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Author SHA1 Message Date
Rekai Nyangadzayi Musuka 9643b520c8 feat: expose module for zig build system 2023-06-25 17:10:49 -05:00
Rekai Nyangadzayi Musuka 78cdb10395 feat: implement ARM7TDMI (and stub ARM946E-S) 2023-06-25 17:10:49 -05:00
22 changed files with 2460 additions and 19 deletions
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36
build.zig
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@ -15,33 +15,39 @@ pub fn build(b: *std.Build) void {
// set a preferred release mode, allowing the user to decide how to optimize. // set a preferred release mode, allowing the user to decide how to optimize.
const optimize = b.standardOptimizeOption(.{}); const optimize = b.standardOptimizeOption(.{});
const lib = b.addStaticLibrary(.{ const util_dep = b.dependency("zba-util", .{});
.name = "arm32", const bitfield_mod = b.createModule(.{ .source_file = .{ .path = "lib/bitfield.zig" }, .dependencies = &.{} });
// In this case the main source file is merely a path, however, in more
// complicated build scripts, this could be a generated file.
.root_source_file = .{ .path = "src/lib.zig" },
.target = target,
.optimize = optimize,
});
// This declares intent for the library to be installed into the standard _ = b.addModule("arm32", .{
// location when the user invokes the "install" step (the default step when .source_file = .{ .path = "src/lib.zig" },
// running `zig build`). .dependencies = &.{
b.installArtifact(lib); .{
.name = "zba-util",
.module = util_dep.module("zba-util"),
},
.{
.name = "bitfield",
.module = bitfield_mod,
},
},
});
// Creates a step for unit testing. This only builds the test executable // Creates a step for unit testing. This only builds the test executable
// but does not run it. // but does not run it.
const main_tests = b.addTest(.{ const lib_tests = b.addTest(.{
.root_source_file = .{ .path = "src/lib.zig" }, .root_source_file = .{ .path = "src/lib.zig" },
.target = target, .target = target,
.optimize = optimize, .optimize = optimize,
}); });
const run_main_tests = b.addRunArtifact(main_tests); lib_tests.addModule("zba-util", util_dep.module("zba-util")); // https://git.musuka.dev/paoda/zba-util
lib_tests.addModule("bitfield", bitfield_mod);
const run_lib_tests = b.addRunArtifact(lib_tests);
// This creates a build step. It will be visible in the `zig build --help` menu, // This creates a build step. It will be visible in the `zig build --help` menu,
// and can be selected like this: `zig build test` // and can be selected like this: `zig build test`
// This will evaluate the `test` step rather than the default, which is "install". // This will evaluate the `test` step rather than the default, which is "install".
const test_step = b.step("test", "Run library tests"); const test_step = b.step("test", "Run library tests");
test_step.dependOn(&run_main_tests.step); test_step.dependOn(&run_lib_tests.step);
} }

10
build.zig.zon Normal file
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@ -0,0 +1,10 @@
.{
.name = "arm32",
.version = "0.1.0",
.dependencies = .{
.@"zba-util" = .{
.url = "https://git.musuka.dev/paoda/zba-util/archive/e616cf09e53f5c402c8f040d14baa211683e70e3.tar.gz",
.hash = "1220b80b2c0989dcc47275ab9d7d70da4858ef3c1fe1f934e8d838e65028127f6ef3",
},
},
}

146
lib/bitfield.zig Normal file
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@ -0,0 +1,146 @@
const std = @import("std");
fn PtrCastPreserveCV(comptime T: type, comptime PtrToT: type, comptime NewT: type) type {
return switch (PtrToT) {
*T => *NewT,
*const T => *const NewT,
*volatile T => *volatile NewT,
*const volatile T => *const volatile NewT,
else => @compileError("wtf you doing"),
};
}
fn BitType(comptime FieldType: type, comptime ValueType: type, comptime shamt: usize) type {
const self_bit: FieldType = (1 << shamt);
return extern struct {
bits: Bitfield(FieldType, shamt, 1),
pub fn set(self: anytype) void {
self.bits.field().* |= self_bit;
}
pub fn unset(self: anytype) void {
self.bits.field().* &= ~self_bit;
}
pub fn read(self: anytype) ValueType {
return @bitCast(ValueType, @truncate(u1, self.bits.field().* >> shamt));
}
// Since these are mostly used with MMIO, I want to avoid
// reading the memory just to write it again, also races
pub fn write(self: anytype, val: ValueType) void {
if (@bitCast(bool, val)) {
self.set();
} else {
self.unset();
}
}
};
}
// Original Bit Constructor
// pub fn Bit(comptime FieldType: type, comptime shamt: usize) type {
// return BitType(FieldType, u1, shamt);
// }
pub fn Bit(comptime FieldType: type, comptime shamt: usize) type {
return BitType(FieldType, bool, shamt);
}
fn Boolean(comptime FieldType: type, comptime shamt: usize) type {
return BitType(FieldType, bool, shamt);
}
pub fn Bitfield(comptime FieldType: type, comptime shamt: usize, comptime num_bits: usize) type {
if (shamt + num_bits > @bitSizeOf(FieldType)) {
@compileError("bitfield doesn't fit");
}
const self_mask: FieldType = ((1 << num_bits) - 1) << shamt;
const ValueType = std.meta.Int(.unsigned, num_bits);
return extern struct {
dummy: FieldType,
fn field(self: anytype) PtrCastPreserveCV(@This(), @TypeOf(self), FieldType) {
return @ptrCast(PtrCastPreserveCV(@This(), @TypeOf(self), FieldType), self);
}
pub fn write(self: anytype, val: ValueType) void {
self.field().* &= ~self_mask;
self.field().* |= @intCast(FieldType, val) << shamt;
}
pub fn read(self: anytype) ValueType {
const val: FieldType = self.field().*;
return @intCast(ValueType, (val & self_mask) >> shamt);
}
};
}
test "bit" {
const S = extern union {
low: Bit(u32, 0),
high: Bit(u32, 1),
val: u32,
};
std.testing.expect(@sizeOf(S) == 4);
std.testing.expect(@bitSizeOf(S) == 32);
var s: S = .{ .val = 1 };
std.testing.expect(s.low.read() == 1);
std.testing.expect(s.high.read() == 0);
s.low.write(0);
s.high.write(1);
std.testing.expect(s.val == 2);
}
test "boolean" {
const S = extern union {
low: Boolean(u32, 0),
high: Boolean(u32, 1),
val: u32,
};
std.testing.expect(@sizeOf(S) == 4);
std.testing.expect(@bitSizeOf(S) == 32);
var s: S = .{ .val = 2 };
std.testing.expect(s.low.read() == false);
std.testing.expect(s.high.read() == true);
s.low.write(true);
s.high.write(false);
std.testing.expect(s.val == 1);
}
test "bitfield" {
const S = extern union {
low: Bitfield(u32, 0, 16),
high: Bitfield(u32, 16, 16),
val: u32,
};
std.testing.expect(@sizeOf(S) == 4);
std.testing.expect(@bitSizeOf(S) == 32);
var s: S = .{ .val = 0x13376969 };
std.testing.expect(s.low.read() == 0x6969);
std.testing.expect(s.high.read() == 0x1337);
s.low.write(0x1337);
s.high.write(0x6969);
std.testing.expect(s.val == 0x69691337);
}

