fftLen; i += n1) |
emilmont | 1:fdd22bb7aa52 | 258 | { |
emilmont | 1:fdd22bb7aa52 | 259 | l = i + n2; |
emilmont | 1:fdd22bb7aa52 | 260 | xt = pSrc[2 * i] - pSrc[2 * l]; |
emilmont | 1:fdd22bb7aa52 | 261 | pSrc[2 * i] = pSrc[2 * i] + pSrc[2 * l]; |
emilmont | 1:fdd22bb7aa52 | 262 | |
emilmont | 1:fdd22bb7aa52 | 263 | yt = pSrc[2 * i + 1] - pSrc[2 * l + 1]; |
emilmont | 1:fdd22bb7aa52 | 264 | pSrc[2 * i + 1] = pSrc[2 * l + 1] + pSrc[2 * i + 1]; |
emilmont | 1:fdd22bb7aa52 | 265 | |
emilmont | 1:fdd22bb7aa52 | 266 | pSrc[2u * l] = xt * cosVal + yt * sinVal; |
emilmont | 1:fdd22bb7aa52 | 267 | |
emilmont | 1:fdd22bb7aa52 | 268 | pSrc[2u * l + 1u] = yt * cosVal - xt * sinVal; |
emilmont | 1:fdd22bb7aa52 | 269 | |
emilmont | 1:fdd22bb7aa52 | 270 | } // butterfly loop end |
emilmont | 1:fdd22bb7aa52 | 271 | |
emilmont | 1:fdd22bb7aa52 | 272 | } // groups loop end |
emilmont | 1:fdd22bb7aa52 | 273 | |
emilmont | 1:fdd22bb7aa52 | 274 | twidCoefModifier = twidCoefModifier << 1u; |
emilmont | 1:fdd22bb7aa52 | 275 | } // stages loop end |
emilmont | 1:fdd22bb7aa52 | 276 | |
emilmont | 1:fdd22bb7aa52 | 277 | n1 = n2; |
emilmont | 1:fdd22bb7aa52 | 278 | n2 = n2 >> 1; |
emilmont | 1:fdd22bb7aa52 | 279 | ia = 0; |
emilmont | 1:fdd22bb7aa52 | 280 | |
emilmont | 1:fdd22bb7aa52 | 281 | cosVal = pCoef[ia * 2]; |
emilmont | 1:fdd22bb7aa52 | 282 | sinVal = pCoef[(ia * 2) + 1]; |
emilmont | 1:fdd22bb7aa52 | 283 | ia = ia + twidCoefModifier; |
emilmont | 1:fdd22bb7aa52 | 284 | |
emilmont | 1:fdd22bb7aa52 | 285 | // loop for butterfly |
emilmont | 1:fdd22bb7aa52 | 286 | for (i = 0; i < fftLen; i += n1) |
emilmont | 1:fdd22bb7aa52 | 287 | { |
emilmont | 1:fdd22bb7aa52 | 288 | l = i + n2; |
emilmont | 1:fdd22bb7aa52 | 289 | xt = pSrc[2 * i] - pSrc[2 * l]; |
emilmont | 1:fdd22bb7aa52 | 290 | pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]); |
emilmont | 1:fdd22bb7aa52 | 291 | |
emilmont | 1:fdd22bb7aa52 | 292 | yt = pSrc[2 * i + 1] - pSrc[2 * l + 1]; |
emilmont | 1:fdd22bb7aa52 | 293 | pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]); |
emilmont | 1:fdd22bb7aa52 | 294 | |
emilmont | 1:fdd22bb7aa52 | 295 | pSrc[2u * l] = xt; |
emilmont | 1:fdd22bb7aa52 | 296 | |
emilmont | 1:fdd22bb7aa52 | 297 | pSrc[2u * l + 1u] = yt; |
emilmont | 1:fdd22bb7aa52 | 298 | |
