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[U-Boot,2/5] arm: add __ilog2 function

Message ID 1308692003-2488-3-git-send-email-robherring2@gmail.com
State Changes Requested
Headers show

Commit Message

Rob Herring June 21, 2011, 9:33 p.m. UTC 
From: Rob Herring <rob.herring@calxeda.com>

Add __ilog2 function for ARM. Needed for ahci.c

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Cc: Albert ARIBAUD <albert.aribaud@free.fr>
---
 arch/arm/include/asm/bitops.h |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)
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Patch

diff --git a/arch/arm/include/asm/bitops.h b/arch/arm/include/asm/bitops.h
index 270f163..0420182 100644
--- a/arch/arm/include/asm/bitops.h
+++ b/arch/arm/include/asm/bitops.h
@@ -106,6 +106,15 @@  static inline int test_bit(int nr, const void * addr)
     return ((unsigned char *) addr)[nr >> 3] & (1U << (nr & 7));
 }
 
+extern __inline__ int __ilog2(unsigned int x)
+{
+	int ret;
+
+	asm("clz\t%0, %1" : "=r" (ret) : "r" (x));
+	ret = 31 - ret;
+	return ret;
+}
+
 /*
  * ffz = Find First Zero in word. Undefined if no zero exists,
  * so code should check against ~0UL first..