arm_cfft_radix2_q15.c

00001 /* ----------------------------------------------------------------------   
00002 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.   
00003 *   
00004 * $Date:        19. March 2015 
00005 * $Revision:    V.1.4.5  
00006 *   
00007 * Project:      CMSIS DSP Library   
00008 * Title:        arm_cfft_radix2_q15.c   
00009 *   
00010 * Description:  Radix-2 Decimation in Frequency CFFT & CIFFT Fixed point processing function   
00011 *   
00012 *   
00013 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
00014 *  
00015 * Redistribution and use in source and binary forms, with or without 
00016 * modification, are permitted provided that the following conditions
00017 * are met:
00018 *   - Redistributions of source code must retain the above copyright
00019 *     notice, this list of conditions and the following disclaimer.
00020 *   - Redistributions in binary form must reproduce the above copyright
00021 *     notice, this list of conditions and the following disclaimer in
00022 *     the documentation and/or other materials provided with the 
00023 *     distribution.
00024 *   - Neither the name of ARM LIMITED nor the names of its contributors
00025 *     may be used to endorse or promote products derived from this
00026 *     software without specific prior written permission.
00027 *
00028 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
00029 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
00030 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
00031 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
00032 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
00033 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
00034 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
00035 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
00036 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
00037 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
00038 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
00039 * POSSIBILITY OF SUCH DAMAGE.   
00040 * -------------------------------------------------------------------- */
00041 
00042 #include "arm_math.h"
00043 
00044 void arm_radix2_butterfly_q15(
00045   q15_t * pSrc,
00046   uint32_t fftLen,
00047   q15_t * pCoef,
00048   uint16_t twidCoefModifier);
00049 
00050 void arm_radix2_butterfly_inverse_q15(
00051   q15_t * pSrc,
00052   uint32_t fftLen,
00053   q15_t * pCoef,
00054   uint16_t twidCoefModifier);
00055     
00056 void arm_bitreversal_q15(
00057   q15_t * pSrc,
00058   uint32_t fftLen,
00059   uint16_t bitRevFactor,
00060   uint16_t * pBitRevTab);
00061 
00062 /**   
00063  * @ingroup groupTransforms   
00064  */
00065 
00066 /**   
00067  * @addtogroup ComplexFFT   
00068  * @{   
00069  */
00070 
00071 /**   
00072  * @details   
00073  * @brief Processing function for the fixed-point CFFT/CIFFT.  
00074  * @deprecated Do not use this function.  It has been superseded by \ref arm_cfft_q15 and will be removed
00075  * @param[in]      *S    points to an instance of the fixed-point CFFT/CIFFT structure.  
00076  * @param[in, out] *pSrc points to the complex data buffer of size <code>2*fftLen</code>. Processing occurs in-place.  
00077  * @return none.  
