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removed generic code from radix2

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and reordered code, to make the savings more obvious to the reader
This commit is contained in:
Ahmet Inan 2015-07-02 15:40:23 +02:00
parent 3d2ca29fb7
commit 0d8082538e
1 changed files with 11 additions and 13 deletions
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24
app/src/main/rs/radix2.rsh
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@ -22,19 +22,17 @@ limitations under the License.
static void radix2(complex_t *out, float *in, int N, int S, int L)
{
switch (N) {
case 1:
out[0] = complex(in[0], 0.0f);
return;
case 2:
out[0] = complex(in[0] + in[S], 0.0f);
out[1] = complex(in[0] - in[S], 0.0f);
return;
case 4:
out[0] = complex(in[0] + in[S] + in[2 * S] + in[3 * S], 0.0f);
out[1] = complex(in[0] - in[2 * S], 0.0f) + radix2_z[1 << L] * (in[S] - in[3 * S]);
out[2] = complex(in[0] - in[S] + in[2 * S] - in[3 * S], 0.0f);
out[3] = complex(in[0] - in[2 * S], 0.0f) + radix2_z[1 << L] * (in[3 * S] - in[S]);
// we only need 4 <= N FFTs
if (N == 4) {
float a = in[0] + in[2 * S];
float b = in[0] - in[2 * S];
float c = in[S] + in[3 * S];
float d = in[S] - in[3 * S];
complex_t e = d * radix2_z[1 << L];
out[0] = complex(a + c, 0.0f);
out[1] = complex(b, 0.0f) + e;
out[2] = complex(a - c, 0.0f);
out[3] = complex(b, 0.0f) - e;
return;
}
radix2(out, in, N / 2, 2 * S, L + 1);