libc: impl/libc_lock.h -> bits/_lock.h

Signed-off-by: Ian Moffett <ian@osmora.org>

1 files changed, 62 insertions, 0 deletions

diff --git a/lib/libc/include/bits/_lock.h b/lib/libc/include/bits/_lock.h
new file mode 100644
index 0000000..c6fdcbc
--- /dev/null
+++ b/lib/libc/include/bits/_lock.h
@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2023-2024 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _LIBC_LOCK_H
+#define _LIBC_LOCK_H
+
+#include <bits/_types.h>
+
+typedef struct {
+    volatile __uint8_t lock;
+} __libc_spinlock_t;
+
+#if defined(__x86_64__)
+__attribute__((__always_inline__, __weak__)) inline int
+__test_and_set(__libc_spinlock_t *lock)
+{
+    int tmp = 0;
+
+    __asm__ __volatile__(
+            "lock; cmpxchgb %b2, %0"
+            : "+m" (lock->lock), "+a" (tmp)
+            : "r" (1)
+            : "cc"
+    );
+
+    return tmp;
+}
+#else
+#warn "Unimplemented arch"
+#endif
+
+#define __spinlock_def(NAME) __libc_spinlock_t NAME = {0};
+#define __spinlock_acquire(LOCKPTR) while (__test_and_set(LOCKPTR))
+#define __spinlock_release(LOCKPTR) ((LOCKPTR)->lock = 0)
+
+#endif  /* _LIBC_LOCK_H */