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feat(bus): implement Gameboy Advance MMIO

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This commit is contained in:
Rekai Nyangadzayi Musuka
2022-01-02 02:36:06 -06:00
parent b63eb2dabc
commit 65c3dd722c
5 changed files with 132 additions and 53 deletions
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14
src/cpu/single_data_transfer.zig
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@@ -21,29 +21,29 @@ pub fn comptimeSingleDataTransfer(comptime I: bool, comptime P: bool, comptime U
if (L) {
if (B) {
// LDRB
cpu.r[rd] = bus.readByte(address);
cpu.r[rd] = bus.read8(address);
} else {
// LDR
// FIXME: Unsure about how I calculate the boundary offset
cpu.r[rd] = std.math.rotl(u32, bus.readWord(address), address % 4);
cpu.r[rd] = std.math.rotl(u32, bus.read32(address), address % 4);
}
} else {
if (B) {
// STRB
const src = @truncate(u8, cpu.r[rd]);
bus.writeByte(address + 3, src);
bus.writeByte(address + 2, src);
bus.writeByte(address + 1, src);
bus.writeByte(address, src);
bus.write8(address + 3, src);
bus.write8(address + 2, src);
bus.write8(address + 1, src);
bus.write8(address, src);
} else {
// STR
// FIXME: Is this right?
const src = cpu.r[rd];
const aligned_addr = address - (address % 4);
bus.writeWord(aligned_addr, src);
bus.write32(aligned_addr, src);
}
}