// --- ---------- -----------------------------------------------------------
// JLH 04/21/2014 Created this file.
//
+//
+// Notes:
+// ------
+// The emulator creates signed 16-bit samples. Make sure there's enough room
+// in your buffer for them!
+//
#include "psg.h"
#include <stdio.h>
#include <string.h>
-
+#include "fileio.h"
struct Voice
{
static Voice voice[8];
static uint8_t memory[0x200];
-//static
static uint32_t sampleRate = 44100;
+static uint32_t divisor;
-extern FILE * psg1;
-extern FILE * psg2;
+void PSGSaveState(FILE * file)
+{
+ size_t ignored = fwrite(memory, 1, 0x200, file);
+ ignored = fwrite(&voice, 1, sizeof(voice), file);
+}
+void PSGLoadState(FILE * file)
+{
+ size_t ignored = fread(memory, 1, 0x200, file);
+ ignored = fread(&voice, 1, sizeof(voice), file);
+}
void InitPSG(uint32_t s/*=44100*/)
{
sampleRate = s;
+ divisor = (uint32_t)((float)s / 0.735); // Voodoo constant
+ // Noise generation will fail if the noise seeds aren't primed...
for(int i=0; i<8; i++)
voice[i].noiseSeed = 1;
}
-
+//
+// Note that it doesn't wipe out the buffer passed in; if you want it wiped,
+// you have to wipe it yourself. :-)
+//
void UpdatePSG(uint8_t * buffer, int count)
{
-/*
-if F == 44100, then counter++ for each sample.
-if F == 88200, then counter += 2 for each sample.
-if F == 22050, then counter += 0.5 for each sample.
-*/
-// memset(buffer, 0, count * 2);
-
// Recast buffer as int16, we're doing 16-bit sound here
int16_t * p = (int16_t *)buffer;
for(int j=0; j<count; j++)
{
-// uint8_t pos = (voice[i].counter / (sampleRate * 2)) & 0x1F;
-// Where does 60000 come from? IDK. This would probably change depending on
-// the playback rate (currently, 44100). N.B.: 58800 is a hair too high in pitch!
-// 44100 / 60000 = 0.735
-// 192000 / 60000 = 3.2
-// uint8_t pos = (voice[i].counter / (60000)) & 0x1F;
- uint8_t pos = (voice[i].counter / (65536)) & 0x1F;
+ uint8_t pos = (voice[i].counter / divisor) & 0x1F;
uint8_t sample = ((pos & 0x01) == 0
? memory[(voice[i].waveform * 16) + (pos / 2)] >> 4
: memory[(voice[i].waveform * 16) + (pos / 2)]) & 0x0F;
-// p[j] += (((memory[(voice[i].waveform * 32) + pos] & 0x0F) - 8)
-// * voice[i].leftVolume) << 5;
p[j] += ((sample - 8) * voice[i].leftVolume) << 5;
voice[i].counter += voice[i].frequency;
}
if ((voice[i].leftVolume == 0) || ((voice[i].frequency & 0xFF) == 0))
continue;
+ // The hold stuff here is VOODOO
+ // Need to figure out what's really going on here, what the clock
+ // rate of this chip is. Also, some freqs can be > 255 according to
+ // Rolling Thunder...
int16_t sample = (7 * voice[i].leftVolume) << 4;
int16_t noiseSign = 1;
int16_t hold = 1 << 1;
for(int j=0; j<count; j++)
{
p[j] += sample * noiseSign;
-#if 0
-if (i == 1)
-{
- fputc(sample & 0xFF, psg1);
- fputc((sample >> 8) & 0xFF , psg1);
-}
-else if (i == 3)
-{
- fputc(sample & 0xFF, psg2);
- fputc((sample >> 8) & 0xFF , psg2);
-}
-#endif
if (hold)
{
}
}
-
void WritePSG(uint16_t address, uint8_t data)
{
if ((address >= 0x100) && (address <= 0x13F))
break;
case 1:
voice[channel].waveform = data >> 4;
- voice[channel].frequency = ((data & 0x0F) << 16)
+ voice[channel].frequency = ((data & 0x0F) << 16)
| (voice[channel].frequency & 0x0FFFF);
-#if 0
-printf("PSG: Setting waveform on channel %i to %i...\n", channel, voice[channel].waveform);
-#endif
break;
case 2:
voice[channel].frequency = (data << 8)
voice[channel].rightVolume = data & 0x0F;
// Noise switch is channel # + 1 (wraps to zero)
voice[(channel + 1) & 0x07].noise = (data & 0x80 ? true : false);
-#if 0
-if (voice[(channel + 1) & 0x07].noise)
-{
- uint8_t ch = (channel + 1) & 0x07;
- printf("PSG: Setting noise on channel %i, vol=%i, freq=%i...\n", ch, voice[ch].leftVolume, voice[ch].frequency);
-}
-#endif
-#if 0
-if (data & 0x0F)
-{
- printf("PSG: Setting right volume on channel %i: vol=%i...\n", channel, voice[channel].rightVolume);
-}
-#endif
break;
}
}
-
-// return;
}
-#if 0
- else
- printf("PSG: Write to $%03X of $%02X...\n", address, data);
-#endif
-
-//if (address < 0x100)
-// printf("PSG: Waveform byte[$%02X] = $%02X...\n", address, data);
memory[address & 0x01FF] = data;
}
-
uint8_t ReadPSG(uint16_t address)
{
return memory[address & 0x01FF];
}
-
projects / thunder / blobdiff