Split the radix functions into forward and backward versions, removed the

"inverse" flag from the state so it can be shared between the forward and
inverse transforms.

libcelt/_kiss_fft_guts.h

@@ -29,7 +29,6 @@ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 
 struct kiss_fft_state{
     int nfft;
-    int inverse;
     int factors[2*MAXFACTORS];
     int *bitrev;
     kiss_fft_cpx twiddles[1];

libcelt/kiss_fft.h

@@ -71,7 +71,7 @@ typedef struct kiss_fft_state* kiss_fft_cfg;
  *      buffer size in *lenmem.
  * */
 
-kiss_fft_cfg kiss_fft_alloc(int nfft,int inverse_fft,void * mem,size_t * lenmem); 
+kiss_fft_cfg kiss_fft_alloc(int nfft,void * mem,size_t * lenmem); 
 
 /*
  * kiss_fft(cfg,in_out_buf)
@@ -84,11 +84,13 @@ kiss_fft_cfg kiss_fft_alloc(int nfft,int inverse_fft,void * mem,size_t * lenmem)
     f[k].r and f[k].i
  * */
 void kiss_fft(kiss_fft_cfg cfg,const kiss_fft_cpx *fin,kiss_fft_cpx *fout);
+void kiss_ifft(kiss_fft_cfg cfg,const kiss_fft_cpx *fin,kiss_fft_cpx *fout);
 
 /*
  A more generic version of the above function. It reads its input from every Nth sample.
  * */
 void kiss_fft_stride(kiss_fft_cfg cfg,const kiss_fft_cpx *fin,kiss_fft_cpx *fout,int fin_stride);
+void kiss_ifft_stride(kiss_fft_cfg cfg,const kiss_fft_cpx *fin,kiss_fft_cpx *fout,int fin_stride);
 
 /* If kiss_fft_alloc allocated a buffer, it is one contiguous 
    buffer and can be simply free()d when no longer needed*/

libcelt/kiss_fftr.c

@@ -33,7 +33,7 @@ struct kiss_fftr_state{
 #endif    
 };
 
-kiss_fftr_cfg kiss_fftr_alloc(int nfft,int inverse_fft,void * mem,size_t * lenmem)
+kiss_fftr_cfg kiss_fftr_alloc(int nfft,void * mem,size_t * lenmem)
 {
     int i;
     kiss_fftr_cfg st = NULL;
@@ -45,7 +45,7 @@ kiss_fftr_cfg kiss_fftr_alloc(int nfft,int inverse_fft,void * mem,size_t * lenme
     }
     nfft >>= 1;
 
-    kiss_fft_alloc (nfft, inverse_fft, NULL, &subsize);
+    kiss_fft_alloc (nfft, NULL, &subsize);
     memneeded = sizeof(struct kiss_fftr_state) + subsize + sizeof(kiss_fft_cpx) * ( nfft * 2);
 
     if (lenmem == NULL) {
@@ -61,7 +61,7 @@ kiss_fftr_cfg kiss_fftr_alloc(int nfft,int inverse_fft,void * mem,size_t * lenme
     st->substate = (kiss_fft_cfg) (st + 1); /*just beyond kiss_fftr_state struct */
     st->tmpbuf = (kiss_fft_cpx *) (((char *) st->substate) + subsize);
     st->super_twiddles = st->tmpbuf + nfft;
-    kiss_fft_alloc(nfft, inverse_fft, st->substate, &subsize);
+    kiss_fft_alloc(nfft, st->substate, &subsize);
 
 #ifdef FIXED_POINT
     for (i=0;i<nfft;++i) {
@@ -85,10 +85,6 @@ void kiss_fftr(kiss_fftr_cfg st,const kiss_fft_scalar *timedata,kiss_fft_scalar
    kiss_fft_cpx f2k,tdc;
    celt_word32_t f1kr, f1ki, twr, twi;
 
-   if ( st->substate->inverse) {
-      celt_fatal("kiss fft usage error: improper alloc\n");
-   }
-
    ncfft = st->substate->nfft;
 
    /*perform the parallel fft of two real signals packed in real,imag*/
@@ -142,10 +138,6 @@ void kiss_fftri(kiss_fftr_cfg st,const kiss_fft_scalar *freqdata,kiss_fft_scalar
    /* input buffer timedata is stored row-wise */
    int k, ncfft;
 
-   if (st->substate->inverse == 0) {
-      celt_fatal ("kiss fft usage error: improper alloc\n");
-   }
-
    ncfft = st->substate->nfft;
 
    st->tmpbuf[0].r = freqdata[0] + freqdata[1];
@@ -169,5 +161,5 @@ void kiss_fftri(kiss_fftr_cfg st,const kiss_fft_scalar *freqdata,kiss_fft_scalar
       st->tmpbuf[ncfft - k].i *= -1;
 #endif
    }
-   kiss_fft (st->substate, st->tmpbuf, (kiss_fft_cpx *) timedata);
+   kiss_ifft (st->substate, st->tmpbuf, (kiss_fft_cpx *) timedata);
 }

libcelt/kiss_fftr.h

@@ -18,7 +18,7 @@ extern "C" {
 typedef struct kiss_fftr_state *kiss_fftr_cfg;
 
