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chore(io): replace some bitfields with enums

This commit is contained in:
Rekai Nyangadzayi Musuka 2022-02-24 17:15:08 -06:00
parent 441ebc38c7
commit ac0486be1b
2 changed files with 18 additions and 12 deletions
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24
src/bus/io.zig
View File

@ -14,7 +14,7 @@ pub const Io = struct {
ie: InterruptEnable,
irq: InterruptRequest,
postflg: PostFlag,
is_halted: bool,
haltcnt: HaltControl,
keyinput: KeyInput,
@ -23,9 +23,9 @@ pub const Io = struct {
.ime = false,
.ie = .{ .raw = 0x0000 },
.irq = .{ .raw = 0x0000 },
.postflg = .{ .raw = 0x00 },
.keyinput = .{ .raw = 0x03FF },
.is_halted = false,
.postflg = .FirstBoot,
.haltcnt = .Execute,
};
}
};
@ -169,7 +169,7 @@ pub fn read8(bus: *const Bus, addr: u32) u8 {
0x0400_0000 => @truncate(u8, bus.ppu.dispcnt.raw),
0x0400_0004 => @truncate(u8, bus.ppu.dispstat.raw),
0x0400_0200 => @truncate(u8, bus.io.ie.raw),
0x0400_0300 => bus.io.postflg.raw,
0x0400_0300 => @enumToInt(bus.io.postflg),
0x0400_0006 => @truncate(u8, bus.ppu.vcount.raw),
0x0400_0089 => failed_read("Tried to read (high) byte from SOUNDBIAS", .{}),
else => std.debug.panic("Tried to read byte from 0x{X:0>8}", .{addr}),
@ -181,7 +181,7 @@ pub fn write8(self: *Bus, addr: u32, byte: u8) void {
0x0400_0004 => self.ppu.dispstat.raw = (self.ppu.dispstat.raw & 0xFF00) | byte,
0x0400_0005 => self.ppu.dispstat.raw = (@as(u16, byte) << 8) | (self.ppu.dispstat.raw & 0xFF),
0x0400_0208 => self.io.ime = byte & 1 == 1,
0x0400_0301 => self.io.is_halted = byte >> 7 & 1 == 0, // TODO: Implement Stop?
0x0400_0301 => self.io.haltcnt = if (byte >> 7 & 1 == 0) .Halt else std.debug.panic("TODO: Implement STOP", .{}),
0x0400_0063 => log.warn("Tried to write 0x{X:0>2} to SOUND1CNT_H (high)", .{byte}),
0x0400_0065 => log.warn("Tried to write 0x{X:0>2} to SOUND1CNT_X (high)", .{byte}),
0x0400_0069 => log.warn("Tried to write 0x{X:0>2} to SOUND2CNT_L (high)", .{byte}),
@ -201,10 +201,16 @@ fn failed_read(comptime format: []const u8, args: anytype) u8 {
}
/// Read / Write
pub const PostFlag = extern union {
/// 0 if First Boot, 1 if a Reset has been done
not_first_boot: Bit(u8, 0),
raw: u8,
pub const PostFlag = enum(u1) {
FirstBoot = 0,
FurtherBoots = 1,
};
/// Write Only
pub const HaltControl = enum {
Halt,
Stop,
Execute,
};
/// Read / Write

4
src/cpu.zig
View File

@ -247,7 +247,7 @@ pub const Arm7tdmi = struct {
pub fn step(self: *Self) u64 {
// If we're halted, the cpu is disabled
if (self.bus.io.is_halted) return 1;
if (self.bus.io.haltcnt == .Halt) return 1;
if (self.cpsr.t.read()) {
const opcode = self.thumbFetch();
@ -270,7 +270,7 @@ pub const Arm7tdmi = struct {
const should_handle = self.bus.io.ie.raw & self.bus.io.irq.raw;
if (should_handle != 0) {
self.bus.io.is_halted = false;
self.bus.io.haltcnt = .Execute;
// log.info("An Interrupt was Fired!", .{});
// Either IME is not true or I in CPSR is true