39 lines
669 B
C
39 lines
669 B
C
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#include <math.h> //sqrt
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static float csa[8][2]; /* antialias */
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void alias_init()
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{
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float Ci[8] =
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{
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-0.6f, -0.535f, -0.33f, -0.185f, -0.095f, -0.041f, -0.0142f, -0.0037f
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};
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int i;
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for (i = 0; i < 8; i++)
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{
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csa[i][0] = (float) (1.0 / sqrt(1.0 + Ci[i] * Ci[i]));
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csa[i][1] = (float) (Ci[i] / sqrt(1.0 + Ci[i] * Ci[i]));
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}
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}
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void antialias(float x[], int n)
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{
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int i, k;
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float a, b;
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for (k = 0; k < n; k++)
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{
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for (i = 0; i < 8; i++)
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{
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a = x[17 - i];
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b = x[18 + i];
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x[17 - i] = a * csa[i][0] - b * csa[i][1];
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x[18 + i] = b * csa[i][0] + a * csa[i][1];
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}
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x += 18;
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}
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}
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