add clock interface

Author: piotrfila

examples/raspberrypi/rp2xxx/src/async_blinky.zig

@@ -3,7 +3,6 @@ const microzig = @import("microzig");
 const time = microzig.drivers.time;
 
 const rp2xxx = microzig.hal;
-const get_time_since_boot = rp2xxx.time.get_time_since_boot;
 const Io = rp2xxx.Io;
 
 pub const microzig_options = microzig.Options{
@@ -24,7 +23,7 @@ const uart = rp2xxx.uart.instance.num(0);
 
 // Blink the led with given half-period.
 fn task_blink(io: *Io.RoundRobin, delay: u32) callconv(.c) noreturn {
-    var deadline: time.Absolute = get_time_since_boot();
+    var deadline: time.Absolute = io.monotonic_clock();
     while (true) {
         pins.led.toggle();
         deadline = deadline.add_duration(.from_us(delay));
@@ -50,7 +49,7 @@ pub fn main() !void {
     io.async(task_blink, .{ &io, 24_000 });
     io.async(task_blink, .{ &io, 25_000 });
 
-    var deadline: time.Absolute = get_time_since_boot();
+    var deadline: time.Absolute = io.monotonic_clock();
     var cnt: u32 = 0;
     while (true) {
         try uart.writer().print("Hello! {}\r\n", .{cnt});

port/raspberrypi/rp2xxx/src/hal/Io.zig

@@ -35,6 +35,7 @@ pub const PauseReason = union(enum) {
     /// Task volutarily gave up execution, but is ready to continue.
     yield,
     sleep_until: time.Absolute align(@alignOf(StackUint)),
+    bits_mask_any_high: struct { ptr: *const usize, mask: usize },
     /// This value means there is no context stored on this stack
     /// so it can be used to launch a new task.
     no_task,
@@ -46,11 +47,13 @@ pub const PauseReason = union(enum) {
     /// Check if the task should be resumed.
     /// The io interface may not be necessary.
     pub fn can_resume(this: *const @This(), io: anytype) bool {
-        _ = io;
         return switch (this.*) {
             .no_task => false,
             .yield => true,
-            .sleep_until => |t| t.is_reached_by(rp2xxx.time.get_time_since_boot()),
+            .bits_mask_any_high => |info| {
+                return @atomicLoad(usize, info.ptr, .acquire) & info.mask != 0;
+            },
+            .sleep_until => |t| t.is_reached_by(io.monotonic_clock()),
         };
     }
 
@@ -300,4 +303,9 @@ pub const RoundRobin = struct {
         // Maybe we could wait for them to complete instead?
         std.debug.panic("Cannot launch more tasks.", .{});
     }
+
+    pub fn monotonic_clock(this: *@This()) time.Absolute {
+        _ = this;
+        return rp2xxx.time.get_time_since_boot();
+    }
 };