diff options
Diffstat (limited to 'externals/grill/fftease/src/fold.c')
-rw-r--r-- | externals/grill/fftease/src/fold.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/externals/grill/fftease/src/fold.c b/externals/grill/fftease/src/fold.c new file mode 100644 index 00000000..0ecee5d6 --- /dev/null +++ b/externals/grill/fftease/src/fold.c @@ -0,0 +1,24 @@ +/* + * multiply current input I by window W (both of length Nw); + * using modulus arithmetic, fold and rotate windowed input + * into output array O of (FFT) length N according to current + * input time n + */ +void fold( float *I, float *W, int Nw, float *O, int N, int n ) +{ + + int i; + + for ( i = 0; i < N; i++ ) + O[i] = 0.; + + while ( n < 0 ) + n += N; + n %= N; + for ( i = 0; i < Nw; i++ ) { + O[n] += I[i]*W[i]; + if ( ++n == N ) + n = 0; + } +} + |