chore: update to lastest zig

while I figure out the interface with zba, disable the exe example
since it doesn't have an emu to pass to gdbstub

build.zig

@@ -1,38 +1,60 @@
 const std = @import("std");
 
-pub fn build(b: *std.build.Builder) void {
-    // Standard target options allows the person running `zig build` to choose
-    // what target to build for. Here we do not override the defaults, which
-    // means any target is allowed, and the default is native. Other options
-    // for restricting supported target set are available.
-    const target = b.standardTargetOptions(.{});
+fn path(comptime suffix: []const u8) []const u8 {
+    if (suffix[0] == '/') @compileError("expected a relative path");
+    return comptime (std.fs.path.dirname(@src().file) orelse ".") ++ std.fs.path.sep_str ++ suffix;
+}
 
-    // Standard release options allow the person running `zig build` to select
-    // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall.
-    const mode = b.standardReleaseOptions();
+const pkgs = struct {
+    const Pkg = std.build.Pkg;
 
-    const exe = b.addExecutable("zba-gdbstub", "src/main.zig");
+    pub const gdbstub: Pkg = .{
+        .name = "gdbstub",
+        .source = .{ .path = path("src/lib.zig") },
+        .dependencies = &[_]Pkg{network},
+    };
 
     // https://github.com/MasterQ32/zig-network
-    exe.addPackagePath("network", "lib/zig-network/network.zig");
+    pub const network: Pkg = .{
+        .name = "network",
+        .source = .{ .path = path("lib/zig-network/network.zig") },
+    };
+};
 
-    exe.setTarget(target);
-    exe.setBuildMode(mode);
-    exe.install();
-
-    const run_cmd = exe.run();
-    run_cmd.step.dependOn(b.getInstallStep());
-    if (b.args) |args| {
-        run_cmd.addArgs(args);
+pub fn link(exe: *std.build.LibExeObjStep) void {
+    exe.addPackage(pkgs.gdbstub);
 }
 
-    const run_step = b.step("run", "Run the app");
-    run_step.dependOn(&run_cmd.step);
+pub fn build(b: *std.build.Builder) void {
+    const target = b.standardTargetOptions(.{});
+    _ = target;
+    const mode = b.standardReleaseOptions();
 
-    const exe_tests = b.addTest("src/main.zig");
-    exe_tests.setTarget(target);
-    exe_tests.setBuildMode(mode);
+    // -- library --
+    const lib = b.addStaticLibrary("gdbstub", "src/lib.zig");
+    lib.addPackage(pkgs.network);
 
-    const test_step = b.step("test", "Run unit tests");
-    test_step.dependOn(&exe_tests.step);
+    lib.setBuildMode(mode);
+    lib.install();
+
+    const lib_tests = b.addTest("src/lib.zig");
+    lib_tests.setBuildMode(mode);
+
+    const test_step = b.step("lib-test", "Run Library Tests");
+    test_step.dependOn(&lib_tests.step);
+
+    // // -- Executable --
+    // const exe = b.addExecutable("gdbserver", "src/main.zig");
+    // link(exe);
+
+    // exe.setTarget(target);
+    // exe.setBuildMode(mode);
+    // exe.install();
+
+    // const run_cmd = exe.run();
+    // run_cmd.step.dependOn(b.getInstallStep());
+    // if (b.args) |args| run_cmd.addArgs(args);
+
+    // const run_step = b.step("run", "Run the app");
+    // run_step.dependOn(&run_cmd.step);
 }

