bsnes/higan/fc/cartridge/chip/vrc6.cpp

311 lines
6.6 KiB
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struct VRC6 : Chip {
VRC6(Board& board) : Chip(board) {
}
struct Pulse {
auto clock() -> void {
if(--divider == 0) {
divider = frequency + 1;
cycle++;
output = (mode == 1 || cycle > duty) ? volume : (uint4)0;
}
if(enable == false) output = 0;
}
auto serialize(serializer& s) -> void {
s.integer(mode);
s.integer(duty);
s.integer(volume);
s.integer(enable);
s.integer(frequency);
s.integer(divider);
s.integer(cycle);
s.integer(output);
}
bool mode;
uint3 duty;
uint4 volume;
bool enable;
uint12 frequency;
uint12 divider;
uint4 cycle;
uint4 output;
} pulse1, pulse2;
struct Sawtooth {
auto clock() -> void {
if(--divider == 0) {
divider = frequency + 1;
if(++phase == 0) {
accumulator += rate;
if(++stage == 7) {
stage = 0;
accumulator = 0;
}
}
}
output = accumulator >> 3;
if(enable == false) output = 0;
}
auto serialize(serializer& s) -> void {
s.integer(rate);
s.integer(enable);
s.integer(frequency);
s.integer(divider);
s.integer(phase);
s.integer(stage);
s.integer(accumulator);
s.integer(output);
}
uint6 rate;
bool enable;
uint12 frequency;
uint12 divider;
uint1 phase;
uint3 stage;
uint8 accumulator;
uint5 output;
} sawtooth;
auto main() -> void {
if(irqEnable) {
if(irqMode == 0) {
irqScalar -= 3;
if(irqScalar <= 0) {
irqScalar += 341;
if(irqCounter == 0xff) {
irqCounter = irqLatch;
irqLine = 1;
} else {
irqCounter++;
}
}
}
if(irqMode == 1) {
if(irqCounter == 0xff) {
irqCounter = irqLatch;
irqLine = 1;
} else {
irqCounter++;
}
}
}
cpu.irqLine(irqLine);
pulse1.clock();
pulse2.clock();
sawtooth.clock();
int output = (pulse1.output + pulse2.output + sawtooth.output) << 7;
apu.setSample(-output);
tick();
}
auto addrPRG(uint addr) const -> uint {
if((addr & 0xc000) == 0x8000) return (prgBank[0] << 14) | (addr & 0x3fff);
if((addr & 0xe000) == 0xc000) return (prgBank[1] << 13) | (addr & 0x1fff);
if((addr & 0xe000) == 0xe000) return ( 0xff << 13) | (addr & 0x1fff);
}
auto addrCHR(uint addr) const -> uint {
uint bank = chrBank[(addr >> 10) & 7];
return (bank << 10) | (addr & 0x03ff);
}
auto addrCIRAM(uint addr) const -> uint {
switch(mirror) {
case 0: return ((addr & 0x0400) >> 0) | (addr & 0x03ff); //vertical mirroring
case 1: return ((addr & 0x0800) >> 1) | (addr & 0x03ff); //horizontal mirroring
case 2: return 0x0000 | (addr & 0x03ff); //one-screen mirroring (first)
case 3: return 0x0400 | (addr & 0x03ff); //one-screen mirroring (second)
}
}
auto readRAM(uint addr) -> uint8 {
return board.prgram.data[addr & 0x1fff];
}
auto writeRAM(uint addr, uint8 data) -> void {
board.prgram.data[addr & 0x1fff] = data;
}
auto writeIO(uint addr, uint8 data) -> void {
switch(addr) {
case 0x8000: case 0x8001: case 0x8002: case 0x8003:
