Commit bceab143 authored by Russell King (Oracle)'s avatar Russell King (Oracle)
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ARM: findbit: provide more efficient ARMv7 implementation 



Provide a more efficient ARMv7 implementation to determine the first
set bit in the supplied value.

Signed-off-by: default avatarRussell King (Oracle) <rmk@armlinux.org.uk>
parent 7e009387

arch/arm/lib/findbit.S

+5 −1
Original line number Diff line number Diff line
@@ -170,7 +170,11 @@ ENDPROC(_find_next_bit_be) 
 * One or more bits in the LSB of r3 are assumed to be set.

 */

.L_found:

#if __LINUX_ARM_ARCH__ >= 5

#if __LINUX_ARM_ARCH__ >= 7

		rbit	r3, r3			@ reverse bits

		clz	r3, r3			@ count high zero bits

		add	r0, r2, r3		@ add offset of first set bit

#elif __LINUX_ARM_ARCH__ >= 5

		rsb	r0, r3, #0

		and	r3, r3, r0		@ mask out lowest bit set

		clz	r3, r3			@ count high zero bits