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chore: debug read takes advantage of fastmem 

deduplicate slowmem backup read handler
This commit is contained in:
Rekai Nyangadzayi Musuka 2022-12-15 23:18:23 -04:00
parent 63fa972afa
commit 8e1a539e70
1 changed files with 42 additions and 30 deletions
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72
src/core/Bus.zig
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@ -197,8 +197,29 @@ fn fillTableExternalMemory(bus: *Self, addr: usize) ?*anyopaque {
return &bus.pak.buf[masked_addr];
}
// TODO: Take advantage of fastmem here too?
pub fn dbgRead(self: *const Self, comptime T: type, unaligned_address: u32) T {
const bits = @typeInfo(std.math.IntFittingRange(0, page_size - 1)).Int.bits;
const page = unaligned_address >> bits;
const offset = unaligned_address & (page_size - 1);
// We're doing some serious out-of-bounds open-bus reads
if (page >= table_len) return self.openBus(T, unaligned_address);
if (self.read_table[page]) |some_ptr| {
// We have a pointer to a page, cast the pointer to it's underlying type
const Ptr = [*]const T;
const alignment = @alignOf(std.meta.Child(Ptr));
const ptr = @ptrCast(Ptr, @alignCast(alignment, some_ptr));
// Note: We don't check array length, since we force align the
// lower bits of the address as the GBA would
return ptr[forceAlign(T, offset) / @sizeOf(T)];
}
return self.dbgSlowRead(T, unaligned_address);
}
fn dbgSlowRead(self: *const Self, comptime T: type, unaligned_address: u32) T {
const page = @truncate(u8, unaligned_address >> 24);
const address = forceAlign(T, unaligned_address);
@ -210,29 +231,18 @@ pub fn dbgRead(self: *const Self, comptime T: type, unaligned_address: u32) T {
break :blk self.openBus(T, address);
},
0x02 => self.ewram.read(T, address),
0x03 => self.iwram.read(T, address),
0x02 => unreachable, // handled by fastmem
0x03 => unreachable, // handled by fastmem
0x04 => self.readIo(T, address),
// Internal Display Memory
0x05 => self.ppu.palette.read(T, address),
0x06 => self.ppu.vram.read(T, address),
0x07 => self.ppu.oam.read(T, address),
0x05 => unreachable, // handled by fastmem
0x06 => unreachable, // handled by fastmem
0x07 => unreachable, // handled by fastmem
// External Memory (Game Pak)
0x08...0x0D => self.pak.dbgRead(T, address),
0x0E...0x0F => blk: {
const value = self.pak.backup.read(unaligned_address);
const multiplier = switch (T) {
u32 => 0x01010101,
u16 => 0x0101,
u8 => 1,
else => @compileError("Backup: Unsupported read width"),
};
break :blk @as(T, value) * multiplier;
},
0x0E...0x0F => self.readBackup(T, unaligned_address),
else => self.openBus(T, address),
};
}
@ -352,22 +362,24 @@ fn slowRead(self: *Self, comptime T: type, unaligned_address: u32) T {
// External Memory (Game Pak)
0x08...0x0D => self.pak.read(T, address),
0x0E...0x0F => blk: {
const value = self.pak.backup.read(unaligned_address);
const multiplier = switch (T) {
u32 => 0x01010101,
u16 => 0x0101,
u8 => 1,
else => @compileError("Backup: Unsupported read width"),
};
break :blk @as(T, value) * multiplier;
},
0x0E...0x0F => self.readBackup(T, unaligned_address),
else => self.openBus(T, address),
};
}
fn readBackup(self: *const Self, comptime T: type, unaligned_address: u32) T {
const value = self.pak.backup.read(unaligned_address);
const multiplier = switch (T) {
u32 => 0x01010101,
u16 => 0x0101,
u8 => 1,
else => @compileError("Backup: Unsupported read width"),
};
return @as(T, value) * multiplier;
}
pub fn write(self: *Self, comptime T: type, unaligned_address: u32, value: T) void {
const bits = @typeInfo(std.math.IntFittingRange(0, page_size - 1)).Int.bits;
const page = unaligned_address >> bits;