emilmont | 1:fdd22bb7aa52 | 299 | } // groups loop end |
emilmont | 1:fdd22bb7aa52 | 300 | |
emilmont | 1:fdd22bb7aa52 | 301 | #else |
emilmont | 1:fdd22bb7aa52 | 302 | |
emilmont | 1:fdd22bb7aa52 | 303 | //N = fftLen; |
emilmont | 1:fdd22bb7aa52 | 304 | n2 = fftLen; |
emilmont | 1:fdd22bb7aa52 | 305 | |
emilmont | 1:fdd22bb7aa52 | 306 | // loop for stage |
emilmont | 1:fdd22bb7aa52 | 307 | for (k = fftLen; k > 1; k = k >> 1) |
emilmont | 1:fdd22bb7aa52 | 308 | { |
emilmont | 1:fdd22bb7aa52 | 309 | n1 = n2; |
emilmont | 1:fdd22bb7aa52 | 310 | n2 = n2 >> 1; |
emilmont | 1:fdd22bb7aa52 | 311 | ia = 0; |
emilmont | 1:fdd22bb7aa52 | 312 | |
emilmont | 1:fdd22bb7aa52 | 313 | // loop for groups |
emilmont | 1:fdd22bb7aa52 | 314 | for (j = 0; j < n2; j++) |
emilmont | 1:fdd22bb7aa52 | 315 | { |
emilmont | 1:fdd22bb7aa52 | 316 | cosVal = pCoef[ia * 2]; |
emilmont | 1:fdd22bb7aa52 | 317 | sinVal = pCoef[(ia * 2) + 1]; |
emilmont | 1:fdd22bb7aa52 | 318 | ia = ia + twidCoefModifier; |
emilmont | 1:fdd22bb7aa52 | 319 | |
emilmont | 1:fdd22bb7aa52 | 320 | // loop for butterfly |
emilmont | 1:fdd22bb7aa52 | 321 | for (i = j; i < fftLen; i += n1) |
emilmont | 1:fdd22bb7aa52 | 322 | { |
emilmont | 1:fdd22bb7aa52 | 323 | l = i + n2; |
emilmont | 1:fdd22bb7aa52 | 324 | xt = pSrc[2 * i] - pSrc[2 * l]; |
emilmont | 1:fdd22bb7aa52 | 325 | pSrc[2 * i] = pSrc[2 * i] + pSrc[2 * l]; |
emilmont | 1:fdd22bb7aa52 | 326 | |
emilmont | 1:fdd22bb7aa52 | 327 | yt = pSrc[2 * i + 1] - pSrc[2 * l + 1]; |
emilmont | 1:fdd22bb7aa52 | 328 | pSrc[2 * i + 1] = pSrc[2 * l + 1] + pSrc[2 * i + 1]; |
emilmont | 1:fdd22bb7aa52 | 329 | |
emilmont | 1:fdd22bb7aa52 | 330 | pSrc[2 * l] = (cosVal * xt + sinVal * yt); // >> 15; |
emilmont | 1:fdd22bb7aa52 | 331 | pSrc[2 * l + 1] = (cosVal * yt - sinVal * xt); // >> 15; |
emilmont | 1:fdd22bb7aa52 | 332 | |
emilmont | 1:fdd22bb7aa52 | 333 | } |
emilmont | 1:fdd22bb7aa52 | 334 | } |
emilmont | 1:fdd22bb7aa52 | 335 | twidCoefModifier = twidCoefModifier << 1u; |
emilmont | 1:fdd22bb7aa52 | 336 | } |
emilmont | 1:fdd22bb7aa52 | 337 | |
emilmont | 1:fdd22bb7aa52 | 338 | #endif // #ifndef ARM_MATH_CM0 |
emilmont | 1:fdd22bb7aa52 | 339 | |
emilmont | 1:fdd22bb7aa52 | 340 | } |
emilmont | 1:fdd22bb7aa52 | 341 | |
emilmont | 1:fdd22bb7aa52 | 342 | |