461
src/arm.zig Normal file
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@ -0,0 +1,461 @@
const std = @import("std");
const Architecture = enum { v4t, v5te };
const Interpreter = @import("lib.zig").Interpreter;
const Bus = @import("lib.zig").Bus;
const Scheduler = @import("lib.zig").Scheduler;
const Bitfield = @import("bitfield").Bitfield;
const Bit = @import("bitfield").Bit;
const condition_lut = [_]u16{
0xF0F0, // EQ - Equal
0x0F0F, // NE - Not Equal
0xCCCC, // CS - Unsigned higher or same
0x3333, // CC - Unsigned lower
0xFF00, // MI - Negative
0x00FF, // PL - Positive or Zero
0xAAAA, // VS - Overflow
0x5555, // VC - No Overflow
0x0C0C, // HI - unsigned hierh
0xF3F3, // LS - unsigned lower or same
0xAA55, // GE - greater or equal
0x55AA, // LT - less than
0x0A05, // GT - greater than
0xF5FA, // LE - less than or equal
0xFFFF, // AL - always
0x0000, // NV - never
};
pub fn Arm32(comptime arch: Architecture) type {
return struct {
const Self = @This();
r: [16]u32 = [_]u32{0x00} ** 16,
pipe: Pipeline = Pipeline.init(),
sched: Scheduler,
bus: Bus,
cpsr: PSR,
spsr: PSR,
bank: Bank = Bank.create(),
const arm = @import("arm/v4t.zig").arm(Self);
const thumb = @import("arm/v4t.zig").thumb(Self);
const Pipeline = struct {
stage: [2]?u32,
flushed: bool,
fn init() @This() {
return .{
.stage = [_]?u32{null} ** 2,
.flushed = false,
};
}
pub fn isFull(self: *const @This()) bool {
return self.stage[0] != null and self.stage[1] != null;
}
pub fn step(self: *@This(), cpu: *Self, comptime T: type) ?u32 {
comptime std.debug.assert(T == u32 or T == u16);
const opcode = self.stage[0];
self.stage[0] = self.stage[1];
self.stage[1] = cpu.fetch(T, cpu.r[15]);
return opcode;
}
pub fn reload(self: *@This(), cpu: *Self) void {
if (cpu.cpsr.t.read()) {
self.stage[0] = cpu.fetch(u16, cpu.r[15]);
self.stage[1] = cpu.fetch(u16, cpu.r[15] + 2);
cpu.r[15] += 4;
} else {
self.stage[0] = cpu.fetch(u32, cpu.r[15]);
self.stage[1] = cpu.fetch(u32, cpu.r[15] + 4);
cpu.r[15] += 8;
}
self.flushed = true;
}
};
/// Bank of Registers from other CPU Modes
const Bank = struct {
/// Storage for r13_<mode>, r14_<mode>
/// e.g. [r13, r14, r13_svc, r14_svc]
r: [2 * 6]u32,
/// Storage for R8_fiq -> R12_fiq and their normal counterparts
/// e.g [r[0 + 8], fiq_r[0 + 8], r[1 + 8], fiq_r[1 + 8]...]
fiq: [2 * 5]u32,
spsr: [5]PSR,
const Kind = enum(u1) {
R13 = 0,
R14,
};
pub fn create() Bank {
return .{
.r = [_]u32{0x00} ** 12,
.fiq = [_]u32{0x00} ** 10,
.spsr = [_]PSR{.{ .raw = 0x0000_0000 }} ** 5,
};
}
inline fn regIdx(mode: Mode, kind: Kind) usize {
const idx: usize = switch (mode) {
.User, .System => 0,
.Supervisor => 1,
.Abort => 2,
.Undefined => 3,
.Irq => 4,
.Fiq => 5,
};
return (idx * 2) + if (kind == .R14) @as(usize, 1) else 0;
}
inline fn spsrIdx(mode: Mode) usize {
return switch (mode) {
.Supervisor => 0,
.Abort => 1,
.Undefined => 2,
.Irq => 3,
.Fiq => 4,
else => std.debug.panic("[CPU/Mode] {} does not have a SPSR Register", .{mode}),
};
}
inline fn fiqIdx(i: usize, mode: Mode) usize {
return (i * 2) + if (mode == .Fiq) @as(usize, 1) else 0;
}
};
pub fn init(scheduler: Scheduler, bus: Bus) Self {
return Self{
.sched = scheduler,
.bus = bus,
.cpsr = .{ .raw = 0x0000_001F },
.spsr = .{ .raw = 0x0000_0000 },
};
}
// FIXME: Resetting disables logging (if enabled)
pub fn reset(self: *Self) void {
self.* = .{
.sched = self.sched,
.bus = self.bus,
.cpsr = .{ .raw = 0x0000_001F },
.spsr = .{ .raw = 0x0000_0000 },
};
}
pub inline fn hasSPSR(self: *const Self) bool {
const mode = Mode.getChecked(self, self.cpsr.mode.read());
return switch (mode) {
.System, .User => false,
else => true,
};
}
pub inline fn isPrivileged(self: *const Self) bool {
const mode = Mode.getChecked(self, self.cpsr.mode.read());
return switch (mode) {
.User => false,
else => true,
};
}
pub inline fn isHalted(self: *const Self) bool {
return self.bus.io.haltcnt == .Halt;
}
pub fn setCpsr(self: *Self, value: u32) void {
if (value & 0x1F != self.cpsr.raw & 0x1F) self.changeModeFromIdx(@truncate(u5, value & 0x1F));
self.cpsr.raw = value;
}
fn changeModeFromIdx(self: *Self, next: u5) void {
self.changeMode(Mode.getChecked(self, next));
}
pub fn setUserModeRegister(self: *Self, idx: usize, value: u32) void {
const current = Mode.getChecked(self, self.cpsr.mode.read());
switch (idx) {
8...12 => {
if (current == .Fiq) {
self.bank.fiq[Bank.fiqIdx(idx - 8, .User)] = value;
} else self.r[idx] = value;
},
13, 14 => switch (current) {
.User, .System => self.r[idx] = value,
else => {
const kind = std.meta.intToEnum(Bank.Kind, idx - 13) catch unreachable;
self.bank.r[Bank.regIdx(.User, kind)] = value;
},
},
else => self.r[idx] = value, // R0 -> R7 and R15
}
}
pub fn getUserModeRegister(self: *Self, idx: usize) u32 {
const current = Mode.getChecked(self, self.cpsr.mode.read());
return switch (idx) {
8...12 => if (current == .Fiq) self.bank.fiq[Bank.fiqIdx(idx - 8, .User)] else self.r[idx],
13, 14 => switch (current) {
.User, .System => self.r[idx],
else => blk: {
const kind = std.meta.intToEnum(Bank.Kind, idx - 13) catch unreachable;
break :blk self.bank.r[Bank.regIdx(.User, kind)];
},
},
else => self.r[idx], // R0 -> R7 and R15
};
}
pub fn changeMode(self: *Self, next: Mode) void {
const now = Mode.getChecked(self, self.cpsr.mode.read());
// Bank R8 -> r12
for (0..5) |i| {
self.bank.fiq[Bank.fiqIdx(i, now)] = self.r[8 + i];
}
// Bank r13, r14, SPSR
switch (now) {
.User, .System => {
self.bank.r[Bank.regIdx(now, .R13)] = self.r[13];
self.bank.r[Bank.regIdx(now, .R14)] = self.r[14];
},
else => {
self.bank.r[Bank.regIdx(now, .R13)] = self.r[13];
self.bank.r[Bank.regIdx(now, .R14)] = self.r[14];
self.bank.spsr[Bank.spsrIdx(now)] = self.spsr;
},
}
// Grab R8 -> R12
for (0..5) |i| {
self.r[8 + i] = self.bank.fiq[Bank.fiqIdx(i, next)];
}
// Grab r13, r14, SPSR
switch (next) {
.User, .System => {
self.r[13] = self.bank.r[Bank.regIdx(next, .R13)];
self.r[14] = self.bank.r[Bank.regIdx(next, .R14)];
},
else => {
self.r[13] = self.bank.r[Bank.regIdx(next, .R13)];
self.r[14] = self.bank.r[Bank.regIdx(next, .R14)];
self.spsr = self.bank.spsr[Bank.spsrIdx(next)];
},
}
self.cpsr.mode.write(@enumToInt(next));
}
/// Advances state so that the BIOS is skipped
///
/// Note: This accesses the CPU's bus ptr so it only may be called
/// once the Bus has been properly initialized
///
/// TODO: Make above notice impossible to do in code
pub fn fastBoot(self: *Self) void {
self.r = std.mem.zeroes([16]u32);
// self.r[0] = 0x08000000;
// self.r[1] = 0x000000EA;
self.r[13] = 0x0300_7F00;
self.r[15] = 0x0800_0000;
self.bank.r[Bank.regIdx(.Irq, .R13)] = 0x0300_7FA0;
self.bank.r[Bank.regIdx(.Supervisor, .R13)] = 0x0300_7FE0;
// self.cpsr.raw = 0x6000001F;
self.cpsr.raw = 0x0000_001F;
self.bus.bios.addr_latch = 0x0000_00DC + 8;
}
pub fn step(self: *Self) void {
defer {
if (!self.pipe.flushed) self.r[15] += if (self.cpsr.t.read()) 2 else @as(u32, 4);
self.pipe.flushed = false;
}
if (self.cpsr.t.read()) {
const opcode = @truncate(u16, self.pipe.step(self, u16) orelse return);
thumb.lut[thumb.idx(opcode)](self, self.bus, opcode);
} else {
const opcode = self.pipe.step(self, u32) orelse return;
if (self.cpsr.check(@truncate(u4, opcode >> 28))) {
arm.lut[arm.idx(opcode)](self, self.bus, opcode);
}
}
}
pub fn stepDmaTransfer(self: *Self) bool {
inline for (0..4) |i| {
if (self.bus.dma[i].in_progress) {
self.bus.dma[i].step(self);
return true;
}
}
return false;
}
pub fn handleInterrupt(self: *Self) void {
const should_handle = self.bus.io.ie.raw & self.bus.io.irq.raw;
// Return if IME is disabled, CPSR I is set or there is nothing to handle
if (!self.bus.io.ime or self.cpsr.i.read() or should_handle == 0) return;
// If Pipeline isn't full, we have a bug
std.debug.assert(self.pipe.isFull());
// log.debug("Handling Interrupt!", .{});
self.bus.io.haltcnt = .Execute;
// FIXME: This seems weird, but retAddr.gba suggests I need to make these changes
const ret_addr = self.r[15] - if (self.cpsr.t.read()) 0 else @as(u32, 4);
const new_spsr = self.cpsr.raw;
self.changeMode(.Irq);
self.cpsr.t.write(false);
self.cpsr.i.write(true);
self.r[14] = ret_addr;
self.spsr.raw = new_spsr;
self.r[15] = 0x0000_0018;
self.pipe.reload(self);
}
inline fn fetch(self: *Self, comptime T: type, address: u32) T {
comptime std.debug.assert(T == u32 or T == u16); // Opcode may be 32-bit (ARM) or 16-bit (THUMB)
// Bus.read will advance the scheduler. There are different timings for CPU fetches,
// so we want to undo what Bus.read will apply. We can do this by caching the current tick
// This is very dumb.
//
// FIXME: Please rework this
// FIXME: Please Re-enable this
// const tick_cache = self.sched.tick;
// defer self.sched.tick = tick_cache + Bus.fetch_timings[@boolToInt(T == u32)][@truncate(u4, address >> 24)];
return self.bus.read(T, address);
}
pub fn panic(self: *const Self, comptime format: []const u8, args: anytype) noreturn {
var i: usize = 0;
while (i < 16) : (i += 4) {
const i_1 = i + 1;
const i_2 = i + 2;
const i_3 = i + 3;
std.debug.print("R{}: 0x{X:0>8}\tR{}: 0x{X:0>8}\tR{}: 0x{X:0>8}\tR{}: 0x{X:0>8}\n", .{ i, self.r[i], i_1, self.r[i_1], i_2, self.r[i_2], i_3, self.r[i_3] });
}
std.debug.print("cpsr: 0x{X:0>8} ", .{self.cpsr.raw});
self.cpsr.toString();
std.debug.print("spsr: 0x{X:0>8} ", .{self.spsr.raw});
self.spsr.toString();
std.debug.print("pipeline: {??X:0>8}\n", .{self.pipe.stage});
if (self.cpsr.t.read()) {
const opcode = self.bus.dbgRead(u16, self.r[15] - 4);
const id = thumb.idx(opcode);
std.debug.print("opcode: ID: 0x{b:0>10} 0x{X:0>4}\n", .{ id, opcode });
} else {
const opcode = self.bus.dbgRead(u32, self.r[15] - 4);
const id = arm.idx(opcode);
std.debug.print("opcode: ID: 0x{X:0>3} 0x{X:0>8}\n", .{ id, opcode });
}
std.debug.print("tick: {}\n\n", .{self.sched.now()});
std.debug.panic(format, args);
}
pub fn interface(self: *Self) Interpreter {
return switch (arch) {
.v4t => .{ .v4t = self },
.v5te => .{ .v5te = self },
};
}
};
}
pub const Mode = enum(u5) {
User = 0b10000,
Fiq = 0b10001,
Irq = 0b10010,
Supervisor = 0b10011,
Abort = 0b10111,
Undefined = 0b11011,
System = 0b11111,
pub fn toString(self: Mode) []const u8 {
return switch (self) {
.User => "usr",
.Fiq => "fiq",
.Irq => "irq",
.Supervisor => "svc",
.Abort => "abt",
.Undefined => "und",
.System => "sys",
};
}
fn get(bits: u5) ?Mode {
return std.meta.intToEnum(Mode, bits) catch null;
}
fn getChecked(cpu: anytype, bits: u5) Mode {
return get(bits) orelse cpu.panic("[CPU/CPSR] 0b{b:0>5} is an invalid CPU mode", .{bits});
}
};
pub const PSR = extern union {
mode: Bitfield(u32, 0, 5),
t: Bit(u32, 5),
f: Bit(u32, 6),
i: Bit(u32, 7),
v: Bit(u32, 28),
c: Bit(u32, 29),
z: Bit(u32, 30),
n: Bit(u32, 31),
raw: u32,
fn toString(self: @This()) void {
std.debug.print("[", .{});
if (self.n.read()) std.debug.print("N", .{}) else std.debug.print("-", .{});
if (self.z.read()) std.debug.print("Z", .{}) else std.debug.print("-", .{});
if (self.c.read()) std.debug.print("C", .{}) else std.debug.print("-", .{});
if (self.v.read()) std.debug.print("V", .{}) else std.debug.print("-", .{});
if (self.i.read()) std.debug.print("I", .{}) else std.debug.print("-", .{});
if (self.f.read()) std.debug.print("F", .{}) else std.debug.print("-", .{});
if (self.t.read()) std.debug.print("T", .{}) else std.debug.print("-", .{});
std.debug.print("|", .{});
if (Mode.get(self.mode.read())) |m| std.debug.print("{s}", .{m.toString()}) else std.debug.print("---", .{});
std.debug.print("]\n", .{});
}
pub inline fn check(self: @This(), cond: u4) bool {
const flags = @truncate(u4, self.raw >> 28);
return condition_lut[cond] & (@as(u16, 1) << flags) != 0;
}
};