00078  */
00079 
00080 void arm_cfft_radix2_q15(
00081   const arm_cfft_radix2_instance_q15 * S,
00082   q15_t * pSrc)
00083 {
00084 
00085   if(S->ifftFlag == 1u)
00086   {
00087     arm_radix2_butterfly_inverse_q15(pSrc, S->fftLen,
00088                                      S->pTwiddle, S->twidCoefModifier);
00089   }
00090   else
00091   {
00092     arm_radix2_butterfly_q15(pSrc, S->fftLen,
00093                              S->pTwiddle, S->twidCoefModifier);
00094   }
00095 
00096   arm_bitreversal_q15(pSrc, S->fftLen, S->bitRevFactor, S->pBitRevTable);
00097 }
00098 
00099 /**   
00100  * @} end of ComplexFFT group   
00101  */
00102 
00103 void arm_radix2_butterfly_q15(
00104   q15_t * pSrc,
00105   uint32_t fftLen,
00106   q15_t * pCoef,
00107   uint16_t twidCoefModifier)
00108 {
00109 #ifndef ARM_MATH_CM0_FAMILY
00110 
00111   unsigned i, j, k, l;
00112   unsigned n1, n2, ia;
00113   q15_t in;
00114   q31_t T, S, R;
00115   q31_t coeff, out1, out2;
00116 
00117   //N = fftLen; 
00118   n2 = fftLen;
00119 
00120   n1 = n2;
00121   n2 = n2 >> 1;
00122   ia = 0;
00123 
00124   // loop for groups 
00125   for (i = 0; i < n2; i++)
00126   {
00127     coeff = _SIMD32_OFFSET(pCoef + (ia * 2u));
00128 
00129     ia = ia + twidCoefModifier;
00130 
00131     l = i + n2;
00132 
00133     T = _SIMD32_OFFSET(pSrc + (2 * i));
00134     in = ((int16_t) (T & 0xFFFF)) >> 1;
00135     T = ((T >> 1) & 0xFFFF0000) | (in & 0xFFFF);
00136 
00137     S = _SIMD32_OFFSET(pSrc + (2 * l));
00138     in = ((int16_t) (S & 0xFFFF)) >> 1;
00139     S = ((S >> 1) & 0xFFFF0000) | (in & 0xFFFF);
00140 
00141     R = __QSUB16(T, S);
00142 
00143     _SIMD32_OFFSET(pSrc + (2 * i)) = __SHADD16(T, S);
00144 
00145 #ifndef ARM_MATH_BIG_ENDIAN
00146 
00147     out1 = __SMUAD(coeff, R) >> 16;
00148     out2 = __SMUSDX(coeff, R);
00149 
00150 #else
00151 
00152     out1 = __SMUSDX(R, coeff) >> 16u;
00153     out2 = __SMUAD(coeff, R);
00154 
00155 #endif //     #ifndef ARM_MATH_BIG_ENDIAN
00156 
00157     _SIMD32_OFFSET(pSrc + (2u * l)) =
00158       (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);
00159 
00160     coeff = _SIMD32_OFFSET(pCoef + (ia * 2u));
00161 
00162     ia = ia + twidCoefModifier;
00163 
00164     // loop for butterfly 
00165     i++;
00166     l++;
00167 
00168     T = _SIMD32_OFFSET(pSrc + (2 * i));
00169     in = ((int16_t) (T & 0xFFFF)) >> 1;
00170     T = ((T >> 1) & 0xFFFF0000) | (in & 0xFFFF);
00171 
00172     S = _SIMD32_OFFSET(pSrc + (2 * l));
00173     in = ((int16_t) (S & 0xFFFF)) >> 1;
00174     S = ((S >> 1) & 0xFFFF0000) | (in & 0xFFFF);
00175 
00176     R = __QSUB16(T, S);
00177 
00178     _SIMD32_OFFSET(pSrc + (2 * i)) = __SHADD16(T, S);
00179 
00180 #ifndef ARM_MATH_BIG_ENDIAN
00181 
00182     out1 = __SMUAD(coeff, R) >> 16;
00183     out2 = __SMUSDX(coeff, R);
00184 
00185 #else
00186 
00187     out1 = __SMUSDX(R, coeff) >> 16u;
00188     out2 = __SMUAD(coeff, R);
00189 
00190 #endif //     #ifndef ARM_MATH_BIG_ENDIAN
00191 
00192     _SIMD32_OFFSET(pSrc + (2u * l)) =
00193       (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);
00194 
00195   }                             // groups loop end 
