From d5e66caf2180324d83ad9be30e887849f5ed74da Mon Sep 17 00:00:00 2001
From: Rekai Musuka <rekai@musuka.dev>
Date: Fri, 10 Mar 2023 02:01:26 -0600
Subject: [PATCH] feat: implement a 2-way channel for message passing

---
 src/lib.zig | 33 +++++++++++++++++++++++++++------
 1 file changed, 27 insertions(+), 6 deletions(-)

diff --git a/src/lib.zig b/src/lib.zig
index 4df9855..037422b 100644
--- a/src/lib.zig
+++ b/src/lib.zig
@@ -1,8 +1,29 @@
 const std = @import("std");
-
 const Log2Int = std.math.Log2Int;
 
-pub fn Channel(comptime T: type) type {
+const EmuMessage = enum { Pause, Resume, Quit };
+const GuiMessage = enum { Paused, Quit };
+
+pub const TwoWayChannel = struct {
+    const Self = @This();
+
+    emu: Channel(EmuMessage),
+    gui: Channel(GuiMessage),
+
+    pub fn init(items: []u8) Self {
+        comptime std.debug.assert(@sizeOf(EmuMessage) == @sizeOf(GuiMessage));
+        comptime std.debug.assert(@sizeOf(@typeInfo([]u8).Pointer.child) == @sizeOf(EmuMessage));
+
+        std.debug.assert(items.len % 2 == 0);
+
+        const left = @ptrCast([*]EmuMessage, items)[0 .. items.len / 2];
+        const right = @ptrCast([*]GuiMessage, items)[items.len / 2 .. items.len];
+
+        return .{ .emu = Channel(EmuMessage).init(left), .gui = Channel(GuiMessage).init(right) };
+    }
+};
+
+fn Channel(comptime T: type) type {
     return struct {
         const Self = @This();
         const Index = usize;
@@ -29,12 +50,12 @@ pub fn Channel(comptime T: type) type {
             };
         }
 
-        pub fn push(self: *Self, value: T) Error!void {
+        pub fn push(self: *Self, value: T) void {
             const read_idx = self.read.load(.Acquire);
             const write_idx = self.write.load(.Acquire);
 
             // Check to see if Queue is full
-            if (write_idx - read_idx == self.buf.len) return Error.buffer_full;
+            if (write_idx - read_idx == self.buf.len) @panic("Channel: Buffer is full");
 
             self.buf[self.mask(write_idx)] = value;
 
@@ -49,7 +70,7 @@ pub fn Channel(comptime T: type) type {
             if (read_idx == write_idx) return null;
 
             std.atomic.fence(.Acquire);
-            const value = self.buf[self.mask(self.read)];
+            const value = self.buf[self.mask(read_idx)];
 
             std.atomic.fence(.Release);
             self.read.store(read_idx + 1, .Release);
@@ -159,4 +180,4 @@ pub inline fn rotr(comptime T: type, x: T, r: anytype) T {
 
     const ar = @intCast(Log2Int(T), @mod(r, @typeInfo(T).Int.bits));
     return x >> ar | x << (1 +% ~ar);
-}
\ No newline at end of file
+}