src/Packet.zig

@@ -0,0 +1,230 @@
+const std = @import("std");
+
+const Allocator = std.mem.Allocator;
+const Emulator = @import("lib.zig").Emulator;
+
+const target = @import("Server.zig").target;
+const memory_map = @import("Server.zig").memory_map;
+
+const Self = @This();
+const log = std.log.scoped(.Packet);
+pub const max_len: usize = 0x1000;
+
+contents: []const u8,
+
+pub fn from(allocator: Allocator, str: []const u8) !Self {
+    var tokens = std.mem.tokenize(u8, str, "$#");
+    const contents = tokens.next() orelse return error.InvalidPacket;
+
+    const chksum_str = tokens.next() orelse return error.MissingCheckSum;
+    const chksum = std.fmt.parseInt(u8, chksum_str, 16) catch return error.InvalidChecksum;
+
+    if (!Self.verify(contents, chksum)) return error.ChecksumMismatch;
+
+    return .{ .contents = try allocator.dupe(u8, contents) };
+}
+
+const String = union(enum) {
+    alloc: []const u8,
+    static: []const u8,
+
+    pub fn inner(self: *const @This()) []const u8 {
+        return switch (self.*) {
+            .static => |str| str,
+            .alloc => |str| str,
+        };
+    }
+
+    pub fn deinit(self: *@This(), allocator: Allocator) void {
+        switch (self.*) {
+            .alloc => |string| allocator.free(string),
+            .static => {},
+        }
+
+        self.* = undefined;
+    }
+};
+
+pub fn parse(self: *Self, allocator: Allocator, emu: Emulator) !String {
+    switch (self.contents[0]) {
+        // Required
+        '?' => {
+            const ret = try std.fmt.allocPrint(allocator, "S{x:0>2}", .{@enumToInt(Signal.Int)});
+            return .{ .alloc = ret };
+        },
+        'g' => {
+            const r = emu.registers();
+            const cpsr = emu.cpsr();
+
+            const reg_len = @sizeOf(u32) * 2; // Every byte is represented by 2 characters
+            const ret = try allocator.alloc(u8, r.len * reg_len + reg_len); // r0 -> r15 + CPSR
+
+            {
+                var i: u32 = 0;
+                while (i < r.len + 1) : (i += 1) {
+                    var reg: u32 = if (i < r.len) r[i] else cpsr;
+                    if (i == 15) reg -= if (cpsr >> 5 & 1 == 1) 4 else 8; // PC is ahead
+
+                    // writes the formatted integer to the buffer, returns a slice to the buffer but we ignore that
+                    // GDB also expects the bytes to be in the opposite order for whatever reason
+                    _ = std.fmt.bufPrintIntToSlice(ret[i * 8 ..][0..8], @byteSwap(reg), 16, .lower, .{ .fill = '0', .width = 8 });
+                }
+            }
+
+            return .{ .alloc = ret };
+        },
+        'G' => @panic("TODO: Register Write"),
+        'm' => {
+            var tokens = std.mem.tokenize(u8, self.contents[1..], ",");
+            const addr_str = tokens.next() orelse return .{ .static = "E9999" }; // EUNKNOWN
+            const length_str = tokens.next() orelse return .{ .static = "E9999" }; // EUNKNOWN
+
+            const addr = try std.fmt.parseInt(u32, addr_str, 16);
+            const len = try std.fmt.parseInt(u32, length_str, 16);
+
+            const ret = try allocator.alloc(u8, len * 2);
+
+            {
+                var i: u32 = 0;
+                while (i < len) : (i += 1) {
+                    const value = emu.read(addr + i);
+                    log.debug("read 0x{X:0>2} from 0x{X:0>8}", .{ value, addr + i });
+
+                    // writes the formatted integer to the buffer, returns a slice to the buffer but we ignore that
+                    _ = std.fmt.bufPrintIntToSlice(ret[i * 2 ..][0..2], emu.read(addr + i), 16, .lower, .{ .fill = '0', .width = 2 });
+                }
+            }
+
+            return .{ .alloc = ret };
+        },
+        'M' => @panic("TODO: Memory Write"),
+        'c' => @panic("TODO: Continue"),
+        's' => {
+            // var tokens = std.mem.tokenize(u8, self.contents[1..], " ");
+            // const addr = if (tokens.next()) |s| try std.fmt.parseInt(u32, s, 16) else null;
+
+            emu.step();
+
+            const ret = try std.fmt.allocPrint(allocator, "S{x:0>2}", .{@enumToInt(Signal.Trap)});
+            return .{ .alloc = ret };
+        },
+
+        // Optional
+        'D' => {
+            log.info("Disconnecting...", .{});
+            return .{ .static = "OK" };
+        },
+        'H' => return .{ .static = "" },
+        'v' => {