00196 
00197   twidCoefModifier = twidCoefModifier << 1u;
00198 
00199   // loop for stage 
00200   for (k = fftLen / 2; k > 2; k = k >> 1)
00201   {
00202     n1 = n2;
00203     n2 = n2 >> 1;
00204     ia = 0;
00205 
00206     // loop for groups 
00207     for (j = 0; j < n2; j++)
00208     {
00209       coeff = _SIMD32_OFFSET(pCoef + (ia * 2u));
00210 
00211       ia = ia + twidCoefModifier;
00212 
00213       // loop for butterfly 
00214       for (i = j; i < fftLen; i += n1)
00215       {
00216         l = i + n2;
00217 
00218         T = _SIMD32_OFFSET(pSrc + (2 * i));
00219 
00220         S = _SIMD32_OFFSET(pSrc + (2 * l));
00221 
00222         R = __QSUB16(T, S);
00223 
00224         _SIMD32_OFFSET(pSrc + (2 * i)) = __SHADD16(T, S);
00225 
00226 #ifndef ARM_MATH_BIG_ENDIAN
00227 
00228         out1 = __SMUAD(coeff, R) >> 16;
00229         out2 = __SMUSDX(coeff, R);
00230 
00231 #else
00232 
00233         out1 = __SMUSDX(R, coeff) >> 16u;
00234         out2 = __SMUAD(coeff, R);
00235 
00236 #endif //     #ifndef ARM_MATH_BIG_ENDIAN
00237 
00238         _SIMD32_OFFSET(pSrc + (2u * l)) =
00239           (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);
00240 
00241         i += n1;
00242 
00243         l = i + n2;
00244 
00245         T = _SIMD32_OFFSET(pSrc + (2 * i));
00246 
00247         S = _SIMD32_OFFSET(pSrc + (2 * l));
00248 
00249         R = __QSUB16(T, S);
00250 
00251         _SIMD32_OFFSET(pSrc + (2 * i)) = __SHADD16(T, S);
00252 
00253 #ifndef ARM_MATH_BIG_ENDIAN
00254 
00255         out1 = __SMUAD(coeff, R) >> 16;
00256         out2 = __SMUSDX(coeff, R);
00257 
00258 #else
00259 
00260         out1 = __SMUSDX(R, coeff) >> 16u;
00261         out2 = __SMUAD(coeff, R);
00262 
00263 #endif //     #ifndef ARM_MATH_BIG_ENDIAN
00264 
00265         _SIMD32_OFFSET(pSrc + (2u * l)) =
00266           (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);
00267 
00268       }                         // butterfly loop end 
00269 
00270     }                           // groups loop end 
00271 
00272     twidCoefModifier = twidCoefModifier << 1u;
00273   }                             // stages loop end 
00274 
00275   n1 = n2;
00276   n2 = n2 >> 1;
00277   ia = 0;
00278 
00279   coeff = _SIMD32_OFFSET(pCoef + (ia * 2u));
00280 
00281   ia = ia + twidCoefModifier;
00282 
00283   // loop for butterfly 
00284   for (i = 0; i < fftLen; i += n1)
00285   {
00286     l = i + n2;
00287 
00288     T = _SIMD32_OFFSET(pSrc + (2 * i));
00289 
00290     S = _SIMD32_OFFSET(pSrc + (2 * l));
00291 
00292     R = __QSUB16(T, S);
00293 
00294     _SIMD32_OFFSET(pSrc + (2 * i)) = __QADD16(T, S);
00295 
00296     _SIMD32_OFFSET(pSrc + (2u * l)) = R;
00297 
00298     i += n1;
00299     l = i + n2;
00300 
00301     T = _SIMD32_OFFSET(pSrc + (2 * i));
00302 
00303     S = _SIMD32_OFFSET(pSrc + (2 * l));
00304 
00305     R = __QSUB16(T, S);
00306 
00307     _SIMD32_OFFSET(pSrc + (2 * i)) = __QADD16(T, S);
00308 
00309     _SIMD32_OFFSET(pSrc + (2u * l)) = R;
00310 
00311   }                             // groups loop end 
00312 
00313 
00314 #else
00315 
00316   unsigned i, j, k, l;
