-// Low-level functions for atomic operations: m680x0, x >= 2 version -*- C++ -*-
+// Low-level functions for atomic operations: m68k version -*- C++ -*-
-// Copyright (C) 2001 Free Software Foundation, Inc.
+// Copyright (C) 2001, 2002 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
typedef int _Atomic_word;
+#if defined(__mc68020__) || defined(__mc68030__) \
+ || defined(__mc68040__) || defined(__mc68060__)
+// These variants support compare-and-swap.
+
static inline _Atomic_word
__attribute__ ((__unused__))
__exchange_and_add (volatile _Atomic_word *__mem, int __val)
{
register _Atomic_word __result = *__mem;
register _Atomic_word __temp;
- __asm__ __volatile__ ("1: move%.l %0,%1;"
- " add%.l %2,%1;"
- " cas%.l %0,%1,%3;"
- " jbne 1b"
+ __asm__ __volatile__ ("1: move%.l %0,%1\n\t"
+ "add%.l %2,%1\n\t"
+ "cas%.l %0,%1,%3\n\t"
+ "jbne 1b"
: "=d" (__result), "=&d" (__temp)
: "d" (__val), "m" (*__mem), "0" (__result)
: "memory");
return __result;
}
+#elif !defined(__mcf5200__) && !defined(__mcf5300__)
+// 68000, 68010, cpu32 and 5400 support test-and-set.
+
+template <int __inst>
+struct __Atomicity_lock
+{
+ static volatile unsigned char _S_atomicity_lock;
+};
+
+template <int __inst>
+volatile unsigned char __Atomicity_lock<__inst>::_S_atomicity_lock = 0;
+
+template volatile unsigned char __Atomicity_lock<0>::_S_atomicity_lock;
+
+static inline _Atomic_word
+__attribute__ ((__unused__))
+__exchange_and_add (volatile _Atomic_word *__mem, int __val)
+{
+ _Atomic_word __result;
+
+ __asm__ __volatile__("1: tas %0\n\tjbne 1b"
+ : "=m"(__Atomicity_lock<0>::_S_atomicity_lock)
+ : "m"(__Atomicity_lock<0>::_S_atomicity_lock));
+
+ __result = *__mem;
+ *__mem = __result + __val;
+
+ __Atomicity_lock<0>::_S_atomicity_lock = 0;
+
+ return __result;
+}
+
+#else
+// These variants do not support any atomic operations at all.
+// The best we can hope for is to disable interrupts, which we
+// can only do from supervisor mode.
+
+#if defined(__rtems__) || defined(__vxWorks__) || defined(__embedded__)
+static inline _Atomic_word
+__attribute__ ((__unused__))
+__exchange_and_add (volatile _Atomic_word *__mem, int __val)
+{
+ _Atomic_word __result;
+ short __level, __tmpsr;
+ __asm__ __volatile__ ("move%.w %%sr,%0\n\tor%.l %0,%1\n\tmove%.w %1,%%sr"
+ : "=d"(__level), "=d"(__tmpsr) : "1"(0x700));
+
+ __result = *__mem;
+ *__mem = __result + __val;
+
+ __asm__ __volatile__ ("move%.w %0,%%sr" : : "d"(__level));
+
+ return __result;
+}
+#else
+#warning "__exchange_and_add is not atomic for this target"
+
+static inline _Atomic_word
+__attribute__ ((__unused__))
+__exchange_and_add (volatile _Atomic_word *__mem, int __val)
+{
+ _Atomic_word __result;
+
+ __result = *__mem;
+ *__mem = __result + __val;
+
+ return __result;
+}
+
+#endif /* embedded */
+#endif /* CAS / TAS / IRQ */
+
static inline void
__attribute__ ((__unused__))
__atomic_add (volatile _Atomic_word* __mem, int __val)
{
- __asm__ __volatile__ ("add%.l %0,%1"
- : : "id" (__val), "m" (*__mem) : "memory");
+ // Careful: using add.l with a memory destination is not
+ // architecturally guaranteed to be atomic.
+ (void) __exchange_and_add (__mem, __val);
}
#endif /* atomicity.h */
-
-