 
-kiss_fftr_cfg kiss_fftr_alloc(int nfft,int inverse_fft,void * mem, size_t * lenmem);
+kiss_fftr_cfg kiss_fftr_alloc(int nfft,void * mem, size_t * lenmem);
 /*
  nfft must be even
 

libcelt/mdct.c

@@ -54,8 +54,7 @@ void mdct_init(mdct_lookup *l,int N)
    l->n = N;
    N2 = N/2;
    N4 = N/4;
-   l->kfft = kiss_fft_alloc(N4, 0, NULL, NULL);
-   l->ikfft = kiss_fft_alloc(N4, 1, NULL, NULL);
+   l->kfft = kiss_fft_alloc(N4, NULL, NULL);
    l->trig = celt_alloc(N2*sizeof(float));
    /* We have enough points that sine isn't necessary */
    for (i=0;i<N2;i++)
@@ -66,7 +65,6 @@ void mdct_init(mdct_lookup *l,int N)
 void mdct_clear(mdct_lookup *l)
 {
    kiss_fft_free(l->kfft);
-   kiss_fft_free(l->ikfft);
    celt_free(l->trig);
 }
 
@@ -131,7 +129,7 @@ void mdct_backward(mdct_lookup *l, float *in, float *out)
    }
 
    /* Inverse N/4 complex FFT. This one should *not* downscale even in fixed-point */
-   kiss_fft(l->ikfft, (const kiss_fft_cpx *)out, (kiss_fft_cpx *)f);
+   kiss_ifft(l->kfft, (const kiss_fft_cpx *)out, (kiss_fft_cpx *)f);
    
    /* Post-rotate */
    for(i=0;i<N4;i++)

libcelt/mdct.h

@@ -47,7 +47,6 @@
 typedef struct {
    int n;
    kiss_fft_cfg kfft;
-   kiss_fft_cfg ikfft;
    float *trig;
    float scale;
 } mdct_lookup;

tests/dft-test.c

@@ -42,7 +42,7 @@ void test1d(int nfft,int isinverse)
 
     kiss_fft_cpx  * in = (kiss_fft_cpx*)malloc(buflen);
     kiss_fft_cpx  * out= (kiss_fft_cpx*)malloc(buflen);
-    kiss_fft_cfg  cfg = kiss_fft_alloc(nfft,isinverse,0,0);
+    kiss_fft_cfg  cfg = kiss_fft_alloc(nfft,0,0);
     int k;
 
     for (k=0;k<nfft;++k) {
@@ -50,7 +50,10 @@ void test1d(int nfft,int isinverse)
         in[k].i = (rand() % 65536) - 32768;
     }
 
-    kiss_fft(cfg,in,out);
+    if (isinverse)
+       kiss_ifft(cfg,in,out);
+    else
+       kiss_fft(cfg,in,out);
 
     check(in,out,nfft,isinverse);
 

tests/real-fft-test.c

@@ -96,8 +96,8 @@ int main(void)
         cin[i].i = zero;
     }
 
-    kiss_fft_state = kiss_fft_alloc(NFFT,0,0,0);
-    kiss_fftr_state = kiss_fftr_alloc(NFFT,0,0,0);
+    kiss_fft_state = kiss_fft_alloc(NFFT,0,0);
+    kiss_fftr_state = kiss_fftr_alloc(NFFT,0,0);
     kiss_fft(kiss_fft_state,cin,cout);
     kiss_fftr(kiss_fftr_state,rin,sout);
     
@@ -118,12 +118,6 @@ int main(void)
 
     printf("%d complex ffts took %gs, real took %gs\n",NUMFFTS,tfft,trfft);
 
-    free(kiss_fft_state);
-    free(kiss_fftr_state);
-
-    kiss_fft_state = kiss_fft_alloc(NFFT,1,0,0);
-    kiss_fftr_state = kiss_fftr_alloc(NFFT,1,0,0);
-
     memset(cin,0,sizeof(cin));
 #if 1
     cin[0].r = rand_scalar();
@@ -153,7 +147,7 @@ int main(void)
        fin[2*i+1] = cin[i].i;
     }
     
-    kiss_fft(kiss_fft_state,cin,cout);
+    kiss_ifft(kiss_fft_state,cin,cout);
     kiss_fftri(kiss_fftr_state,fin,rout);
     /*
     printf(" results from inverse kiss_fft : (%f,%f), (%f,%f), (%f,%f), (%f,%f), (%f,%f) ...\n "