[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>

diff --git a/include/asm-frv/bitops.h b/include/asm-frv/bitops.h
index 980ae1b0cd285a5578075b0d6e82866f5f7ea047..97fb746f76c7e09ad5e9ba751e75b893433b7341 100644 (file)
--- 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>