+            if (substr(self.contents[1..], "MustReplyEmpty")) {
+                return .{ .static = "" };
+            }
+
+            log.warn("Unimplemented: {s}", .{self.contents});
+            return .{ .static = "" };
+        },
+        'q' => {
+            if (self.contents[1] == 'C' and self.contents.len == 2) return .{ .static = "QC1" };
+            if (substr(self.contents[1..], "fThreadInfo")) return .{ .static = "m1" };
+            if (substr(self.contents[1..], "sThreadInfo")) return .{ .static = "l" };
+            if (substr(self.contents[1..], "Attached")) return .{ .static = "1" }; // Tell GDB we're attached to a process
+
+            if (substr(self.contents[1..], "Supported")) {
+                const format = "PacketSize={x:};qXfer:features:read+;qXfer:memory-map:read+";
+                // TODO: Anything else?
+
+                const ret = try std.fmt.allocPrint(allocator, format, .{Self.max_len});
+                return .{ .alloc = ret };
+            }
+
+            if (substr(self.contents[1..], "Xfer:features:read")) {
+                var tokens = std.mem.tokenize(u8, self.contents[1..], ":,");
+                _ = tokens.next(); // Xfer
+                _ = tokens.next(); // features
+                _ = tokens.next(); // read
+                const annex = tokens.next() orelse return .{ .static = "E9999" };
+                const offset_str = tokens.next() orelse return .{ .static = "E99999" };
+                const length_str = tokens.next() orelse return .{ .static = "E9999" };
+
+                if (std.mem.eql(u8, annex, "target.xml")) {
+                    const offset = try std.fmt.parseInt(usize, offset_str, 16);
+                    const length = try std.fmt.parseInt(usize, length_str, 16);
+
+                    // + 2 to account for the "m " in the response
+                    // subtract offset so that the allocated buffer isn't
+                    // larger than it needs to be TODO: Test this?
+                    const len = @min(length, (target.len + 1) - offset);
+                    const ret = try allocator.alloc(u8, len);
+
+                    ret[0] = if (ret.len < length) 'l' else 'm';
+                    std.mem.copy(u8, ret[1..], target[offset..]);
+
+                    return .{ .alloc = ret };
+                } else {
+                    log.err("Unexpected Annex: {s}", .{annex});
+                    return .{ .static = "E9999" };
+                }
+
+                return .{ .static = "" };
+            }
+
+            if (substr(self.contents[1..], "Xfer:memory-map:read")) {
+                var tokens = std.mem.tokenize(u8, self.contents[1..], ":,");
+                _ = tokens.next(); // Xfer
+                _ = tokens.next(); // memory-map
+                _ = tokens.next(); // read
+                const offset_str = tokens.next() orelse return .{ .static = "E9999" };
+                const length_str = tokens.next() orelse return .{ .static = "E9999" };
+
+                const offset = try std.fmt.parseInt(usize, offset_str, 16);
+                const length = try std.fmt.parseInt(usize, length_str, 16);
+
+                // see above
+                const len = @min(length, (memory_map.len + 1) - offset);
+                const ret = try allocator.alloc(u8, len);
+
+                ret[0] = if (ret.len < length) 'l' else 'm';
+                std.mem.copy(u8, ret[1..], memory_map[offset..]);
+
+                return .{ .alloc = ret };
+            }
+
+            log.warn("Unimplemented: {s}", .{self.contents});
+            return .{ .static = "" };
+        },
+        else => {
+            log.warn("Unknown:  {s}", .{self.contents});
+
+            return .{ .static = "" };
+        },
+    }
+}
+
+fn substr(haystack: []const u8, needle: []const u8) bool {
+    return std.mem.indexOf(u8, haystack, needle) != null;
+}
+
+pub fn deinit(self: *Self, allocator: Allocator) void {
+    allocator.free(self.contents);
+    self.* = undefined;
+}
+
+pub fn checksum(input: []const u8) u8 {
+    var sum: usize = 0;
+    for (input) |char| sum += char;
+
+    return @truncate(u8, sum);
+}
+
+fn verify(input: []const u8, chksum: u8) bool {
+    return Self.checksum(input) == chksum;
+}
+
+const Signal = enum(u32) {
+    Hup = 1, // Hangup
+    Int, // Interrupt
+    Quit, // Quit
+    Ill, // Illegal Instruction
+    Trap, // Trace/Breakponit trap
+    Abrt, // Aborted
+};

