108 lines
3.8 KiB
C#
108 lines
3.8 KiB
C#
using static SAMSharp.Sam;
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using static SAMSharp.Renderer;
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namespace SAMSharp
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{
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class Process
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{
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static void CombineGlottalAndFormants(byte phase1, byte phase2, byte phase3, byte Y)
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{
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byte tmp;
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tmp = multtable[sinus[phase1] | amplitude1[Y]];
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tmp += multtable[sinus[phase2] | amplitude2[Y]];
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tmp += (byte)(tmp > 255 ? 1 : 0); // if addition above overflows, we for some reason add one;
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tmp += multtable[rectangle[phase3] | amplitude3[Y]];
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tmp += 136;
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tmp >>= 4; // Scale down to 0..15 range of C64 audio.
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Output(0, (byte)(tmp & 0xf));
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}
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// PROCESS THE FRAMES
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//
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// In traditional vocal synthesis, the glottal pulse drives filters, which
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// are attenuated to the frequencies of the formants.
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//
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// SAM generates these formants directly with sin and rectangular waves.
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// To simulate them being driven by the glottal pulse, the waveforms are
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// reset at the beginning of each glottal pulse.
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//
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public static void ProcessFrames(byte mem48)
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{
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byte speedcounter = 72;
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byte phase1 = 0;
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byte phase2 = 0;
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byte phase3 = 0;
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byte mem66 = 0; //!! was not initialized
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byte Y = 0;
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byte glottal_pulse = pitches[0];
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byte mem38 = (byte)(glottal_pulse - (glottal_pulse >> 2)); // mem44 * 0.75
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while (mem48 != 0)
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{
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byte flags = sampledConsonantFlag[Y];
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// unvoiced sampled phoneme?
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if ((flags & 248) != 0)
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{
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RenderSample(mem66, flags, Y);
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// skip ahead two in the phoneme buffer
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Y += 2;
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mem48 -= 2;
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speedcounter = speed;
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}
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else
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{
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CombineGlottalAndFormants(phase1, phase2, phase3, Y);
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speedcounter--;
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if (speedcounter == 0)
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{
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Y++; //go to next amplitude
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// decrement the frame count
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mem48--;
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if (mem48 == 0) return;
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speedcounter = speed;
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}
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--glottal_pulse;
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if (glottal_pulse != 0)
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{
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// not finished with a glottal pulse
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--mem38;
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// within the first 75% of the glottal pulse?
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// is the count non-zero and the sampled flag is zero?
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if ((mem38 != 0) || (flags == 0))
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{
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// reset the phase of the formants to match the pulse
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phase1 += frequency1[Y];
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phase2 += frequency2[Y];
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phase3 += frequency3[Y];
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continue;
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}
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// voiced sampled phonemes interleave the sample with the
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// glottal pulse. The sample flag is non-zero, so render
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// the sample for the phoneme.
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RenderSample(mem66, flags, Y);
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}
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}
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glottal_pulse = pitches[Y];
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mem38 = (byte)(glottal_pulse - (glottal_pulse >> 2)); // mem44 * 0.75
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// reset the formant wave generators to keep them in
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// sync with the glottal pulse
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phase1 = 0;
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phase2 = 0;
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phase3 = 0;
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}
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}
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}
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}
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