65 lines
1.8 KiB
Zig
65 lines
1.8 KiB
Zig
const std = @import("std");
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const Allocator = std.mem.Allocator;
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const log = std.log.scoped(.Bios);
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/// Size of the BIOS in bytes
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pub const size = 0x4000;
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const Self = @This();
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buf: ?[]u8,
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allocator: Allocator,
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addr_latch: u32,
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pub fn init(allocator: Allocator, maybe_path: ?[]const u8) !Self {
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const buf: ?[]u8 = if (maybe_path) |path| blk: {
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const file = try std.fs.cwd().openFile(path, .{});
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defer file.close();
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break :blk try file.readToEndAlloc(allocator, try file.getEndPos());
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} else null;
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return Self{
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.buf = buf,
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.allocator = allocator,
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.addr_latch = 0,
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};
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}
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pub fn deinit(self: *Self) void {
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if (self.buf) |buf| self.allocator.free(buf);
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self.* = undefined;
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}
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pub fn read(self: *Self, comptime T: type, r15: u32, addr: u32) T {
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if (r15 < Self.size) {
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self.addr_latch = addr;
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return self.uncheckedRead(T, addr);
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}
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log.debug("Rejected read since r15=0x{X:0>8}", .{r15});
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return @truncate(T, self.uncheckedRead(T, self.addr_latch + 8));
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}
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pub fn dbgRead(self: *const Self, comptime T: type, r15: u32, addr: u32) T {
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if (r15 < Self.size) return self.uncheckedRead(T, addr);
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return @truncate(T, self.uncheckedRead(T, self.addr_latch + 8));
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}
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fn uncheckedRead(self: *const Self, comptime T: type, addr: u32) T {
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if (self.buf) |buf| {
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return switch (T) {
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u32, u16, u8 => std.mem.readIntSliceLittle(T, buf[addr..][0..@sizeOf(T)]),
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else => @compileError("BIOS: Unsupported read width"),
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};
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}
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std.debug.panic("[BIOS] ZBA tried to read {} from 0x{X:0>8} but not BIOS was present", .{ T, addr });
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}
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pub fn write(_: *Self, comptime T: type, addr: u32, value: T) void {
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@setCold(true);
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log.debug("Tried to write {} 0x{X:} to 0x{X:0>8} ", .{ T, value, addr });
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}
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