bsnes/higan/ms/vdp/io.cpp

168 lines
3.3 KiB
C++
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auto VDP::vcounter() -> uint8 {
if(io.lines240) {
//NTSC 256x240
return io.vcounter;
} else if(io.lines224) {
//NTSC 256x224
return io.vcounter <= 234 ? io.vcounter : io.vcounter - 6;
} else {
//NTSC 256x192
return io.vcounter <= 218 ? io.vcounter : io.vcounter - 6;
}
unreachable;
}
auto VDP::hcounter() -> uint8 {
uint hcounter = io.hcounter >> 1;
return hcounter <= 233 ? hcounter : hcounter - 86;
}
auto VDP::data() -> uint8 {
io.controlLatch = 0;
auto data = io.vramLatch;
io.vramLatch = vram[io.address++];
return data;
}
auto VDP::status() -> uint8 {
io.controlLatch = 0;
uint8 result = 0x00;
result |= io.intFrame << 7;
result |= io.spriteOverflow << 6;
result |= io.spriteCollision << 5;
result |= io.fifthSprite << 0;
io.intLine = 0;
io.intFrame = 0;
io.spriteOverflow = 0;
io.spriteCollision = 0;
io.fifthSprite = 0;
return result;
}
auto VDP::data(uint8 data) -> void {
io.controlLatch = 0;
if(io.code <= 2) {
vram[io.address++] = data;
} else {
uint mask = 0;
if(system.model() == Model::MasterSystem) mask = 0x1f;
if(system.model() == Model::GameGear) mask = 0x3f;
cram[io.address++ & mask] = data;
}
}
auto VDP::control(uint8 data) -> void {
if(io.controlLatch == 0) {
io.controlLatch = 1;
io.address.bits(0,7) = data.bits(0,7);
return;
} else {
io.controlLatch = 0;
io.address.bits(8,13) = data.bits(0,5);
io.code.bits(0,1) = data.bits(6,7);
}
if(io.code == 0) {
io.vramLatch = vram[io.address++];
}
if(io.code == 2) {
registerWrite(io.address.bits(11,8), io.address.bits(7,0));
}
}
auto VDP::registerWrite(uint4 addr, uint8 data) -> void {
switch(addr) {
//mode control 1
case 0x0: {
io.externalSync = data.bit(0);
io.extendedHeight = data.bit(1);
io.mode4 = data.bit(2);
io.spriteShift = data.bit(3);
io.lineInterrupts = data.bit(4);
io.leftClip = data.bit(5);
io.horizontalScrollLock = data.bit(6);
io.verticalScrollLock = data.bit(7);
return;
}
//mode control 2
case 0x1: {
io.spriteDouble = data.bit(0);
io.spriteTile = data.bit(1);
io.lines240 = data.bit(3);
io.lines224 = data.bit(4);
io.frameInterrupts = data.bit(5);
io.displayEnable = data.bit(6);
return;
}
//name table base address
case 0x2: {
io.nameTableMask = data.bit(0);
io.nameTableAddress = data.bits(1,3);
return;
}
//color table base address
case 0x3: {
io.colorTableAddress = data.bits(0,7);
return;
}
//pattern table base address
case 0x4: {
io.patternTableAddress = data.bits(0,7);
return;
}
//sprite attribute table base address
case 0x5: {
io.spriteAttributeTableMask = data.bit(0);
io.spriteAttributeTableAddress = data.bits(1,6);
return;
}
//sprite pattern table base address
case 0x6: {
io.spritePatternTableMask = data.bits(0,1);
io.spritePatternTableAddress = data.bit(2);
return;
}
//backdrop color
case 0x7: {
io.backdropColor = data.bits(0,3);
return;
}
//horizontal scroll offset
case 0x8: {
io.hscroll = data.bits(0,7);
return;
}
//vertical scroll offset
case 0x9: {
io.vscroll = data.bits(0,7);
return;
}
//line counter
case 0xa: {
io.lineCounter = data.bits(0,7);
return;
}
//0xb - 0xf unmapped
}
}