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fix(io): force-align all i/o reads 

Of course, backups being the exception due to flash or sram quirks,
I don't remember lol
This commit is contained in:
Rekai Nyangadzayi Musuka 2022-10-31 05:50:27 -03:00
parent 5101fbd809
commit 5d47e5d167
1 changed files with 48 additions and 50 deletions
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92
src/core/Bus.zig
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@ -73,31 +73,31 @@ pub fn deinit(self: *Self) void {
self.* = undefined; self.* = undefined;
} }
pub fn dbgRead(self: *const Self, comptime T: type, address: u32) T { pub fn dbgRead(self: *const Self, comptime T: type, unaligned_address: u32) T {
const page = @truncate(u8, address >> 24); const page = @truncate(u8, unaligned_address >> 24);
const aligned_addr = forceAlign(T, address); const address = forceAlign(T, unaligned_address);
return switch (page) { return switch (page) {
// General Internal Memory // General Internal Memory
0x00 => blk: { 0x00 => blk: {
if (address < Bios.size) if (address < Bios.size)
break :blk self.bios.dbgRead(T, self.cpu.r[15], aligned_addr); break :blk self.bios.dbgRead(T, self.cpu.r[15], address);
break :blk self.openBus(T, address); break :blk self.openBus(T, address);
}, },
0x02 => self.ewram.read(T, aligned_addr), 0x02 => self.ewram.read(T, address),
0x03 => self.iwram.read(T, aligned_addr), 0x03 => self.iwram.read(T, address),
0x04 => self.readIo(T, address), 0x04 => self.readIo(T, address),
// Internal Display Memory // Internal Display Memory
0x05 => self.ppu.palette.read(T, aligned_addr), 0x05 => self.ppu.palette.read(T, address),
0x06 => self.ppu.vram.read(T, aligned_addr), 0x06 => self.ppu.vram.read(T, address),
0x07 => self.ppu.oam.read(T, aligned_addr), 0x07 => self.ppu.oam.read(T, address),
// External Memory (Game Pak) // External Memory (Game Pak)
0x08...0x0D => self.pak.dbgRead(T, aligned_addr), 0x08...0x0D => self.pak.dbgRead(T, address),
0x0E...0x0F => blk: { 0x0E...0x0F => blk: {
const value = self.pak.backup.read(address); const value = self.pak.backup.read(unaligned_address);
const multiplier = switch (T) { const multiplier = switch (T) {
u32 => 0x01010101, u32 => 0x01010101,
@ -112,10 +112,8 @@ pub fn dbgRead(self: *const Self, comptime T: type, address: u32) T {
}; };
} }
/// TODO: Should open bus read addresses be force-aligned? fn readIo(self: *const Self, comptime T: type, address: u32) T {
fn readIo(self: *const Self, comptime T: type, unaligned_address: u32) T { return io.read(self, T, address) orelse self.openBus(T, address);
const maybe_value = io.read(self, T, forceAlign(T, unaligned_address));
return if (maybe_value) |value| value else self.openBus(T, unaligned_address);
} }
fn openBus(self: *const Self, comptime T: type, address: u32) T { fn openBus(self: *const Self, comptime T: type, address: u32) T {
@ -172,9 +170,9 @@ fn openBus(self: *const Self, comptime T: type, address: u32) T {
return @truncate(T, word); return @truncate(T, word);
} }
pub fn read(self: *Self, comptime T: type, address: u32) T { pub fn read(self: *Self, comptime T: type, unaligned_address: u32) T {
const page = @truncate(u8, address >> 24); const page = @truncate(u8, unaligned_address >> 24);
const aligned_addr = forceAlign(T, address); const address = forceAlign(T, unaligned_address);
self.sched.tick += timings[@boolToInt(T == u32)][@truncate(u4, page)]; self.sched.tick += timings[@boolToInt(T == u32)][@truncate(u4, page)];
@ -182,23 +180,23 @@ pub fn read(self: *Self, comptime T: type, address: u32) T {
// General Internal Memory // General Internal Memory
0x00 => blk: { 0x00 => blk: {
if (address < Bios.size) if (address < Bios.size)
