--- /dev/null	Sun Jun 21 11:00:58 2026
+++ /sys/src/ape/lib/ap/sparc/atom.c	Sun Jun 21 00:00:00 2026
@@ -0,0 +1,30 @@
+#include "../plan9/lib.h"
+#include "../plan9/sys9.h"
+
+extern int tas(int*);
+
+static int atomlock;
+
+long
+ainc(long *p)
+{
+	long v;
+
+	while(tas(&atomlock))
+		;
+	v = (*p += 1);
+	atomlock = 0;
+	return v;
+}
+
+long
+adec(long *p)
+{
+	long v;
+
+	while(tas(&atomlock))
+		;
+	v = (*p -= 1);
+	atomlock = 0;
+	return v;
+}
--- /n/sources/plan9/sys/src/ape/lib/ap/sparc/mkfile	Thu Sep 19 10:50:10 2013
+++ /sys/src/ape/lib/ap/sparc/mkfile	Sun Jun 21 00:00:00 2026
@@ -2,7 +2,7 @@
 <$APE/config
 LIB=/$objtype/lib/ape/libap.a
 OFILES=\
-#	atom.$O\
+	atom.$O\
 	cycles.$O\
 	lock.$O\
 	main9.$O\