From 6bc3fc094bbd1cb0b5a9116ea0294fcefada45db Mon Sep 17 00:00:00 2001
From: Matt Knight <mattnite@protonmail.com>
Date: Sun, 10 Jul 2022 09:03:20 -0700
Subject: [PATCH] add hal or app level clock configuration (#62)

* add hal or app level clock configuration

* fix control flow and typo

* use hal.init(), thanks kuon for the improvement
---
 src/core/empty.zig    |  0
 src/core/microzig.zig |  9 +++++++++
 src/main.zig          | 13 +++++++------
 3 files changed, 16 insertions(+), 6 deletions(-)
 create mode 100644 src/core/empty.zig

diff --git a/src/core/empty.zig b/src/core/empty.zig
new file mode 100644
index 0000000..e69de29
diff --git a/src/core/microzig.zig b/src/core/microzig.zig
index aab89b8..d3decbe 100644
--- a/src/core/microzig.zig
+++ b/src/core/microzig.zig
@@ -176,6 +176,15 @@ export fn microzig_main() noreturn {
     if (info.Fn.calling_convention == .Async)
         @compileError("TODO: Embedded event loop not supported yet. Please try again later.");
 
+    // A hal can export a default init function that runs before main for
+    // procedures like clock configuration. The user may override and customize
+    // this functionality by providing their own init function.
+    // function.
+    if (@hasDecl(app, "init"))
+        app.init()
+    else if (@hasDecl(hal, "init"))
+        hal.init();
+
     if (@typeInfo(return_type) == .ErrorUnion) {
         main() catch |err| {
             // TODO:
diff --git a/src/main.zig b/src/main.zig
index cd30986..af23dbf 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -160,12 +160,13 @@ pub fn addEmbeddedExecutable(
     exe.addPackage(chip_pkg);
     exe.addPackage(cpu_pkg);
 
-    if (options.hal_package_path) |hal_package_path|
-        exe.addPackage(.{
-            .name = "hal",
-            .source = hal_package_path,
-            .dependencies = &.{pkgs.microzig},
-        });
+    exe.addPackage(.{
+        .name = "hal",
+        .source = if (options.hal_package_path) |hal_package_path|
+            hal_package_path
+        else .{ .path = root_path ++ "core/empty.zig" },
+        .dependencies = &.{pkgs.microzig},
+    });
 
     switch (backing) {
         .board => |board| {