src/Server.zig

@@ -0,0 +1,179 @@
+const std = @import("std");
+const network = @import("network");
+const Packet = @import("Packet.zig");
+
+const Socket = network.Socket;
+const Allocator = std.mem.Allocator;
+const Emulator = @import("lib.zig").Emulator;
+
+const Self = @This();
+const log = std.log.scoped(.Server);
+const port: u16 = 2424;
+
+pub const target: []const u8 =
+    \\<target version="1.0">
+    \\    <architecture>armv4t</architecture>
+    \\    <feature name="org.gnu.gdb.arm.core">
+    \\        <reg name="r0" bitsize="32" type="uint32"/>
+    \\        <reg name="r1" bitsize="32" type="uint32"/>
+    \\        <reg name="r2" bitsize="32" type="uint32"/>
+    \\        <reg name="r3" bitsize="32" type="uint32"/>
+    \\        <reg name="r4" bitsize="32" type="uint32"/>
+    \\        <reg name="r5" bitsize="32" type="uint32"/>
+    \\        <reg name="r6" bitsize="32" type="uint32"/>
+    \\        <reg name="r7" bitsize="32" type="uint32"/>
+    \\        <reg name="r8" bitsize="32" type="uint32"/>
+    \\        <reg name="r9" bitsize="32" type="uint32"/>
+    \\        <reg name="r10" bitsize="32" type="uint32"/>
+    \\        <reg name="r11" bitsize="32" type="uint32"/>
+    \\        <reg name="r12" bitsize="32" type="uint32"/>
+    \\        <reg name="sp" bitsize="32" type="data_ptr"/>
+    \\        <reg name="lr" bitsize="32"/>
+    \\        <reg name="pc" bitsize="32" type="code_ptr"/>
+    \\
+    \\        <reg name="cpsr" bitsize="32" regnum="25"/>
+    \\    </feature>
+    \\</target>
+;
+
+// Game Pak SRAM isn't included
+// TODO: Can i be more specific here?
+pub const memory_map: []const u8 =
+    \\ <memory-map version="1.0">
+    \\     <memory type="rom" start="0x00000000" length="0x00004000"/>
+    \\     <memory type="ram" start="0x02000000" length="0x00040000"/>
+    \\     <memory type="ram" start="0x03000000" length="0x00008000"/>
+    \\     <memory type="ram" start="0x04000000" length="0x00000400"/>
+    \\     <memory type="ram" start="0x05000000" length="0x00000400"/>
+    \\     <memory type="ram" start="0x06000000" length="0x00018000"/>
+    \\     <memory type="ram" start="0x07000000" length="0x00000400"/>
+    \\     <memory type="rom" start="0x08000000" length="0x02000000"/>
+    \\     <memory type="rom" start="0x0A000000" length="0x02000000"/>
+    \\     <memory type="rom" start="0x0C000000" length="0x02000000"/>
+    \\ </memory-map>
+;
+
+// FIXME: Shouldn't this be a Packet Struct?
+pkt_cache: ?[]const u8 = null,
+
+client: Socket,
+_socket: Socket,
+
+emu: Emulator,
+
+pub fn init(emulator: Emulator) !Self {
+    try network.init();
+
+    var socket = try Socket.create(.ipv4, .tcp);
+    try socket.bindToPort(port);
+    try socket.listen();
+
+    var client = try socket.accept(); // TODO: This blocks, is this OK?
+
+    const endpoint = try client.getLocalEndPoint();
+    log.info("client connected from {}", .{endpoint});
