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cleanup + more tail instructions
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@190n
190n committed May 16, 2024
1 parent 63ef7af commit 8476b6c
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Showing 3 changed files with 126 additions and 124 deletions.
12 changes: 6 additions & 6 deletions src/bench.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -19,17 +19,17 @@ pub fn main() !void {

const rom = try std.fs.cwd().readFileAlloc(allocator, argv[1], 4096 - 512);
defer allocator.free(rom);
const instructions = try std.fmt.parseInt(usize, argv[2], 10);
var instructions = try std.fmt.parseInt(usize, argv[2], 10);

var cpu = Cpu.init(rom);

const before = std.posix.getrusage(std.posix.rusage.SELF);
// for (0..instructions) |_| {
// try cpu.cycle();
// cpu.dt = 0;
// }

cpu.run(instructions);
while (instructions > 0) {
const to_run = @min(instructions, std.math.maxInt(u16));
cpu.run(to_run);
instructions -= to_run;
}

const after = std.posix.getrusage(std.posix.rusage.SELF);
const before_sec = @as(f64, @floatFromInt(before.utime.tv_sec)) +
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110 changes: 52 additions & 58 deletions src/tail.zig
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
const std = @import("std");

const font_data = @import("./font.zig").font_data;
const tailfuncs = @import("./tailfuncs.zig");

pub const Cpu = struct {
v: [16]u8 = .{0} ** 16,
Expand All @@ -10,7 +11,7 @@ pub const Cpu = struct {
display: [64 * 32 / 8]u8,
mem: [4096]u8,
code: [4096]Inst,
instructions: usize = 0,
instructions: u16 = 0,
random: std.rand.DefaultPrng,

pub fn init(rom: []const u8) Cpu {
Expand All @@ -33,20 +34,25 @@ pub const Cpu = struct {
return cpu;
}

pub fn run(self: *Cpu, instructions: usize) void {
pub fn run(self: *Cpu, instructions: u16) void {
self.instructions = instructions;
self.code[self.pc].func(self, self.code[self.pc].decoded.to());
self.code[self.pc].func(self, self.code[self.pc].decoded.toInt());
}
};

const GadgetFunc = *const fn (*Cpu, u32) callconv(.C) void;
const GadgetFunc = *const fn (*Cpu, u32) void;

pub const Decoded = union {
xy: [2]u4,
xnn: struct { u4, u8 },
nnn: u12,
xyn: [3]u4,

pub const Int = @Type(.{ .Int = .{
.signedness = .unsigned,
.bits = 8 * @sizeOf(Decoded),
} });

fn decode(opcode: u16, which: enum { xy, xnn, nnn, xyn }) Decoded {
switch (which) {
.xy => {
Expand All @@ -69,12 +75,12 @@ pub const Decoded = union {
}
}

pub inline fn from(x: u32) Decoded {
pub inline fn fromInt(x: Int) Decoded {
return @as(*const Decoded, @ptrCast(&x)).*;
}

pub inline fn to(self: Decoded) u32 {
return @as(*align(2) const u32, @ptrCast(&self)).*;
pub inline fn toInt(self: Decoded) Int {
return @as(*align(@alignOf(Decoded)) const Int, @ptrCast(&self)).*;
}
};

Expand All @@ -83,89 +89,77 @@ const Inst = struct {
decoded: Decoded,
};

fn decode(cpu: *Cpu, decoded: u32) callconv(.C) void {
_ = decoded;

