arm_cfft_radix2_q31.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_q31.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_q31(
00045   q31_t * pSrc,
00046   uint32_t fftLen,
00047   q31_t * pCoef,
00048   uint16_t twidCoefModifier);
00049 
00050 void arm_radix2_butterfly_inverse_q31(
00051   q31_t * pSrc,
00052   uint32_t fftLen,
00053   q31_t * pCoef,
00054   uint16_t twidCoefModifier);
00055 
00056 void arm_bitreversal_q31(
00057   q31_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_q31 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_q31(
00081 const arm_cfft_radix2_instance_q31 * S,
00082 q31_t * pSrc)
00083 {
00084 
00085    if(S->ifftFlag == 1u)
00086    {
00087       arm_radix2_butterfly_inverse_q31(pSrc, S->fftLen,
00088       S->pTwiddle, S->twidCoefModifier);
00089    }
00090    else
00091    {
00092       arm_radix2_butterfly_q31(pSrc, S->fftLen,
00093       S->pTwiddle, S->twidCoefModifier);
00094    }
00095 
00096    arm_bitreversal_q31(pSrc, S->fftLen, S->bitRevFactor, S->pBitRevTable);
00097 }
00098 
00099 /**   
00100 * @} end of ComplexFFT group   
00101 */
00102 
00103 void arm_radix2_butterfly_q31(
00104 q31_t * pSrc,
00105 uint32_t fftLen,
00106 q31_t * pCoef,
00107 uint16_t twidCoefModifier)
00108 {
00109 
00110    unsigned i, j, k, l, m;
00111    unsigned n1, n2, ia;
00112    q31_t xt, yt, cosVal, sinVal;
00113    q31_t p0, p1;
00114 
00115    //N = fftLen; 
00116    n2 = fftLen;
00117 
00118    n1 = n2;
00119    n2 = n2 >> 1;
00120    ia = 0;
00121 
00122    // loop for groups 
00123    for (i = 0; i < n2; i++)
00124    {
00125       cosVal = pCoef[ia * 2];
00126       sinVal = pCoef[(ia * 2) + 1];
00127       ia = ia + twidCoefModifier;
00128 
00129       l = i + n2;
00130       xt = (pSrc[2 * i] >> 1u) - (pSrc[2 * l] >> 1u);
00131       pSrc[2 * i] = ((pSrc[2 * i] >> 1u) + (pSrc[2 * l] >> 1u)) >> 1u;
00132       
00133       yt = (pSrc[2 * i + 1] >> 1u) - (pSrc[2 * l + 1] >> 1u);
00134       pSrc[2 * i + 1] =
00135         ((pSrc[2 * l + 1] >> 1u) + (pSrc[2 * i + 1] >> 1u)) >> 1u;
00136 
00137       mult_32x32_keep32_R(p0, xt, cosVal);
00138       mult_32x32_keep32_R(p1, yt, cosVal);
00139       multAcc_32x32_keep32_R(p0, yt, sinVal); 
00140       multSub_32x32_keep32_R(p1, xt, sinVal);
00141       
00142       pSrc[2u * l] = p0;
00143       pSrc[2u * l + 1u] = p1;
00144 
00145    }                             // groups loop end 
00146 
00147    twidCoefModifier <<= 1u;
00148 
00149    // loop for stage 
00150    for (k = fftLen / 2; k > 2; k = k >> 1)
00151    {
00152       n1 = n2;
00153       n2 = n2 >> 1;
00154       ia = 0;
00155 
00156       // loop for groups 
00157       for (j = 0; j < n2; j++)
00158       {
00159          cosVal = pCoef[ia * 2];
00160          sinVal = pCoef[(ia * 2) + 1];
00161          ia = ia + twidCoefModifier;
00162 
00163          // loop for butterfly 
00164          i = j;
00165          m = fftLen / n1;
00166          do
00167          {
00168             l = i + n2;
00169             xt = pSrc[2 * i] - pSrc[2 * l];
00170             pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) >> 1u;
00171             
00172             yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
00173             pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) >> 1u;
00174 
00175             mult_32x32_keep32_R(p0, xt, cosVal);
00176             mult_32x32_keep32_R(p1, yt, cosVal);
00177             multAcc_32x32_keep32_R(p0, yt, sinVal);
00178             multSub_32x32_keep32_R(p1, xt, sinVal);
00179             
00180             pSrc[2u * l] = p0;
00181             pSrc[2u * l + 1u] = p1;
00182             i += n1;
00183             m--;
00184          } while( m > 0);                   // butterfly loop end 
00185 
00186       }                           // groups loop end 
00187 
00188       twidCoefModifier <<= 1u;
00189    }                             // stages loop end 
00190 
00191    n1 = n2;
00192    n2 = n2 >> 1;
00193    ia = 0;
00194 
00195    cosVal = pCoef[ia * 2];
00196    sinVal = pCoef[(ia * 2) + 1];
00197    ia = ia + twidCoefModifier;
00198 
00199    // loop for butterfly 
00200    for (i = 0; i < fftLen; i += n1)
00201    {
00202       l = i + n2;
00203       xt = pSrc[2 * i] - pSrc[2 * l];
00204       pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);
00205 
00206       yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
00207       pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);
