From 9faa11cddcf2a9fad24aa057fe55d37427ab739f Mon Sep 17 00:00:00 2001
From: Max Wash <mbswash@gmail.com>
Date: Tue, 24 Mar 2026 19:09:36 +0000
Subject: [PATCH] kernel: add atomic operations

---
 include/kernel/atomic.h | 66 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 include/kernel/atomic.h

diff --git a/include/kernel/atomic.h b/include/kernel/atomic.h
new file mode 100644
index 0000000..0230c99
--- /dev/null
+++ b/include/kernel/atomic.h
@@ -0,0 +1,66 @@
+#ifndef KERNEL_ATOMIC_H_
+#define KERNEL_ATOMIC_H_
+
+#include <stdbool.h>
+#include <stdint.h>
+
+typedef int64_t atomic_t;
+
+/* load and return the value pointed to by `v` */
+static inline atomic_t atomic_load(atomic_t *v)
+{
+	return __atomic_load_n(v, __ATOMIC_ACQUIRE);
+}
+/* store the value `v` to the pointer `dest` */
+static inline void atomic_store(atomic_t *dest, atomic_t v)
+{
+	__atomic_store_n(dest, v, __ATOMIC_ACQUIRE);
+}
+/* store the value `v` to the pointer `dest`, and return the value previously
+ * stored at `dest` */
+static inline atomic_t atomic_exchange(atomic_t *dest, atomic_t v)
+{
+	return __atomic_exchange_n(dest, v, __ATOMIC_ACQUIRE);
+}
+/* compare the contents of `ptr` to the contents of `expected`.
+ * if they match, store the value `desired` to the pointer `ptr` and return
+ * true. if the do NOT match, store the value `*ptr` to the pointer `desired`
+ * and return false.
+ */
+static inline bool atomic_compare_exchange(
+	atomic_t *ptr,
+	atomic_t *expected,
+	atomic_t desired)
+{
+	return __atomic_compare_exchange_n(
+		ptr,
+		expected,
+		desired,
+		false,
+		__ATOMIC_ACQUIRE,
+		__ATOMIC_ACQUIRE);
+}
+
+/* perform the operation *ptr += val, and return the result */
+static inline atomic_t atomic_add_fetch(atomic_t *ptr, atomic_t val)
+{
+	return __atomic_add_fetch(ptr, val, __ATOMIC_ACQUIRE);
+}
+/* perform the operation *ptr -= val, and return the result */
+static inline atomic_t atomic_sub_fetch(atomic_t *ptr, atomic_t val)
+{
+	return __atomic_sub_fetch(ptr, val, __ATOMIC_ACQUIRE);
+}
+
+/* perform the operation *ptr += val, and return the previous value of *ptr */
+static inline atomic_t atomic_fetch_add(atomic_t *ptr, atomic_t val)
+{
+	return __atomic_fetch_add(ptr, val, __ATOMIC_ACQUIRE);
+}
+/* perform the operation *ptr -= val, and return the previous value of *ptr */
+static inline atomic_t atomic_fetch_sub(atomic_t *ptr, atomic_t val)
+{
+	return __atomic_fetch_sub(ptr, val, __ATOMIC_ACQUIRE);
+}
+
+#endif