emilmont | 1:fdd22bb7aa52 | 343 | void arm_radix2_butterfly_inverse_f32( |
emilmont | 1:fdd22bb7aa52 | 344 | float32_t * pSrc, |
emilmont | 1:fdd22bb7aa52 | 345 | uint32_t fftLen, |
emilmont | 1:fdd22bb7aa52 | 346 | float32_t * pCoef, |
emilmont | 1:fdd22bb7aa52 | 347 | uint16_t twidCoefModifier, |
emilmont | 1:fdd22bb7aa52 | 348 | float32_t onebyfftLen) |
emilmont | 1:fdd22bb7aa52 | 349 | { |
emilmont | 1:fdd22bb7aa52 | 350 | |
emilmont | 1:fdd22bb7aa52 | 351 | int i, j, k, l; |
emilmont | 1:fdd22bb7aa52 | 352 | int n1, n2, ia; |
emilmont | 1:fdd22bb7aa52 | 353 | float32_t xt, yt, cosVal, sinVal; |
emilmont | 1:fdd22bb7aa52 | 354 | |
emilmont | 1:fdd22bb7aa52 | 355 | #ifndef ARM_MATH_CM0 |
emilmont | 1:fdd22bb7aa52 | 356 | |
emilmont | 1:fdd22bb7aa52 | 357 | //N = fftLen; |
emilmont | 1:fdd22bb7aa52 | 358 | n2 = fftLen; |
emilmont | 1:fdd22bb7aa52 | 359 | |
emilmont | 1:fdd22bb7aa52 | 360 | n1 = n2; |
emilmont | 1:fdd22bb7aa52 | 361 | n2 = n2 >> 1; |
emilmont | 1:fdd22bb7aa52 | 362 | ia = 0; |
emilmont | 1:fdd22bb7aa52 | 363 | |
emilmont | 1:fdd22bb7aa52 | 364 | // loop for groups |
emilmont | 1:fdd22bb7aa52 | 365 | for (i = 0; i < n2; i++) |
emilmont | 1:fdd22bb7aa52 | 366 | { |
emilmont | 1:fdd22bb7aa52 | 367 | cosVal = pCoef[ia * 2]; |
emilmont | 1:fdd22bb7aa52 | 368 | sinVal = pCoef[(ia * 2) + 1]; |
emilmont | 1:fdd22bb7aa52 | 369 | ia = ia + twidCoefModifier; |
emilmont | 1:fdd22bb7aa52 | 370 | |
emilmont | 1:fdd22bb7aa52 | 371 | l = i + n2; |
emilmont | 1:fdd22bb7aa52 | 372 | xt = pSrc[2 * i] - pSrc[2 * l]; |
emilmont | 1:fdd22bb7aa52 | 373 | pSrc[2 * i] = pSrc[2 * i] + pSrc[2 * l]; |
emilmont | 1:fdd22bb7aa52 | 374 | |
emilmont | 1:fdd22bb7aa52 | 375 | yt = pSrc[2 * i + 1] - pSrc[2 * l + 1]; |
emilmont | 1:fdd22bb7aa52 | 376 | pSrc[2 * i + 1] = pSrc[2 * l + 1] + pSrc[2 * i + 1]; |
emilmont | 1:fdd22bb7aa52 | 377 | |
emilmont | 1:fdd22bb7aa52 | 378 | pSrc[2u * l] = xt * cosVal - yt * sinVal; |
emilmont | 1:fdd22bb7aa52 | 379 | |
emilmont | 1:fdd22bb7aa52 | 380 | pSrc[2u * l + 1u] = yt * cosVal + xt * sinVal; |
emilmont | 1:fdd22bb7aa52 | 381 | |
emilmont | 1:fdd22bb7aa52 | 382 | } // groups loop end |
emilmont | 1:fdd22bb7aa52 | 383 | |
emilmont | 1:fdd22bb7aa52 | 384 | twidCoefModifier = twidCoefModifier << 1u; |
emilmont | 1:fdd22bb7aa52 | 385 | |