00208 
00209       pSrc[2u * l] = xt;
00210 
00211       pSrc[2u * l + 1u] = yt;
00212 
00213       i += n1;
00214       l = i + n2;
00215 
00216       xt = pSrc[2 * i] - pSrc[2 * l];
00217       pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);
00218 
00219       yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
00220       pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);
00221 
00222       pSrc[2u * l] = xt;
00223 
00224       pSrc[2u * l + 1u] = yt;
00225 
00226    }                             // butterfly loop end 
00227 
00228 }
00229 
00230 
00231 void arm_radix2_butterfly_inverse_q31(
00232 q31_t * pSrc,
00233 uint32_t fftLen,
00234 q31_t * pCoef,
00235 uint16_t twidCoefModifier)
00236 {
00237 
00238    unsigned i, j, k, l;
00239    unsigned n1, n2, ia;
00240    q31_t xt, yt, cosVal, sinVal;
00241    q31_t p0, p1;
00242 
00243    //N = fftLen; 
00244    n2 = fftLen;
00245 
00246    n1 = n2;
00247    n2 = n2 >> 1;
00248    ia = 0;
00249 
00250    // loop for groups 
00251    for (i = 0; i < n2; i++)
00252    {
00253       cosVal = pCoef[ia * 2];
00254       sinVal = pCoef[(ia * 2) + 1];
00255       ia = ia + twidCoefModifier;
00256 
00257       l = i + n2;
00258       xt = (pSrc[2 * i] >> 1u) - (pSrc[2 * l] >> 1u);
00259       pSrc[2 * i] = ((pSrc[2 * i] >> 1u) + (pSrc[2 * l] >> 1u)) >> 1u;
00260       
00261       yt = (pSrc[2 * i + 1] >> 1u) - (pSrc[2 * l + 1] >> 1u);
00262       pSrc[2 * i + 1] =
00263         ((pSrc[2 * l + 1] >> 1u) + (pSrc[2 * i + 1] >> 1u)) >> 1u;
00264 
00265       mult_32x32_keep32_R(p0, xt, cosVal);
00266       mult_32x32_keep32_R(p1, yt, cosVal);
00267       multSub_32x32_keep32_R(p0, yt, sinVal);
00268       multAcc_32x32_keep32_R(p1, xt, sinVal);
00269       
00270       pSrc[2u * l] = p0;
00271       pSrc[2u * l + 1u] = p1;
00272    }                             // groups loop end 
00273 
00274    twidCoefModifier = twidCoefModifier << 1u;
00275 
00276    // loop for stage 
00277    for (k = fftLen / 2; k > 2; k = k >> 1)
00278    {
00279       n1 = n2;
00280       n2 = n2 >> 1;
00281       ia = 0;
00282 
00283       // loop for groups 
00284       for (j = 0; j < n2; j++)
00285       {
00286          cosVal = pCoef[ia * 2];
00287          sinVal = pCoef[(ia * 2) + 1];
00288          ia = ia + twidCoefModifier;
00289 
00290          // loop for butterfly 
00291          for (i = j; i < fftLen; i += n1)
00292          {
00293             l = i + n2;
00294             xt = pSrc[2 * i] - pSrc[2 * l];
00295             pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) >> 1u;
00296       
00297             yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
00298             pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) >> 1u;
00299 
00300             mult_32x32_keep32_R(p0, xt, cosVal);
00301             mult_32x32_keep32_R(p1, yt, cosVal);
00302             multSub_32x32_keep32_R(p0, yt, sinVal);
00303             multAcc_32x32_keep32_R(p1, xt, sinVal);
00304             
00305             pSrc[2u * l] = p0;
00306             pSrc[2u * l + 1u] = p1;
00307          }                         // butterfly loop end 
00308 
00309       }                           // groups loop end 
00310 
00311       twidCoefModifier = twidCoefModifier << 1u;
00312    }                             // stages loop end 
00313 
00314    n1 = n2;
00315    n2 = n2 >> 1;
00316    ia = 0;
00317 
00318    cosVal = pCoef[ia * 2];
00319    sinVal = pCoef[(ia * 2) + 1];
00320    ia = ia + twidCoefModifier;
00321 
00322    // loop for butterfly 
00323    for (i = 0; i < fftLen; i += n1)
00324    {
00325       l = i + n2;
00326       xt = pSrc[2 * i] - pSrc[2 * l];
00327       pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);
00328 
00329       yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
00330       pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);
00331 
00332       pSrc[2u * l] = xt;
00333 
00334       pSrc[2u * l + 1u] = yt;
00335 
00336       i += n1;
00337       l = i + n2;
00338 
00339       xt = pSrc[2 * i] - pSrc[2 * l];
00340       pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);
00341 
00342       yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
00343       pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);
00344 
00345       pSrc[2u * l] = xt;
00346 
00347       pSrc[2u * l + 1u] = yt;
00348 
00349    }                             // butterfly loop end 
00350 
00351 }