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Commit 838e8bb7 authored by Uros Bizjak's avatar Uros Bizjak Committed by H. Peter Anvin
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x86: Implement change_bit with immediate operand as "lock xorb" 



Impact: Minor optimization.

Implement change_bit with immediate bit count as "lock xorb". This is
similar to  "lock orb" and "lock andb"  for set_bit and clear_bit
functions.

Signed-off-by: default avatarUros Bizjak <ubizjak@gmail.com>
Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
parent a376f30a

arch/x86/include/asm/bitops.h

+9 −1
Original line number Diff line number Diff line
@@ -168,7 +168,15 @@ static inline void __change_bit(int nr, volatile unsigned long *addr) 
 */

static inline void change_bit(int nr, volatile unsigned long *addr)

{

	asm volatile(LOCK_PREFIX "btc %1,%0" : ADDR : "Ir" (nr));

	if (IS_IMMEDIATE(nr)) {

		asm volatile(LOCK_PREFIX "xorb %1,%0"

			: CONST_MASK_ADDR(nr, addr)

			: "iq" ((u8)CONST_MASK(nr)));

	} else {

		asm volatile(LOCK_PREFIX "btc %1,%0"

			: BITOP_ADDR(addr)

			: "Ir" (nr));

	}

}



/**