add __ctzdi2 to sparc64 kernel

If __builtin_ctzl() is used on sparc64, gcc 4.2 will emit a call to
__ctzdi2.  For userland this is in libgcc or compiler-rt.  In the kernel
we put these functions in libkern.

'looks good' deraadt@ miod@

1 files changed, 61 insertions, 0 deletions

diff --git a/sys/lib/libkern/ctzdi2.c b/sys/lib/libkern/ctzdi2.c
new file mode 100644
index 00000000000..495657b6011
--- /dev/null
+++ b/sys/lib/libkern/ctzdi2.c
@@ -0,0 +1,61 @@
+/*	$OpenBSD: ctzdi2.c,v 1.1 2022/12/14 23:50:31 jsg Exp $	*/
+
+/*
+ * Public domain.
+ * Written by Dale Rahn.
+ */
+
+#include <lib/libkern/libkern.h>
+
+/*
+ * ffsl -- vax ffs instruction with long arg
+ */
+
+#ifdef __LP64__
+static int
+ffsl(long mask)
+{
+	int bit;
+	unsigned long r = mask;
+	static const signed char t[16] = {
+		-60, 1, 2, 1,
+		  3, 1, 2, 1,
+		  4, 1, 2, 1,
+		  3, 1, 2, 1
+	};
+
+	bit = 0;
+	if (!(r & 0xffffffff)) {
+		bit += 32;
+		r >>= 32;
+	}
+	if (!(r & 0xffff)) {
+		bit += 16;
+		r >>= 16;
+	}
+	if (!(r & 0xff)) {
+		bit += 8;
+		r >>= 8;
+	}
+	if (!(r & 0xf)) {
+		bit += 4;
+		r >>= 4;
+	}
+
+	return (bit + t[ r & 0xf ]);
+}
+#else
+static int
+ffsl(long mask)
+{
+	return ffs(mask);
+}
+#endif
+
+int
+__ctzdi2(long mask)
+{
+	if (mask == 0)
+		return 0;
+	return ffsl(mask) - 1;
+}