arm_cfft_radix2_q15.c

00001 /* ----------------------------------------------------------------------   
00002 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.   
00003 *   
00004 * $Date:        12. March 2014  
00005 * $Revision:    V1.4.3  
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  * @param[in]      *S    points to an instance of the fixed-point CFFT/CIFFT structure.  
00075  * @param[in, out] *pSrc points to the complex data buffer of size <code>2*fftLen</code>. Processing occurs in-place.  
00076  * @return none.  
00077  */
00078 
00079 void arm_cfft_radix2_q15(
00080   const arm_cfft_radix2_instance_q15 * S,
00081   q15_t * pSrc)
00082 {
00083 
00084   if(S->ifftFlag == 1u)
00085   {
00086     arm_radix2_butterfly_inverse_q15(pSrc, S->fftLen,
00087                                      S->pTwiddle, S->twidCoefModifier);
00088   }
00089   else
00090   {
00091     arm_radix2_butterfly_q15(pSrc, S->fftLen,
00092                              S->pTwiddle, S->twidCoefModifier);
00093   }
00094 
00095   arm_bitreversal_q15(pSrc, S->fftLen, S->bitRevFactor, S->pBitRevTable);
00096 }
00097 
00098 /**   
00099  * @} end of ComplexFFT group   
00100  */
00101 
00102 void arm_radix2_butterfly_q15(
00103   q15_t * pSrc,
00104   uint32_t fftLen,
00105   q15_t * pCoef,
00106   uint16_t twidCoefModifier)
00107 {
00108 #ifndef ARM_MATH_CM0_FAMILY
00109 
00110   unsigned i, j, k, l;
00111   unsigned n1, n2, ia;
00112   q15_t in;
00113   q31_t T, S, R;
00114   q31_t coeff, out1, out2;
00115 
00116   //N = fftLen; 
00117   n2 = fftLen;
00118 
00119   n1 = n2;
00120   n2 = n2 >> 1;
00121   ia = 0;
00122 
00123   // loop for groups 
00124   for (i = 0; i < n2; i++)
00125   {
00126     coeff = _SIMD32_OFFSET(pCoef + (ia * 2u));
00127 
00128     ia = ia + twidCoefModifier;
00129 
00130     l = i + n2;
00131 
00132     T = _SIMD32_OFFSET(pSrc + (2 * i));
00133     in = ((int16_t) (T & 0xFFFF)) >> 1;
00134     T = ((T >> 1) & 0xFFFF0000) | (in & 0xFFFF);
00135 
00136     S = _SIMD32_OFFSET(pSrc + (2 * l));
00137     in = ((int16_t) (S & 0xFFFF)) >> 1;
00138     S = ((S >> 1) & 0xFFFF0000) | (in & 0xFFFF);
00139 
00140     R = __QSUB16(T, S);
00141 
00142     _SIMD32_OFFSET(pSrc + (2 * i)) = __SHADD16(T, S);
00143 
00144 #ifndef ARM_MATH_BIG_ENDIAN
00145 
00146     out1 = __SMUAD(coeff, R) >> 16;
00147     out2 = __SMUSDX(coeff, R);
00148 
00149 #else
00150 
00151     out1 = __SMUSDX(R, coeff) >> 16u;
00152     out2 = __SMUAD(coeff, R);
00153 
00154 #endif //     #ifndef ARM_MATH_BIG_ENDIAN
00155 
00156     _SIMD32_OFFSET(pSrc + (2u * l)) =
00157       (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);
00158 
00159     coeff = _SIMD32_OFFSET(pCoef + (ia * 2u));
00160 
00161     ia = ia + twidCoefModifier;
00162 
00163     // loop for butterfly 
00164     i++;
00165     l++;
00166 
00167     T = _SIMD32_OFFSET(pSrc + (2 * i));
00168     in = ((int16_t) (T & 0xFFFF)) >> 1;
00169     T = ((T >> 1) & 0xFFFF0000) | (in & 0xFFFF);
00170 
00171     S = _SIMD32_OFFSET(pSrc + (2 * l));
00172     in = ((int16_t) (S & 0xFFFF)) >> 1;
00173     S = ((S >> 1) & 0xFFFF0000) | (in & 0xFFFF);
00174 
00175     R = __QSUB16(T, S);
00176 
00177     _SIMD32_OFFSET(pSrc + (2 * i)) = __SHADD16(T, S);
00178 
