mirror of
https://git.code.sf.net/p/quake/quakeforge
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12ab283c22
And fix an error in floatview. The z-transform program is so I can test out my math and eventually develop some hopefully interesting sound generators.
50 lines
842 B
R
50 lines
842 B
R
#include <math.h>
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void printf (string fnt, ...) = #0;
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#define SAMPLES 4
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float output[SAMPLES];
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float input[SAMPLES];
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float T=0.1;
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float w=2;
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float a=0.5;
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float A[3], B[3];
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void
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z_transform (float *y, float *x, float *A, float *B, int n, int zind)
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{
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zind %= SAMPLES;
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float c = x[zind] * A[0];
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for (int i = 1; i < n; i++) {
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int z = (SAMPLES + zind - i) % SAMPLES;
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c += x[z] * A[i] - y[z] * B[i];
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}
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y[zind] = c / B[0];
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}
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int
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main ()
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{
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float e = exp (-a*T);
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float c = cos (w*T);
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float s = sin (w*T);
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B[0] = 1;
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B[1] = -2 * e * c;
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B[2] = e * e;
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A[0] = 0;
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A[1] = 1 - e*(c + (a/w)*s);
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A[2] = e*e + e*((a/w)*s - c);
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for (int i = 0; i < 200; i++) {
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int ind = i % SAMPLES;
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input[ind] = 1;//i ? 0 : 1;
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z_transform (output, input, A, B, 3, i);
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printf ("%2d %7.4f %7.4f\n", i, input[ind], output[ind]);
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}
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return 0;
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}
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