111
src/arm/cpu/arm/block_data_transfer.zig Normal file
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@ -0,0 +1,111 @@
const Bus = @import("../../../lib.zig").Bus;
pub fn blockDataTransfer(comptime InstrFn: type, comptime P: bool, comptime U: bool, comptime S: bool, comptime W: bool, comptime L: bool) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, bus: Bus, opcode: u32) void {
const rn = @truncate(u4, opcode >> 16 & 0xF);
const rlist = opcode & 0xFFFF;
const r15 = rlist >> 15 & 1 == 1;
var count: u32 = 0;
var i: u5 = 0;
var first: u4 = 0;
var write_to_base = true;
while (i < 16) : (i += 1) {
const r = @truncate(u4, 15 - i);
if (rlist >> r & 1 == 1) {
first = r;
count += 1;
}
}
var start = cpu.r[rn];
if (U) {
start += if (P) 4 else 0;
} else {
start = start - (4 * count) + if (!P) 4 else 0;
}
var end = cpu.r[rn];
if (U) {
end = end + (4 * count) - if (!P) 4 else 0;
} else {
end -= if (P) 4 else 0;
}
var new_base = cpu.r[rn];
if (U) {
new_base += 4 * count;
} else {
new_base -= 4 * count;
}
var address = start;
if (rlist == 0) {
var und_addr = cpu.r[rn];
if (U) {
und_addr += if (P) 4 else 0;
} else {
und_addr -= 0x40 - if (!P) 4 else 0;
}
if (L) {
cpu.r[15] = bus.read(u32, und_addr);
cpu.pipe.reload(cpu);
} else {
bus.write(u32, und_addr, cpu.r[15] + 4);
}
cpu.r[rn] = if (U) cpu.r[rn] + 0x40 else cpu.r[rn] - 0x40;
return;
}
i = first;
while (i < 16) : (i += 1) {
if (rlist >> i & 1 == 1) {
transfer(cpu, bus, r15, i, address);
address += 4;
if (W and !L and write_to_base) {
cpu.r[rn] = new_base;
write_to_base = false;
}
}
}
if (W and L and rlist >> rn & 1 == 0) cpu.r[rn] = new_base;
}
fn transfer(cpu: Arm32, bus: Bus, r15_present: bool, i: u5, address: u32) void {
if (L) {
if (S and !r15_present) {
// Always Transfer User mode Registers
cpu.setUserModeRegister(i, bus.read(u32, address));
} else {
const value = bus.read(u32, address);
cpu.r[i] = value;
if (i == 0xF) {
cpu.r[i] &= ~@as(u32, 3); // Align r15
cpu.pipe.reload(cpu);
if (S) cpu.setCpsr(cpu.spsr.raw);
}
}
} else {
if (S) {
// Always Transfer User mode Registers
// This happens regardless if r15 is in the list
const value = cpu.getUserModeRegister(i);
bus.write(u32, address, value + if (i == 0xF) 4 else @as(u32, 0)); // PC is already 8 ahead to make 12
} else {
bus.write(u32, address, cpu.r[i] + if (i == 0xF) 4 else @as(u32, 0));
}
}
}
}.inner;
}

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const Bus = @import("../../../lib.zig").Bus;
const sext = @import("zba-util").sext;
pub fn branch(comptime InstrFn: type, comptime L: bool) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, _: Bus, opcode: u32) void {
if (L) cpu.r[14] = cpu.r[15] - 4;
cpu.r[15] +%= sext(u32, u24, opcode) << 2;
cpu.pipe.reload(cpu);
}
}.inner;
}
pub fn branchAndExchange(comptime InstrFn: type) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
pub fn inner(cpu: Arm32, _: Bus, opcode: u32) void {
const rn = opcode & 0xF;
const thumb = cpu.r[rn] & 1 == 1;
cpu.r[15] = cpu.r[rn] & if (thumb) ~@as(u32, 1) else ~@as(u32, 3);
cpu.cpsr.t.write(thumb);
cpu.pipe.reload(cpu);
}
}.inner;
}

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const Bus = @import("../../../lib.zig").Bus;
const exec = @import("../barrel_shifter.zig").exec;
const ror = @import("../barrel_shifter.zig").ror;
pub fn dataProcessing(comptime InstrFn: type, comptime I: bool, comptime S: bool, comptime kind: u4) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, _: Bus, opcode: u32) void {
const rd = @truncate(u4, opcode >> 12 & 0xF);
const rn = opcode >> 16 & 0xF;
const old_carry = @boolToInt(cpu.cpsr.c.read());
// If certain conditions are met, PC is 12 ahead instead of 8
// TODO: Why these conditions?
if (!I and opcode >> 4 & 1 == 1) cpu.r[15] += 4;
const op1 = cpu.r[rn];
const amount = @truncate(u8, (opcode >> 8 & 0xF) << 1);
const op2 = if (I) ror(S, &cpu.cpsr, opcode & 0xFF, amount) else exec(S, cpu, opcode);
// Undo special condition from above
if (!I and opcode >> 4 & 1 == 1) cpu.r[15] -= 4;
var result: u32 = undefined;
var overflow: u1 = undefined;
// Perform Data Processing Logic
switch (kind) {
0x0 => result = op1 & op2, // AND
0x1 => result = op1 ^ op2, // EOR
0x2 => result = op1 -% op2, // SUB
0x3 => result = op2 -% op1, // RSB
0x4 => result = add(&overflow, op1, op2), // ADD
0x5 => result = adc(&overflow, op1, op2, old_carry), // ADC
0x6 => result = sbc(op1, op2, old_carry), // SBC
0x7 => result = sbc(op2, op1, old_carry), // RSC
0x8 => {
// TST
if (rd == 0xF)
return undefinedTestBehaviour(cpu);
result = op1 & op2;
},
0x9 => {
// TEQ
if (rd == 0xF)
return undefinedTestBehaviour(cpu);
result = op1 ^ op2;
},
0xA => {
// CMP
if (rd == 0xF)
return undefinedTestBehaviour(cpu);
result = op1 -% op2;
},
0xB => {
// CMN
if (rd == 0xF)
return undefinedTestBehaviour(cpu);
const tmp = @addWithOverflow(op1, op2);
result = tmp[0];
overflow = tmp[1];
},
0xC => result = op1 | op2, // ORR
0xD => result = op2, // MOV
0xE => result = op1 & ~op2, // BIC
0xF => result = ~op2, // MVN
}
// Write to Destination Register
switch (kind) {
0x8, 0x9, 0xA, 0xB => {}, // Test Operations
else => {
cpu.r[rd] = result;
if (rd == 0xF) {
if (S) cpu.setCpsr(cpu.spsr.raw);
cpu.pipe.reload(cpu);
}
},
}
// Write Flags
switch (kind) {
0x0, 0x1, 0xC, 0xD, 0xE, 0xF => if (S and rd != 0xF) {
// Logic Operation Flags
cpu.cpsr.n.write(result >> 31 & 1 == 1);
cpu.cpsr.z.write(result == 0);
// C set by Barrel Shifter, V is unaffected
},
0x2, 0x3 => if (S and rd != 0xF) {
// SUB, RSB Flags
cpu.cpsr.n.write(result >> 31 & 1 == 1);
cpu.cpsr.z.write(result == 0);
if (kind == 0x2) {
// SUB specific
cpu.cpsr.c.write(op2 <= op1);
cpu.cpsr.v.write(((op1 ^ result) & (~op2 ^ result)) >> 31 & 1 == 1);
} else {
// RSB Specific
cpu.cpsr.c.write(op1 <= op2);
cpu.cpsr.v.write(((op2 ^ result) & (~op1 ^ result)) >> 31 & 1 == 1);
}
},
0x4, 0x5 => if (S and rd != 0xF) {
// ADD, ADC Flags
cpu.cpsr.n.write(result >> 31 & 1 == 1);
cpu.cpsr.z.write(result == 0);
cpu.cpsr.c.write(overflow == 0b1);
cpu.cpsr.v.write(((op1 ^ result) & (op2 ^ result)) >> 31 & 1 == 1);
},
0x6, 0x7 => if (S and rd != 0xF) {
// SBC, RSC Flags
cpu.cpsr.n.write(result >> 31 & 1 == 1);
cpu.cpsr.z.write(result == 0);
if (kind == 0x6) {
// SBC specific
const subtrahend = @as(u64, op2) -% old_carry +% 1;
cpu.cpsr.c.write(subtrahend <= op1);
cpu.cpsr.v.write(((op1 ^ result) & (~op2 ^ result)) >> 31 & 1 == 1);
} else {
// RSC Specific
const subtrahend = @as(u64, op1) -% old_carry +% 1;
cpu.cpsr.c.write(subtrahend <= op2);
cpu.cpsr.v.write(((op2 ^ result) & (~op1 ^ result)) >> 31 & 1 == 1);
}
},
0x8, 0x9, 0xA, 0xB => {
// Test Operation Flags
cpu.cpsr.n.write(result >> 31 & 1 == 1);
cpu.cpsr.z.write(result == 0);
if (kind == 0xA) {
// CMP specific
cpu.cpsr.c.write(op2 <= op1);
cpu.cpsr.v.write(((op1 ^ result) & (~op2 ^ result)) >> 31 & 1 == 1);
} else if (kind == 0xB) {
// CMN specific
cpu.cpsr.c.write(overflow == 0b1);
cpu.cpsr.v.write(((op1 ^ result) & (op2 ^ result)) >> 31 & 1 == 1);
} else {
// TST, TEQ specific
// Barrel Shifter should always calc CPSR C in TST
if (!S) _ = exec(true, cpu, opcode);
}
},
}
}
fn undefinedTestBehaviour(cpu: Arm32) void {
@setCold(true);
cpu.setCpsr(cpu.spsr.raw);
}
}.inner;
}
pub fn sbc(left: u32, right: u32, old_carry: u1) u32 {
// TODO: Make your own version (thanks peach.bot)
const subtrahend = @as(u64, right) -% old_carry +% 1;
const ret = @truncate(u32, left -% subtrahend);
return ret;
}
pub fn add(overflow: *u1, left: u32, right: u32) u32 {
const ret = @addWithOverflow(left, right);
overflow.* = ret[1];
return ret[0];
}
pub fn adc(overflow: *u1, left: u32, right: u32, old_carry: u1) u32 {
const tmp = @addWithOverflow(left, right);
const ret = @addWithOverflow(tmp[0], old_carry);
overflow.* = tmp[1] | ret[1];
return ret[0];
}

