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tedsound.cpp
150 lines (138 loc) · 4.12 KB
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tedsound.cpp
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#include "sound.h"
#include "tedmem.h"
#define PRECISION 4
#define OSCRELOADVAL (0x3FF << PRECISION)
static int Volume;
static int channelStatus[2];
static int SndNoiseStatus;
static int DAStatus;
static unsigned short Freq[2];
static int NoiseCounter;
static int FlipFlop;
static int oscCount[2];
static int OscReload[2];
static int oscStep;
static unsigned char noise[256]; // 0-8
static unsigned int MixingFreq;
static unsigned int originalFreq;
static int volumeTable[64];
static int cachedDigiSample;
static int cachedSoundSample[2];
void TED::tedSoundInit(unsigned int mixingFreq)
{
originalFreq = TED_SOUND_CLOCK / 8;
MixingFreq = mixingFreq;
setClockStep(originalFreq, MixingFreq);
FlipFlop = 0;
oscCount[0] = oscCount[1] = 0;
NoiseCounter = 0;
Freq[0] = Freq[1] = 0;
DAStatus = cachedDigiSample = 0;
cachedSoundSample[0] = cachedSoundSample[1] = 0;
unsigned char im = 0xff;
for (int i=0; i < 256; i++) {
im = (im << 1)|(((im >> 7) ^ (im >> 5) ^ (im >> 4) ^ (im >> 1)) & 1);
noise[i] = (im & 1) << 5;
}
for (int i = 0; i < 64; i++) {
int chdbl = (i & 0x30) == 0x30;
int vol = ((i & 0x0F) < 9 ? (i & 0x0F) : 8);
int nonl = ((chdbl && vol > 1) ? vol * vol * 54 - 173 * vol + 162 : 0);
volumeTable[i] = (vol && i & 0x30) ?
(nonl + (586 + (vol - 1) * 1024) << (chdbl ? 1 : 0)) : 0;
}
}
void TED::setClockStep(unsigned int originalFreq, unsigned int samplingFreq)
{
oscStep = (int)((originalFreq * (double)(1 << PRECISION)) / (double)(samplingFreq) + 0.5);
}
void TED::setFrequency(unsigned int frequency)
{
originalFreq = frequency;
setClockStep(frequency, MixingFreq);
}
void TED::setSampleRate(unsigned int sampleRate)
{
MixingFreq = sampleRate;
setClockStep(originalFreq, sampleRate);
}
void TED::calcSamples(short *buffer, unsigned int nrsamples)
{
// Rendering...
// Calculate the buffer...
if (DAStatus) {// digi?
for (;nrsamples--;) {
*buffer++ = cachedDigiSample;
}
} else {
for (;nrsamples--;) {
// Channel 1
if (OscReload[0] != (0x3FF << PRECISION)) {
if ((oscCount[0] += oscStep) >= OSCRELOADVAL) {
FlipFlop ^= 0x10;
cachedSoundSample[0] = Volume | (FlipFlop & channelStatus[0]);
oscCount[0] = OscReload[0] + (oscCount[0] - OSCRELOADVAL);
}
}
// Channel 2
if (OscReload[1] != (0x3FF << PRECISION)) {
if ((oscCount[1] += oscStep) >= OSCRELOADVAL) {
FlipFlop ^= 0x20;
cachedSoundSample[1] = Volume | (FlipFlop & channelStatus[1]) | (noise[NoiseCounter] & SndNoiseStatus);
if (++NoiseCounter == 255)
NoiseCounter = 0;
oscCount[1] = OscReload[1] + (oscCount[1] - OSCRELOADVAL);
}
}
*buffer++ = volumeTable[cachedSoundSample[0] | cachedSoundSample[1]];
} // for
}
}
inline void setFreq(unsigned int channel, int freq)
{
if (freq == 0x3FE) {
FlipFlop |= 0x10 << channel;
if (!channel)
cachedSoundSample[0] = Volume | (channelStatus[0]);
else
cachedSoundSample[1] = Volume | (channelStatus[1] | (SndNoiseStatus >> 1));
}
OscReload[channel] = ((freq + 1) & 0x3FF) << PRECISION;
}
void TED::writeSoundReg(ClockCycle cycle, unsigned int reg, unsigned char value)
{
flushBuffer(cycle, TED_SOUND_CLOCK);
switch (reg) {
case 0:
Freq[0] = (Freq[0] & 0x300) | value;
setFreq(0, Freq[0]);
break;
case 1:
Freq[1] = (Freq[1] & 0x300) | value;
setFreq(1, Freq[1]);
break;
case 2:
Freq[1] = (Freq[1] & 0xFF) | (value << 8);
setFreq(1, Freq[1]);
break;
case 3:
if ((DAStatus = (value & 0x80))) {
FlipFlop = 0x30;
oscCount[0] = OscReload[0];
oscCount[1] = OscReload[1];
NoiseCounter = 0;
cachedDigiSample = volumeTable[value & 0x3F];
}
Volume = value & 0x0F;
channelStatus[0] = value & 0x10;
channelStatus[1] = value & 0x20;
SndNoiseStatus = ((value & 0x40) >> 1) & (channelStatus[1] ^ 0x20);
cachedSoundSample[0] = Volume | (FlipFlop & channelStatus[0]);
cachedSoundSample[1] = Volume | (FlipFlop & channelStatus[1]) | (noise[NoiseCounter] & SndNoiseStatus);
break;
case 4:
Freq[0] = (Freq[0] & 0xFF) | (value << 8);
setFreq(0, Freq[0]);
break;
}
}