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authorDavid Howells <dhowells@redhat.com>2006-09-25 23:32:07 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-09-26 08:48:53 -0700
commit92fc707208bb2e601c24b5ab65db37bcb361b658 (patch)
treea0b2d56c30ade74946e9edd74f2d516f475c68f5 /include/asm-frv
parentaf8c65b57aaa4ae321af34dbfc5ca7f5625263fe (diff)
downloadlinux-92fc707208bb2e601c24b5ab65db37bcb361b658.tar.gz
[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>
Diffstat (limited to 'include/asm-frv')
-rw-r--r--include/asm-frv/bitops.h21
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>