emilmont | 1:fdd22bb7aa52 | 386 | // loop for stage |
emilmont | 1:fdd22bb7aa52 | 387 | for (k = fftLen / 2; k > 2; k = k >> 1) |
emilmont | 1:fdd22bb7aa52 | 388 | { |
emilmont | 1:fdd22bb7aa52 | 389 | n1 = n2; |
emilmont | 1:fdd22bb7aa52 | 390 | n2 = n2 >> 1; |
emilmont | 1:fdd22bb7aa52 | 391 | ia = 0; |
emilmont | 1:fdd22bb7aa52 | 392 | |
emilmont | 1:fdd22bb7aa52 | 393 | // loop for groups |
emilmont | 1:fdd22bb7aa52 | 394 | for (j = 0; j < n2; j++) |
emilmont | 1:fdd22bb7aa52 | 395 | { |
emilmont | 1:fdd22bb7aa52 | 396 | cosVal = pCoef[ia * 2]; |
emilmont | 1:fdd22bb7aa52 | 397 | sinVal = pCoef[(ia * 2) + 1]; |
emilmont | 1:fdd22bb7aa52 | 398 | ia = ia + twidCoefModifier; |
emilmont | 1:fdd22bb7aa52 | 399 | |
emilmont | 1:fdd22bb7aa52 | 400 | // loop for butterfly |
emilmont | 1:fdd22bb7aa52 | 401 | for (i = j; i < fftLen; i += n1) |
emilmont | 1:fdd22bb7aa52 | 402 | { |
emilmont | 1:fdd22bb7aa52 | 403 | l = i + n2; |
emilmont | 1:fdd22bb7aa52 | 404 | xt = pSrc[2 * i] - pSrc[2 * l]; |
emilmont | 1:fdd22bb7aa52 | 405 | pSrc[2 * i] = pSrc[2 * i] + pSrc[2 * l]; |
emilmont | 1:fdd22bb7aa52 | 406 | |
emilmont | 1:fdd22bb7aa52 | 407 | yt = pSrc[2 * i + 1] - pSrc[2 * l + 1]; |
emilmont | 1:fdd22bb7aa52 | 408 | pSrc[2 * i + 1] = pSrc[2 * l + 1] + pSrc[2 * i + 1]; |
emilmont | 1:fdd22bb7aa52 | 409 | |
emilmont | 1:fdd22bb7aa52 | 410 | pSrc[2u * l] = xt * cosVal - yt * sinVal; |
emilmont | 1:fdd22bb7aa52 | 411 | |
emilmont | 1:fdd22bb7aa52 | 412 | pSrc[2u * l + 1u] = yt * cosVal + xt * sinVal; |
emilmont | 1:fdd22bb7aa52 | 413 | |
emilmont | 1:fdd22bb7aa52 | 414 | } // butterfly loop end |
emilmont | 1:fdd22bb7aa52 | 415 | |
emilmont | 1:fdd22bb7aa52 | 416 | } // groups loop end |
emilmont | 1:fdd22bb7aa52 | 417 | |
emilmont | 1:fdd22bb7aa52 | 418 | twidCoefModifier = twidCoefModifier << 1u; |
emilmont | 1:fdd22bb7aa52 | 419 | } // stages loop end |
emilmont | 1:fdd22bb7aa52 | 420 | |
emilmont | 1:fdd22bb7aa52 | 421 | n1 = n2; |
emilmont | 1:fdd22bb7aa52 | 422 | n2 = n2 >> 1; |
emilmont | 1:fdd22bb7aa52 | 423 | ia = 0; |
emilmont | 1:fdd22bb7aa52 | 424 | |
emilmont | 1:fdd22bb7aa52 | 425 | cosVal = pCoef[ia * 2]; |
emilmont | 1:fdd22bb7aa52 | 426 | sinVal = pCoef[(ia * 2) + 1]; |
emilmont | 1:fdd22bb7aa52 | 427 | ia = ia + twidCoefModifier; |
emilmont | 1:fdd22bb7aa52 | 428 | |