+
+    return .{ .emu = emulator, ._socket = socket, .client = client };
+}
+
+pub fn deinit(self: *Self, allocator: Allocator) void {
+    self.reset(allocator);
+
+    self.client.close();
+    self._socket.close();
+    network.deinit();
+
+    self.* = undefined;
+}
+
+const Action = union(enum) {
+    nothing,
+    send: []const u8,
+    retry,
+    ack,
+    nack,
+};
+
+pub fn run(self: *Self, allocator: Allocator) !void {
+    var buf: [Packet.max_len]u8 = undefined;
+
+    while (true) {
+        const len = try self.client.receive(&buf);
+        if (len == 0) break;
+
+        const action = try self.parse(allocator, buf[0..len]);
+        try self.send(allocator, action);
+    }
+}
+
+fn parse(self: *Self, allocator: Allocator, input: []const u8) !Action {
+    // log.debug("-> {s}", .{input});
+
+    return switch (input[0]) {
+        '+' => blk: {
+            if (input.len == 1) break :blk .nothing;
+
+            break :blk switch (input[1]) {
+                '$' => self.handlePacket(allocator, input[1..]),
+                else => std.debug.panic("Unknown: {s}", .{input}),
+            };
+        },
+        '-' => .retry,
+        '$' => try self.handlePacket(allocator, input),
+        '\x03' => .nothing,
+        else => std.debug.panic("Unknown: {s}", .{input}),
+    };
+}
+
+fn handlePacket(self: *Self, allocator: Allocator, input: []const u8) !Action {
+    var packet = Packet.from(allocator, input) catch return .nack;
+    defer packet.deinit(allocator);
+
+    var string = packet.parse(allocator, self.emu) catch return .nack;
+    defer string.deinit(allocator);
+
+    const reply = string.inner();
+
+    // deallocated by the caller
+    const response = try std.fmt.allocPrint(allocator, "+${s}#{x:0>2}", .{ reply, Packet.checksum(reply) });
+
+    return .{ .send = response };
+}
+
+fn send(self: *Self, allocator: Allocator, action: Action) !void {
+    switch (action) {
+        .send => |pkt| {
+            _ = try self.client.send(pkt);
+            // log.debug("<- {s}", .{pkt});
+
+            self.reset(allocator);
+            self.pkt_cache = pkt;
+        },
+        .retry => {
+            log.warn("received nack, resending: \"{?s}\"", .{self.pkt_cache});
+
+            if (self.pkt_cache) |pkt| {
+                _ = try self.client.send(pkt);
+                // log.debug("<- {s}", .{pkt});
+            }
+        },
+        .ack => {
+            _ = try self.client.send("+");
+            // log.debug("<- +", .{});
+
+            self.reset(allocator);
+        },
+        .nack => {
+            _ = try self.client.send("-");
+            // log.debug("<- -", .{});
+
+            self.reset(allocator);
+        },
+        .nothing => self.reset(allocator),
+    }
+}
+
+fn reset(self: *Self, allocator: Allocator) void {
+    if (self.pkt_cache) |pkt| allocator.free(pkt);
+    self.pkt_cache = null;
+}