prgBank[0] = data;
break;
case 0x9000:
pulse1.mode = data & 0x80;
pulse1.duty = (data & 0x70) >> 4;
pulse1.volume = data & 0x0f;
break;
case 0x9001:
pulse1.frequency = (pulse1.frequency & 0x0f00) | ((data & 0xff) << 0);
break;
case 0x9002:
pulse1.frequency = (pulse1.frequency & 0x00ff) | ((data & 0x0f) << 8);
pulse1.enable = data & 0x80;
break;
case 0xa000:
pulse2.mode = data & 0x80;
pulse2.duty = (data & 0x70) >> 4;
pulse2.volume = data & 0x0f;
break;
case 0xa001:
pulse2.frequency = (pulse2.frequency & 0x0f00) | ((data & 0xff) << 0);
break;
case 0xa002:
pulse2.frequency = (pulse2.frequency & 0x00ff) | ((data & 0x0f) << 8);
pulse2.enable = data & 0x80;
break;
case 0xb000:
sawtooth.rate = data & 0x3f;
break;
case 0xb001:
sawtooth.frequency = (sawtooth.frequency & 0x0f00) | ((data & 0xff) << 0);
break;
case 0xb002:
sawtooth.frequency = (sawtooth.frequency & 0x00ff) | ((data & 0x0f) << 8);
sawtooth.enable = data & 0x80;
break;
case 0xb003:
mirror = (data >> 2) & 3;
break;
case 0xc000: case 0xc001: case 0xc002: case 0xc003:
prgBank[1] = data;
break;
case 0xd000: case 0xd001: case 0xd002: case 0xd003:
chrBank[0 + (addr & 3)] = data;
break;
case 0xe000: case 0xe001: case 0xe002: case 0xe003:
chrBank[4 + (addr & 3)] = data;
break;
case 0xf000:
irqLatch = data;
break;
case 0xf001:
irqMode = data & 0x04;
irqEnable = data & 0x02;
irqAcknowledge = data & 0x01;
if(irqEnable) {
irqCounter = irqLatch;
irqScalar = 341;
}
irqLine = 0;
break;
case 0xf002:
irqEnable = irqAcknowledge;
irqLine = 0;
break;
}
}
auto power() -> void {
prgBank[0] = 0;
prgBank[1] = 0;
chrBank[0] = 0;
chrBank[1] = 0;
chrBank[2] = 0;
chrBank[3] = 0;
chrBank[4] = 0;
chrBank[5] = 0;
chrBank[6] = 0;
chrBank[7] = 0;
mirror = 0;
irqLatch = 0;
irqMode = 0;
irqEnable = 0;
irqAcknowledge = 0;
irqCounter = 0;
irqScalar = 0;
irqLine = 0;
pulse1.mode = 0;
pulse1.duty = 0;
pulse1.volume = 0;
pulse1.enable = 0;
pulse1.frequency = 0;
pulse1.divider = 1;
pulse1.cycle = 0;
pulse1.output = 0;
pulse2.mode = 0;
pulse2.duty = 0;
pulse2.volume = 0;
pulse2.enable = 0;
pulse2.frequency = 0;
pulse2.divider = 1;
pulse2.cycle = 0;
pulse2.output = 0;
sawtooth.rate = 0;
sawtooth.enable = 0;
sawtooth.frequency = 0;
sawtooth.divider = 1;
sawtooth.phase = 0;
sawtooth.stage = 0;
sawtooth.accumulator = 0;
sawtooth.output = 0;
}
auto serialize(serializer& s) -> void {
pulse1.serialize(s);
pulse2.serialize(s);
sawtooth.serialize(s);
s.array(prgBank);
s.array(chrBank);
s.integer(mirror);
s.integer(irqLatch);
s.integer(irqMode);
s.integer(irqEnable);
s.integer(irqAcknowledge);
s.integer(irqCounter);
s.integer(irqScalar);
s.integer(irqLine);
}
uint8 prgBank[2];
uint8 chrBank[8];
uint2 mirror;
uint8 irqLatch;
bool irqMode;
bool irqEnable;
bool irqAcknowledge;
uint8 irqCounter;
int irqScalar;
bool irqLine;
};