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const Bus = @import("../../../lib.zig").Bus;
const sext = @import("zba-util").sext;
const rotr = @import("zba-util").rotr;
pub fn halfAndSignedDataTransfer(comptime InstrFn: type, comptime P: bool, comptime U: bool, comptime I: bool, comptime W: bool, comptime L: bool) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, bus: Bus, opcode: u32) void {
const rn = opcode >> 16 & 0xF;
const rd = opcode >> 12 & 0xF;
const rm = opcode & 0xF;
const imm_offset_high = opcode >> 8 & 0xF;
const base = cpu.r[rn] + if (!L and rn == 0xF) 4 else @as(u32, 0);
const offset = if (I) imm_offset_high << 4 | rm else cpu.r[rm];
const modified_base = if (U) base +% offset else base -% offset;
var address = if (P) modified_base else base;
var result: u32 = undefined;
if (L) {
switch (@truncate(u2, opcode >> 5)) {
0b01 => {
// LDRH
const value = bus.read(u16, address);
result = rotr(u32, value, 8 * (address & 1));
},
0b10 => {
// LDRSB
result = sext(u32, u8, bus.read(u8, address));
},
0b11 => {
// LDRSH
const value = bus.read(u16, address);
result = if (address & 1 == 1) sext(u32, u8, @truncate(u8, value >> 8)) else sext(u32, u16, value);
},
0b00 => unreachable, // SWP
}
} else {
if (opcode >> 5 & 0x01 == 0x01) {
// STRH
bus.write(u16, address, @truncate(u16, cpu.r[rd]));
} else unreachable; // SWP
}
address = modified_base;
if (W and P or !P) cpu.r[rn] = address;
if (L) cpu.r[rd] = result; // // This emulates the LDR rd == rn behaviour
}
}.inner;
}

59
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const Bus = @import("../../../lib.zig").Bus;
pub fn multiply(comptime InstrFn: type, comptime A: bool, comptime S: bool) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, _: Bus, opcode: u32) void {
const rd = opcode >> 16 & 0xF;
const rn = opcode >> 12 & 0xF;
const rs = opcode >> 8 & 0xF;
const rm = opcode & 0xF;
const temp: u64 = @as(u64, cpu.r[rm]) * @as(u64, cpu.r[rs]) + if (A) cpu.r[rn] else 0;
const result = @truncate(u32, temp);
cpu.r[rd] = result;
if (S) {
cpu.cpsr.n.write(result >> 31 & 1 == 1);
cpu.cpsr.z.write(result == 0);
// V is unaffected, C is *actually* undefined in ARMv4
}
}
}.inner;
}
pub fn multiplyLong(comptime InstrFn: type, comptime U: bool, comptime A: bool, comptime S: bool) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, _: Bus, opcode: u32) void {
const rd_hi = opcode >> 16 & 0xF;
const rd_lo = opcode >> 12 & 0xF;
const rs = opcode >> 8 & 0xF;
const rm = opcode & 0xF;
if (U) {
// Signed (WHY IS IT U THEN?)
var result: i64 = @as(i64, @bitCast(i32, cpu.r[rm])) * @as(i64, @bitCast(i32, cpu.r[rs]));
if (A) result +%= @bitCast(i64, @as(u64, cpu.r[rd_hi]) << 32 | @as(u64, cpu.r[rd_lo]));
cpu.r[rd_hi] = @bitCast(u32, @truncate(i32, result >> 32));
cpu.r[rd_lo] = @bitCast(u32, @truncate(i32, result));
} else {
// Unsigned
var result: u64 = @as(u64, cpu.r[rm]) * @as(u64, cpu.r[rs]);
if (A) result +%= @as(u64, cpu.r[rd_hi]) << 32 | @as(u64, cpu.r[rd_lo]);
cpu.r[rd_hi] = @truncate(u32, result >> 32);
cpu.r[rd_lo] = @truncate(u32, result);
}
if (S) {
cpu.cpsr.z.write(cpu.r[rd_hi] == 0 and cpu.r[rd_lo] == 0);
cpu.cpsr.n.write(cpu.r[rd_hi] >> 31 & 1 == 1);
// C and V are set to meaningless values
}
}
}.inner;
}

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const std = @import("std");
const Bus = @import("../../../lib.zig").Bus;
const PSR = @import("../../../arm.zig").PSR;
const log = std.log.scoped(.PsrTransfer);
const rotr = @import("zba-util").rotr;
pub fn psrTransfer(comptime InstrFn: type, comptime I: bool, comptime R: bool, comptime kind: u2) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, _: Bus, opcode: u32) void {
switch (kind) {
0b00 => {
// MRS
const rd = opcode >> 12 & 0xF;
if (R and !cpu.hasSPSR()) log.err("Tried to read SPSR from User/System Mode", .{});
cpu.r[rd] = if (R) cpu.spsr.raw else cpu.cpsr.raw;
},
0b10 => {
// MSR
const field_mask = @truncate(u4, opcode >> 16 & 0xF);
const rm_idx = opcode & 0xF;
const right = if (I) rotr(u32, opcode & 0xFF, (opcode >> 8 & 0xF) * 2) else cpu.r[rm_idx];
if (R and !cpu.hasSPSR()) log.err("Tried to write to SPSR in User/System Mode", .{});
if (R) {
// arm.gba seems to expect the SPSR to do somethign in SYS mode,
// so we just assume that despite writing to the SPSR in USR or SYS mode
// being UNPREDICTABLE, it just magically has a working SPSR somehow
cpu.spsr.raw = fieldMask(&cpu.spsr, field_mask, right);
} else {
if (cpu.isPrivileged()) cpu.setCpsr(fieldMask(&cpu.cpsr, field_mask, right));
}
},
else => cpu.panic("[CPU/PSR Transfer] Bits 21:220 of {X:0>8} are undefined", .{opcode}),
}
}
}.inner;
}
fn fieldMask(psr: *const PSR, field_mask: u4, right: u32) u32 {
// This bitwise ORs bits 3 and 0 of the field mask into a u2
// We do this because we only care about bits 7:0 and 31:28 of the CPSR
const bits = @truncate(u2, (field_mask >> 2 & 0x2) | (field_mask & 1));
const mask: u32 = switch (bits) {
0b00 => 0x0000_0000,
0b01 => 0x0000_00FF,
0b10 => 0xF000_0000,
0b11 => 0xF000_00FF,
};
return (psr.raw & ~mask) | (right & mask);
}

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const Bus = @import("../../../lib.zig").Bus;
const rotr = @import("zba-util").rotr;
pub fn singleDataSwap(comptime InstrFn: type, comptime B: bool) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, bus: Bus, opcode: u32) void {
const rn = opcode >> 16 & 0xF;
const rd = opcode >> 12 & 0xF;
const rm = opcode & 0xF;
const address = cpu.r[rn];
if (B) {
// SWPB
const value = bus.read(u8, address);
bus.write(u8, address, @truncate(u8, cpu.r[rm]));
cpu.r[rd] = value;
} else {
// SWP
const value = rotr(u32, bus.read(u32, address), 8 * (address & 0x3));
bus.write(u32, address, cpu.r[rm]);
cpu.r[rd] = value;
}
}
}.inner;
}

