ref: 559e8ff602f172470b7f7faa37a1e531e83faf28
parent: 6c24524b88b280832dcae97cc0d428cad9a83ae3
author: Jean-Marc Valin <[email protected]>
date: Sat Dec 29 19:02:00 EST 2007
simplified exp_rotation()
--- a/libcelt/bands.c
+++ b/libcelt/bands.c
@@ -35,70 +35,50 @@
#include "vq.h"
#include "cwrs.h"
-/* Applies a series of rotations so that pulses are spread like a two-sided expo
-nential */
+/* Applies a series of rotations so that pulses are spread like a two-sided
+exponential */
static void exp_rotation(float *X, int len, float theta, int dir)
{- int i;
+ int i, k, stride=2;
float c, s;
c = cos(theta);
s = sin(theta);
if (dir > 0)
{- for (i=0;i<(len/2)-1;i++)
+ for (i=0;i<len-2;i++)
{float x1, x2;
- x1 = X[2*i];
- x2 = X[2*i+2];
- X[2*i] = c*x1 - s*x2;
- X[2*i+2] = c*x2 + s*x1;
-
- x1 = X[2*i+1];
- x2 = X[2*i+3];
- X[2*i+1] = c*x1 - s*x2;
- X[2*i+3] = c*x2 + s*x1;
+ x1 = X[i];
+ x2 = X[i+2];
+ X[i] = c*x1 - s*x2;
+ X[i+2] = c*x2 + s*x1;
}
- for (i=(len/2)-3;i>=0;i--)
+ for (i=len-5;i>=0;i--)
{float x1, x2;
- x1 = X[2*i];
- x2 = X[2*i+2];
- X[2*i] = c*x1 - s*x2;
- X[2*i+2] = c*x2 + s*x1;
-
- x1 = X[2*i+1];
- x2 = X[2*i+3];
- X[2*i+1] = c*x1 - s*x2;
- X[2*i+3] = c*x2 + s*x1;
+ x1 = X[i];
+ x2 = X[i+2];
+ X[i] = c*x1 - s*x2;
+ X[i+2] = c*x2 + s*x1;
}
} else {- for (i=0;i<(len/2)-2;i++)
+ for (i=0;i<len-4;i++)
{float x1, x2;
- x1 = X[2*i];
- x2 = X[2*i+2];
- X[2*i] = c*x1 + s*x2;
- X[2*i+2] = c*x2 - s*x1;
-
- x1 = X[2*i+1];
- x2 = X[2*i+3];
- X[2*i+1] = c*x1 + s*x2;
- X[2*i+3] = c*x2 - s*x1;
+ x1 = X[i];
+ x2 = X[i+2];
+ X[i] = c*x1 + s*x2;
+ X[i+2] = c*x2 - s*x1;
}
- for (i=(len/2)-2;i>=0;i--)
+ for (i=len-3;i>=0;i--)
{float x1, x2;
- x1 = X[2*i];
- x2 = X[2*i+2];
- X[2*i] = c*x1 + s*x2;
- X[2*i+2] = c*x2 - s*x1;
-
- x1 = X[2*i+1];
- x2 = X[2*i+3];
- X[2*i+1] = c*x1 + s*x2;
- X[2*i+3] = c*x2 - s*x1;
+ x1 = X[i];
+ x2 = X[i+2];
+ X[i] = c*x1 + s*x2;
+ X[i+2] = c*x2 - s*x1;
}
}
}