refactor internal atomic.h

rather than having each arch provide its own atomic.h, there is a new
shared atomic.h in src/internal which pulls arch-specific definitions
from arc/$(ARCH)/atomic_arch.h. the latter can be extremely minimal,
defining only a_cas or new ll/sc type primitives which the shared
atomic.h will use to construct everything else.

this commit avoids making heavy changes to the individual archs'
atomic implementations. definitions which are identical or
near-identical to what the new shared atomic.h would produce have been
removed, but otherwise the changes made are just hooking up the
arch-specific files to the new infrastructure. major changes to take
advantage of the new system will come in subsequent commits.

1 files changed, 15 insertions, 0 deletions

diff --git a/arch/powerpc/atomic_arch.h b/arch/powerpc/atomic_arch.h
new file mode 100644
index 00000000..f014e3b8
--- /dev/null
+++ b/arch/powerpc/atomic_arch.h
@@ -0,0 +1,15 @@
+#define a_cas a_cas
+static inline int a_cas(volatile int *p, int t, int s)
+{
+	__asm__("\n"
+		"	sync\n"
+		"1:	lwarx %0, 0, %4\n"
+		"	cmpw %0, %2\n"
+		"	bne 1f\n"
+		"	stwcx. %3, 0, %4\n"
+		"	bne- 1b\n"
+		"	isync\n"
+		"1:	\n"
+		: "=&r"(t), "+m"(*p) : "r"(t), "r"(s), "r"(p) : "cc", "memory" );
+        return t;
+}