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feat(bus): implement echo RAM

This commit is contained in:
Rekai Nyangadzayi Musuka 2021-04-08 17:58:20 -05:00
parent 2733bbe6d7
commit 41081e9cce
1 changed files with 26 additions and 2 deletions
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28
src/bus.rs
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@ -110,7 +110,19 @@ impl Bus {
}
0xE000..=0xFDFF => {
// Mirror of 0xC000 to 0xDDFF
unimplemented!("Unable to read {:#06X} in Restricted Mirror", addr);
// ECHO RAM
match addr {
0xE000..=0xEFFF => {
// 4KB Work RAM Bank 0
self.wram.read_byte(addr)
}
0xF000..=0xFDFF => {
// 4KB Work RAM Bank 1 -> N
self.vwram.read_byte(addr)
}
_ => unreachable!("{:#06X} was incorrectly handled by ECHO RAM", addr),
}
}
0xFE00..=0xFE9F => {
// Sprite Attribute Table
@ -200,7 +212,19 @@ impl Bus {
}
0xE000..=0xFDFF => {
// Mirror of 0xC000 to 0xDDFF
unimplemented!("Unable to write to {:#06X} in Restricted Mirror", addr);
// ECHO RAM
match addr {
0xE000..=0xEFFF => {
// 4KB Work RAM Bank 0
self.wram.write_byte(addr, byte);
}
0xF000..=0xFDFF => {
// 4KB Work RAM Bank 1 -> N
self.vwram.write_byte(addr, byte);
}
_ => unreachable!("{:#06X} was incorrectly handled by ECHO RAM", addr),
}
}
0xFE00..=0xFE9F => {
// Sprite Attribute Table