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const shifter = @import("../barrel_shifter.zig");
const Bus = @import("../../../lib.zig").Bus;
const rotr = @import("zba-util").rotr;
pub fn singleDataTransfer(comptime InstrFn: type, comptime I: bool, comptime P: bool, comptime U: bool, comptime B: bool, comptime W: bool, comptime L: bool) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, bus: Bus, opcode: u32) void {
const rn = opcode >> 16 & 0xF;
const rd = opcode >> 12 & 0xF;
const base = cpu.r[rn];
const offset = if (I) shifter.immediate(false, cpu, opcode) else opcode & 0xFFF;
const modified_base = if (U) base +% offset else base -% offset;
var address = if (P) modified_base else base;
var result: u32 = undefined;
if (L) {
if (B) {
// LDRB
result = bus.read(u8, address);
} else {
// LDR
const value = bus.read(u32, address);
result = rotr(u32, value, 8 * (address & 0x3));
}
} else {
if (B) {
// STRB
const value = cpu.r[rd] + if (rd == 0xF) 4 else @as(u32, 0); // PC is 12 ahead
bus.write(u8, address, @truncate(u8, value));
} else {
// STR
const value = cpu.r[rd] + if (rd == 0xF) 4 else @as(u32, 0);
bus.write(u32, address, value);
}
}
address = modified_base;
if (W and P or !P) {
cpu.r[rn] = address;
if (rn == 0xF) cpu.pipe.reload(cpu);
}
if (L) {
// This emulates the LDR rd == rn behaviour
cpu.r[rd] = result;
if (rd == 0xF) cpu.pipe.reload(cpu);
}
}
}.inner;
}

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const Bus = @import("../../../lib.zig").Bus;
pub fn armSoftwareInterrupt(comptime InstrFn: type) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, _: Bus, _: u32) void {
// Copy Values from Current Mode
const ret_addr = cpu.r[15] - 4;
const cpsr = cpu.cpsr.raw;
// Switch Mode
cpu.changeMode(.Supervisor);
cpu.cpsr.t.write(false); // Force ARM Mode
cpu.cpsr.i.write(true); // Disable normal interrupts
cpu.r[14] = ret_addr; // Resume Execution
cpu.spsr.raw = cpsr; // Previous mode CPSR
cpu.r[15] = 0x0000_0008;
cpu.pipe.reload(cpu);
}
}.inner;
}

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const CPSR = @import("../../arm.zig").PSR;
const rotr = @import("zba-util").rotr;
pub fn exec(comptime S: bool, cpu: anytype, opcode: u32) u32 {
var result: u32 = undefined;
if (opcode >> 4 & 1 == 1) {
result = register(S, cpu, opcode);
} else {
result = immediate(S, cpu, opcode);
}
return result;
}
fn register(comptime S: bool, cpu: anytype, opcode: u32) u32 {
const rs_idx = opcode >> 8 & 0xF;
const rm = cpu.r[opcode & 0xF];
const rs = @truncate(u8, cpu.r[rs_idx]);
return switch (@truncate(u2, opcode >> 5)) {
0b00 => lsl(S, &cpu.cpsr, rm, rs),
0b01 => lsr(S, &cpu.cpsr, rm, rs),
0b10 => asr(S, &cpu.cpsr, rm, rs),
0b11 => ror(S, &cpu.cpsr, rm, rs),
};
}
pub fn immediate(comptime S: bool, cpu: anytype, opcode: u32) u32 {
const amount = @truncate(u8, opcode >> 7 & 0x1F);
const rm = cpu.r[opcode & 0xF];
var result: u32 = undefined;
if (amount == 0) {
switch (@truncate(u2, opcode >> 5)) {
0b00 => {
// LSL #0
result = rm;
},
0b01 => {
// LSR #0 aka LSR #32
if (S) cpu.cpsr.c.write(rm >> 31 & 1 == 1);
result = 0x0000_0000;
},
0b10 => {
// ASR #0 aka ASR #32
result = @bitCast(u32, @bitCast(i32, rm) >> 31);
if (S) cpu.cpsr.c.write(result >> 31 & 1 == 1);
},
0b11 => {
// ROR #0 aka RRX
const carry: u32 = @boolToInt(cpu.cpsr.c.read());
if (S) cpu.cpsr.c.write(rm & 1 == 1);
result = (carry << 31) | (rm >> 1);
},
}
} else {
switch (@truncate(u2, opcode >> 5)) {
0b00 => result = lsl(S, &cpu.cpsr, rm, amount),
0b01 => result = lsr(S, &cpu.cpsr, rm, amount),
0b10 => result = asr(S, &cpu.cpsr, rm, amount),
0b11 => result = ror(S, &cpu.cpsr, rm, amount),
}
}
return result;
}
pub fn lsl(comptime S: bool, cpsr: *CPSR, rm: u32, total_amount: u8) u32 {
const amount = @truncate(u5, total_amount);
const bit_count: u8 = @typeInfo(u32).Int.bits;
var result: u32 = 0x0000_0000;
if (total_amount < bit_count) {
// We can perform a well-defined shift here
result = rm << amount;
if (S and total_amount != 0) {
const carry_bit = @truncate(u5, bit_count - amount);
cpsr.c.write(rm >> carry_bit & 1 == 1);
}
} else {
if (S) {
if (total_amount == bit_count) {
// Shifted all bits out, carry bit is bit 0 of rm
cpsr.c.write(rm & 1 == 1);
} else {
cpsr.c.write(false);
}
}
}
return result;
}
pub fn lsr(comptime S: bool, cpsr: *CPSR, rm: u32, total_amount: u32) u32 {
const amount = @truncate(u5, total_amount);
const bit_count: u8 = @typeInfo(u32).Int.bits;
var result: u32 = 0x0000_0000;
if (total_amount < bit_count) {
// We can perform a well-defined shift
result = rm >> amount;
if (S and total_amount != 0) cpsr.c.write(rm >> (amount - 1) & 1 == 1);
} else {
if (S) {
if (total_amount == bit_count) {
// LSR #32
cpsr.c.write(rm >> 31 & 1 == 1);
} else {
// All bits have been shifted out, including carry bit
cpsr.c.write(false);
}
}
}
return result;
}
pub fn asr(comptime S: bool, cpsr: *CPSR, rm: u32, total_amount: u8) u32 {
const amount = @truncate(u5, total_amount);
const bit_count: u8 = @typeInfo(u32).Int.bits;
var result: u32 = 0x0000_0000;
if (total_amount < bit_count) {
result = @bitCast(u32, @bitCast(i32, rm) >> amount);
if (S and total_amount != 0) cpsr.c.write(rm >> (amount - 1) & 1 == 1);
} else {
// ASR #32 and ASR #>32 have the same result
result = @bitCast(u32, @bitCast(i32, rm) >> 31);
if (S) cpsr.c.write(result >> 31 & 1 == 1);
}
return result;
}
pub fn ror(comptime S: bool, cpsr: *CPSR, rm: u32, total_amount: u8) u32 {
const result = rotr(u32, rm, total_amount);
if (S and total_amount != 0) {
cpsr.c.write(result >> 31 & 1 == 1);
}
return result;
}

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const Bus = @import("../../../lib.zig").Bus;
const adc = @import("../arm/data_processing.zig").adc;
const sbc = @import("../arm/data_processing.zig").sbc;
const lsl = @import("../barrel_shifter.zig").lsl;
const lsr = @import("../barrel_shifter.zig").lsr;
const asr = @import("../barrel_shifter.zig").asr;
const ror = @import("../barrel_shifter.zig").ror;
pub fn fmt4(comptime InstrFn: type, comptime op: u4) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, _: Bus, opcode: u16) void {
const rs = opcode >> 3 & 0x7;
const rd = opcode & 0x7;
const carry = @boolToInt(cpu.cpsr.c.read());
const op1 = cpu.r[rd];
const op2 = cpu.r[rs];
var result: u32 = undefined;
var overflow: u1 = undefined;
switch (op) {
0x0 => result = op1 & op2, // AND
0x1 => result = op1 ^ op2, // EOR
0x2 => result = lsl(true, &cpu.cpsr, op1, @truncate(u8, op2)), // LSL
0x3 => result = lsr(true, &cpu.cpsr, op1, @truncate(u8, op2)), // LSR
0x4 => result = asr(true, &cpu.cpsr, op1, @truncate(u8, op2)), // ASR
0x5 => result = adc(&overflow, op1, op2, carry), // ADC
0x6 => result = sbc(op1, op2, carry), // SBC
0x7 => result = ror(true, &cpu.cpsr, op1, @truncate(u8, op2)), // ROR
0x8 => result = op1 & op2, // TST
0x9 => result = 0 -% op2, // NEG
0xA => result = op1 -% op2, // CMP
0xB => {
// CMN
const tmp = @addWithOverflow(op1, op2);
result = tmp[0];
overflow = tmp[1];
},
0xC => result = op1 | op2, // ORR
0xD => result = @truncate(u32, @as(u64, op2) * @as(u64, op1)),
0xE => result = op1 & ~op2,
0xF => result = ~op2,
}
// Write to Destination Register
switch (op) {
0x8, 0xA, 0xB => {},
else => cpu.r[rd] = result,
}
// Write Flags
switch (op) {
0x0, 0x1, 0x2, 0x3, 0x4, 0x7, 0xC, 0xE, 0xF => {
// Logic Operations
cpu.cpsr.n.write(result >> 31 & 1 == 1);
cpu.cpsr.z.write(result == 0);
// C set by Barrel Shifter, V is unaffected
},
0x8, 0xA => {
// Test Flags
// CMN (0xB) is handled with ADC
cpu.cpsr.n.write(result >> 31 & 1 == 1);
cpu.cpsr.z.write(result == 0);
if (op == 0xA) {
// CMP specific
cpu.cpsr.c.write(op2 <= op1);
cpu.cpsr.v.write(((op1 ^ result) & (~op2 ^ result)) >> 31 & 1 == 1);
}
},
0x5, 0xB => {
// ADC, CMN
cpu.cpsr.n.write(result >> 31 & 1 == 1);
cpu.cpsr.z.write(result == 0);
cpu.cpsr.c.write(overflow == 0b1);
cpu.cpsr.v.write(((op1 ^ result) & (op2 ^ result)) >> 31 & 1 == 1);
},
0x6 => {
// SBC
cpu.cpsr.n.write(result >> 31 & 1 == 1);
cpu.cpsr.z.write(result == 0);
const subtrahend = @as(u64, op2) -% carry +% 1;
cpu.cpsr.c.write(subtrahend <= op1);
cpu.cpsr.v.write(((op1 ^ result) & (~op2 ^ result)) >> 31 & 1 == 1);
},
0x9 => {
// NEG
cpu.cpsr.n.write(result >> 31 & 1 == 1);
cpu.cpsr.z.write(result == 0);
cpu.cpsr.c.write(op2 <= 0);
cpu.cpsr.v.write(((0 ^ result) & (~op2 ^ result)) >> 31 & 1 == 1);
},
0xD => {
// Multiplication
cpu.cpsr.n.write(result >> 31 & 1 == 1);
cpu.cpsr.z.write(result == 0);
// V is unaffected, assuming similar behaviour to ARMv4 MUL C is undefined
},
}
}
}.inner;
}