00179 #ifndef ARM_MATH_BIG_ENDIAN
00180 
00181     out1 = __SMUAD(coeff, R) >> 16;
00182     out2 = __SMUSDX(coeff, R);
00183 
00184 #else
00185 
00186     out1 = __SMUSDX(R, coeff) >> 16u;
00187     out2 = __SMUAD(coeff, R);
00188 
00189 #endif //     #ifndef ARM_MATH_BIG_ENDIAN
00190 
00191     _SIMD32_OFFSET(pSrc + (2u * l)) =
00192       (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);
00193 
00194   }                             // groups loop end 
00195 
00196   twidCoefModifier = twidCoefModifier << 1u;
00197 
00198   // loop for stage 
00199   for (k = fftLen / 2; k > 2; k = k >> 1)
00200   {
00201     n1 = n2;
00202     n2 = n2 >> 1;
00203     ia = 0;
00204 
00205     // loop for groups 
00206     for (j = 0; j < n2; j++)
00207     {
00208       coeff = _SIMD32_OFFSET(pCoef + (ia * 2u));
00209 
00210       ia = ia + twidCoefModifier;
00211 
00212       // loop for butterfly 
00213       for (i = j; i < fftLen; i += n1)
00214       {
00215         l = i + n2;
00216 
00217         T = _SIMD32_OFFSET(pSrc + (2 * i));
00218 
00219         S = _SIMD32_OFFSET(pSrc + (2 * l));
00220 
00221         R = __QSUB16(T, S);
00222 
00223         _SIMD32_OFFSET(pSrc + (2 * i)) = __SHADD16(T, S);
00224 
00225 #ifndef ARM_MATH_BIG_ENDIAN
00226 
00227         out1 = __SMUAD(coeff, R) >> 16;
00228         out2 = __SMUSDX(coeff, R);
00229 
00230 #else
00231 
00232         out1 = __SMUSDX(R, coeff) >> 16u;
00233         out2 = __SMUAD(coeff, R);
00234 
00235 #endif //     #ifndef ARM_MATH_BIG_ENDIAN
00236 
00237         _SIMD32_OFFSET(pSrc + (2u * l)) =
00238           (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);
00239 
00240         i += n1;
00241 
00242         l = i + n2;
00243 
00244         T = _SIMD32_OFFSET(pSrc + (2 * i));
00245 
00246         S = _SIMD32_OFFSET(pSrc + (2 * l));
00247 
00248         R = __QSUB16(T, S);
00249 
00250         _SIMD32_OFFSET(pSrc + (2 * i)) = __SHADD16(T, S);
00251 
00252 #ifndef ARM_MATH_BIG_ENDIAN
00253 
00254         out1 = __SMUAD(coeff, R) >> 16;
00255         out2 = __SMUSDX(coeff, R);
00256 
00257 #else
00258 
00259         out1 = __SMUSDX(R, coeff) >> 16u;
00260         out2 = __SMUAD(coeff, R);
00261 
00262 #endif //     #ifndef ARM_MATH_BIG_ENDIAN
00263 
00264         _SIMD32_OFFSET(pSrc + (2u * l)) =
00265           (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);
00266 
00267       }                         // butterfly loop end 
00268 
00269     }                           // groups loop end 
00270 
00271     twidCoefModifier = twidCoefModifier << 1u;
00272   }                             // stages loop end 
00273 
00274   n1 = n2;
00275   n2 = n2 >> 1;
00276   ia = 0;
00277 
00278   coeff = _SIMD32_OFFSET(pCoef + (ia * 2u));
00279 
00280   ia = ia + twidCoefModifier;
00281 
00282   // loop for butterfly 
00283   for (i = 0; i < fftLen; i += n1)
00284   {
00285     l = i + n2;
00286 
00287     T = _SIMD32_OFFSET(pSrc + (2 * i));
00288 
00289     S = _SIMD32_OFFSET(pSrc + (2 * l));
00290 
00291     R = __QSUB16(T, S);
00292 
00293     _SIMD32_OFFSET(pSrc + (2 * i)) = __QADD16(T, S);
00294 
00295     _SIMD32_OFFSET(pSrc + (2u * l)) = R;
00296 
00297     i += n1;
00298     l = i + n2;
00299 
00300     T = _SIMD32_OFFSET(pSrc + (2 * i));
