ppc: Modernize atomic.S.

* Stub out atomic_get_and_set. This needs completed.

src/system/libroot/os/arch/ppc/atomic.S

@@ -3,7 +3,7 @@
  * Distributed under the terms of the MIT License.
  */
 
-#define FUNCTION(x) .global x; .type x,@function; x
+#include <asm_defs.h>
 
 .text
 
@@ -17,6 +17,7 @@ lost1:	lwarx	%r5, 0, %r3		// reserve memory address located in "r3"
 		bne-	lost1			// try again if reservation was lost
 		mr		%r3, %r5		// return old value (was in "r5")
 		blr
+FUNCTION_END(atomic_add)
 
 /* int atomic_and(int *value, int andValue)
  * (r3)           r3          r4
@@ -28,6 +29,7 @@ lost2:	lwarx	%r5, 0, %r3
 		bne-	lost2
 		mr		%r3, %r5
 		blr
+FUNCTION_END(atomic_and)
 
 /* int atomic_or(int *value, int orValue)
  * (r3)          r3          r4
@@ -39,6 +41,7 @@ lost3:	lwarx	%r5, 0, %r3
 		bne-	lost3
 		mr		%r3, %r5
 		blr
+FUNCTION_END(atomic_or)
 
 /* int atomic_set(int *value, int setTo)
  * (r3)           r3          r4
@@ -49,6 +52,7 @@ lost4:	lwarx	%r5, 0, %r3
 		bne-	lost4
 		mr		%r3, %r5
 		blr
+FUNCTION_END(atomic_set)
 
 /* int atomic_test_and_set(int *value, int setTo, int testValue)
  * (r3)                    r3          r4         r5
@@ -61,6 +65,13 @@ lost5:	lwarx	%r6, 0, %r3
 		bne-	lost5
 out5:	mr		%r3, %r6
 		blr
+FUNCTION_END(atomic_test_and_set)
+
+// TODO: PowerPC atomic_get_and_set
+FUNCTION(atomic_get_and_set):
+		sync
+		blr
+FUNCTION_END(atomic_get_and_set)
 
 /* int atomic_get(int *value)
  * (r3)           r3
@@ -71,3 +82,4 @@ lost6:	lwarx	%r5, 0, %r3
 		bne-	lost6
 		mr		%r3, %r5
 		blr
+FUNCTION_END(atomic_get)