108 lines
3.2 KiB
C++
108 lines
3.2 KiB
C++
#pragma once
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#include <cmath>
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#include <cstdint>
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#include <stdlib.h>
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namespace trnr {
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// ulaw compansion based on code by Chris Johnson
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class ulaw {
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public:
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ulaw()
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{
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fpd_l = 1.0;
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while (fpd_l < 16386) fpd_l = rand() * UINT32_MAX;
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fpd_r = 1.0;
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while (fpd_r < 16386) fpd_r = rand() * UINT32_MAX;
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}
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void encode_samples(double& input_sample_l, double& input_sample_r)
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{
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// ulaw encoding
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static int noisesource_l = 0;
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static int noisesource_r = 850010;
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int residue;
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double applyresidue;
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noisesource_l = noisesource_l % 1700021;
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noisesource_l++;
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residue = noisesource_l * noisesource_l;
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residue = residue % 170003;
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residue *= residue;
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residue = residue % 17011;
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residue *= residue;
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residue = residue % 1709;
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residue *= residue;
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residue = residue % 173;
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residue *= residue;
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residue = residue % 17;
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applyresidue = residue;
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applyresidue *= 0.00000001;
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applyresidue *= 0.00000001;
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input_sample_l += applyresidue;
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if (input_sample_l < 1.2e-38 && -input_sample_l < 1.2e-38) { input_sample_l -= applyresidue; }
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noisesource_r = noisesource_r % 1700021;
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noisesource_r++;
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residue = noisesource_r * noisesource_r;
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residue = residue % 170003;
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residue *= residue;
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residue = residue % 17011;
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residue *= residue;
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residue = residue % 1709;
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residue *= residue;
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residue = residue % 173;
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residue *= residue;
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residue = residue % 17;
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applyresidue = residue;
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applyresidue *= 0.00000001;
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applyresidue *= 0.00000001;
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input_sample_r += applyresidue;
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if (input_sample_r < 1.2e-38 && -input_sample_r < 1.2e-38) { input_sample_r -= applyresidue; }
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if (input_sample_l > 1.0) input_sample_l = 1.0;
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if (input_sample_l < -1.0) input_sample_l = -1.0;
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if (input_sample_r > 1.0) input_sample_r = 1.0;
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if (input_sample_r < -1.0) input_sample_r = -1.0;
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if (input_sample_l > 0) input_sample_l = log(1.0 + (255 * fabs(input_sample_l))) / log(256);
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if (input_sample_l < 0) input_sample_l = -log(1.0 + (255 * fabs(input_sample_l))) / log(256);
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if (input_sample_r > 0) input_sample_r = log(1.0 + (255 * fabs(input_sample_r))) / log(256);
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if (input_sample_r < 0) input_sample_r = -log(1.0 + (255 * fabs(input_sample_r))) / log(256);
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}
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void decode_samples(double& input_sample_l, double& input_sample_r)
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{
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// ulaw decoding
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if (fabs(input_sample_l) < 1.18e-23) input_sample_l = fpd_l * 1.18e-17;
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if (fabs(input_sample_r) < 1.18e-23) input_sample_r = fpd_r * 1.18e-17;
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if (input_sample_l > 1.0) input_sample_l = 1.0;
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if (input_sample_l < -1.0) input_sample_l = -1.0;
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if (input_sample_r > 1.0) input_sample_r = 1.0;
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if (input_sample_r < -1.0) input_sample_r = -1.0;
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if (input_sample_l > 0) input_sample_l = (pow(256, fabs(input_sample_l)) - 1.0) / 255;
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if (input_sample_l < 0) input_sample_l = -(pow(256, fabs(input_sample_l)) - 1.0) / 255;
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if (input_sample_r > 0) input_sample_r = (pow(256, fabs(input_sample_r)) - 1.0) / 255;
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if (input_sample_r < 0) input_sample_r = -(pow(256, fabs(input_sample_r)) - 1.0) / 255;
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// 64 bit stereo floating point dither
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fpd_l ^= fpd_l << 13;
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fpd_l ^= fpd_l >> 17;
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fpd_l ^= fpd_l << 5;
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fpd_r ^= fpd_r << 13;
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fpd_r ^= fpd_r >> 17;
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fpd_r ^= fpd_r << 5;
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}
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private:
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uint32_t fpd_l;
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uint32_t fpd_r;
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};
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} // namespace trnr
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