src/lib.zig

@@ -0,0 +1,81 @@
+/// Re-export of the server interface
+pub const Server = @import("Server.zig");
+
+/// Interface for interacting between GDB and a GBA emu
+pub const Emulator = struct {
+    const Self = @This();
+
+    ptr: *anyopaque,
+
+    readFn: *const fn (*anyopaque, u32) u8,
+    writeFn: *const fn (*anyopaque, u32, u8) void,
+
+    registersFn: *const fn (*anyopaque) *[16]u32,
+    cpsrFn: *const fn (*anyopaque) u32,
+
+    stepFn: *const fn (*anyopaque) void,
+
+    pub fn init(ptr: anytype) Self {
+        const Ptr = @TypeOf(ptr);
+        const ptr_info = @typeInfo(Ptr);
+
+        if (ptr_info != .Pointer) @compileError("ptr must be a pointer");
+        if (ptr_info.Pointer.size != .One) @compileError("ptr must be a single-item pointer");
+
+        const alignment = ptr_info.Pointer.alignment;
+
+        const gen = struct {
+            pub fn readImpl(pointer: *anyopaque, addr: u32) u8 {
+                const self = @ptrCast(Ptr, @alignCast(alignment, pointer));
+
+                return @call(.always_inline, ptr_info.Pointer.child.read, .{ self, addr });
+            }
+
+            pub fn writeImpl(pointer: *anyopaque, addr: u32, value: u8) void {
+                const self = @ptrCast(Ptr, @alignCast(alignment, pointer));
+
+                return @call(.always_inline, ptr_info.Pointer.child.write, .{ self, addr, value });
+            }
+
+            pub fn registersImpl(pointer: *anyopaque) *[16]u32 {
+                const self = @ptrCast(Ptr, @alignCast(alignment, pointer));
+
+                return @call(.always_inline, ptr_info.Pointer.child.registers, .{self});
+            }
+
+            pub fn cpsrImpl(pointer: *anyopaque) u32 {
+                const self = @ptrCast(Ptr, @alignCast(alignment, pointer));
+
+                return @call(.always_inline, ptr_info.Pointer.child.cpsr, .{self});
+            }
+
+            pub fn stepImpl(pointer: *anyopaque) void {
+                const self = @ptrCast(Ptr, @alignCast(alignment, pointer));
+
+                return @call(.always_inline, ptr_info.Pointer.child.step, .{self});
+            }
+        };
+
+        return .{ .ptr = ptr, .readFn = gen.readImpl, .writeFn = gen.writeImpl, .registersFn = gen.registersImpl, .cpsrFn = gen.cpsrImpl, .stepFn = gen.stepImpl };
+    }
+
+    pub inline fn read(self: Self, addr: u32) u8 {
+        return self.readFn(self.ptr, addr);
+    }
+
+    pub inline fn write(self: Self, addr: u32, value: u8) void {
+        self.writeFn(self.ptr, addr, value);
+    }
+
+    pub inline fn registers(self: Self) *[16]u32 {
+        return self.registersFn(self.ptr);
+    }
+
+    pub inline fn cpsr(self: Self) u32 {
+        return self.cpsrFn(self.ptr);
+    }
+
+    pub inline fn step(self: Self) void {
+        self.stepFn(self.ptr);
+    }
+};

src/main.zig

@@ -1,291 +1,18 @@
 const std = @import("std");
-const network = @import("network");
-
-const Allocator = std.mem.Allocator;
-const Socket = network.Socket;
-
-const port: u16 = 2424;
-
-const target: []const u8 =
-    \\<target version="1.0">
-    \\    <architecture>armv4t</architecture>
-    \\    <feature name="org.gnu.gdb.arm.core">
-    \\        <reg name="r0" bitsize="32" type="uint32"/>
-    \\        <reg name="r1" bitsize="32" type="uint32"/>
-    \\        <reg name="r2" bitsize="32" type="uint32"/>
-    \\        <reg name="r3" bitsize="32" type="uint32"/>
-    \\        <reg name="r4" bitsize="32" type="uint32"/>
-    \\        <reg name="r5" bitsize="32" type="uint32"/>
-    \\        <reg name="r6" bitsize="32" type="uint32"/>
-    \\        <reg name="r7" bitsize="32" type="uint32"/>
-    \\        <reg name="r8" bitsize="32" type="uint32"/>
-    \\        <reg name="r9" bitsize="32" type="uint32"/>
-    \\        <reg name="r10" bitsize="32" type="uint32"/>
-    \\        <reg name="r11" bitsize="32" type="uint32"/>
-    \\        <reg name="r12" bitsize="32" type="uint32"/>
-    \\        <reg name="sp" bitsize="32" type="data_ptr"/>
-    \\        <reg name="lr" bitsize="32"/>
-    \\        <reg name="pc" bitsize="32" type="code_ptr"/>
-    \\
-    \\        <reg name="cpsr" bitsize="32" regnum="25"/>
-    \\    </feature>
-    \\</target>
-;
+const Server = @import("gdbstub").Server;
 
 pub fn main() !void {
-    const log = std.log.scoped(.Server);
+    const log = std.log.scoped(.Main);
 
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};
     defer std.debug.assert(!gpa.deinit());
 
     const allocator = gpa.allocator();
 
-    try network.init();
-    defer network.deinit();
+    var server = try Server.init();
+    defer server.deinit(allocator);
 