pub fn decode(cpu: *Cpu, _: Decoded.Int) void {
const opcode = std.mem.readInt(u16, cpu.mem[cpu.pc..][0..2], .big);
const inst: Inst = switch (@as(u4, @truncate(opcode >> 12))) {
0x0 => switch (opcode & 0xff) {
0xE0 => .{ .func = &funcs.clear, .decoded = undefined },
0xEE => .{ .func = &funcs.ret, .decoded = undefined },
0xE0 => .{ .func = &tailfuncs.clear, .decoded = undefined },
0xEE => .{ .func = &tailfuncs.ret, .decoded = undefined },
else => .{ .func = &invalid, .decoded = undefined },
},
0x1 => .{ .func = &funcs.jump, .decoded = Decoded.decode(opcode, .nnn) },
0x2 => .{ .func = &funcs.call, .decoded = Decoded.decode(opcode, .nnn) },
0x3 => .{ .func = &funcs.skipIfEqual, .decoded = Decoded.decode(opcode, .xnn) },
0x4 => .{ .func = &funcs.skipIfNotEqual, .decoded = Decoded.decode(opcode, .xnn) },
0x1 => .{ .func = &tailfuncs.jump, .decoded = Decoded.decode(opcode, .nnn) },
0x2 => .{ .func = &tailfuncs.call, .decoded = Decoded.decode(opcode, .nnn) },
0x3 => .{ .func = &tailfuncs.skipIfEqual, .decoded = Decoded.decode(opcode, .xnn) },
0x4 => .{ .func = &tailfuncs.skipIfNotEqual, .decoded = Decoded.decode(opcode, .xnn) },
0x5 => switch (opcode & 0xf) {
0x0 => .{ .func = &funcs.skipIfRegistersEqual, .decoded = Decoded.decode(opcode, .xy) },
0x0 => .{ .func = &tailfuncs.skipIfRegistersEqual, .decoded = Decoded.decode(opcode, .xy) },
else => .{ .func = &invalid, .decoded = undefined },
},
0x6 => .{ .func = &funcs.setRegister, .decoded = Decoded.decode(opcode, .xnn) },
0x7 => .{ .func = &funcs.addImmediate, .decoded = Decoded.decode(opcode, .xnn) },
0x6 => .{ .func = &tailfuncs.setRegister, .decoded = Decoded.decode(opcode, .xnn) },
0x7 => .{ .func = &tailfuncs.addImmediate, .decoded = Decoded.decode(opcode, .xnn) },
0x8 => .{
.func = switch (@as(u4, @truncate(opcode))) {
0x0 => &funcs.setRegisterToRegister,
0x1 => &funcs.bitwiseOr,
0x2 => &funcs.bitwiseAnd,
0x3 => &funcs.bitwiseXor,
0x4 => &funcs.addRegisters,
0x5 => &funcs.subRegisters,
0x6 => &funcs.shiftRight,
0x7 => &funcs.subRegistersReverse,
0xE => &funcs.shiftLeft,
0x0 => &tailfuncs.setRegisterToRegister,
0x1 => &tailfuncs.bitwiseOr,
0x2 => &tailfuncs.bitwiseAnd,
0x3 => &tailfuncs.bitwiseXor,
0x4 => &tailfuncs.addRegisters,
0x5 => &tailfuncs.subRegisters,
0x6 => &tailfuncs.shiftRight,
0x7 => &tailfuncs.subRegistersReverse,
0xE => &tailfuncs.shiftLeft,
else => &invalid,
},
.decoded = Decoded.decode(opcode, .xy),
},
0x9 => switch (opcode & 0xf) {
0x0 => .{ .func = &funcs.skipIfRegistersNotEqual, .decoded = Decoded.decode(opcode, .xy) },
0x0 => .{ .func = &tailfuncs.skipIfRegistersNotEqual, .decoded = Decoded.decode(opcode, .xy) },
else => .{ .func = &invalid, .decoded = undefined },
},
0xA => .{ .func = &funcs.setI, .decoded = Decoded.decode(opcode, .nnn) },
0xB => .{ .func = &funcs.jumpV0, .decoded = Decoded.decode(opcode, .nnn) },
0xC => .{ .func = &funcs.random, .decoded = Decoded.decode(opcode, .xnn) },
0xD => .{ .func = &funcs.draw, .decoded = Decoded.decode(opcode, .xyn) },
0xA => .{ .func = &tailfuncs.setI, .decoded = Decoded.decode(opcode, .nnn) },
0xB => .{ .func = &tailfuncs.jumpV0, .decoded = Decoded.decode(opcode, .nnn) },
0xC => .{ .func = &tailfuncs.random, .decoded = Decoded.decode(opcode, .xnn) },
0xD => .{ .func = &tailfuncs.draw, .decoded = Decoded.decode(opcode, .xyn) },
0xE => switch (opcode & 0xff) {
0x9E => .{ .func = &funcs.skipIfPressed, .decoded = Decoded.decode(opcode, .xnn) },
0xA1 => .{ .func = &funcs.skipIfNotPressed, .decoded = Decoded.decode(opcode, .xnn) },
0x9E => .{ .func = &tailfuncs.skipIfPressed, .decoded = Decoded.decode(opcode, .xnn) },
0xA1 => .{ .func = &tailfuncs.skipIfNotPressed, .decoded = Decoded.decode(opcode, .xnn) },
else => .{ .func = &invalid, .decoded = undefined },
},
0xF => .{
.func = switch (opcode & 0xff) {
0x07 => &funcs.readDt,
0x0A => &funcs.waitForKey,
0x15 => &funcs.setDt,
0x18 => &funcs.setSt,
0x1E => &funcs.incrementI,
0x29 => &funcs.setIToFont,
0x33 => &funcs.storeBcd,
0x55 => &funcs.store,
0x65 => &funcs.load,
0x75 => &funcs.storeFlags,
0x85 => &funcs.loadFlags,
0x07 => &tailfuncs.readDt,
0x0A => &tailfuncs.waitForKey,
0x15 => &tailfuncs.setDt,
0x18 => &tailfuncs.setSt,
0x1E => &tailfuncs.incrementI,
0x29 => &tailfuncs.setIToFont,
0x33 => &tailfuncs.storeBcd,
0x55 => &tailfuncs.store,
0x65 => &tailfuncs.load,
0x75 => &tailfuncs.storeFlags,
0x85 => &tailfuncs.loadFlags,
else => &invalid,
},
.decoded = Decoded.decode(opcode, .xnn),
},
};
cpu.code[cpu.pc] = inst;
@call(.always_tail, inst.func, .{ cpu, inst.decoded.to() });
@call(.always_tail, inst.func, .{ cpu, inst.decoded.toInt() });
}

fn invalid(cpu: *Cpu, decoded: u32) callconv(.C) void {
_ = decoded; // autofix
fn invalid(cpu: *Cpu, _: Decoded.Int) void {
std.debug.panic(
"invalid instruction: {x:0>4}",
.{std.mem.readInt(u16, cpu.mem[cpu.pc..][0..2], .big)},
);
}

const funcs = @import("./tailfuncs.zig");

// export fn inc_stub(cpu: *Cpu, decoded: Decoded, pc: u16) void {
// // const decoded: Decoded = @bitCast(decoded_i);
// decoded.xy[0].*, cpu.v[0xf] = @addWithOverflow(decoded.xy[0].*, decoded.xy[1].*);
// const next = cpu.code[cpu.pc + 2];
// @call(.always_tail, next.func, .{ cpu, next.decoded, pc + 2 });
// }
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