00317   unsigned n1, n2, ia;
00318   q15_t xt, yt, cosVal, sinVal;
00319 
00320 
00321   //N = fftLen; 
00322   n2 = fftLen;
00323 
00324   n1 = n2;
00325   n2 = n2 >> 1;
00326   ia = 0;
00327 
00328   // loop for groups 
00329   for (j = 0; j < n2; j++)
00330   {
00331     cosVal = pCoef[ia * 2];
00332     sinVal = pCoef[(ia * 2) + 1];
00333     ia = ia + twidCoefModifier;
00334 
00335     // loop for butterfly 
00336     for (i = j; i < fftLen; i += n1)
00337     {
00338       l = i + n2;
00339       xt = (pSrc[2 * i] >> 1u) - (pSrc[2 * l] >> 1u);
00340       pSrc[2 * i] = ((pSrc[2 * i] >> 1u) + (pSrc[2 * l] >> 1u)) >> 1u;
00341 
00342       yt = (pSrc[2 * i + 1] >> 1u) - (pSrc[2 * l + 1] >> 1u);
00343       pSrc[2 * i + 1] =
00344         ((pSrc[2 * l + 1] >> 1u) + (pSrc[2 * i + 1] >> 1u)) >> 1u;
00345 
00346       pSrc[2u * l] = (((int16_t) (((q31_t) xt * cosVal) >> 16)) +
00347                       ((int16_t) (((q31_t) yt * sinVal) >> 16)));
00348 
00349       pSrc[2u * l + 1u] = (((int16_t) (((q31_t) yt * cosVal) >> 16)) -
00350                            ((int16_t) (((q31_t) xt * sinVal) >> 16)));
00351 
00352     }                           // butterfly loop end 
00353 
00354   }                             // groups loop end 
00355 
00356   twidCoefModifier = twidCoefModifier << 1u;
00357 
00358   // loop for stage 
00359   for (k = fftLen / 2; k > 2; k = k >> 1)
00360   {
00361     n1 = n2;
00362     n2 = n2 >> 1;
00363     ia = 0;
00364 
00365     // loop for groups 
00366     for (j = 0; j < n2; j++)
00367     {
00368       cosVal = pCoef[ia * 2];
00369       sinVal = pCoef[(ia * 2) + 1];
00370       ia = ia + twidCoefModifier;
00371 
00372       // loop for butterfly 
00373       for (i = j; i < fftLen; i += n1)
00374       {
00375         l = i + n2;
00376         xt = pSrc[2 * i] - pSrc[2 * l];
00377         pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) >> 1u;
00378 
00379         yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
00380         pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) >> 1u;
00381 
00382         pSrc[2u * l] = (((int16_t) (((q31_t) xt * cosVal) >> 16)) +
00383                         ((int16_t) (((q31_t) yt * sinVal) >> 16)));
00384 
00385         pSrc[2u * l + 1u] = (((int16_t) (((q31_t) yt * cosVal) >> 16)) -
00386                              ((int16_t) (((q31_t) xt * sinVal) >> 16)));
00387 
00388       }                         // butterfly loop end 
00389 
00390     }                           // groups loop end 
00391 
00392     twidCoefModifier = twidCoefModifier << 1u;
00393   }                             // stages loop end 
00394 
00395   n1 = n2;
00396   n2 = n2 >> 1;
00397   ia = 0;
00398 
00399   // loop for groups 
00400   for (j = 0; j < n2; j++)
00401   {
00402     cosVal = pCoef[ia * 2];
00403     sinVal = pCoef[(ia * 2) + 1];
00404 
00405     ia = ia + twidCoefModifier;
00406 
00407     // loop for butterfly 
00408     for (i = j; i < fftLen; i += n1)
00409     {
00410       l = i + n2;
00411       xt = pSrc[2 * i] - pSrc[2 * l];
00412       pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);
00413 
