Change spinlock_trylock to arch-agnostic atomic implementation

Author: darcagn

include/kos/spinlock.h

@@ -26,16 +26,14 @@
 #include <kos/cdefs.h>
 __BEGIN_DECLS
 
+#include <stdatomic.h>
 #include <stdbool.h>
 #include <kos/thread.h>
 
 
 /** \brief  Spinlock data type. */
 typedef volatile int spinlock_t;
 
-/* Include architecture-specific implementations */
-#include <arch/spinlock.h>
-
 /** \brief  Spinlock initializer.
 
     All created spinlocks should be initialized with this initializer so that
@@ -67,7 +65,14 @@ static inline void spinlock_init(spinlock_t *lock) {
                             the lock was successfully obtained.
 */
 static inline bool spinlock_trylock(spinlock_t *lock) {
-    return arch_spinlock_trylock(lock);
+    int locked = 0;
+    return atomic_compare_exchange_strong_explicit(
+        lock,
+        &locked,
+        1,
+        memory_order_acquire,
+        memory_order_relaxed
+    );
 }
 
 /** \brief  Spin on a lock.

kernel/arch/dreamcast/include/arch/spinlock.h

@@ -1,40 +1,10 @@
 /* KallistiOS ##version##
 
-   arch/dreamcast/include/arch/spinlock.h
-   Copyright (C) 2001 Megan Potter
+   kernel/arch/dreamcast/include/arch/spinlock.h
 
 */
 
-#ifndef __KOS_SPINLOCK_H
-#pragma GCC warning "The `<arch/spinlock.h>` header has been moved to `<kos/spinlock.h>`."
 #include <kos/spinlock.h>
-#endif
 
-#ifndef __ARCH_SPINLOCK_H
-#define __ARCH_SPINLOCK_H
+#warning "The `<arch/spinlock.h>` header has been moved to `<kos/spinlock.h>`."
 
-/* Defines processor specific spinlock implementation */
-
-#include <stdbool.h>
-
-/* Use a test-and-set to attempt to acquire a lock atomically.
-   In one instruction, tas.b writes 0x80 to the spinlock and
-   sets T flag to 1 if if the previous value was zero, or sets
-   0 if the previous value was non-zero. Therefore, this function
-   returns true if we've successfully locked the spinlock, or
-   false if the spinlock was already taken.
-*/
-
-static inline bool arch_spinlock_trylock(spinlock_t *lock) {
-    bool locked = false;
-
-    __asm__ __volatile__("tas.b @%2\n\t"
-                         "movt %0\n\t"
-                         : "=r"(locked), "=m"(*lock)
-                         : "r"(lock)
-                         : "t");
-
-    return locked;
-}
-
-#endif  /* __ARCH_SPINLOCK_H */