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fix(bus): Fix address calculation error in Echo RAM

This commit is contained in:
Rekai Nyangadzayi Musuka 2021-06-07 00:22:11 -05:00
parent d5e67568dd
commit dd86330e1d
1 changed files with 18 additions and 9 deletions
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27
src/bus.rs
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@ -117,16 +117,19 @@ impl Bus {
0xD000..=0xDFFF => self.var_ram.read_byte(addr), // 4KB Work RAM Bank 1 -> N
0xE000..=0xFDFF => {
// Mirror of 0xC000 to 0xDDFF (ECHO RAM)
match addr & 0x1FFF {
let masked_addr = addr & 0x1FFF;
let equiv_addr = 0xC000 + masked_addr;
match masked_addr {
// 0xE000 ..= 0xEFFF
0x0000..=0x0FFF => {
// 4KB Work RAM Bank 0
self.work_ram.read_byte(addr)
self.work_ram.read_byte(equiv_addr)
}
// 0xF000 ..= 0xFDFF
0x1000..=0x1DFF => {
// 4KB Work RAM Bank 1 -> N
self.var_ram.read_byte(addr)
self.var_ram.read_byte(equiv_addr)
}
_ => unreachable!("{:#06X} was incorrectly handled by ECHO RAM", addr),
}
@ -177,16 +180,19 @@ impl BusIo for Bus {
0xD000..=0xDFFF => self.var_ram.read_byte(addr), // 4KB Work RAM Bank 1 -> N
0xE000..=0xFDFF => {
// Mirror of 0xC000 to 0xDDFF (ECHO RAM)
match addr & 0x1FFF {
let masked_addr = addr & 0x1FFF;
let equiv_addr = 0xC000 + masked_addr;
match masked_addr {
// 0xE000 ..= 0xEFFF
0x0000..=0x0FFF => {
// 4KB Work RAM Bank 0
self.work_ram.read_byte(addr)
self.work_ram.read_byte(equiv_addr)
}
// 0xF000 ..= 0xFDFF
0x1000..=0x1DFF => {
// 4KB Work RAM Bank 1 -> N
self.var_ram.read_byte(addr)
self.var_ram.read_byte(equiv_addr)
}
_ => unreachable!("{:#06X} was incorrectly handled by ECHO RAM", addr),
}
@ -292,16 +298,19 @@ impl BusIo for Bus {
0xD000..=0xDFFF => self.var_ram.write_byte(addr, byte), // 4KB Work RAM Bank 1 -> N
0xE000..=0xFDFF => {
// Mirror of 0xC000 to 0xDDFF (ECHO RAM)
match addr & 0x1FFF {
let masked_addr = addr & 0x1FFF;
let equiv_addr = 0xC000 + masked_addr;
match masked_addr {
// 0xE000 ..= 0xEFFF
0x0000..=0x0FFF => {
// 4KB Work RAM Bank 0
self.work_ram.write_byte(addr, byte);
self.work_ram.write_byte(equiv_addr, byte);
}
// 0xF000 ..= 0xFDFF
0x1000..=0x1DFF => {
// 4KB Work RAM Bank 1 -> N
self.var_ram.write_byte(addr, byte);
self.var_ram.write_byte(equiv_addr, byte);
}
_ => unreachable!("{:#06X} was incorrectly handled by ECHO RAM", addr),
}