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| bfc108 | 1 | /* ---------------------------------------------------------------------- |
| Q | 2 | * Copyright (C) 2010-2014 ARM Limited. All rights reserved. |
| 3 | * | |
| 4 | * $Date: 19. March 2015 | |
| 5 | * $Revision: V.1.4.5 | |
| 6 | * | |
| 7 | * Project: CMSIS DSP Library | |
| 8 | * Title: arm_rfft_q31.c | |
| 9 | * | |
| 10 | * Description: RFFT & RIFFT Q31 process function | |
| 11 | * | |
| 12 | * | |
| 13 | * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 | |
| 14 | * | |
| 15 | * Redistribution and use in source and binary forms, with or without | |
| 16 | * modification, are permitted provided that the following conditions | |
| 17 | * are met: | |
| 18 | * - Redistributions of source code must retain the above copyright | |
| 19 | * notice, this list of conditions and the following disclaimer. | |
| 20 | * - Redistributions in binary form must reproduce the above copyright | |
| 21 | * notice, this list of conditions and the following disclaimer in | |
| 22 | * the documentation and/or other materials provided with the | |
| 23 | * distribution. | |
| 24 | * - Neither the name of ARM LIMITED nor the names of its contributors | |
| 25 | * may be used to endorse or promote products derived from this | |
| 26 | * software without specific prior written permission. | |
| 27 | * | |
| 28 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
| 29 | * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
| 30 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS | |
| 31 | * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE | |
| 32 | * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, | |
| 33 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, | |
| 34 | * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; | |
| 35 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER | |
| 36 | * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
| 37 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN | |
| 38 | * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE | |
| 39 | * POSSIBILITY OF SUCH DAMAGE. | |
| 40 | * -------------------------------------------------------------------- */ | |
| 41 | ||
| 42 | #include "arm_math.h" | |
| 43 | ||
| 44 | /*-------------------------------------------------------------------- | |
| 45 | * Internal functions prototypes | |
| 46 | --------------------------------------------------------------------*/ | |
| 47 | ||
| 48 | void arm_split_rfft_q31( | |
| 49 | q31_t * pSrc, | |
| 50 | uint32_t fftLen, | |
| 51 | q31_t * pATable, | |
| 52 | q31_t * pBTable, | |
| 53 | q31_t * pDst, | |
| 54 | uint32_t modifier); | |
| 55 | ||
| 56 | void arm_split_rifft_q31( | |
| 57 | q31_t * pSrc, | |
| 58 | uint32_t fftLen, | |
| 59 | q31_t * pATable, | |
| 60 | q31_t * pBTable, | |
| 61 | q31_t * pDst, | |
| 62 | uint32_t modifier); | |
| 63 | ||
| 64 | /** | |
| 65 | * @addtogroup RealFFT | |
