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cleaned up radix2.rsh

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This commit is contained in:
Ahmet Inan 2015-07-31 09:54:33 +02:00
parent eb216e7c69
commit 85504bc1a3
2 changed files with 24 additions and 23 deletions
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45
app/src/main/rs/radix2.rsh
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@ -20,34 +20,35 @@ limitations under the License.
#include "complex.rsh"
#include "radix2_generated.rsh"
static void radix2(complex_t *out, float *in, int N, int S, int L)
static inline void dft2(complex_t *out0, complex_t *out1, complex_t in0, complex_t in1)
{
*out0 = in0 + in1;
*out1 = in0 - in1;
}
static inline void fwd4(complex_t *out0, complex_t *out1, complex_t *out2, complex_t *out3,
float in0, float in1, float in2, float in3)
{
// we only need 4 <= N forward FFTs
if (N == 4) {
float in0 = in[0];
float in1 = in[S];
float in2 = in[2 * S];
float in3 = in[3 * S];
float a = in0 + in2;
float b = in0 - in2;
float c = in1 + in3;
out[0] = complex(a + c, 0.0f);
out[1] = complex(b, in3 - in1);
out[2] = complex(a - c, 0.0f);
out[3] = complex(b, in1 - in3);
*out0 = complex(a + c, 0.0f);
*out1 = complex(b, in3 - in1);
*out2 = complex(a - c, 0.0f);
*out3 = complex(b, in1 - in3);
}
static void radix2(complex_t *out, float *in, int N, int S)
{
// we only need 4 <= N forward FFTs
if (N == 4) {
fwd4(out, out + 1, out + 2, out + 3, in[0], in[S], in[2 * S], in[3 * S]);
return;
}
radix2(out, in, N / 2, 2 * S, L + 1);
radix2(out + N / 2, in + S, N / 2, 2 * S, L + 1);
for (int k = 0; k < N / 2; ++k) {
int ke = k;
int ko = k + N / 2;
complex_t w = radix2_z[k << L];
complex_t even = out[ke];
complex_t odd = cmul(w, out[ko]);
out[ke] = even + odd;
out[ko] = even - odd;
}
radix2(out, in, N / 2, 2 * S);
radix2(out + N / 2, in + S, N / 2, 2 * S);
for (int k0 = 0, k1 = N / 2, l1 = 0; k0 < N / 2; ++k0, ++k1, l1 += S)
dft2(out + k0, out + k1, out[k0], cmul(radix2_z[l1], out[k1]));
}
#endif

2
app/src/main/rs/stft.rsh
View file

@ -136,7 +136,7 @@ static void spectrum_analyzer(int amplitude)
for (int i = 0; i < stft_N; ++i)
input[i&(radix2_N-1)] += stft_w[i] * buffer[(i+n)&(stft_N-1)];
// yep, were wasting 2x performance
radix2(output, input, radix2_N, 1, 0);
radix2(output, input, radix2_N, 1);
for (int i = 0; i < radix2_N; ++i)
input[i] = 0.0f;
for (int j = spectrogram_height - 1; 0 < j; --j)