00414       yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
00415       pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);
00416 
00417       pSrc[2u * l] = xt;
00418 
00419       pSrc[2u * l + 1u] = yt;
00420 
00421     }                           // butterfly loop end 
00422 
00423   }                             // groups loop end 
00424 
00425   twidCoefModifier = twidCoefModifier << 1u;
00426 
00427 #endif //             #ifndef ARM_MATH_CM0_FAMILY
00428 
00429 }
00430 
00431 
00432 void arm_radix2_butterfly_inverse_q15(
00433   q15_t * pSrc,
00434   uint32_t fftLen,
00435   q15_t * pCoef,
00436   uint16_t twidCoefModifier)
00437 {
00438 #ifndef ARM_MATH_CM0_FAMILY
00439 
00440   unsigned i, j, k, l;
00441   unsigned n1, n2, ia;
00442   q15_t in;
00443   q31_t T, S, R;
00444   q31_t coeff, out1, out2;
00445 
00446   //N = fftLen; 
00447   n2 = fftLen;
00448 
00449   n1 = n2;
00450   n2 = n2 >> 1;
00451   ia = 0;
00452 
00453   // loop for groups 
00454   for (i = 0; i < n2; i++)
00455   {
00456     coeff = _SIMD32_OFFSET(pCoef + (ia * 2u));
00457 
00458     ia = ia + twidCoefModifier;
00459 
00460     l = i + n2;
00461 
00462     T = _SIMD32_OFFSET(pSrc + (2 * i));
00463     in = ((int16_t) (T & 0xFFFF)) >> 1;
00464     T = ((T >> 1) & 0xFFFF0000) | (in & 0xFFFF);
00465 
00466     S = _SIMD32_OFFSET(pSrc + (2 * l));
00467     in = ((int16_t) (S & 0xFFFF)) >> 1;
00468     S = ((S >> 1) & 0xFFFF0000) | (in & 0xFFFF);
00469 
00470     R = __QSUB16(T, S);
00471 
00472     _SIMD32_OFFSET(pSrc + (2 * i)) = __SHADD16(T, S);
00473 
00474 #ifndef ARM_MATH_BIG_ENDIAN
00475 
00476     out1 = __SMUSD(coeff, R) >> 16;
00477     out2 = __SMUADX(coeff, R);
00478 #else
00479 
00480     out1 = __SMUADX(R, coeff) >> 16u;
00481     out2 = __SMUSD(__QSUB(0, coeff), R);
00482 
00483 #endif //     #ifndef ARM_MATH_BIG_ENDIAN
00484 
00485     _SIMD32_OFFSET(pSrc + (2u * l)) =
00486       (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);
00487 
00488     coeff = _SIMD32_OFFSET(pCoef + (ia * 2u));
00489 
00490     ia = ia + twidCoefModifier;
00491 
00492     // loop for butterfly 
00493     i++;
00494     l++;
00495 
00496     T = _SIMD32_OFFSET(pSrc + (2 * i));
00497     in = ((int16_t) (T & 0xFFFF)) >> 1;
00498     T = ((T >> 1) & 0xFFFF0000) | (in & 0xFFFF);
00499 
00500     S = _SIMD32_OFFSET(pSrc + (2 * l));
00501     in = ((int16_t) (S & 0xFFFF)) >> 1;
00502     S = ((S >> 1) & 0xFFFF0000) | (in & 0xFFFF);
00503 
00504     R = __QSUB16(T, S);
00505 
00506     _SIMD32_OFFSET(pSrc + (2 * i)) = __SHADD16(T, S);
00507 
00508 #ifndef ARM_MATH_BIG_ENDIAN
00509 
00510     out1 = __SMUSD(coeff, R) >> 16;
00511     out2 = __SMUADX(coeff, R);
00512 #else
00513 
00514     out1 = __SMUADX(R, coeff) >> 16u;
00515     out2 = __SMUSD(__QSUB(0, coeff), R);
00516 
00517 #endif //     #ifndef ARM_MATH_BIG_ENDIAN
00518 
00519     _SIMD32_OFFSET(pSrc + (2u * l)) =
00520       (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);
00521 
00522   }                             // groups loop end 
00523 
00524   twidCoefModifier = twidCoefModifier << 1u;
00525 
00526   // loop for stage 
00527   for (k = fftLen / 2; k > 2; k = k >> 1)
