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This commit is contained in:
Wolfgang Hottgenroth
2024-03-26 21:05:48 +01:00
parent 73d2bbc730
commit 9989a52c38
5 changed files with 115 additions and 68 deletions
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15
sound-driver/psg.c
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@ -39,6 +39,8 @@ const uint16_t frequencyCodes[8][12] = {
#define R14 014
#define R15 015
uint8_t psgShadowRegisters[14];
inline static void BUS_OP_NACT() {
BUS_CTRL_REG &= ~(BDIR | BC1);
}
@ -61,7 +63,13 @@ asm volatile (
);
}
uint8_t psgReadShadow(uint8_t address) {
return psgShadowRegisters[address];
}
void psgWrite(uint8_t address, uint8_t data) {
psgShadowRegisters[address] = data;
// according to "State Timing" (p. 15) of datasheet
// put bus into inactive state
@ -92,7 +100,12 @@ void psgWriteFrequency(uint8_t channel, uint16_t frequencyCode) {
}
void psgPlayTone(uint8_t channel, t_octave octave, t_note note) {
psgWriteFrequency(channel, frequencyCodes[octave][note]);
if (note == e_Pause) {
psgWrite(R7, psgReadShadow(R7) | (1 << channel));
} else {
psgWrite(R7, psgReadShadow(R7) & ~(1 << channel));
psgWriteFrequency(channel, frequencyCodes[octave][note]);
}
}
void playSomething(void *handle) {