ring buffer for the keyboard

src/console.zig

@@ -1,9 +1,6 @@
 usingnamespace @import("index.zig");
 
-// shitty ring buffer, fight me.
-var input_ring_buffer: [1024]u8 = [_]u8{0} ** 1024;
-var input_read_index: u10 = 0;
-var input_write_index: u10 = 0;
+var input_ring: Ring(u8) = undefined;
 
 var command: [10]u8 = undefined;
 var command_len: usize = 0;
@@ -52,19 +49,17 @@ pub fn keypress(char: u8) void {
     }
 }
 
-pub fn buffer_write(char: u8) void {
-    input_ring_buffer[input_write_index] = char;
-    input_write_index +%= 1;
+pub fn keyboard_callback(char: u8) void {
+    input_ring.write(char);
 }
 
 pub fn loop() void {
-    ps2.keyboard_callback = buffer_write;
+    input_ring.init() catch unreachable;
+    input_ring.task = task.current_task;
+    ps2.keyboard_callback = keyboard_callback;
     print("> ");
     while (true) {
-        if (input_write_index - input_read_index > 0) {
-            keypress(input_ring_buffer[input_read_index]);
-            input_read_index +%= 1;
-        }
-        // task.usleep(10 * 1000) catch unreachable;
+        while (input_ring.read()) |c| keypress(c);
+        task.block(.IOWait);
     }
 }

src/index.zig

@@ -3,6 +3,7 @@ pub const builtin = @import("builtin");
 pub const std = @import("std");
 pub const assert = std.debug.assert;
 pub usingnamespace @import("delta_queue.zig");
+pub usingnamespace @import("ring_buffer.zig");
 pub usingnamespace @import("vga.zig");
 
 ///arch

src/main.zig

@@ -22,7 +22,7 @@ export fn kmain(magic: u32, info: *const multiboot.MultibootInfo) noreturn {
     println("--- x86 initialization ---");
     x86.x86_main(info);
     println("--- core initialization ---");
-    vmem.initialize();
+    vmem.init();
     pci.scan();
 
     task.cleaner_task = task.new(@ptrToInt(task.cleaner_loop)) catch unreachable;

src/ring_buffer.zig

@@ -0,0 +1,31 @@
+usingnamespace @import("index.zig");
+
+pub fn Ring(comptime T: type) type {
+    return struct {
+        const Self = @This();
+        const Size = u10; // 0-1024
+        const size = @import("std").math.maxInt(Size);
+        buffer: *[size]T,
+        task: ?*task.TaskNode = null,
+        read_index: Size = 0,
+        write_index: Size = 0,
+
+        //TODO: allocator argument and remove the namespace
+        pub fn init(ring: *Self) !void {
+            ring.buffer = try vmem.create(@typeOf(ring.buffer.*));
+        }
+
+        pub fn write(ring: *Self, elem: T) void {
+            ring.buffer[ring.write_index] = elem;
+            ring.write_index +%= 1;
+            if (ring.task) |t| task.unblock(t);
+        }
+
+        pub fn read(ring: *Self) ?T {
+            if (ring.write_index == ring.read_index) return null;
+            const id = ring.read_index;
+            ring.read_index +%= 1;
+            return ring.buffer[id];
+        }
+    };
+}

src/task.zig

@@ -25,11 +25,12 @@ pub fn update_time_used() void {
 }
 
 pub const TaskState = enum {
-    Running,
-    ReadyToRun,
-    Paused,
-    Sleeping,
-    Terminated,
+    Running, // <=> current_task
+    ReadyToRun, // <=> inside of ready_tasks
+    IOWait, // waiting to be woken up by IO
+    Paused, // unpaused arbitrarily by another process
+    Sleeping, // woken up by timer
+    Terminated, // <=> inside of terminated_tasks, waiting to be destroyed
 };
 
 pub const Task = struct {
@@ -124,6 +125,8 @@ pub fn block(state: TaskState) void {
     assert(state != .Running);
     assert(state != .ReadyToRun);
 
+    // println("blocking {} as {}", current_task.data.tid, state);
+
     lock_scheduler();
     defer unlock_scheduler();
 
@@ -134,17 +137,22 @@ pub fn block(state: TaskState) void {
 }
 
 pub fn unblock(node: *TaskNode) void {
+    if (node.data.state != .Paused and node.data.state != .IOWait) return;
     lock_scheduler();
+    defer unlock_scheduler();
+
     node.data.state = .ReadyToRun;
     blocked_tasks.remove(node);
-    if (ready_tasks.first == null) {
-        // Only one task was running before, so pre-empt
-        switch_to(node);
-    } else {
-        // There's at least one task on the "ready to run" queue already, so don't pre-empt
-        ready_tasks.append(node);
-        unlock_scheduler();
-    }
+
+    // TODO: find a way to fastpath here, hard because of unblock inside of interrupts
+    // if (current_task.data.state != .Running and ready_tasks.first == null) {
+    //     // Only one task was running before, fastpath
+    //     switch_to(node);
+    // } else {
+    //     // There's at least one task on the "ready to run" queue already, so don't pre-empt
+    //     ready_tasks.append(node);
+    // }
+    ready_tasks.append(node);
 }
 
 pub fn terminate() void {

src/vmem.zig

@@ -1,4 +1,5 @@
 pub usingnamespace @import("index.zig");
+pub const allocator: std.mem.Allocator = undefined;
 
 // TODO: make a better memory allocator
 // stupid simple virtual memory allocator
@@ -39,7 +40,7 @@ pub fn free(address: usize) void {
     stack_index += 1;
 }
 
-pub fn initialize() void {
+pub fn init() void {
     var addr: usize = layout.HEAP;
     while (addr < layout.HEAP_END) : (addr += x86.PAGE_SIZE) {
         // println("addr {x}", addr);