00528   {
00529     n1 = n2;
00530     n2 = n2 >> 1;
00531     ia = 0;
00532 
00533     // loop for groups 
00534     for (j = 0; j < n2; j++)
00535     {
00536       coeff = _SIMD32_OFFSET(pCoef + (ia * 2u));
00537 
00538       ia = ia + twidCoefModifier;
00539 
00540       // loop for butterfly 
00541       for (i = j; i < fftLen; i += n1)
00542       {
00543         l = i + n2;
00544 
00545         T = _SIMD32_OFFSET(pSrc + (2 * i));
00546 
00547         S = _SIMD32_OFFSET(pSrc + (2 * l));
00548 
00549         R = __QSUB16(T, S);
00550 
00551         _SIMD32_OFFSET(pSrc + (2 * i)) = __SHADD16(T, S);
00552 
00553 #ifndef ARM_MATH_BIG_ENDIAN
00554 
00555         out1 = __SMUSD(coeff, R) >> 16;
00556         out2 = __SMUADX(coeff, R);
00557 
00558 #else
00559 
00560         out1 = __SMUADX(R, coeff) >> 16u;
00561         out2 = __SMUSD(__QSUB(0, coeff), R);
00562 
00563 #endif //     #ifndef ARM_MATH_BIG_ENDIAN
00564 
00565         _SIMD32_OFFSET(pSrc + (2u * l)) =
00566           (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);
00567 
00568         i += n1;
00569 
00570         l = i + n2;
00571 
00572         T = _SIMD32_OFFSET(pSrc + (2 * i));
00573 
00574         S = _SIMD32_OFFSET(pSrc + (2 * l));
00575 
00576         R = __QSUB16(T, S);
00577 
00578         _SIMD32_OFFSET(pSrc + (2 * i)) = __SHADD16(T, S);
00579 
00580 #ifndef ARM_MATH_BIG_ENDIAN
00581 
00582         out1 = __SMUSD(coeff, R) >> 16;
00583         out2 = __SMUADX(coeff, R);
00584 #else
00585 
00586         out1 = __SMUADX(R, coeff) >> 16u;
00587         out2 = __SMUSD(__QSUB(0, coeff), R);
00588 
00589 #endif //     #ifndef ARM_MATH_BIG_ENDIAN
00590 
00591         _SIMD32_OFFSET(pSrc + (2u * l)) =
00592           (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);
00593 
00594       }                         // butterfly loop end 
00595 
00596     }                           // groups loop end 
00597 
00598     twidCoefModifier = twidCoefModifier << 1u;
00599   }                             // stages loop end 
00600 
00601   n1 = n2;
00602   n2 = n2 >> 1;
00603   ia = 0;
00604 
00605   // loop for groups 
00606   for (j = 0; j < n2; j++)
00607   {
00608     coeff = _SIMD32_OFFSET(pCoef + (ia * 2u));
00609 
00610     ia = ia + twidCoefModifier;
00611 
00612     // loop for butterfly 
00613     for (i = j; i < fftLen; i += n1)
00614     {
00615       l = i + n2;
00616 
00617       T = _SIMD32_OFFSET(pSrc + (2 * i));
00618 
00619       S = _SIMD32_OFFSET(pSrc + (2 * l));
00620 
00621       R = __QSUB16(T, S);
00622 
00623       _SIMD32_OFFSET(pSrc + (2 * i)) = __QADD16(T, S);
00624 
00625       _SIMD32_OFFSET(pSrc + (2u * l)) = R;
00626 
00627     }                           // butterfly loop end 
00628 
00629   }                             // groups loop end 
00630 
00631   twidCoefModifier = twidCoefModifier << 1u;
00632 
00633 #else
00634 
00635 
00636   unsigned i, j, k, l;
00637   unsigned n1, n2, ia;
00638   q15_t xt, yt, cosVal, sinVal;
00639 
00640   //N = fftLen; 
00641   n2 = fftLen;
00642 
00643   n1 = n2;
00644   n2 = n2 >> 1;
00645   ia = 0;
00646 
00647   // loop for groups 
00648   for (j = 0; j < n2; j++)