emilmont | 1:fdd22bb7aa52 | 429 | // loop for butterfly |
emilmont | 1:fdd22bb7aa52 | 430 | for (i = 0; i < fftLen; i += n1) |
emilmont | 1:fdd22bb7aa52 | 431 | { |
emilmont | 1:fdd22bb7aa52 | 432 | l = i + n2; |
emilmont | 1:fdd22bb7aa52 | 433 | xt = pSrc[2 * i] - pSrc[2 * l]; |
emilmont | 1:fdd22bb7aa52 | 434 | pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) * onebyfftLen; |
emilmont | 1:fdd22bb7aa52 | 435 | |
emilmont | 1:fdd22bb7aa52 | 436 | yt = pSrc[2 * i + 1] - pSrc[2 * l + 1]; |
emilmont | 1:fdd22bb7aa52 | 437 | pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) * onebyfftLen; |
emilmont | 1:fdd22bb7aa52 | 438 | |
emilmont | 1:fdd22bb7aa52 | 439 | pSrc[2u * l] = xt * onebyfftLen; |
emilmont | 1:fdd22bb7aa52 | 440 | |
emilmont | 1:fdd22bb7aa52 | 441 | pSrc[2u * l + 1u] = yt * onebyfftLen; |
emilmont | 1:fdd22bb7aa52 | 442 | |
emilmont | 1:fdd22bb7aa52 | 443 | } // butterfly loop end |
emilmont | 1:fdd22bb7aa52 | 444 | |
emilmont | 1:fdd22bb7aa52 | 445 | #else |
emilmont | 1:fdd22bb7aa52 | 446 | |
emilmont | 1:fdd22bb7aa52 | 447 | //N = fftLen; |
emilmont | 1:fdd22bb7aa52 | 448 | n2 = fftLen; |
emilmont | 1:fdd22bb7aa52 | 449 | |
emilmont | 1:fdd22bb7aa52 | 450 | // loop for stage |
emilmont | 1:fdd22bb7aa52 | 451 | for (k = fftLen; k > 2; k = k >> 1) |
emilmont | 1:fdd22bb7aa52 | 452 | { |
emilmont | 1:fdd22bb7aa52 | 453 | n1 = n2; |
emilmont | 1:fdd22bb7aa52 | 454 | n2 = n2 >> 1; |
emilmont | 1:fdd22bb7aa52 | 455 | ia = 0; |
emilmont | 1:fdd22bb7aa52 | 456 | |
emilmont | 1:fdd22bb7aa52 | 457 | // loop for groups |
emilmont | 1:fdd22bb7aa52 | 458 | for (j = 0; j < n2; j++) |
emilmont | 1:fdd22bb7aa52 | 459 | { |
emilmont | 1:fdd22bb7aa52 | 460 | cosVal = pCoef[ia * 2]; |
emilmont | 1:fdd22bb7aa52 | 461 | sinVal = pCoef[(ia * 2) + 1]; |
emilmont | 1:fdd22bb7aa52 | 462 | ia = ia + twidCoefModifier; |
emilmont | 1:fdd22bb7aa52 | 463 | |
emilmont | 1:fdd22bb7aa52 | 464 | // loop for butterfly |
emilmont | 1:fdd22bb7aa52 | 465 | for (i = j; i < fftLen; i += n1) |
emilmont | 1:fdd22bb7aa52 | 466 | { |
emilmont | 1:fdd22bb7aa52 | 467 | l = i + n2; |
emilmont | 1:fdd22bb7aa52 | 468 | xt = pSrc[2 * i] - pSrc[2 * l]; |
emilmont | 1:fdd22bb7aa52 | 469 | pSrc[2 * i] = pSrc[2 * i] + pSrc[2 * l]; |
emilmont | 1:fdd22bb7aa52 | 470 | |
