move almost all functionality into core

Author: piotrfila

core/src/core.zig

@@ -1,5 +1,6 @@
 pub const experimental = @import("core/experimental.zig");
 pub const heap = @import("core/heap.zig");
+pub const Io = @import("core/Io.zig");
 /// USB data types and helper functions
 pub const usb = @import("core/usb.zig");
 

port/raspberrypi/rp2xxx/src/hal/Io.zig renamed to core/src/core/Io.zig

@@ -1,13 +1,8 @@
-//! I'm not sure how much of this functionality could be moved into core.
-//! Context switches could probably made available project-wide,
-//! but that might be enough scope for a separate project.
-
 const builtin = @import("builtin");
 const std = @import("std");
-const microzig = @import("microzig");
+const drivers = @import("drivers");
 const assert = std.debug.assert;
-const rp2xxx = microzig.hal;
-const time = microzig.drivers.time;
+const time = drivers.time;
 
 /// Unsigned integer with the same alignment as the stack.
 const StackUint = usize;
@@ -271,6 +266,7 @@ pub fn prepare_task_stack(comptime F: type, f: *const F, stack: *PauseReason) st
 pub const RoundRobin = struct {
     next_swap: usize,
     tasks: []*PauseReason,
+    vtable: VTable,
 
     /// Pause the current task allow others to run.
     pub fn pause(this: *@This(), reason: *const PauseReason) void {
@@ -305,7 +301,13 @@ pub const RoundRobin = struct {
     }
 
     pub fn monotonic_clock(this: *@This()) time.Absolute {
-        _ = this;
-        return rp2xxx.time.get_time_since_boot();
+        return this.vtable.monotonic_clock();
     }
 };
+
+/// Common functionality between all implementations.
+/// Needs to be specified by every port.
+pub const VTable = struct {
+    /// A clock source that only ever goes up, not synchronized with epoch.
+    monotonic_clock: *const fn () time.Absolute,
+};

examples/raspberrypi/rp2xxx/src/async_blinky.zig

@@ -1,9 +1,9 @@
 const std = @import("std");
 const microzig = @import("microzig");
 const time = microzig.drivers.time;
+const Io = microzig.core.Io;
 
 const rp2xxx = microzig.hal;
-const Io = rp2xxx.Io;
 
 pub const microzig_options = microzig.Options{
     .log_level = .info,
@@ -43,7 +43,7 @@ pub fn main() !void {
     for (&task_stacks, &task_stacks_data) |*dst, *src|
         dst.* = Io.prepare_empty_stack(src);
 
-    var io: Io.RoundRobin = .{ .next_swap = 0, .tasks = &task_stacks };
+    var io: Io.RoundRobin = .{ .next_swap = 0, .tasks = &task_stacks, .vtable = rp2xxx.Io.vtable };
 
     // Mixing (xoring) two squarewaves of almost the same frequency produces a beat frequency.
     io.async(task_blink, .{ &io, 24_000 });

port/raspberrypi/rp2xxx/src/hal.zig

@@ -19,7 +19,11 @@ pub const dma = @import("hal/dma.zig");
 pub const drivers = @import("hal/drivers.zig");
 pub const flash = @import("hal/flash.zig");
 pub const gpio = @import("hal/gpio.zig");
-pub const Io = @import("hal/Io.zig");
+pub const Io = struct {
+    pub const vtable: microzig.core.Io.VTable = .{
+        .monotonic_clock = time.get_time_since_boot,
+    };
+};
 pub const multicore = @import("hal/multicore.zig");
 pub const mutex = @import("hal/mutex.zig");
 pub const pins = @import("hal/pins.zig");