-    var socket = try Socket.create(.ipv4, .tcp);
-    defer socket.close();
-
-    try socket.bindToPort(port);
-    try socket.listen();
-
-    var client = try socket.accept();
-    defer client.close();
-
-    const endpoint = try client.getLocalEndPoint();
-    log.info("client connected from {}", .{endpoint});
-
-    try gdbStubServer(allocator, client);
+    try server.run(allocator);
 
     log.info("Client disconnected", .{});
 }
-
-fn gdbStubServer(allocator: Allocator, client: Socket) !void {
-    var buf: [Packet.size]u8 = undefined;
-    var previous: ?[]const u8 = null;
-    defer if (previous) |packet| allocator.free(packet);
-
-    while (true) {
-        const len = try client.receive(&buf);
-        if (len == 0) break;
-
-        switch (try parse(allocator, client, previous, buf[0..len])) {
-            .send => |response| {
-                if (previous) |packet| allocator.free(packet);
-                previous = response;
-            },
-            .recv_ack => {
-                if (previous) |packet| allocator.free(packet);
-                previous = null;
-            },
-            .recv_nack => {},
-        }
-    }
-}
-
-const Action = union(enum) {
-    send: []const u8,
-    recv_nack,
-    recv_ack,
-};
-
-fn parse(allocator: Allocator, client: Socket, previous: ?[]const u8, input: []const u8) !Action {
-    const log = std.log.scoped(.GdbStubParser);
-
-    return switch (input[0]) {
-        '+' => .recv_ack,
-        '-' => blk: {
-            if (previous) |packet| {
-                log.warn("received nack, resending: \"{s}\"", .{packet});
-                _ = try client.send(packet);
-            } else {
-                log.err("received nack, but we don't recall sending anything", .{});
-            }
-
-            break :blk .recv_nack;
-        },
-        '$' => blk: {
-            // Packet
-            var packet = try Packet.from(allocator, input);
-            defer packet.deinit(allocator);
-
-            var string = try packet.parse(allocator);
-            defer string.deinit(allocator);
-
-            const reply = string.inner();
-
-            _ = try client.send("+"); // Acknowledge
-
-            // deallocated by the caller
-            const response = try std.fmt.allocPrint(allocator, "${s}#{x:0>2}", .{ reply, Packet.checksum(reply) });
-            _ = try client.send(response);
-
-            break :blk .{ .send = response };
-        },
-        else => std.debug.panic("Unknown: {s}", .{input}),
-    };
-}
-
-const Packet = struct {
-    const Self = @This();
-    const log = std.log.scoped(.Packet);
-    const size: usize = 0x1000;
-
-    contents: []const u8,
-
-    pub fn from(allocator: Allocator, str: []const u8) !Self {
-        var tokens = std.mem.tokenize(u8, str, "$#");
-        const contents = tokens.next() orelse return error.InvalidPacket;
-
-        const chksum_str = tokens.next() orelse return error.MissingCheckSum;
-        const chksum = std.fmt.parseInt(u8, chksum_str, 16) catch return error.InvalidChecksum;
-
-        // log.info("Contents: {s}", .{contents});
-
-        if (!Self.verify(contents, chksum)) return error.ChecksumMismatch;
-
-        return .{ .contents = try allocator.dupe(u8, contents) };
-    }
-
-    const String = union(enum) {
-        alloc: []const u8,
-        static: []const u8,
-
-        pub fn inner(self: *const @This()) []const u8 {
-            return switch (self.*) {
-                .static => |str| str,
-                .alloc => |str| str,
-            };
-        }
-
-        pub fn deinit(self: *@This(), allocator: Allocator) void {
-            switch (self.*) {
-                .alloc => |string| allocator.free(string),
-                .static => {},
-            }
-
-            self.* = undefined;
-        }
-    };
-
-    pub fn parse(self: *Self, allocator: Allocator) !String {
-        switch (self.contents[0]) {
-            // Required
-            '?' => {
-                const ret: Signal = .Trap;
-
-                // Deallocated by the caller
-                return .{ .alloc = try std.fmt.allocPrint(allocator, "T{x:0>2}thread:1;", .{@enumToInt(ret)}) };
-            },
-            'g', 'G' => @panic("TODO: Register Access"),
-            'm', 'M' => @panic("TODO: Memory Access"),