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const Bus = @import("../../../lib.zig").Bus;
pub fn fmt14(comptime InstrFn: type, comptime L: bool, comptime R: bool) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, bus: Bus, opcode: u16) void {
const count = @boolToInt(R) + countRlist(opcode);
const start = cpu.r[13] - if (!L) count * 4 else 0;
var end = cpu.r[13];
if (L) {
end += count * 4;
} else {
end -= 4;
}
var address = start;
var i: u4 = 0;
while (i < 8) : (i += 1) {
if (opcode >> i & 1 == 1) {
if (L) {
cpu.r[i] = bus.read(u32, address);
} else {
bus.write(u32, address, cpu.r[i]);
}
address += 4;
}
}
if (R) {
if (L) {
const value = bus.read(u32, address);
cpu.r[15] = value & ~@as(u32, 1);
cpu.pipe.reload(cpu);
} else {
bus.write(u32, address, cpu.r[14]);
}
address += 4;
}
cpu.r[13] = if (L) end else start;
}
}.inner;
}
pub fn fmt15(comptime InstrFn: type, comptime L: bool, comptime rb: u3) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, bus: Bus, opcode: u16) void {
var address = cpu.r[rb];
const end_address = cpu.r[rb] + 4 * countRlist(opcode);
if (opcode & 0xFF == 0) {
if (L) {
cpu.r[15] = bus.read(u32, address);
cpu.pipe.reload(cpu);
} else {
bus.write(u32, address, cpu.r[15] + 2);
}
cpu.r[rb] += 0x40;
return;
}
var i: u4 = 0;
var first_write = true;
while (i < 8) : (i += 1) {
if (opcode >> i & 1 == 1) {
if (L) {
cpu.r[i] = bus.read(u32, address);
} else {
bus.write(u32, address, cpu.r[i]);
}
if (!L and first_write) {
cpu.r[rb] = end_address;
first_write = false;
}
address += 4;
}
}
if (L and opcode >> rb & 1 != 1) cpu.r[rb] = address;
}
}.inner;
}
inline fn countRlist(opcode: u16) u32 {
var count: u32 = 0;
inline for (0..8) |i| {
if (opcode >> (7 - i) & 1 == 1) count += 1;
}
return count;
}

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const Bus = @import("../../../lib.zig").Bus;
const sext = @import("zba-util").sext;
pub fn fmt16(comptime InstrFn: type, comptime cond: u4) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, _: Bus, opcode: u16) void {
// B
if (cond == 0xE or cond == 0xF)
cpu.panic("[CPU/THUMB.16] Undefined conditional branch with condition {}", .{cond});
if (!cpu.cpsr.check(cond)) return;
cpu.r[15] +%= sext(u32, u8, opcode & 0xFF) << 1;
cpu.pipe.reload(cpu);
}
}.inner;
}
pub fn fmt18(comptime InstrFn: type) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
// B but conditional
fn inner(cpu: Arm32, _: Bus, opcode: u16) void {
cpu.r[15] +%= sext(u32, u11, opcode & 0x7FF) << 1;
cpu.pipe.reload(cpu);
}
}.inner;
}
pub fn fmt19(comptime InstrFn: type, comptime is_low: bool) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, _: Bus, opcode: u16) void {
// BL
const offset = opcode & 0x7FF;
if (is_low) {
// Instruction 2
const next_opcode = cpu.r[15] - 2;
cpu.r[15] = cpu.r[14] +% (offset << 1);
cpu.r[14] = next_opcode | 1;
cpu.pipe.reload(cpu);
} else {
// Instruction 1
const lr_offset = sext(u32, u11, offset) << 12;
cpu.r[14] = (cpu.r[15] +% lr_offset) & ~@as(u32, 1);
}
}
}.inner;
}

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const Bus = @import("../../../lib.zig").Bus;
const add = @import("../arm/data_processing.zig").add;
const lsl = @import("../barrel_shifter.zig").lsl;
const lsr = @import("../barrel_shifter.zig").lsr;
const asr = @import("../barrel_shifter.zig").asr;
pub fn fmt1(comptime InstrFn: type, comptime op: u2, comptime offset: u5) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, _: Bus, opcode: u16) void {
const rs = opcode >> 3 & 0x7;
const rd = opcode & 0x7;
const result = switch (op) {
0b00 => blk: {
// LSL
if (offset == 0) {
break :blk cpu.r[rs];
} else {
break :blk lsl(true, &cpu.cpsr, cpu.r[rs], offset);
}
},
0b01 => blk: {
// LSR
if (offset == 0) {
cpu.cpsr.c.write(cpu.r[rs] >> 31 & 1 == 1);
break :blk @as(u32, 0);
} else {
break :blk lsr(true, &cpu.cpsr, cpu.r[rs], offset);
}
},
0b10 => blk: {
// ASR
if (offset == 0) {
cpu.cpsr.c.write(cpu.r[rs] >> 31 & 1 == 1);
break :blk @bitCast(u32, @bitCast(i32, cpu.r[rs]) >> 31);
} else {
break :blk asr(true, &cpu.cpsr, cpu.r[rs], offset);
}
},
else => cpu.panic("[CPU/THUMB.1] 0b{b:0>2} is not a valid op", .{op}),
};
// Equivalent to an ARM MOVS
cpu.r[rd] = result;
// Write Flags
cpu.cpsr.n.write(result >> 31 & 1 == 1);
cpu.cpsr.z.write(result == 0);
}
}.inner;
}
pub fn fmt5(comptime InstrFn: type, comptime op: u2, comptime h1: u1, comptime h2: u1) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, _: Bus, opcode: u16) void {
const rs = @as(u4, h2) << 3 | (opcode >> 3 & 0x7);
const rd = @as(u4, h1) << 3 | (opcode & 0x7);
const op1 = cpu.r[rd];
const op2 = cpu.r[rs];
var result: u32 = undefined;
var overflow: u1 = undefined;
switch (op) {
0b00 => result = add(&overflow, op1, op2), // ADD
0b01 => result = op1 -% op2, // CMP
0b10 => result = op2, // MOV
0b11 => {},
}
// Write to Destination Register
switch (op) {
0b01 => {}, // Test Instruction
0b11 => {
// BX
const is_thumb = op2 & 1 == 1;
cpu.r[15] = op2 & ~@as(u32, 1);
cpu.cpsr.t.write(is_thumb);
cpu.pipe.reload(cpu);
},
else => {
cpu.r[rd] = result;
if (rd == 0xF) {
cpu.r[15] &= ~@as(u32, 1);
cpu.pipe.reload(cpu);
}
},
}
// Write Flags
switch (op) {
0b01 => {
// CMP
cpu.cpsr.n.write(result >> 31 & 1 == 1);
cpu.cpsr.z.write(result == 0);
cpu.cpsr.c.write(op2 <= op1);
cpu.cpsr.v.write(((op1 ^ result) & (~op2 ^ result)) >> 31 & 1 == 1);
},
0b00, 0b10, 0b11 => {}, // MOV and Branch Instruction
}
}
}.inner;
}
pub fn fmt2(comptime InstrFn: type, comptime I: bool, is_sub: bool, rn: u3) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, _: Bus, opcode: u16) void {
const rs = opcode >> 3 & 0x7;
const rd = @truncate(u3, opcode);
const op1 = cpu.r[rs];
const op2: u32 = if (I) rn else cpu.r[rn];
if (is_sub) {
// SUB
const result = op1 -% op2;
cpu.r[rd] = result;
cpu.cpsr.n.write(result >> 31 & 1 == 1);
cpu.cpsr.z.write(result == 0);
cpu.cpsr.c.write(op2 <= op1);
cpu.cpsr.v.write(((op1 ^ result) & (~op2 ^ result)) >> 31 & 1 == 1);
} else {
// ADD
var overflow: u1 = undefined;
const result = add(&overflow, op1, op2);
cpu.r[rd] = result;
cpu.cpsr.n.write(result >> 31 & 1 == 1);
cpu.cpsr.z.write(result == 0);
cpu.cpsr.c.write(overflow == 0b1);
cpu.cpsr.v.write(((op1 ^ result) & (op2 ^ result)) >> 31 & 1 == 1);
}
}
}.inner;
}
pub fn fmt3(comptime InstrFn: type, comptime op: u2, comptime rd: u3) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, _: Bus, opcode: u16) void {
const op1 = cpu.r[rd];
const op2: u32 = opcode & 0xFF; // Offset
var overflow: u1 = undefined;
const result: u32 = switch (op) {
0b00 => op2, // MOV
0b01 => op1 -% op2, // CMP
0b10 => add(&overflow, op1, op2), // ADD
0b11 => op1 -% op2, // SUB
};
// Write to Register
if (op != 0b01) cpu.r[rd] = result;
// Write Flags
cpu.cpsr.n.write(result >> 31 & 1 == 1);
cpu.cpsr.z.write(result == 0);
switch (op) {
0b00 => {}, // MOV | C set by Barrel Shifter, V is unaffected
0b01, 0b11 => {
// SUB, CMP
cpu.cpsr.c.write(op2 <= op1);
cpu.cpsr.v.write(((op1 ^ result) & (~op2 ^ result)) >> 31 & 1 == 1);
},
0b10 => {
// ADD
cpu.cpsr.c.write(overflow == 0b1);
cpu.cpsr.v.write(((op1 ^ result) & (op2 ^ result)) >> 31 & 1 == 1);
},
}
}
}.inner;
}
pub fn fmt12(comptime InstrFn: type, comptime isSP: bool, comptime rd: u3) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, _: Bus, opcode: u16) void {
// ADD
const left = if (isSP) cpu.r[13] else cpu.r[15] & ~@as(u32, 2);
const right = (opcode & 0xFF) << 2;
cpu.r[rd] = left + right;
}
}.inner;
}
pub fn fmt13(comptime InstrFn: type, comptime S: bool) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, _: Bus, opcode: u16) void {
// ADD
const offset = (opcode & 0x7F) << 2;
cpu.r[13] = if (S) cpu.r[13] - offset else cpu.r[13] + offset;
}
}.inner;
}

