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

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

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 17 insertions, 4 deletions

diff --git a/include/asm-frv/bitops.h b/include/asm-frv/bitops.h
index 980ae1b0cd28..97fb746f76c7 100644
--- a/include/asm-frv/bitops.h
+++ b/include/asm-frv/bitops.h
@@ -161,16 +161,29 @@ static inline int __test_bit(int nr, const volatile void * addr)
 #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>