| 66 | * @{ | |
| 67 | */ | |
| 68 | ||
| 69 | /** | |
| 70 | * @brief Processing function for the Q31 RFFT/RIFFT. | |
| 71 | * @param[in] *S points to an instance of the Q31 RFFT/RIFFT structure. | |
| 72 | * @param[in] *pSrc points to the input buffer. | |
| 73 | * @param[out] *pDst points to the output buffer. | |
| 74 | * @return none. | |
| 75 | * | |
| 76 | * \par Input an output formats: | |
| 77 | * \par | |
| 78 | * Internally input is downscaled by 2 for every stage to avoid saturations inside CFFT/CIFFT process. | |
| 79 | * Hence the output format is different for different RFFT sizes. | |
| 80 | * The input and output formats for different RFFT sizes and number of bits to upscale are mentioned in the tables below for RFFT and RIFFT: | |
| 81 | * \par | |
| 82 | * \image html RFFTQ31.gif "Input and Output Formats for Q31 RFFT" | |
| 83 | * | |
| 84 | * \par | |
| 85 | * \image html RIFFTQ31.gif "Input and Output Formats for Q31 RIFFT" | |
| 86 | */ | |
| 87 | void arm_rfft_q31( | |
| 88 | const arm_rfft_instance_q31 * S, | |
| 89 | q31_t * pSrc, | |
| 90 | q31_t * pDst) | |
| 91 | { | |
| 92 | const arm_cfft_instance_q31 *S_CFFT = S->pCfft; | |
| 93 | uint32_t i; | |
| 94 | uint32_t L2 = S->fftLenReal >> 1; | |
| 95 | ||
| 96 | /* Calculation of RIFFT of input */ | |
| 97 | if(S->ifftFlagR == 1u) | |
| 98 | { | |
| 99 | /* Real IFFT core process */ | |
| 100 | arm_split_rifft_q31(pSrc, L2, S->pTwiddleAReal, | |
| 101 | S->pTwiddleBReal, pDst, S->twidCoefRModifier); | |
| 102 | ||
| 103 | /* Complex IFFT process */ | |
| 104 | arm_cfft_q31(S_CFFT, pDst, S->ifftFlagR, S->bitReverseFlagR); | |
| 105 | ||
| 106 | for(i=0;i<S->fftLenReal;i++) | |
| 107 | { | |
| 108 | pDst[i] = pDst[i] << 1; | |
| 109 | } | |
| 110 | } | |
| 111 | else | |
| 112 | { | |
| 113 | /* Calculation of RFFT of input */ | |
| 114 | ||
| 115 | /* Complex FFT process */ | |
| 116 | arm_cfft_q31(S_CFFT, pSrc, S->ifftFlagR, S->bitReverseFlagR); | |
| 117 | ||
| 118 | /* Real FFT core process */ | |
| 119 | arm_split_rfft_q31(pSrc, L2, S->pTwiddleAReal, | |
| 120 | S->pTwiddleBReal, pDst, S->twidCoefRModifier); | |
| 121 | } | |
| 122 | } | |
| 123 | ||
| 124 | /** | |
| 125 | * @} end of RealFFT group | |
| 126 | */ | |
| 127 | ||
| 128 | /** | |
| 129 | * @brief Core Real FFT process | |
| 130 | * @param[in] *pSrc points to the input buffer. | |
| 131 | * @param[in] fftLen length of FFT. | |
| 132 | * @param[in] *pATable points to the twiddle Coef A buffer. | |
| 133 | * @param[in] *pBTable points to the twiddle Coef B buffer. | |
| 134 | * @param[out] *pDst points to the output buffer. | |
| 135 | * @param[in] modifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table. | |
| 136 | * @return none. | |
| 137 | */ | |
| 138 | void arm_split_rfft_q31( | |
| 139 | q31_t * pSrc, | |
| 140 | uint32_t fftLen, | |
| 141 | q31_t * pATable, | |
| 142 | q31_t * pBTable, | |
| 143 | q31_t * pDst, | |
| 144 | uint32_t modifier) | |
