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Making the real/single FFT easier to replace

--- a/libcelt/kfft_single.h

+++ b/libcelt/kfft_single.h

@@ -48,4 +48,10 @@

 #include "kiss_fftr.h"

 #include "_kiss_fft_guts.h"

+#define real16_fft_alloc(length) kiss_fftr_alloc_celt_single(length, 0, 0);

+#define real16_fft_free(state) kiss_fft_free(state)

+#define real16_fft_inplace(state, X) kiss_fftr_inplace(state,X)

+#define BITREV(state, i) ((state)->substate->bitrev[i])

+#define real16_ifft(state, X, Y) kiss_fftri(state,X, Y)

+

 #endif /* KFFT_SINGLE_H */

--- a/libcelt/kiss_fftr.c

+++ b/libcelt/kiss_fftr.c

@@ -128,6 +128,12 @@

    kiss_fftr_twiddles(st,freqdata);

 }

+void kiss_fftr_inplace(kiss_fftr_cfg st, kiss_fft_scalar *X)

+{

+   kf_work((kiss_fft_cpx*)X, NULL, 1,1, st->substate->factors,st->substate, 1, 1, 1);

+   kiss_fftr_twiddles(st,X);

+}

+

 void kiss_fftri(kiss_fftr_cfg st,const kiss_fft_scalar *freqdata,kiss_fft_scalar *timedata)

 {

    /* input buffer timedata is stored row-wise */

--- a/libcelt/kiss_fftr.h

+++ b/libcelt/kiss_fftr.h

@@ -47,6 +47,7 @@

 void kiss_fftr_twiddles(kiss_fftr_cfg st,kiss_fft_scalar *freqdata);

 void kiss_fftr(kiss_fftr_cfg st,const kiss_fft_scalar *timedata,kiss_fft_scalar *freqdata);

+void kiss_fftr_inplace(kiss_fftr_cfg st, kiss_fft_scalar *X);

 void kiss_fftri(kiss_fftr_cfg st,const kiss_fft_scalar *freqdata, kiss_fft_scalar *timedata);

--- a/libcelt/pitch.c

+++ b/libcelt/pitch.c

@@ -51,12 +51,12 @@

 kiss_fftr_cfg pitch_state_alloc(int max_lag)

 {

-   return kiss_fftr_alloc_celt_single(max_lag, 0, 0);

+   return real16_fft_alloc(max_lag);

 }

 void pitch_state_free(kiss_fftr_cfg st)

 {

-   kiss_fft_free(st);

+   real16_fft_free(st);

 }

 #ifdef FIXED_POINT

@@ -124,8 +124,8 @@

    {

       for (i=0;i<L2;i++)

       {

-         X[2*bitrev[i]] += SHR32(x[C*(2*i)+c],INPUT_SHIFT);

-         X[2*bitrev[i]+1] += SHR32(x[C*(2*i+1)+c],INPUT_SHIFT);

+         X[2*BITREV(fft,i)] += SHR32(x[C*(2*i)+c],INPUT_SHIFT);

+         X[2*BITREV(fft,i)+1] += SHR32(x[C*(2*i+1)+c],INPUT_SHIFT);

       }

    }

    /* Applying the window in the bit-reverse domain. It's a bit weird, but it

@@ -132,16 +132,15 @@

       can help save memory */

    for (i=0;i<overlap/2;i++)

    {

-      X[2*bitrev[i]] = MULT16_16_Q15(window[2*i], X[2*bitrev[i]]);

-      X[2*bitrev[i]+1] = MULT16_16_Q15(window[2*i+1], X[2*bitrev[i]+1]);

-      X[2*bitrev[L2-i-1]] = MULT16_16_Q15(window[2*i+1], X[2*bitrev[L2-i-1]]);

-      X[2*bitrev[L2-i-1]+1] = MULT16_16_Q15(window[2*i], X[2*bitrev[L2-i-1]+1]);

+      X[2*BITREV(fft,i)] = MULT16_16_Q15(window[2*i], X[2*BITREV(fft,i)]);

+      X[2*BITREV(fft,i)+1] = MULT16_16_Q15(window[2*i+1], X[2*BITREV(fft,i)+1]);

+      X[2*BITREV(fft,L2-i-1)] = MULT16_16_Q15(window[2*i+1], X[2*BITREV(fft,L2-i-1)]);

+      X[2*BITREV(fft,L2-i-1)+1] = MULT16_16_Q15(window[2*i], X[2*BITREV(fft,L2-i-1)+1]);

    }

    normalise16(X, lag, 8192);

    /*for (i=0;i<lag;i++) printf ("%d ", X[i]);printf ("\n");*/

    /* Forward real FFT (in-place) */

-   kf_work((kiss_fft_cpx*)X, NULL, 1,1, fft->substate->factors,fft->substate, 1, 1, 1);

-   kiss_fftr_twiddles(fft,X);

+   real16_fft_inplace(fft, X);

    compute_masking(decay, X, curve, lag);

@@ -154,14 +153,13 @@

    {

       for (i=0;i<n2;i++)

       {

-         Y[2*bitrev[i]] += SHR32(y[C*(2*i)+c],INPUT_SHIFT);

-         Y[2*bitrev[i]+1] += SHR32(y[C*(2*i+1)+c],INPUT_SHIFT);

+         Y[2*BITREV(fft,i)] += SHR32(y[C*(2*i)+c],INPUT_SHIFT);

+         Y[2*BITREV(fft,i)+1] += SHR32(y[C*(2*i+1)+c],INPUT_SHIFT);

       }

    }

    normalise16(Y, lag, 8192);

    /* Forward real FFT (in-place) */

-   kf_work((kiss_fft_cpx*)Y, NULL, 1,1, fft->substate->factors,fft->substate, 1, 1, 1);

-   kiss_fftr_twiddles(fft,Y);

+   real16_fft_inplace(fft, Y);

    /* Compute cross-spectrum using the inverse masking curve as weighting */

    for (i=1;i<n2;i++)

@@ -181,7 +179,7 @@

    /*for (i=0;i<lag;i++) printf ("%d ", X[i]);printf ("\n");*/

    normalise16(X, lag, 50);

    /* Inverse half-complex to real FFT gives us the correlation */

-   kiss_fftri(fft, X, Y);

+   real16_ifft(fft, X, Y);

    /* The peak in the correlation gives us the pitch */

    max_corr=-VERY_LARGE32;