break :blk self.bios.read(T, self.cpu.r[15], aligned_addr); break :blk self.bios.read(T, self.cpu.r[15], address);
break :blk self.openBus(T, address); break :blk self.openBus(T, address);
}, },
0x02 => self.ewram.read(T, aligned_addr), 0x02 => self.ewram.read(T, address),
0x03 => self.iwram.read(T, aligned_addr), 0x03 => self.iwram.read(T, address),
0x04 => self.readIo(T, address), 0x04 => self.readIo(T, address),
// Internal Display Memory // Internal Display Memory
0x05 => self.ppu.palette.read(T, aligned_addr), 0x05 => self.ppu.palette.read(T, address),
0x06 => self.ppu.vram.read(T, aligned_addr), 0x06 => self.ppu.vram.read(T, address),
0x07 => self.ppu.oam.read(T, aligned_addr), 0x07 => self.ppu.oam.read(T, address),
// External Memory (Game Pak) // External Memory (Game Pak)
0x08...0x0D => self.pak.read(T, aligned_addr), 0x08...0x0D => self.pak.read(T, address),
0x0E...0x0F => blk: { 0x0E...0x0F => blk: {
const value = self.pak.backup.read(address); const value = self.pak.backup.read(unaligned_address);
const multiplier = switch (T) { const multiplier = switch (T) {
u32 => 0x01010101, u32 => 0x01010101,
@ -213,44 +211,44 @@ pub fn read(self: *Self, comptime T: type, address: u32) T {
}; };
} }
pub fn write(self: *Self, comptime T: type, address: u32, value: T) void { pub fn write(self: *Self, comptime T: type, unaligned_address: u32, value: T) void {
const page = @truncate(u8, address >> 24); const page = @truncate(u8, unaligned_address >> 24);
const aligned_addr = forceAlign(T, address); const address = forceAlign(T, unaligned_address);
self.sched.tick += timings[@boolToInt(T == u32)][@truncate(u4, page)]; self.sched.tick += timings[@boolToInt(T == u32)][@truncate(u4, page)];
switch (page) { switch (page) {
// General Internal Memory // General Internal Memory
0x00 => self.bios.write(T, aligned_addr, value), 0x00 => self.bios.write(T, address, value),
0x02 => self.ewram.write(T, aligned_addr, value), 0x02 => self.ewram.write(T, address, value),
0x03 => self.iwram.write(T, aligned_addr, value), 0x03 => self.iwram.write(T, address, value),
0x04 => io.write(self, T, aligned_addr, value), 0x04 => io.write(self, T, address, value),
// Internal Display Memory // Internal Display Memory
0x05 => self.ppu.palette.write(T, aligned_addr, value), 0x05 => self.ppu.palette.write(T, address, value),
0x06 => self.ppu.vram.write(T, self.ppu.dispcnt, aligned_addr, value), 0x06 => self.ppu.vram.write(T, self.ppu.dispcnt, address, value),
0x07 => self.ppu.oam.write(T, aligned_addr, value), 0x07 => self.ppu.oam.write(T, address, value),
// External Memory (Game Pak) // External Memory (Game Pak)
0x08...0x0D => self.pak.write(T, self.dma[3].word_count, aligned_addr, value), 0x08...0x0D => self.pak.write(T, self.dma[3].word_count, address, value),
0x0E...0x0F => { 0x0E...0x0F => self.pak.backup.write(unaligned_address, @truncate(u8, rotr(T, value, 8 * rotateBy(T, unaligned_address)))),
const rotate_by = switch (T) { else => {},
}
}
inline fn rotateBy(comptime T: type, address: u32) u32 {
return switch (T) {
u32 => address & 3, u32 => address & 3,
u16 => address & 1, u16 => address & 1,
u8 => 0, u8 => 0,
else => @compileError("Backup: Unsupported write width"), else => @compileError("Backup: Unsupported write width"),
}; };
self.pak.backup.write(address, @truncate(u8, rotr(T, value, 8 * rotate_by)));
},
else => {},
}
} }
fn forceAlign(comptime T: type, address: u32) u32 { inline fn forceAlign(comptime T: type, address: u32) u32 {
return switch (T) { return switch (T) {
u32 => address & 0xFFFF_FFFC, u32 => address & ~@as(u32, 3),
u16 => address & 0xFFFF_FFFE, u16 => address & ~@as(u32, 1),
u8 => address, u8 => address,
else => @compileError("Bus: Invalid read/write type"), else => @compileError("Bus: Invalid read/write type"),
}; };