| 145 | { | |
| 146 | uint32_t i; /* Loop Counter */ | |
| 147 | q31_t outR, outI; /* Temporary variables for output */ | |
| 148 | q31_t *pCoefA, *pCoefB; /* Temporary pointers for twiddle factors */ | |
| 149 | q31_t CoefA1, CoefA2, CoefB1; /* Temporary variables for twiddle coefficients */ | |
| 150 | q31_t *pOut1 = &pDst[2], *pOut2 = &pDst[(4u * fftLen) - 1u]; | |
| 151 | q31_t *pIn1 = &pSrc[2], *pIn2 = &pSrc[(2u * fftLen) - 1u]; | |
| 152 | ||
| 153 | /* Init coefficient pointers */ | |
| 154 | pCoefA = &pATable[modifier * 2u]; | |
| 155 | pCoefB = &pBTable[modifier * 2u]; | |
| 156 | ||
| 157 | i = fftLen - 1u; | |
| 158 | ||
| 159 | while(i > 0u) | |
| 160 | { | |
| 161 | /* | |
| 162 | outR = (pSrc[2 * i] * pATable[2 * i] - pSrc[2 * i + 1] * pATable[2 * i + 1] | |
| 163 | + pSrc[2 * n - 2 * i] * pBTable[2 * i] + | |
| 164 | pSrc[2 * n - 2 * i + 1] * pBTable[2 * i + 1]); | |
| 165 | */ | |
| 166 | ||
| 167 | /* outI = (pIn[2 * i + 1] * pATable[2 * i] + pIn[2 * i] * pATable[2 * i + 1] + | |
| 168 | pIn[2 * n - 2 * i] * pBTable[2 * i + 1] - | |
| 169 | pIn[2 * n - 2 * i + 1] * pBTable[2 * i]); */ | |
| 170 | ||
| 171 | CoefA1 = *pCoefA++; | |
| 172 | CoefA2 = *pCoefA; | |
| 173 | ||
| 174 | /* outR = (pSrc[2 * i] * pATable[2 * i] */ | |
| 175 | mult_32x32_keep32_R(outR, *pIn1, CoefA1); | |
| 176 | ||
| 177 | /* outI = pIn[2 * i] * pATable[2 * i + 1] */ | |
| 178 | mult_32x32_keep32_R(outI, *pIn1++, CoefA2); | |
| 179 | ||
| 180 | /* - pSrc[2 * i + 1] * pATable[2 * i + 1] */ | |
| 181 | multSub_32x32_keep32_R(outR, *pIn1, CoefA2); | |
| 182 | ||
| 183 | /* (pIn[2 * i + 1] * pATable[2 * i] */ | |
| 184 | multAcc_32x32_keep32_R(outI, *pIn1++, CoefA1); | |
| 185 | ||
| 186 | /* pSrc[2 * n - 2 * i] * pBTable[2 * i] */ | |
| 187 | multSub_32x32_keep32_R(outR, *pIn2, CoefA2); | |
| 188 | CoefB1 = *pCoefB; | |
| 189 | ||
| 190 | /* pIn[2 * n - 2 * i] * pBTable[2 * i + 1] */ | |
| 191 | multSub_32x32_keep32_R(outI, *pIn2--, CoefB1); | |
| 192 | ||
| 193 | /* pSrc[2 * n - 2 * i + 1] * pBTable[2 * i + 1] */ | |
| 194 | multAcc_32x32_keep32_R(outR, *pIn2, CoefB1); | |
| 195 | ||
| 196 | /* pIn[2 * n - 2 * i + 1] * pBTable[2 * i] */ | |
| 197 | multSub_32x32_keep32_R(outI, *pIn2--, CoefA2); | |
| 198 | ||
| 199 | /* write output */ | |
| 200 | *pOut1++ = outR; | |
| 201 | *pOut1++ = outI; | |
| 202 | ||
| 203 | /* write complex conjugate output */ | |
| 204 | *pOut2-- = -outI; | |
| 205 | *pOut2-- = outR; | |
| 206 | ||
| 207 | /* update coefficient pointer */ | |
| 208 | pCoefB = pCoefB + (modifier * 2u); | |
| 209 | pCoefA = pCoefA + ((modifier * 2u) - 1u); | |
| 210 | ||
| 211 | i--; | |
| 212 | } | |
| 213 | pDst[2u * fftLen] = (pSrc[0] - pSrc[1]) >> 1; | |
| 214 | pDst[(2u * fftLen) + 1u] = 0; | |
| 215 | ||
| 216 | pDst[0] = (pSrc[0] + pSrc[1]) >> 1; | |
| 217 | pDst[1] = 0; | |
| 218 | } | |
| 219 | ||
| 220 | /** | |
| 221 | * @brief Core Real IFFT process | |