00301 
00302     S = _SIMD32_OFFSET(pSrc + (2 * l));
00303 
00304     R = __QSUB16(T, S);
00305 
00306     _SIMD32_OFFSET(pSrc + (2 * i)) = __QADD16(T, S);
00307 
00308     _SIMD32_OFFSET(pSrc + (2u * l)) = R;
00309 
00310   }                             // groups loop end 
00311 
00312 
00313 #else
00314 
00315   unsigned i, j, k, l;
00316   unsigned n1, n2, ia;
00317   q15_t xt, yt, cosVal, sinVal;
00318 
00319 
00320   //N = fftLen; 
00321   n2 = fftLen;
00322 
00323   n1 = n2;
00324   n2 = n2 >> 1;
00325   ia = 0;
00326 
00327   // loop for groups 
00328   for (j = 0; j < n2; j++)
00329   {
00330     cosVal = pCoef[ia * 2];
00331     sinVal = pCoef[(ia * 2) + 1];
00332     ia = ia + twidCoefModifier;
00333 
00334     // loop for butterfly 
00335     for (i = j; i < fftLen; i += n1)
00336     {
00337       l = i + n2;
00338       xt = (pSrc[2 * i] >> 1u) - (pSrc[2 * l] >> 1u);
00339       pSrc[2 * i] = ((pSrc[2 * i] >> 1u) + (pSrc[2 * l] >> 1u)) >> 1u;
00340 
00341       yt = (pSrc[2 * i + 1] >> 1u) - (pSrc[2 * l + 1] >> 1u);
00342       pSrc[2 * i + 1] =
00343         ((pSrc[2 * l + 1] >> 1u) + (pSrc[2 * i + 1] >> 1u)) >> 1u;
00344 
00345       pSrc[2u * l] = (((int16_t) (((q31_t) xt * cosVal) >> 16)) +
00346                       ((int16_t) (((q31_t) yt * sinVal) >> 16)));
00347 
00348       pSrc[2u * l + 1u] = (((int16_t) (((q31_t) yt * cosVal) >> 16)) -
00349                            ((int16_t) (((q31_t) xt * sinVal) >> 16)));
00350 
00351     }                           // butterfly loop end 
00352 
00353   }                             // groups loop end 
00354 
00355   twidCoefModifier = twidCoefModifier << 1u;
00356 
00357   // loop for stage 
00358   for (k = fftLen / 2; k > 2; k = k >> 1)
00359   {
00360     n1 = n2;
00361     n2 = n2 >> 1;
00362     ia = 0;
00363 
00364     // loop for groups 
00365     for (j = 0; j < n2; j++)
00366     {
00367       cosVal = pCoef[ia * 2];
00368       sinVal = pCoef[(ia * 2) + 1];
00369       ia = ia + twidCoefModifier;
00370 
00371       // loop for butterfly 
00372       for (i = j; i < fftLen; i += n1)
00373       {
00374         l = i + n2;
00375         xt = pSrc[2 * i] - pSrc[2 * l];
00376         pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) >> 1u;
00377 
00378         yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
00379         pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) >> 1u;
00380 
00381         pSrc[2u * l] = (((int16_t) (((q31_t) xt * cosVal) >> 16)) +
00382                         ((int16_t) (((q31_t) yt * sinVal) >> 16)));
00383 
00384         pSrc[2u * l + 1u] = (((int16_t) (((q31_t) yt * cosVal) >> 16)) -
00385                              ((int16_t) (((q31_t) xt * sinVal) >> 16)));
00386 
00387       }                         // butterfly loop end 
00388 
00389     }                           // groups loop end 
00390 
00391     twidCoefModifier = twidCoefModifier << 1u;
00392   }                             // stages loop end 
00393 
00394   n1 = n2;
00395   n2 = n2 >> 1;
00396   ia = 0;
00397 
00398   // loop for groups 
00399   for (j = 0; j < n2; j++)
00400   {
00401     cosVal = pCoef[ia * 2];
00402     sinVal = pCoef[(ia * 2) + 1];
00403 
00404     ia = ia + twidCoefModifier;
