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| author | Russell King (Oracle) <rmk+kernel@armlinux.org.uk> | 2022-07-29 17:10:49 +0200 |
|---|---|---|
| committer | Russell King (Oracle) <rmk+kernel@armlinux.org.uk> | 2022-11-14 13:00:58 +0100 |
| commit | bceab1431e0789794cbcc8bb71d500a74c8213f2 (patch) | |
| tree | a736f5f081dd3f1f74f010fb188d8ecce9b121c5 /arch | |
| parent | ARM: findbit: document ARMv5 bit offset calculation (diff) | |
| download | linux-bceab1431e0789794cbcc8bb71d500a74c8213f2.tar.xz linux-bceab1431e0789794cbcc8bb71d500a74c8213f2.zip | |
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: Russell King (Oracle) <rmk@armlinux.org.uk>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm/lib/findbit.S | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/arch/arm/lib/findbit.S b/arch/arm/lib/findbit.S index 4c584bc4704b..256e095d490b 100644 --- a/arch/arm/lib/findbit.S +++ b/arch/arm/lib/findbit.S @@ -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 |