| 222 | * @param[in] *pSrc points to the input buffer. | |
| 223 | * @param[in] fftLen length of FFT. | |
| 224 | * @param[in] *pATable points to the twiddle Coef A buffer. | |
| 225 | * @param[in] *pBTable points to the twiddle Coef B buffer. | |
| 226 | * @param[out] *pDst points to the output buffer. | |
| 227 | * @param[in] modifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table. | |
| 228 | * @return none. | |
| 229 | */ | |
| 230 | void arm_split_rifft_q31( | |
| 231 | q31_t * pSrc, | |
| 232 | uint32_t fftLen, | |
| 233 | q31_t * pATable, | |
| 234 | q31_t * pBTable, | |
| 235 | q31_t * pDst, | |
| 236 | uint32_t modifier) | |
| 237 | { | |
| 238 | q31_t outR, outI; /* Temporary variables for output */ | |
| 239 | q31_t *pCoefA, *pCoefB; /* Temporary pointers for twiddle factors */ | |
| 240 | q31_t CoefA1, CoefA2, CoefB1; /* Temporary variables for twiddle coefficients */ | |
| 241 | q31_t *pIn1 = &pSrc[0], *pIn2 = &pSrc[(2u * fftLen) + 1u]; | |
| 242 | ||
| 243 | pCoefA = &pATable[0]; | |
| 244 | pCoefB = &pBTable[0]; | |
| 245 | ||
| 246 | while(fftLen > 0u) | |
| 247 | { | |
| 248 | /* | |
| 249 | outR = (pIn[2 * i] * pATable[2 * i] + pIn[2 * i + 1] * pATable[2 * i + 1] + | |
| 250 | pIn[2 * n - 2 * i] * pBTable[2 * i] - | |
| 251 | pIn[2 * n - 2 * i + 1] * pBTable[2 * i + 1]); | |
| 252 | ||
| 253 | outI = (pIn[2 * i + 1] * pATable[2 * i] - pIn[2 * i] * pATable[2 * i + 1] - | |
| 254 | pIn[2 * n - 2 * i] * pBTable[2 * i + 1] - | |
| 255 | pIn[2 * n - 2 * i + 1] * pBTable[2 * i]); | |
| 256 | */ | |
| 257 | CoefA1 = *pCoefA++; | |
| 258 | CoefA2 = *pCoefA; | |
| 259 | ||
| 260 | /* outR = (pIn[2 * i] * pATable[2 * i] */ | |
| 261 | mult_32x32_keep32_R(outR, *pIn1, CoefA1); | |
| 262 | ||
| 263 | /* - pIn[2 * i] * pATable[2 * i + 1] */ | |
| 264 | mult_32x32_keep32_R(outI, *pIn1++, -CoefA2); | |
| 265 | ||
| 266 | /* pIn[2 * i + 1] * pATable[2 * i + 1] */ | |
| 267 | multAcc_32x32_keep32_R(outR, *pIn1, CoefA2); | |
| 268 | ||
| 269 | /* pIn[2 * i + 1] * pATable[2 * i] */ | |
| 270 | multAcc_32x32_keep32_R(outI, *pIn1++, CoefA1); | |
| 271 | ||
| 272 | /* pIn[2 * n - 2 * i] * pBTable[2 * i] */ | |
| 273 | multAcc_32x32_keep32_R(outR, *pIn2, CoefA2); | |
| 274 | CoefB1 = *pCoefB; | |
| 275 | ||
| 276 | /* pIn[2 * n - 2 * i] * pBTable[2 * i + 1] */ | |
| 277 | multSub_32x32_keep32_R(outI, *pIn2--, CoefB1); | |
| 278 | ||
| 279 | /* pIn[2 * n - 2 * i + 1] * pBTable[2 * i + 1] */ | |
| 280 | multAcc_32x32_keep32_R(outR, *pIn2, CoefB1); | |
| 281 | ||
| 282 | /* pIn[2 * n - 2 * i + 1] * pBTable[2 * i] */ | |
| 283 | multAcc_32x32_keep32_R(outI, *pIn2--, CoefA2); | |
| 284 | ||
| 285 | /* write output */ | |
| 286 | *pDst++ = outR; | |
| 287 | *pDst++ = outI; | |
| 288 | ||
| 289 | /* update coefficient pointer */ | |
| 290 | pCoefB = pCoefB + (modifier * 2u); | |
| 291 | pCoefA = pCoefA + ((modifier * 2u) - 1u); | |
| 292 | ||
| 293 | /* Decrement loop count */ | |
| 294 | fftLen--; | |
| 295 | } | |
| 296 | } | |
