kfc.c

/*
Copyright (c) 2003-2010 Mark Borgerding
Copyright (c) 2017 Mark Straver BASc

Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright notice,
      this list of conditions and the following disclaimer.
    * 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.
    * 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.

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.
*/

#include "kfc.h"

typedef struct cached_fft *kfc_cfg;

struct cached_fft
{
    int nfft;
    int inverse;
    kiss_fft_cfg cfg;
    kfc_cfg next;
};

static kfc_cfg cache_root=NULL;
static int ncached=0;

static kiss_fft_cfg find_cached_fft(int nfft,int inverse)
{
    size_t len;
    kfc_cfg  cur=cache_root;
    kfc_cfg  prev=NULL;
    while ( cur ) {
        if ( cur->nfft == nfft && inverse == cur->inverse )
            break;/*found the right node*/
        prev = cur;
        cur = prev->next;
    }
    if (cur== NULL) {
        /* no cached node found, need to create a new one*/
        kiss_fft_alloc(nfft,inverse,0,&len);
#ifdef USE_SIMD
        int padding = (16-sizeof(struct cached_fft)) & 15;
        // make sure the cfg aligns on a 16 byte boundary
        len += padding;
#endif
        cur = (kfc_cfg)KISS_FFT_MALLOC((sizeof(struct cached_fft) + len ));
        if (cur == NULL)
            return NULL;
        cur->cfg = (kiss_fft_cfg)(cur+1);
#ifdef USE_SIMD
        cur->cfg = (kiss_fft_cfg) ((char*)(cur+1)+padding);
#endif
        kiss_fft_alloc(nfft,inverse,cur->cfg,&len);
        cur->nfft=nfft;
        cur->inverse=inverse;
        cur->next = NULL;
        if ( prev )
            prev->next = cur;
        else
            cache_root = cur;
        ++ncached;
    }
    return cur->cfg;
}

void kfc_cleanup(void)
{
    kfc_cfg  cur=cache_root;
    kfc_cfg  next=NULL;
    while (cur){
        next = cur->next;
        free(cur);
        cur=next;
    }
    ncached=0;
    cache_root = NULL;
}
void kfc_fft(int nfft, const kiss_fft_cpx * fin,kiss_fft_cpx * fout)
{
    kiss_fft( find_cached_fft(nfft,0),fin,fout );
}

void kfc_ifft(int nfft, const kiss_fft_cpx * fin,kiss_fft_cpx * fout)
{
    kiss_fft( find_cached_fft(nfft,1),fin,fout );
}

#ifdef KFC_TEST
static void check(int nc)
{
    if (ncached != nc) {
        fprintf(stderr,"ncached should be %d,but it is %d\n",nc,ncached);
        exit(1);
    }
}

int main(void)
{
    kiss_fft_cpx buf1[1024],buf2[1024];
    memset(buf1,0,sizeof(buf1));
    check(0);
    kfc_fft(512,buf1,buf2);
    check(1);
    kfc_fft(512,buf1,buf2);
    check(1);
    kfc_ifft(512,buf1,buf2);
    check(2);
    kfc_cleanup();
    check(0);
    return 0;
}
#endif