shithub: opus

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Just realised half the twiddles in the real FFT weren't even used. Removing
them saves another 1kB for fixed-point (2kB for float or full precision)

--- a/libcelt/kiss_fftr.c

+++ b/libcelt/kiss_fftr.c

@@ -35,6 +35,7 @@

 kiss_fftr_cfg kiss_fftr_alloc(int nfft,void * mem,size_t * lenmem)

 {

     int i;

+    int twiddle_size;

     kiss_fftr_cfg st = NULL;

     size_t subsize, memneeded;

@@ -43,9 +44,9 @@

         return NULL;

     }

     nfft >>= 1;

-

+    twiddle_size = nfft/2+1;

     kiss_fft_alloc (nfft, NULL, &subsize);

-    memneeded = sizeof(struct kiss_fftr_state) + subsize + sizeof(kiss_twiddle_cpx)*nfft;

+    memneeded = sizeof(struct kiss_fftr_state) + subsize + sizeof(kiss_twiddle_cpx)*twiddle_size;

     if (lenmem == NULL) {

         st = (kiss_fftr_cfg) KISS_FFT_MALLOC (memneeded);

@@ -65,12 +66,12 @@

 #endif

 #if defined (FIXED_POINT) && !defined(DOUBLE_PRECISION)

-    for (i=0;i<nfft;++i) {

+    for (i=0;i<twiddle_size;++i) {

        celt_word32_t phase = i+(nfft>>1);

        kf_cexp2(st->super_twiddles+i, DIV32(SHL32(phase,16),nfft));

     }

 #else

-    for (i=0;i<nfft;++i) {

+    for (i=0;i<twiddle_size;++i) {

        const double pi=3.14159265358979323846264338327;

        double phase = pi*(((double)i) /nfft + .5);

        kf_cexp(st->super_twiddles+i, phase );