From: Akinobu Mita <mita@miraclelinux•com>
To: linux-kernel@vger•kernel.org
Cc: Akinobu Mita <mita@miraclelinux•com>,
linux-mips@linux-mips•org, dev-etrax@axis•com,
linux-ia64@vger•kernel.org, ultralinux@vger•kernel.org,
Ian Molton <spyro@f2s•com>,
Hirokazu Takata <takata@linux-m32r•org>,
linuxsh-shmedia-dev@lists•sourceforge.net,
linuxppc-dev@ozlabs•org,
Ivan Kokshaysky <ink@jurassic•park.msu.ru>,
linuxsh-dev@lists•sourceforge.net, sparclinux@vger•kernel.org,
Chris Zankel <chris@zankel•net>,
parisc-linux@parisc-linux•org,
Russell King <rmk@arm•linux.org.uk>,
Richard Henderson <rth@twiddle•net>
Subject: [patch 06/44] generic __{, test_and_}{set, clear, change}_bit() and test_bit()
Date: Wed, 01 Feb 2006 18:02:30 +0900 [thread overview]
Message-ID: <20060201090322.422243000@localhost.localdomain> (raw)
In-Reply-To: 20060201090224.536581000@localhost.localdomain
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 <mita@miraclelinux•com>
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 <asm/types.h>
+
+#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_ */
--
next parent reply other threads:[~2006-02-01 9:03 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20060201090224.536581000@localhost.localdomain>
2006-02-01 9:02 ` Akinobu Mita [this message]
2006-02-01 9:02 ` [patch 10/44] generic fls64() Akinobu Mita
2006-02-01 9:02 ` [patch 12/44] generic sched_find_first_bit() Akinobu Mita
2006-02-03 3:58 ` [parisc-linux] " Grant Grundler
2006-02-01 9:02 ` [patch 14/44] generic hweight{64,32,16,8}() Akinobu Mita
2006-02-01 9:06 ` Andi Kleen
2006-02-01 9:26 ` Michael Tokarev
2006-02-01 10:24 ` Andi Kleen
2006-02-02 12:50 ` Akinobu Mita
2006-02-02 1:26 ` Gabriel Paubert
2006-02-06 11:52 ` Akinobu Mita
2006-02-03 8:31 ` Ulrich Eckhardt
2006-02-01 9:02 ` [patch 31/44] powerpc: use generic bitops Akinobu Mita
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