-            'c' => @panic("TODO: Continue"),
-            's' => @panic("TODO: Step"),
-
-            // Optional
-            'H' => {
-                log.warn("{s}", .{self.contents});
-
-                switch (self.contents[1]) {
-                    'g', 'c' => return .{ .static = "OK" },
-                    else => {
-                        log.warn("Unimplemented: {s}", .{self.contents});
-                        return .{ .static = "" };
-                    },
-                }
-            },
-            'v' => {
-                if (substr(self.contents[1..], "MustReplyEmpty")) {
-                    return .{ .static = "" };
-                }
-
-                log.warn("Unimplemented: {s}", .{self.contents});
-                return .{ .static = "" };
-            },
-            'q' => {
-                if (self.contents[1] == 'C' and self.contents.len == 2) return .{ .static = "QC1" };
-                if (substr(self.contents[1..], "fThreadInfo")) return .{ .static = "m1" };
-                if (substr(self.contents[1..], "sThreadInfo")) return .{ .static = "l" };
-                if (substr(self.contents[1..], "Attached")) return .{ .static = "1" }; // Tell GDB we're attached to a process
-
-                if (substr(self.contents[1..], "Supported")) {
-                    const format = "PacketSize={x:};qXfer:features:read+;qXfer:memory-map:read+";
-                    // TODO: Anything else?
-
-                    const ret = try std.fmt.allocPrint(allocator, format, .{Packet.size});
-                    return .{ .alloc = ret };
-                }
-
-                if (substr(self.contents[1..], "Xfer:features:read")) {
-                    var tokens = std.mem.tokenize(u8, self.contents[1..], ":,");
-                    _ = tokens.next(); // qXfer
-                    _ = tokens.next(); // features
-                    _ = tokens.next(); // read
-                    const annex = tokens.next() orelse return .{ .static = "E00" };
-                    const offset_str = tokens.next() orelse return .{ .static = "E00" };
-                    const length_str = tokens.next() orelse return .{ .static = "E00" };
-
-                    if (std.mem.eql(u8, annex, "target.xml")) {
-                        log.info("Providing ARMv4T target description", .{});
-
-                        const offset = try std.fmt.parseInt(usize, offset_str, 16);
-                        const length = try std.fmt.parseInt(usize, length_str, 16);
-
-                        // + 2 to account for the "m " in the response
-                        // subtract offset so that the allocated buffer isn't
-                        // larger than it needs to be TODO: Test this?
-                        const len = @min(length, (target.len + 1) - offset);
-                        const ret = try allocator.alloc(u8, len);
-
-                        ret[0] = if (ret.len < length) 'l' else 'm';
-                        std.mem.copy(u8, ret[1..], target[offset..]);
-
-                        return .{ .alloc = ret };
-                    } else {
-                        log.err("Unexpected Annex: {s}", .{annex});
-                        return .{ .static = "E00" };
-                    }
-
-                    return .{ .static = "" };
-                }
-
-                log.warn("Unimplemented: {s}", .{self.contents});
-                return .{ .static = "" };
-            },
-            else => {
-                log.warn("Unknown:  {s}", .{self.contents});
-
-                return .{ .static = "" };
-            },
-        }
-    }
-
-    fn substr(haystack: []const u8, needle: []const u8) bool {
-        return std.mem.indexOf(u8, haystack, needle) != null;
-    }
-
-    fn deinit(self: *Self, allocator: Allocator) void {
-        allocator.free(self.contents);
-        self.* = undefined;
-    }
-
-    pub fn checksum(input: []const u8) u8 {
-        var sum: usize = 0;
-        for (input) |char| sum += char;
-
-        return @truncate(u8, sum);
-    }
-
-    fn verify(input: []const u8, chksum: u8) bool {
-        return Self.checksum(input) == chksum;
-    }
-};
-
-const Signal = enum(u32) {
-    Hup, // Hangup
-    Int, // Interrupt
-    Quit, // Quit
-    Ill, // Illegal Instruction
-    Trap, // Trace/Breakponit trap
-    Abrt, // Aborted
-};