1 files changed, 50 insertions, 0 deletions
diff --git a/kernel/src/util.rs b/kernel/src/util.rs
new file mode 100644
index 0000000..93c684d
--- /dev/null
+++ b/kernel/src/util.rs
@@ -0,0 +1,50 @@
+//! Miscellaneous utilities.
+
+#[cold]
+#[inline(always)]
+fn cold() {}
+
+/// A hint that `b` is likely to be true. See `core::intrinsics::likely`.
+#[inline(always)]
+pub fn likely(b: bool) -> bool {
+    if !b {
+        cold()
+    }
+    b
+}
+
+/// A hint that `b` is likely to be false. See `core::intrinsics::unlikely`.
+#[inline(always)]
+pub fn unlikely(b: bool) -> bool {
+    if b {
+        cold()
+    }
+    b
+}
+
+/// A version of `std::dbg` built on top of `log::debug` instead of
+/// `std::eprintln`.
+///
+/// This code is copied from libstd, and inherits its copyright.
+#[macro_export]
+macro_rules! dbg {
+    // NOTE: We cannot use `concat!` to make a static string as a format
+    // argument of `log::debug!` because the `$expr` expression could be a
+    // block (`{ .. }`), in which case the format string will be malformed.
+    () => {
+        log::debug!("")
+    };
+    ($expr:expr $(,)?) => {
+        // Use of `match` here is intentional because it affects the lifetimes
+        // of temporaries - https://stackoverflow.com/a/48732525/1063961
+        match $expr {
+            tmp => {
+                log::debug!("{} = {:#?}", core::stringify!($expr), &tmp);
+                tmp
+            }
+        }
+    };
+    ($($expr:expr),+ $(,)?) => {
+        ($($crate::dbg!($expr)),+,)
+    };
+}