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const Bus = @import("../../../lib.zig").Bus;
const rotr = @import("zba-util").rotr;
const sext = @import("zba-util").sext;
pub fn fmt6(comptime InstrFn: type, comptime rd: u3) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, bus: Bus, opcode: u16) void {
// LDR
const offset = (opcode & 0xFF) << 2;
// Bit 1 of the PC intentionally ignored
cpu.r[rd] = bus.read(u32, (cpu.r[15] & ~@as(u32, 2)) + offset);
}
}.inner;
}
pub fn fmt78(comptime InstrFn: type, comptime op: u2, comptime T: bool) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, bus: Bus, opcode: u16) void {
const ro = opcode >> 6 & 0x7;
const rb = opcode >> 3 & 0x7;
const rd = opcode & 0x7;
const address = cpu.r[rb] +% cpu.r[ro];
if (T) {
// Format 8
switch (op) {
0b00 => {
// STRH
bus.write(u16, address, @truncate(u16, cpu.r[rd]));
},
0b01 => {
// LDSB
cpu.r[rd] = sext(u32, u8, bus.read(u8, address));
},
0b10 => {
// LDRH
const value = bus.read(u16, address);
cpu.r[rd] = rotr(u32, value, 8 * (address & 1));
},
0b11 => {
// LDRSH
const value = bus.read(u16, address);
cpu.r[rd] = if (address & 1 == 1) sext(u32, u8, @truncate(u8, value >> 8)) else sext(u32, u16, value);
},
}
} else {
// Format 7
switch (op) {
0b00 => {
// STR
bus.write(u32, address, cpu.r[rd]);
},
0b01 => {
// STRB
bus.write(u8, address, @truncate(u8, cpu.r[rd]));
},
0b10 => {
// LDR
const value = bus.read(u32, address);
cpu.r[rd] = rotr(u32, value, 8 * (address & 0x3));
},
0b11 => {
// LDRB
cpu.r[rd] = bus.read(u8, address);
},
}
}
}
}.inner;
}
pub fn fmt9(comptime InstrFn: type, comptime B: bool, comptime L: bool, comptime offset: u5) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, bus: Bus, opcode: u16) void {
const rb = opcode >> 3 & 0x7;
const rd = opcode & 0x7;
if (L) {
if (B) {
// LDRB
const address = cpu.r[rb] + offset;
cpu.r[rd] = bus.read(u8, address);
} else {
// LDR
const address = cpu.r[rb] + (@as(u32, offset) << 2);
const value = bus.read(u32, address);
cpu.r[rd] = rotr(u32, value, 8 * (address & 0x3));
}
} else {
if (B) {
// STRB
const address = cpu.r[rb] + offset;
bus.write(u8, address, @truncate(u8, cpu.r[rd]));
} else {
// STR
const address = cpu.r[rb] + (@as(u32, offset) << 2);
bus.write(u32, address, cpu.r[rd]);
}
}
}
}.inner;
}
pub fn fmt10(comptime InstrFn: type, comptime L: bool, comptime offset: u5) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, bus: Bus, opcode: u16) void {
const rb = opcode >> 3 & 0x7;
const rd = opcode & 0x7;
const address = cpu.r[rb] + (@as(u6, offset) << 1);
if (L) {
// LDRH
const value = bus.read(u16, address);
cpu.r[rd] = rotr(u32, value, 8 * (address & 1));
} else {
// STRH
bus.write(u16, address, @truncate(u16, cpu.r[rd]));
}
}
}.inner;
}
pub fn fmt11(comptime InstrFn: type, comptime L: bool, comptime rd: u3) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, bus: Bus, opcode: u16) void {
const offset = (opcode & 0xFF) << 2;
const address = cpu.r[13] + offset;
if (L) {
// LDR
const value = bus.read(u32, address);
cpu.r[rd] = rotr(u32, value, 8 * (address & 0x3));
} else {
// STR
bus.write(u32, address, cpu.r[rd]);
}
}
}.inner;
}

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const Bus = @import("../../../lib.zig").Bus;
pub fn fmt17(comptime InstrFn: type) InstrFn {
const Arm32 = @typeInfo(@typeInfo(InstrFn).Pointer.child).Fn.params[0].type.?;
return struct {
fn inner(cpu: Arm32, _: Bus, _: u16) void {
// Copy Values from Current Mode
const ret_addr = cpu.r[15] - 2;
const cpsr = cpu.cpsr.raw;
// Switch Mode
cpu.changeMode(.Supervisor);
cpu.cpsr.t.write(false); // Force ARM Mode
cpu.cpsr.i.write(true); // Disable normal interrupts
cpu.r[14] = ret_addr; // Resume Execution
cpu.spsr.raw = cpsr; // Previous mode CPSR
cpu.r[15] = 0x0000_0008;
cpu.pipe.reload(cpu);
}
}.inner;
}

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const Bus = @import("../lib.zig").Bus;
pub fn arm(comptime Arm32: type) type {
return struct {
pub const InstrFn = *const fn (*Arm32, Bus, u32) void;
pub const lut: [0x1000]InstrFn = populate();
const processing = @import("cpu/arm/data_processing.zig").dataProcessing;
const psrTransfer = @import("cpu/arm/psr_transfer.zig").psrTransfer;
const transfer = @import("cpu/arm/single_data_transfer.zig").singleDataTransfer;
const halfSignedTransfer = @import("cpu/arm/half_signed_data_transfer.zig").halfAndSignedDataTransfer;
const blockTransfer = @import("cpu/arm/block_data_transfer.zig").blockDataTransfer;
const branch = @import("cpu/arm/branch.zig").branch;
const branchExchange = @import("cpu/arm/branch.zig").branchAndExchange;
const swi = @import("cpu/arm/software_interrupt.zig").armSoftwareInterrupt;
const swap = @import("cpu/arm/single_data_swap.zig").singleDataSwap;
const multiply = @import("cpu/arm/multiply.zig").multiply;
const multiplyLong = @import("cpu/arm/multiply.zig").multiplyLong;
/// Determine index into ARM InstrFn LUT
pub fn idx(opcode: u32) u12 {
return @truncate(u12, opcode >> 20 & 0xFF) << 4 | @truncate(u12, opcode >> 4 & 0xF);
}
// Undefined ARM Instruction handler
fn und(cpu: *Arm32, _: Bus, opcode: u32) void {
const id = idx(opcode);
cpu.panic("[CPU/Decode] ID: 0x{X:0>3} 0x{X:0>8} is an illegal opcode", .{ id, opcode });
}
fn populate() [0x1000]InstrFn {
return comptime comptime_blk: {
@setEvalBranchQuota(0xE000);
var table = [_]InstrFn{und} ** 0x1000;
for (&table, 0..) |*handler, i| {
handler.* = switch (@as(u2, i >> 10)) {
0b00 => if (i == 0x121) blk: {
break :blk branchExchange(InstrFn);
} else if (i & 0xFCF == 0x009) blk: {
const A = i >> 5 & 1 == 1;
const S = i >> 4 & 1 == 1;
break :blk multiply(InstrFn, A, S);
} else if (i & 0xFBF == 0x109) blk: {
const B = i >> 6 & 1 == 1;
break :blk swap(InstrFn, B);
} else if (i & 0xF8F == 0x089) blk: {
const U = i >> 6 & 1 == 1;
const A = i >> 5 & 1 == 1;
const S = i >> 4 & 1 == 1;
break :blk multiplyLong(InstrFn, U, A, S);
} else if (i & 0xE49 == 0x009 or i & 0xE49 == 0x049) blk: {
const P = i >> 8 & 1 == 1;
const U = i >> 7 & 1 == 1;
const I = i >> 6 & 1 == 1;
const W = i >> 5 & 1 == 1;
const L = i >> 4 & 1 == 1;
break :blk halfSignedTransfer(InstrFn, P, U, I, W, L);
} else if (i & 0xD90 == 0x100) blk: {
const I = i >> 9 & 1 == 1;
const R = i >> 6 & 1 == 1;
const kind = i >> 4 & 0x3;
break :blk psrTransfer(InstrFn, I, R, kind);
} else blk: {
const I = i >> 9 & 1 == 1;
const S = i >> 4 & 1 == 1;
const instrKind = i >> 5 & 0xF;
break :blk processing(InstrFn, I, S, instrKind);
},
0b01 => if (i >> 9 & 1 == 1 and i & 1 == 1) und else blk: {
const I = i >> 9 & 1 == 1;
const P = i >> 8 & 1 == 1;
const U = i >> 7 & 1 == 1;
const B = i >> 6 & 1 == 1;
const W = i >> 5 & 1 == 1;
const L = i >> 4 & 1 == 1;
break :blk transfer(InstrFn, I, P, U, B, W, L);
},
else => switch (@as(u2, i >> 9 & 0x3)) {
// MSB is guaranteed to be 1
0b00 => blk: {
const P = i >> 8 & 1 == 1;
const U = i >> 7 & 1 == 1;
const S = i >> 6 & 1 == 1;
const W = i >> 5 & 1 == 1;
const L = i >> 4 & 1 == 1;
break :blk blockTransfer(InstrFn, P, U, S, W, L);
},
0b01 => blk: {
const L = i >> 8 & 1 == 1;
break :blk branch(InstrFn, L);
},
0b10 => und, // COP Data Transfer
0b11 => if (i >> 8 & 1 == 1) swi(InstrFn) else und, // COP Data Operation + Register Transfer
},
};
}
break :comptime_blk table;
};
}
};
}
pub fn thumb(comptime Arm32: type) type {
return struct {
pub const InstrFn = *const fn (*Arm32, Bus, u16) void;
pub const lut: [0x400]InstrFn = populate();
const processing = @import("cpu/thumb/data_processing.zig");
const alu = @import("cpu/thumb/alu.zig").fmt4;
const transfer = @import("cpu/thumb/data_transfer.zig");
const block_transfer = @import("cpu/thumb/block_data_transfer.zig");
const swi = @import("cpu/thumb/software_interrupt.zig").fmt17;
const branch = @import("cpu/thumb/branch.zig");
/// Determine index into THUMB InstrFn LUT
pub fn idx(opcode: u16) u10 {
return @truncate(u10, opcode >> 6);
}
/// Undefined THUMB Instruction Handler
fn und(cpu: *Arm32, _: Bus, opcode: u16) void {
const id = idx(opcode);
cpu.panic("[CPU/Decode] ID: 0b{b:0>10} 0x{X:0>2} is an illegal opcode", .{ id, opcode });
}
fn populate() [0x400]InstrFn {
return comptime comptime_blk: {
@setEvalBranchQuota(5025); // This is exact
var table = [_]InstrFn{und} ** 0x400;
for (&table, 0..) |*handler, i| {
handler.* = switch (@as(u3, i >> 7 & 0x7)) {
0b000 => if (i >> 5 & 0x3 == 0b11) blk: {
const I = i >> 4 & 1 == 1;
const is_sub = i >> 3 & 1 == 1;
const rn = i & 0x7;
break :blk processing.fmt2(InstrFn, I, is_sub, rn);
} else blk: {
const op = i >> 5 & 0x3;
const offset = i & 0x1F;
break :blk processing.fmt1(InstrFn, op, offset);
},
0b001 => blk: {
const op = i >> 5 & 0x3;
const rd = i >> 2 & 0x7;
break :blk processing.fmt3(InstrFn, op, rd);
},
0b010 => switch (@as(u2, i >> 5 & 0x3)) {
0b00 => if (i >> 4 & 1 == 1) blk: {
const op = i >> 2 & 0x3;
const h1 = i >> 1 & 1;
const h2 = i & 1;
break :blk processing.fmt5(InstrFn, op, h1, h2);
} else blk: {
const op = i & 0xF;
break :blk alu(InstrFn, op);
},
0b01 => blk: {
const rd = i >> 2 & 0x7;
break :blk transfer.fmt6(InstrFn, rd);
},
else => blk: {
const op = i >> 4 & 0x3;
const T = i >> 3 & 1 == 1;
break :blk transfer.fmt78(InstrFn, op, T);
},
},
0b011 => blk: {
const B = i >> 6 & 1 == 1;
const L = i >> 5 & 1 == 1;
const offset = i & 0x1F;
break :blk transfer.fmt9(InstrFn, B, L, offset);
},
else => switch (@as(u3, i >> 6 & 0x7)) {
// MSB is guaranteed to be 1
0b000 => blk: {
const L = i >> 5 & 1 == 1;
const offset = i & 0x1F;
break :blk transfer.fmt10(InstrFn, L, offset);
},
0b001 => blk: {
const L = i >> 5 & 1 == 1;
const rd = i >> 2 & 0x7;
break :blk transfer.fmt11(InstrFn, L, rd);
},
0b010 => blk: {
const isSP = i >> 5 & 1 == 1;
const rd = i >> 2 & 0x7;
break :blk processing.fmt12(InstrFn, isSP, rd);
},
0b011 => if (i >> 4 & 1 == 1) blk: {
const L = i >> 5 & 1 == 1;
const R = i >> 2 & 1 == 1;
break :blk block_transfer.fmt14(InstrFn, L, R);
} else blk: {
const S = i >> 1 & 1 == 1;
break :blk processing.fmt13(InstrFn, S);
},
0b100 => blk: {
const L = i >> 5 & 1 == 1;
const rb = i >> 2 & 0x7;
break :blk block_transfer.fmt15(InstrFn, L, rb);
},
0b101 => if (i >> 2 & 0xF == 0b1111) blk: {
break :blk swi(InstrFn);
} else blk: {
const cond = i >> 2 & 0xF;
break :blk branch.fmt16(InstrFn, cond);
},
0b110 => branch.fmt18(
InstrFn,
),
0b111 => blk: {
const is_low = i >> 5 & 1 == 1;
break :blk branch.fmt19(InstrFn, is_low);
},
},
};
}
break :comptime_blk table;
};
}
};
}