00405 
00406     // loop for butterfly 
00407     for (i = j; i < fftLen; i += n1)
00408     {
00409       l = i + n2;
00410       xt = pSrc[2 * i] - pSrc[2 * l];
00411       pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);
00412 
00413       yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
00414       pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);
00415 
00416       pSrc[2u * l] = xt;
00417 
00418       pSrc[2u * l + 1u] = yt;
00419 
00420     }                           // butterfly loop end 
00421 
00422   }                             // groups loop end 
00423 
00424   twidCoefModifier = twidCoefModifier << 1u;
00425 
00426 #endif //             #ifndef ARM_MATH_CM0_FAMILY
00427 
00428 }
00429 
00430 
00431 void arm_radix2_butterfly_inverse_q15(
00432   q15_t * pSrc,
00433   uint32_t fftLen,
00434   q15_t * pCoef,
00435   uint16_t twidCoefModifier)
00436 {
00437 #ifndef ARM_MATH_CM0_FAMILY
00438 
00439   unsigned i, j, k, l;
00440   unsigned n1, n2, ia;
00441   q15_t in;
00442   q31_t T, S, R;
00443   q31_t coeff, out1, out2;
00444 
00445   //N = fftLen; 
00446   n2 = fftLen;
00447 
00448   n1 = n2;
00449   n2 = n2 >> 1;
00450   ia = 0;
00451 
00452   // loop for groups 
00453   for (i = 0; i < n2; i++)
00454   {
00455     coeff = _SIMD32_OFFSET(pCoef + (ia * 2u));
00456 
00457     ia = ia + twidCoefModifier;
00458 
00459     l = i + n2;
00460 
00461     T = _SIMD32_OFFSET(pSrc + (2 * i));
00462     in = ((int16_t) (T & 0xFFFF)) >> 1;
00463     T = ((T >> 1) & 0xFFFF0000) | (in & 0xFFFF);
00464 
00465     S = _SIMD32_OFFSET(pSrc + (2 * l));
00466     in = ((int16_t) (S & 0xFFFF)) >> 1;
00467     S = ((S >> 1) & 0xFFFF0000) | (in & 0xFFFF);
00468 
00469     R = __QSUB16(T, S);
00470 
00471     _SIMD32_OFFSET(pSrc + (2 * i)) = __SHADD16(T, S);
00472 
00473 #ifndef ARM_MATH_BIG_ENDIAN
00474 
00475     out1 = __SMUSD(coeff, R) >> 16;
00476     out2 = __SMUADX(coeff, R);
00477 #else
00478 
00479     out1 = __SMUADX(R, coeff) >> 16u;
00480     out2 = __SMUSD(__QSUB(0, coeff), R);
00481 
00482 #endif //     #ifndef ARM_MATH_BIG_ENDIAN
00483 
00484     _SIMD32_OFFSET(pSrc + (2u * l)) =
00485       (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);
00486 
00487     coeff = _SIMD32_OFFSET(pCoef + (ia * 2u));
00488 
00489     ia = ia + twidCoefModifier;
00490 
00491     // loop for butterfly 
00492     i++;
00493     l++;
00494 
00495     T = _SIMD32_OFFSET(pSrc + (2 * i));
00496     in = ((int16_t) (T & 0xFFFF)) >> 1;
00497     T = ((T >> 1) & 0xFFFF0000) | (in & 0xFFFF);
00498 
00499     S = _SIMD32_OFFSET(pSrc + (2 * l));
00500     in = ((int16_t) (S & 0xFFFF)) >> 1;
00501     S = ((S >> 1) & 0xFFFF0000) | (in & 0xFFFF);
00502 
00503     R = __QSUB16(T, S);
00504 
00505     _SIMD32_OFFSET(pSrc + (2 * i)) = __SHADD16(T, S);
00506 
00507 #ifndef ARM_MATH_BIG_ENDIAN
00508 
00509     out1 = __SMUSD(coeff, R) >> 16;
00510     out2 = __SMUADX(coeff, R);
00511 #else
00512 
00513     out1 = __SMUADX(R, coeff) >> 16u;
00514     out2 = __SMUSD(__QSUB(0, coeff), R);
00515 
00516 #endif //     #ifndef ARM_MATH_BIG_ENDIAN
00517 
00518     _SIMD32_OFFSET(pSrc + (2u * l)) =
00519       (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);
00520 
