[PATCH 1/6] FRV: Fix fls() to handle bit 31 being set correctly

David Howells
2006-09-13T13:03:10Z

From: David Howells <dhowells@redhat.com>

Fix FRV fls() to handle bit 31 being set correctly (it should return 32 not 0).

Signed-Off-By: David Howells <dhowells@redhat.com>
---

include/asm-frv/bitops.h | 21 +++++++++++++++++----
1 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/include/asm-frv/bitops.h b/include/asm-frv/bitops.h
index 980ae1b..97fb746 100644
--- a/include/asm-frv/bitops.h
+++ b/include/asm-frv/bitops.h
@@ -161,16 +161,29 @@ #include <asm-generic/bitops/ffs.h>
#include <asm-generic/bitops/__ffs.h>
#include <asm-generic/bitops/find.h>

-/*
- * fls: find last bit set.
+/**
+ * fls - find last bit set
+ * @x: the word to search
+ *
+ * This is defined the same way as ffs:
+ * - return 32..1 to indicate bit 31..0 most significant bit set
+ * - return 0 to indicate no bits set
*/
#define fls(x) \
({ \
int bit; \
\
- asm("scan %1,gr0,%0" : "=r"(bit) : "r"(x)); \
+ asm(" subcc %1,gr0,gr0,icc0 \n" \
+ " ckne icc0,cc4 \n" \
+ " cscan.p %1,gr0,%0 ,cc4,#1 \n" \
+ " csub %0,%0,%0 ,cc4,#0 \n" \
+ " csub %2,%0,%0 ,cc4,#1 \n" \
+ : "=&r"(bit) \
+ : "r"(x), "r"(32) \
+ : "icc0", "cc4" \
+ ); \
\
- bit ? 33 - bit : bit; \
+ bit; \
})

#include <asm-generic/bitops/fls64.h>