fix: general bug fixes

1) prevent integer overflow if the PC is less than 0x0000_0004
2) gracefully exit when gdb gracefully exits
3) rename server to socket in Server.zig

src/Packet.zig

@@ -3,6 +3,7 @@ const std = @import("std");
 const Allocator = std.mem.Allocator;
 const Emulator = @import("lib.zig").Emulator;
 const State = @import("State.zig");
+const Server = @import("Server.zig");
 
 const target = @import("Server.zig").target;
 const memory_map = @import("Server.zig").memory_map;
@@ -46,7 +47,7 @@ const String = union(enum) {
     }
 };
 
-pub fn parse(self: *Self, allocator: Allocator, emu: *Emulator) !String {
+pub fn parse(self: *Self, allocator: Allocator, state: *Server.State, emu: *Emulator) !String {
     switch (self.contents[0]) {
         // Required
         '?' => return .{ .static = "T05" }, // FIXME: which errno?
@@ -61,7 +62,7 @@ pub fn parse(self: *Self, allocator: Allocator, emu: *Emulator) !String {
                 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
+                    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
@@ -191,6 +192,8 @@ pub fn parse(self: *Self, allocator: Allocator, emu: *Emulator) !String {
         // TODO: Figure out the difference between 'M' and 'X'
         'D' => {
             log.info("Disconnecting...", .{});
+
+            state.should_quit = true;
             return .{ .static = "OK" };
         },
         'H' => return .{ .static = "" },

src/Server.zig

@@ -57,20 +57,23 @@ pub const memory_map: []const u8 =
 // FIXME: Shouldn't this be a Packet Struct?
 pkt_cache: ?[]const u8 = null,
 
-server: Server,
+socket: Server,
+state: State = .{},
 
 emu: Emulator,
 
+pub const State = struct { should_quit: bool = false };
+
 pub fn init(emulator: Emulator) !Self {
     var server = std.net.StreamServer.init(.{});
     try server.listen(std.net.Address.initIp4([_]u8{0} ** 4, port));
 
-    return .{ .emu = emulator, .server = server };
+    return .{ .emu = emulator, .socket = server };
 }
 
 pub fn deinit(self: *Self, allocator: Allocator) void {
     self.reset(allocator);
-    self.server.deinit();
+    self.socket.deinit();
 
     self.* = undefined;
 }
@@ -86,11 +89,13 @@ const Action = union(enum) {
 pub fn run(self: *Self, allocator: Allocator, quit: *Atomic(bool)) !void {
     var buf: [Packet.max_len]u8 = undefined;
 
-    var client = try self.server.accept();
+    var client = try self.socket.accept();
     log.info("client connected from {}", .{client.address});
 
     while (true) {
-        const len = try client.stream.readAll(&buf);
+        if (self.state.should_quit) break;
+
+        const len = try client.stream.read(&buf);
         if (len == 0) break;
 
         if (quit.load(.Monotonic)) break;
@@ -127,7 +132,7 @@ 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;
+    var string = packet.parse(allocator, &self.state, &self.emu) catch return .nack;
     defer string.deinit(allocator);
 
     const reply = string.inner();

src/test.zig

@@ -60,7 +60,7 @@ test Server {
     var server = try Server.init(iface);
     defer server.deinit(allocator);
 
-    const t = try std.Thread.spawn(.{}, clientFn, .{server.server.listen_address});
+    const t = try std.Thread.spawn(.{}, clientFn, .{server.socket.listen_address});
     defer t.join();
 
     var should_quit = std.atomic.Atomic(bool).init(false);