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chore: remove unnecessary 32MB allocation

This commit is contained in:
Rekai Nyangadzayi Musuka 2022-04-13 21:25:41 -03:00
parent 714209565b
commit ffbb31c767
1 changed files with 35 additions and 16 deletions
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51
src/bus/GamePak.zig
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@ -18,23 +18,11 @@ pub fn init(alloc: Allocator, rom_path: []const u8, save_path: ?[]const u8) !Sel
defer file.close();
const file_buf = try file.readToEndAlloc(alloc, try file.getEndPos());
defer alloc.free(file_buf);
const title = parseTitle(file_buf);
const kind = Backup.guessKind(file_buf) orelse .None;
const buf = try alloc.alloc(u8, 0x200_0000); // 32MiB
// GamePak addressable space has known values if there's no cartridge inserted
var i: usize = 0;
while (i < buf.len) : (i += @sizeOf(u16)) {
std.mem.copy(u8, buf[i..][0..2], &intToBytes(u16, @truncate(u16, i / 2)));
}
std.mem.copy(u8, buf[0..file_buf.len], file_buf[0..file_buf.len]); // Copy over ROM
const pak = Self{
.buf = buf,
.buf = file_buf,
.alloc = alloc,
.title = title,
.backup = try Backup.init(alloc, kind, title, save_path),
@ -78,9 +66,40 @@ pub fn read(self: *const Self, comptime T: type, address: u32) T {
const addr = address & 0x1FF_FFFF;
return switch (T) {
u32 => (@as(T, self.buf[addr + 3]) << 24) | (@as(T, self.buf[addr + 2]) << 16) | (@as(T, self.buf[addr + 1]) << 8) | (@as(T, self.buf[addr])),
u16 => (@as(T, self.buf[addr + 1]) << 8) | @as(T, self.buf[addr]),
u8 => self.buf[addr],
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)),
u8 => self.get(addr),
else => @compileError("GamePak: Unsupported read width"),
};
}
fn get(self: *const Self, i: u32) u8 {
@setRuntimeSafety(false);
if (i >= self.buf.len) {
const lhs = i >> 1 & 0xFFFF;
return @truncate(u8, lhs >> 8 * @truncate(u5, i & 1));
}
return self.buf[i];
}
test "OOB Access" {
const title = .{ 'H', 'E', 'L', 'L', 'O', ' ', 'W', 'O', 'R', 'L', 'D', '!' };
const alloc = std.testing.allocator;
const pak = Self{
.buf = &.{},
.alloc = alloc,
.title = title,
.backup = try Backup.init(alloc, .None, title, null),
};
std.debug.assert(pak.get(0) == 0x00); // 0x0000
std.debug.assert(pak.get(1) == 0x00);
std.debug.assert(pak.get(2) == 0x01); // 0x0001
std.debug.assert(pak.get(3) == 0x00);
std.debug.assert(pak.get(4) == 0x02); // 0x0002
std.debug.assert(pak.get(5) == 0x00);
}