00521   }                             // groups loop end 
00522 
00523   twidCoefModifier = twidCoefModifier << 1u;
00524 
00525   // loop for stage 
00526   for (k = fftLen / 2; k > 2; k = k >> 1)
00527   {
00528     n1 = n2;
00529     n2 = n2 >> 1;
00530     ia = 0;
00531 
00532     // loop for groups 
00533     for (j = 0; j < n2; j++)
00534     {
00535       coeff = _SIMD32_OFFSET(pCoef + (ia * 2u));
00536 
00537       ia = ia + twidCoefModifier;
00538 
00539       // loop for butterfly 
00540       for (i = j; i < fftLen; i += n1)
00541       {
00542         l = i + n2;
00543 
00544         T = _SIMD32_OFFSET(pSrc + (2 * i));
00545 
00546         S = _SIMD32_OFFSET(pSrc + (2 * l));
00547 
00548         R = __QSUB16(T, S);
00549 
00550         _SIMD32_OFFSET(pSrc + (2 * i)) = __SHADD16(T, S);
00551 
00552 #ifndef ARM_MATH_BIG_ENDIAN
00553 
00554         out1 = __SMUSD(coeff, R) >> 16;
00555         out2 = __SMUADX(coeff, R);
00556 
00557 #else
00558 
00559         out1 = __SMUADX(R, coeff) >> 16u;
00560         out2 = __SMUSD(__QSUB(0, coeff), R);
00561 
00562 #endif //     #ifndef ARM_MATH_BIG_ENDIAN
00563 
00564         _SIMD32_OFFSET(pSrc + (2u * l)) =
00565           (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);
00566 
00567         i += n1;
00568 
00569         l = i + n2;
00570 
00571         T = _SIMD32_OFFSET(pSrc + (2 * i));
00572 
00573         S = _SIMD32_OFFSET(pSrc + (2 * l));
00574 
00575         R = __QSUB16(T, S);
00576 
00577         _SIMD32_OFFSET(pSrc + (2 * i)) = __SHADD16(T, S);
00578 
00579 #ifndef ARM_MATH_BIG_ENDIAN
00580 
00581         out1 = __SMUSD(coeff, R) >> 16;
00582         out2 = __SMUADX(coeff, R);
00583 #else
00584 
00585         out1 = __SMUADX(R, coeff) >> 16u;
00586         out2 = __SMUSD(__QSUB(0, coeff), R);
00587 
00588 #endif //     #ifndef ARM_MATH_BIG_ENDIAN
00589 
00590         _SIMD32_OFFSET(pSrc + (2u * l)) =
00591           (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);
00592 
00593       }                         // butterfly loop end 
00594 
00595     }                           // groups loop end 
00596 
00597     twidCoefModifier = twidCoefModifier << 1u;
00598   }                             // stages loop end 
00599 
00600   n1 = n2;
00601   n2 = n2 >> 1;
00602   ia = 0;
00603 
00604   // loop for groups 
00605   for (j = 0; j < n2; j++)
00606   {
00607     coeff = _SIMD32_OFFSET(pCoef + (ia * 2u));
00608 
00609     ia = ia + twidCoefModifier;
00610 
00611     // loop for butterfly 
00612     for (i = j; i < fftLen; i += n1)
00613     {
00614       l = i + n2;
00615 
00616       T = _SIMD32_OFFSET(pSrc + (2 * i));
00617 
00618       S = _SIMD32_OFFSET(pSrc + (2 * l));
00619 
00620       R = __QSUB16(T, S);
00621 
00622       _SIMD32_OFFSET(pSrc + (2 * i)) = __QADD16(T, S);
00623 
00624       _SIMD32_OFFSET(pSrc + (2u * l)) = R;
00625 
00626     }                           // butterfly loop end 
00627 
00628   }                             // groups loop end 
00629 
00630   twidCoefModifier = twidCoefModifier << 1u;
00631 
00632 #else
00633 
00634 
00635   unsigned i, j, k, l;
00636   unsigned n1, n2, ia;
00637   q15_t xt, yt, cosVal, sinVal;
00638 
00639   //N = fftLen; 
00640   n2 = fftLen;
00641 
00642   n1 = n2;
00643   n2 = n2 >> 1;