00649   {
00650     cosVal = pCoef[ia * 2];
00651     sinVal = pCoef[(ia * 2) + 1];
00652     ia = ia + twidCoefModifier;
00653 
00654     // loop for butterfly 
00655     for (i = j; i < fftLen; i += n1)
00656     {
00657       l = i + n2;
00658       xt = (pSrc[2 * i] >> 1u) - (pSrc[2 * l] >> 1u);
00659       pSrc[2 * i] = ((pSrc[2 * i] >> 1u) + (pSrc[2 * l] >> 1u)) >> 1u;
00660 
00661       yt = (pSrc[2 * i + 1] >> 1u) - (pSrc[2 * l + 1] >> 1u);
00662       pSrc[2 * i + 1] =
00663         ((pSrc[2 * l + 1] >> 1u) + (pSrc[2 * i + 1] >> 1u)) >> 1u;
00664 
00665       pSrc[2u * l] = (((int16_t) (((q31_t) xt * cosVal) >> 16)) -
00666                       ((int16_t) (((q31_t) yt * sinVal) >> 16)));
00667 
00668       pSrc[2u * l + 1u] = (((int16_t) (((q31_t) yt * cosVal) >> 16)) +
00669                            ((int16_t) (((q31_t) xt * sinVal) >> 16)));
00670 
00671     }                           // butterfly loop end 
00672 
00673   }                             // groups loop end 
00674 
00675   twidCoefModifier = twidCoefModifier << 1u;
00676 
00677   // loop for stage 
00678   for (k = fftLen / 2; k > 2; k = k >> 1)
00679   {
00680     n1 = n2;
00681     n2 = n2 >> 1;
00682     ia = 0;
00683 
00684     // loop for groups 
00685     for (j = 0; j < n2; j++)
00686     {
00687       cosVal = pCoef[ia * 2];
00688       sinVal = pCoef[(ia * 2) + 1];
00689       ia = ia + twidCoefModifier;
00690 
00691       // loop for butterfly 
00692       for (i = j; i < fftLen; i += n1)
00693       {
00694         l = i + n2;
00695         xt = pSrc[2 * i] - pSrc[2 * l];
00696         pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) >> 1u;
00697 
00698         yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
00699         pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) >> 1u;
00700 
00701         pSrc[2u * l] = (((int16_t) (((q31_t) xt * cosVal) >> 16)) -
00702                         ((int16_t) (((q31_t) yt * sinVal) >> 16)));
00703 
00704         pSrc[2u * l + 1u] = (((int16_t) (((q31_t) yt * cosVal) >> 16)) +
00705                              ((int16_t) (((q31_t) xt * sinVal) >> 16)));
00706 
00707       }                         // butterfly loop end 
00708 
00709     }                           // groups loop end 
00710 
00711     twidCoefModifier = twidCoefModifier << 1u;
00712   }                             // stages loop end 
00713 
00714   n1 = n2;
00715   n2 = n2 >> 1;
00716   ia = 0;
00717 
00718   cosVal = pCoef[ia * 2];
00719   sinVal = pCoef[(ia * 2) + 1];
00720 
00721   ia = ia + twidCoefModifier;
00722 
00723   // loop for butterfly 
00724   for (i = 0; i < fftLen; i += n1)
00725   {
00726     l = i + n2;
00727     xt = pSrc[2 * i] - pSrc[2 * l];
00728     pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);
00729 
00730     yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
00731     pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);
00732 
00733     pSrc[2u * l] = xt;
00734 
00735     pSrc[2u * l + 1u] = yt;
00736 
00737   }                             // groups loop end 
00738 
00739 
00740 #endif //             #ifndef ARM_MATH_CM0_FAMILY
00741 
00742 }