emilmont | 1:fdd22bb7aa52 | 471 | yt = pSrc[2 * i + 1] - pSrc[2 * l + 1]; |
emilmont | 1:fdd22bb7aa52 | 472 | pSrc[2 * i + 1] = pSrc[2 * l + 1] + pSrc[2 * i + 1]; |
emilmont | 1:fdd22bb7aa52 | 473 | |
emilmont | 1:fdd22bb7aa52 | 474 | pSrc[2u * l] = xt * cosVal - yt * sinVal; |
emilmont | 1:fdd22bb7aa52 | 475 | |
emilmont | 1:fdd22bb7aa52 | 476 | pSrc[2u * l + 1u] = yt * cosVal + xt * sinVal; |
emilmont | 1:fdd22bb7aa52 | 477 | |
emilmont | 1:fdd22bb7aa52 | 478 | } // butterfly loop end |
emilmont | 1:fdd22bb7aa52 | 479 | |
emilmont | 1:fdd22bb7aa52 | 480 | } // groups loop end |
emilmont | 1:fdd22bb7aa52 | 481 | |
emilmont | 1:fdd22bb7aa52 | 482 | twidCoefModifier = twidCoefModifier << 1u; |
emilmont | 1:fdd22bb7aa52 | 483 | } // stages loop end |
emilmont | 1:fdd22bb7aa52 | 484 | |
emilmont | 1:fdd22bb7aa52 | 485 | n1 = n2; |
emilmont | 1:fdd22bb7aa52 | 486 | n2 = n2 >> 1; |
emilmont | 1:fdd22bb7aa52 | 487 | ia = 0; |
emilmont | 1:fdd22bb7aa52 | 488 | |
emilmont | 1:fdd22bb7aa52 | 489 | cosVal = pCoef[ia * 2]; |
emilmont | 1:fdd22bb7aa52 | 490 | sinVal = pCoef[(ia * 2) + 1]; |
emilmont | 1:fdd22bb7aa52 | 491 | ia = ia + twidCoefModifier; |
emilmont | 1:fdd22bb7aa52 | 492 | |
emilmont | 1:fdd22bb7aa52 | 493 | // loop for butterfly |
emilmont | 1:fdd22bb7aa52 | 494 | for (i = 0; i < fftLen; i += n1) |
emilmont | 1:fdd22bb7aa52 | 495 | { |
emilmont | 1:fdd22bb7aa52 | 496 | l = i + n2; |
emilmont | 1:fdd22bb7aa52 | 497 | xt = pSrc[2 * i] - pSrc[2 * l]; |
emilmont | 1:fdd22bb7aa52 | 498 | pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) * onebyfftLen; |
emilmont | 1:fdd22bb7aa52 | 499 | |
emilmont | 1:fdd22bb7aa52 | 500 | yt = pSrc[2 * i + 1] - pSrc[2 * l + 1]; |
emilmont | 1:fdd22bb7aa52 | 501 | pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) * onebyfftLen; |
emilmont | 1:fdd22bb7aa52 | 502 | |
emilmont | 1:fdd22bb7aa52 | 503 | pSrc[2u * l] = xt * onebyfftLen; |
emilmont | 1:fdd22bb7aa52 | 504 | |
emilmont | 1:fdd22bb7aa52 | 505 | pSrc[2u * l + 1u] = yt * onebyfftLen; |
emilmont | 1:fdd22bb7aa52 | 506 | |
emilmont | 1:fdd22bb7aa52 | 507 | } // butterfly loop end |
emilmont | 1:fdd22bb7aa52 | 508 | |
emilmont | 1:fdd22bb7aa52 | 509 | #endif // #ifndef ARM_MATH_CM0 |
emilmont | 1:fdd22bb7aa52 | 510 | |
emilmont | 1:fdd22bb7aa52 | 511 | } |