00644   ia = 0;
00645 
00646   // loop for groups 
00647   for (j = 0; j < n2; j++)
00648   {
00649     cosVal = pCoef[ia * 2];
00650     sinVal = pCoef[(ia * 2) + 1];
00651     ia = ia + twidCoefModifier;
00652 
00653     // loop for butterfly 
00654     for (i = j; i < fftLen; i += n1)
00655     {
00656       l = i + n2;
00657       xt = (pSrc[2 * i] >> 1u) - (pSrc[2 * l] >> 1u);
00658       pSrc[2 * i] = ((pSrc[2 * i] >> 1u) + (pSrc[2 * l] >> 1u)) >> 1u;
00659 
00660       yt = (pSrc[2 * i + 1] >> 1u) - (pSrc[2 * l + 1] >> 1u);
00661       pSrc[2 * i + 1] =
00662         ((pSrc[2 * l + 1] >> 1u) + (pSrc[2 * i + 1] >> 1u)) >> 1u;
00663 
00664       pSrc[2u * l] = (((int16_t) (((q31_t) xt * cosVal) >> 16)) -
00665                       ((int16_t) (((q31_t) yt * sinVal) >> 16)));
00666 
00667       pSrc[2u * l + 1u] = (((int16_t) (((q31_t) yt * cosVal) >> 16)) +
00668                            ((int16_t) (((q31_t) xt * sinVal) >> 16)));
00669 
00670     }                           // butterfly loop end 
00671 
00672   }                             // groups loop end 
00673 
00674   twidCoefModifier = twidCoefModifier << 1u;
00675 
00676   // loop for stage 
00677   for (k = fftLen / 2; k > 2; k = k >> 1)
00678   {
00679     n1 = n2;
00680     n2 = n2 >> 1;
00681     ia = 0;
00682 
00683     // loop for groups 
00684     for (j = 0; j < n2; j++)
00685     {
00686       cosVal = pCoef[ia * 2];
00687       sinVal = pCoef[(ia * 2) + 1];
00688       ia = ia + twidCoefModifier;
00689 
00690       // loop for butterfly 
00691       for (i = j; i < fftLen; i += n1)
00692       {
00693         l = i + n2;
00694         xt = pSrc[2 * i] - pSrc[2 * l];
00695         pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) >> 1u;
00696 
00697         yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
00698         pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) >> 1u;
00699 
00700         pSrc[2u * l] = (((int16_t) (((q31_t) xt * cosVal) >> 16)) -
00701                         ((int16_t) (((q31_t) yt * sinVal) >> 16)));
00702 
00703         pSrc[2u * l + 1u] = (((int16_t) (((q31_t) yt * cosVal) >> 16)) +
00704                              ((int16_t) (((q31_t) xt * sinVal) >> 16)));
00705 
00706       }                         // butterfly loop end 
00707 
00708     }                           // groups loop end 
00709 
00710     twidCoefModifier = twidCoefModifier << 1u;
00711   }                             // stages loop end 
00712 
00713   n1 = n2;
00714   n2 = n2 >> 1;
00715   ia = 0;
00716 
00717   cosVal = pCoef[ia * 2];
00718   sinVal = pCoef[(ia * 2) + 1];
00719 
00720   ia = ia + twidCoefModifier;
00721 
00722   // loop for butterfly 
00723   for (i = 0; i < fftLen; i += n1)
00724   {
00725     l = i + n2;
00726     xt = pSrc[2 * i] - pSrc[2 * l];
00727     pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);
00728 
00729     yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
00730     pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);
00731 
00732     pSrc[2u * l] = xt;
00733 
00734     pSrc[2u * l + 1u] = yt;
00735 
00736   }                             // groups loop end 
00737 
00738 
00739 #endif //             #ifndef ARM_MATH_CM0_FAMILY
00740 
00741 }