apps/plugins/fft/kiss_fftr.c

   1 /*
   2 Copyright (c) 2003-2004, Mark Borgerding
   3
   4 All rights reserved.
   5
   6 Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
   7
   8     * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
   9     * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
  10     * Neither the author nor the names of any contributors may be used to endorse or promote products derived from this software without specific prior written permission.
  11
  12 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  13 */
  14
  15 #include "kiss_fftr.h"
  16 #include "_kiss_fft_guts.h"
  17
  18 kiss_fftr_cfg kiss_fftr_alloc(int nfft,int inverse_fft,void * mem,size_t * lenmem)
  19 {
  20     int i;
  21     kiss_fftr_cfg st = NULL;
  22     size_t subsize, memneeded;
  23
  24     if (nfft & 1) {
  25         DEBUGF("Real FFT optimization must be even.\n");
  26         return NULL;
  27     }
  28     nfft >>= 1;
  29
  30     kiss_fft_alloc (nfft, inverse_fft, NULL, &subsize);
  31     memneeded = sizeof(struct kiss_fftr_state) + subsize + sizeof(kiss_fft_cpx) * ( nfft * 3 / 2);
  32
  33     if (lenmem == NULL) {
  34         DEBUGF("Cannot use malloc!"); /*st = (kiss_fftr_cfg) KISS_FFT_MALLOC (memneeded);*/
  35     } else {
  36         if (*lenmem >= memneeded)
  37             st = (kiss_fftr_cfg) mem;
  38         *lenmem = memneeded;
  39     }
  40     if (!st)
  41         return NULL;
  42
  43     st->substate = (kiss_fft_cfg) (st + 1); /*just beyond kiss_fftr_state struct */
  44     st->tmpbuf = (kiss_fft_cpx *) (((char *) st->substate) + subsize);
  45     st->super_twiddles = st->tmpbuf + nfft;
  46     kiss_fft_alloc(nfft, inverse_fft, st->substate, &subsize);
  47
  48     for (i = 0; i < nfft/2; ++i) {
  49         /*double phase =
  50             -3.14159265358979323846264338327 * ((double) (i+1) / nfft + .5);*/
  51         if (inverse_fft)
  52         {
  53             DEBUGF("Inverse FFT not implemented!"); /*phase *= -1;*/
  54         }
  55
  56         kf_cexp_round (st->super_twiddles+i, i+1, nfft);
  57     }
  58     return st;
  59 }
  60
  61 void kiss_fftr(kiss_fftr_cfg st,const kiss_fft_scalar *timedata,kiss_fft_cpx *freqdata)
  62 {
  63     /* input buffer timedata is stored row-wise */
  64     int k,ncfft;
  65     kiss_fft_cpx fpnk,fpk,f1k,f2k,tw,tdc;
  66
  67     if ( st->substate->inverse) {
  68         DEBUGF("kiss fft usage error: improper alloc\n");
  69         return;
  70     }
  71
  72     ncfft = st->substate->nfft;
  73
  74     /*perform the parallel fft of two real signals packed in real,imag*/
  75     kiss_fft( st->substate , (const kiss_fft_cpx*)timedata, st->tmpbuf );
  76     /* The real part of the DC element of the frequency spectrum in st->tmpbuf
  77      * contains the sum of the even-numbered elements of the input time sequence
  78      * The imag part is the sum of the odd-numbered elements
  79      *
  80      * The sum of tdc.r and tdc.i is the sum of the input time sequence.
  81      *      yielding DC of input time sequence
  82      * The difference of tdc.r - tdc.i is the sum of the input (dot product) [1,-1,1,-1...
  83      *      yielding Nyquist bin of input time sequence
  84      */
  85
  86     tdc.r = st->tmpbuf[0].r;
  87     tdc.i = st->tmpbuf[0].i;
  88     C_FIXDIV(tdc,2);
  89     CHECK_OVERFLOW_OP(tdc.r ,+, tdc.i);
  90     CHECK_OVERFLOW_OP(tdc.r ,-, tdc.i);
  91     freqdata[0].r = tdc.r + tdc.i;
  92     freqdata[ncfft].r = tdc.r - tdc.i;
  93 #ifdef USE_SIMD
  94     freqdata[ncfft].i = freqdata[0].i = _mm_set1_ps(0);
  95 #else
  96     freqdata[ncfft].i = freqdata[0].i = 0;
  97 #endif
  98
  99     for ( k=1;k <= ncfft/2 ; ++k ) {
 100         fpk    = st->tmpbuf[k];
 101         fpnk.r =   st->tmpbuf[ncfft-k].r;
 102         fpnk.i = - st->tmpbuf[ncfft-k].i;
 103         C_FIXDIV(fpk,2);
 104         C_FIXDIV(fpnk,2);
 105
 106         C_ADD( f1k, fpk , fpnk );
 107         C_SUB( f2k, fpk , fpnk );
 108         C_MUL( tw , f2k , st->super_twiddles[k-1]);
 109
 110         freqdata[k].r = HALF_OF(f1k.r + tw.r);
 111         freqdata[k].i = HALF_OF(f1k.i + tw.i);
 112         freqdata[ncfft-k].r = HALF_OF(f1k.r - tw.r);
 113         freqdata[ncfft-k].i = HALF_OF(tw.i - f1k.i);
 114     }
 115 }
 116
 117 void kiss_fftri(kiss_fftr_cfg st,const kiss_fft_cpx *freqdata,kiss_fft_scalar *timedata)
 118 {
 119     /* input buffer timedata is stored row-wise */
 120     int k, ncfft;
 121
 122     if (st->substate->inverse == 0) {
 123         DEBUGF("kiss fft usage error: improper alloc\n");
 124         return;
 125     }
 126
 127     ncfft = st->substate->nfft;
 128
 129     st->tmpbuf[0].r = freqdata[0].r + freqdata[ncfft].r;
 130     st->tmpbuf[0].i = freqdata[0].r - freqdata[ncfft].r;
 131     C_FIXDIV(st->tmpbuf[0],2);
 132
 133     for (k = 1; k <= ncfft / 2; ++k) {
 134         kiss_fft_cpx fk, fnkc, fek, fok, tmp;
 135         fk = freqdata[k];
 136         fnkc.r = freqdata[ncfft - k].r;
 137         fnkc.i = -freqdata[ncfft - k].i;
 138         C_FIXDIV( fk , 2 );
 139         C_FIXDIV( fnkc , 2 );
 140
 141         C_ADD (fek, fk, fnkc);
 142         C_SUB (tmp, fk, fnkc);
 143         C_MUL (fok, tmp, st->super_twiddles[k-1]);
 144         C_ADD (st->tmpbuf[k],     fek, fok);
 145         C_SUB (st->tmpbuf[ncfft - k], fek, fok);
 146 #ifdef USE_SIMD
 147         st->tmpbuf[ncfft - k].i *= _mm_set1_ps(-1.0);
 148 #else
 149         st->tmpbuf[ncfft - k].i *= -1;
 150 #endif
 151     }
 152     kiss_fft (st->substate, st->tmpbuf, (kiss_fft_cpx *) timedata);
 153 }