Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964900AbWBAJV6 (ORCPT ); Wed, 1 Feb 2006 04:21:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932445AbWBAJUL (ORCPT ); Wed, 1 Feb 2006 04:20:11 -0500 Received: from ns.miraclelinux.com ([219.118.163.66]:74 "EHLO mail01.miraclelinux.com") by vger.kernel.org with ESMTP id S932067AbWBAJDZ (ORCPT ); Wed, 1 Feb 2006 04:03:25 -0500 Message-Id: <20060201090322.422243000@localhost.localdomain> References: <20060201090224.536581000@localhost.localdomain> Date: Wed, 01 Feb 2006 18:02:30 +0900 From: Akinobu Mita To: linux-kernel@vger.kernel.org Cc: Richard Henderson , Ivan Kokshaysky , Russell King , Ian Molton , dev-etrax@axis.com, linux-ia64@vger.kernel.org, Hirokazu Takata , linux-mips@linux-mips.org, parisc-linux@parisc-linux.org, linuxppc-dev@ozlabs.org, linuxsh-dev@lists.sourceforge.net, linuxsh-shmedia-dev@lists.sourceforge.net, sparclinux@vger.kernel.org, ultralinux@vger.kernel.org, Chris Zankel , Akinobu Mita Subject: [patch 06/44] generic __{,test_and_}{set,clear,change}_bit() and test_bit() Content-Disposition: inline; filename=non-atomic-bitops.h Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4521 Lines: 142 This patch introduces the C-language equivalents of the functions below: void __set_bit(int nr, volatile unsigned long *addr); void __clear_bit(int nr, volatile unsigned long *addr); void __change_bit(int nr, volatile unsigned long *addr); int __test_and_set_bit(int nr, volatile unsigned long *addr); int __test_and_clear_bit(int nr, volatile unsigned long *addr); int __test_and_change_bit(int nr, volatile unsigned long *addr); int test_bit(int nr, const volatile unsigned long *addr); In include/asm-generic/bitops/non-atomic.h This code largely copied from: asm-powerpc/bitops.h Signed-off-by: Akinobu Mita include/asm-generic/bitops/non-atomic.h | 111 ++++++++++++++++++++++++++++++++ 1 files changed, 111 insertions(+) Index: 2.6-git/include/asm-generic/bitops/non-atomic.h =================================================================== --- /dev/null +++ 2.6-git/include/asm-generic/bitops/non-atomic.h @@ -0,0 +1,111 @@ +#ifndef _ASM_GENERIC_BITOPS_NON_ATOMIC_H_ +#define _ASM_GENERIC_BITOPS_NON_ATOMIC_H_ + +#include + +#define BITOP_MASK(nr) (1UL << ((nr) % BITS_PER_LONG)) +#define BITOP_WORD(nr) ((nr) / BITS_PER_LONG) + +/** + * __set_bit - Set a bit in memory + * @nr: the bit to set + * @addr: the address to start counting from + * + * Unlike set_bit(), this function is non-atomic and may be reordered. + * If it's called on the same region of memory simultaneously, the effect + * may be that only one operation succeeds. + */ +static __inline__ void __set_bit(int nr, volatile unsigned long *addr) +{ + unsigned long mask = BITOP_MASK(nr); + unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr); + + *p |= mask; +} + +static __inline__ void __clear_bit(int nr, volatile unsigned long *addr) +{ + unsigned long mask = BITOP_MASK(nr); + unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr); + + *p &= ~mask; +} + +/** + * __change_bit - Toggle a bit in memory + * @nr: the bit to change + * @addr: the address to start counting from + * + * Unlike change_bit(), this function is non-atomic and may be reordered. + * If it's called on the same region of memory simultaneously, the effect + * may be that only one operation succeeds. + */ +static __inline__ void __change_bit(int nr, volatile unsigned long *addr) +{ + unsigned long mask = BITOP_MASK(nr); + unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr); + + *p ^= mask; +} + +/** + * __test_and_set_bit - Set a bit and return its old value + * @nr: Bit to set + * @addr: Address to count from + * + * This operation is non-atomic and can be reordered. + * If two examples of this operation race, one can appear to succeed + * but actually fail. You must protect multiple accesses with a lock. + */ +static __inline__ int __test_and_set_bit(int nr, volatile unsigned long *addr) +{ + unsigned long mask = BITOP_MASK(nr); + unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr); + unsigned long old = *p; + + *p = old | mask; + return (old & mask) != 0; +} + +/** + * __test_and_clear_bit - Clear a bit and return its old value + * @nr: Bit to clear + * @addr: Address to count from + * + * This operation is non-atomic and can be reordered. + * If two examples of this operation race, one can appear to succeed + * but actually fail. You must protect multiple accesses with a lock. + */ +static __inline__ int __test_and_clear_bit(int nr, volatile unsigned long *addr) +{ + unsigned long mask = BITOP_MASK(nr); + unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr); + unsigned long old = *p; + + *p = old & ~mask; + return (old & mask) != 0; +} + +/* WARNING: non atomic and it can be reordered! */ +static __inline__ int __test_and_change_bit(int nr, + volatile unsigned long *addr) +{ + unsigned long mask = BITOP_MASK(nr); + unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr); + unsigned long old = *p; + + *p = old ^ mask; + return (old & mask) != 0; +} + +/** + * test_bit - Determine whether a bit is set + * @nr: bit number to test + * @addr: Address to start counting from + */ +static __inline__ int test_bit(int nr, __const__ volatile unsigned long *addr) +{ + return 1UL & (addr[BITOP_WORD(nr)] >> (nr & (BITS_PER_LONG-1))); +} + +#endif /* _ASM_GENERIC_BITOPS_NON_ATOMIC_H_ */ -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/