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feat: implement EEPROM

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This commit is contained in:
Rekai Nyangadzayi Musuka
2022-04-25 16:08:56 -05:00
parent f4a48d536c
commit 05a432f1c1
3 changed files with 329 additions and 11 deletions
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44
src/bus/GamePak.zig
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@@ -56,6 +56,10 @@ fn lookupMaker(slice: *const [2]u8) ?[]const u8 {
};
}
inline fn isLarge(self: *const Self) bool {
return self.buf.len > 0x100_0000;
}
pub fn deinit(self: Self) void {
self.alloc.free(self.buf);
self.backup.deinit();
@@ -64,6 +68,22 @@ pub fn deinit(self: Self) void {
pub fn read(self: *const Self, comptime T: type, address: u32) T {
const addr = address & 0x1FF_FFFF;
if (self.backup.kind == .Eeprom) {
if (self.isLarge()) {
// Addresses 0x1FF_FF00 to 0x1FF_FFFF are reserved from EEPROM accesses if
// * Backup type is EEPROM
// * Large ROM (Size is greater than 16MB)
if (addr > 0x1FF_FEFF)
return self.backup.eeprom.read();
} else {
// Addresses 0x0D00_0000 to 0x0DFF_FFFF are reserved for EEPROM accesses if
// * Backup type is EEPROM
// * Small ROM (less than 16MB)
if (@truncate(u8, address >> 24) == 0x0D)
return self.backup.eeprom.read();
}
}
return switch (T) {
u32 => (@as(T, self.get(addr + 3)) << 24) | (@as(T, self.get(addr + 2)) << 16) | (@as(T, self.get(addr + 1)) << 8) | (@as(T, self.get(addr))),
u16 => (@as(T, self.get(addr + 1)) << 8) | @as(T, self.get(addr)),
@@ -72,6 +92,30 @@ pub fn read(self: *const Self, comptime T: type, address: u32) T {
};
}
pub fn write(self: *Self, comptime T: type, word_count: u16, address: u32, value: T) void {
const addr = address & 0x1FF_FFFF;
if (self.backup.kind == .Eeprom) {
const bit = @truncate(u1, value);
if (self.isLarge()) {
// Addresses 0x1FF_FF00 to 0x1FF_FFFF are reserved from EEPROM accesses if
// * Backup type is EEPROM
// * Large ROM (Size is greater than 16MB)
if (addr > 0x1FF_FEFF)
return self.backup.eeprom.write(word_count, &self.backup.buf, bit);
} else {
// Addresses 0x0D00_0000 to 0x0DFF_FFFF are reserved for EEPROM accesses if
// * Backup type is EEPROM
// * Small ROM (less than 16MB)
if (@truncate(u8, address >> 24) == 0x0D)
return self.backup.eeprom.write(word_count, &self.backup.buf, bit);
}
}
log.err("Wrote {} {X:} to 0x{X:0>8}", .{ T, value, address });
}
fn get(self: *const Self, i: u32) u8 {
@setRuntimeSafety(false);