194
src/lib.zig
View File

@ -1,10 +1,196 @@
const std = @import("std"); const std = @import("std");
const testing = std.testing; const testing = std.testing;
export fn add(a: i32, b: i32) i32 { const Arm32 = @import("arm.zig").Arm32;
return a + b;
pub const Arm7tdmi = Arm32(.v4t);
pub const Arm946es = Arm32(.v5te);
pub const Interpreter = union(enum) {
const Self = @This();
v4t: *Arm7tdmi,
v5te: *Arm946es,
pub fn reset(self: Self) void {
switch (self) {
inline else => |s| s.reset(),
}
} }
test "basic add functionality" { pub fn step(self: Self) void {
try testing.expect(add(3, 7) == 10); switch (self) {
inline else => |s| s.step(),
}
}
pub fn panic(self: Self, comptime format: []const u8, comptime args: anytype) noreturn {
switch (self) {
inline else => |s| s.panic(format, args),
}
}
};
pub const Bus = struct {
ptr: *anyopaque,
vtable: *const Vtable,
const Vtable = struct {
read8: *const fn (ptr: *anyopaque, address: u32) u8,
read16: *const fn (ptr: *anyopaque, address: u32) u16,
read32: *const fn (ptr: *anyopaque, address: u32) u32,
write8: *const fn (ptr: *anyopaque, address: u32, value: u8) void,
write16: *const fn (ptr: *anyopaque, address: u32, value: u16) void,
write32: *const fn (ptr: *anyopaque, address: u32, value: u32) void,
};
pub fn init(obj: anytype) @This() {
const P = @TypeOf(obj);
const info = @typeInfo(P);
std.debug.assert(info == .Pointer); // `anytype` is a Pointer
std.debug.assert(info.Pointer.size == .One); // Single-Item Pointer
std.debug.assert(@typeInfo(info.Pointer.child) == .Struct); // Pointer Child is a `struct`
const alignment = info.Pointer.alignment;
const impl = struct {
fn read8(ptr: *anyopaque, address: u32) u8 {
const self = @ptrCast(P, @alignCast(alignment, ptr));
return self.read(u8, address);
}
fn read16(ptr: *anyopaque, address: u32) u16 {
const self = @ptrCast(P, @alignCast(alignment, ptr));
return self.read(u16, address);
}
fn read32(ptr: *anyopaque, address: u32) u32 {
const self = @ptrCast(P, @alignCast(alignment, ptr));
return self.read(u32, address);
}
fn write8(ptr: *anyopaque, address: u32, value: u8) void {
const self = @ptrCast(P, @alignCast(alignment, ptr));
return self.write(u8, address, value);
}
fn write16(ptr: *anyopaque, address: u32, value: u16) void {
const self = @ptrCast(P, @alignCast(alignment, ptr));
return self.write(u16, address, value);
}
fn write32(ptr: *anyopaque, address: u32, value: u32) void {
const self = @ptrCast(P, @alignCast(alignment, ptr));
return self.write(u32, address, value);
}
};
return .{
.ptr = obj,
.vtab = &.{
.read8 = impl.read8,
.read16 = impl.read16,
.read32 = impl.read32,
.write8 = impl.write8,
.write16 = impl.write16,
.write32 = impl.write32,
},
};
}
pub fn read(self: @This(), comptime T: type, address: u32) T {
return switch (T) {
u32 => self.vtable.read32(self.ptr, address),
u16 => self.vtable.read16(self.ptr, address),
u8 => self.vtable.read8(self.ptr, address),
else => @compileError("TODO: Fill this in"),
};
}
pub fn write(self: @This(), comptime T: type, address: u32, value: T) void {
switch (T) {
u32 => self.vtable.write32(self.ptr, address, value),
u16 => self.vtable.write16(self.ptr, address, value),
u8 => self.vtable.write8(self.ptr, address, value),
else => @compileError("TODO: Fill this in"),
}
}
pub fn dbgRead(self: @This(), comptime T: type, address: u32) T {
_ = address;
_ = self;
@panic("TODO: Implement Debug Reads via Bus Interface");
}
pub fn dbgWrite(self: @This(), comptime T: type, address: u32, value: T) void {
_ = self;
_ = value;
_ = address;
@panic("TODO: Implement Debug Writes via Bus Interface");
}
};
pub const Scheduler = struct {
ptr: *anyopaque,
// VTable
nowFn: *const fn (ptr: *anyopaque) u64,
pub fn init(obj: anytype) @This() {
const P = @TypeOf(obj);
const info = @typeInfo(P);
std.debug.assert(info == .Pointer); // `anytype` is a Pointer
std.debug.assert(info.Pointer.size == .One); // Single-Item Pointer
std.debug.assert(@typeInfo(info.Pointer.child) == .Struct); // Pointer Child is a `struct`
const alignment = info.Pointer.alignment;
const impl = struct {
fn now(ptr: *anyopaque) u64 {
const self = @ptrCast(P, @alignCast(alignment, ptr));
return self.now();
}
};
return .{ .ptr = obj, .nowFn = impl.now };
}
pub fn now(self: @This()) u64 {
return self.nowFn(self.ptr);
}
};
test "create ARMv4T interface" {
var bus: Bus = .{ .ptr = undefined, .vtable = undefined };
var scheduler: Scheduler = .{ .ptr = undefined, .nowFn = undefined };
var arm7tdmi = Arm7tdmi{
.sched = scheduler,
.bus = bus,
.cpsr = .{ .raw = 0x0000_001F },
.spsr = .{ .raw = 0x0000_0000 },
};
var icpu = arm7tdmi.interface();
icpu.reset();
icpu.step();
}
test "create ARMv5TE interface" {
var bus: Bus = .{ .ptr = undefined, .vtable = undefined };
var scheduler: Scheduler = .{ .ptr = undefined, .nowFn = undefined };
var arm946es = Arm7tdmi{
.sched = scheduler,
.bus = bus,
.cpsr = .{ .raw = 0x0000_001F },
.spsr = .{ .raw = 0x0000_0000 },
};
_ = arm946es.interface();
} }