[PATCH] Bit operations

From: dhowells
Date: Mon Nov 08 2004 - 09:50:47 EST


The attached patch provides an out-of-line implementation of find_next_bit()
and rearranges linux/bitops.h to avoid a dependency loop between inline
functions in there and in asm/bitops.h trying to include one another.

Signed-Off-By: dhowells@xxxxxxxxxx
---
diffstat bitops-2610rc1mm3.diff
include/linux/bitops.h | 3 +-
lib/Makefile | 1
lib/find_next_bit.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 58 insertions(+), 1 deletion(-)

diff -uNrp /warthog/kernels/linux-2.6.10-rc1-mm3/include/linux/bitops.h linux-2.6.10-rc1-mm3-frv/include/linux/bitops.h
--- /warthog/kernels/linux-2.6.10-rc1-mm3/include/linux/bitops.h 2004-06-18 13:42:16.000000000 +0100
+++ linux-2.6.10-rc1-mm3-frv/include/linux/bitops.h 2004-11-05 14:13:04.362457008 +0000
@@ -1,7 +1,6 @@
#ifndef _LINUX_BITOPS_H
#define _LINUX_BITOPS_H
#include <asm/types.h>
-#include <asm/bitops.h>

/*
* ffs: find first bit set. This is defined the same way as
@@ -71,6 +70,8 @@ extern __inline__ int generic_fls(int x)
return r;
}

+#include <asm/bitops.h>
+
extern __inline__ int get_bitmask_order(unsigned int count)
{
int order;
diff -uNrp /warthog/kernels/linux-2.6.10-rc1-mm3/lib/find_next_bit.c linux-2.6.10-rc1-mm3-frv/lib/find_next_bit.c
--- /warthog/kernels/linux-2.6.10-rc1-mm3/lib/find_next_bit.c 1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.10-rc1-mm3-frv/lib/find_next_bit.c 2004-11-05 14:13:04.571439356 +0000
@@ -0,0 +1,55 @@
+/* find_next_bit.c: fallback find next bit implementation
+ *
+ * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@xxxxxxxxxx)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/bitops.h>
+
+int find_next_bit(const unsigned long *addr, int size, int offset)
+{
+ const unsigned long *base;
+ const int NBITS = sizeof(*addr) * 8;
+ unsigned long tmp;
+
+ base = addr;
+ if (offset) {
+ int suboffset;
+
+ addr += offset / NBITS;
+
+ suboffset = offset % NBITS;
+ if (suboffset) {
+ tmp = *addr;
+ tmp >>= suboffset;
+ if (tmp)
+ goto finish;
+ }
+
+ addr++;
+ }
+
+ while ((tmp = *addr) == 0)
+ addr++;
+
+ offset = (addr - base) * NBITS;
+
+ finish:
+ /* count the remaining bits without using __ffs() since that takes a 32-bit arg */
+ while (!(tmp & 0xff)) {
+ offset += 8;
+ tmp >>= 8;
+ }
+
+ while (!(tmp & 1)) {
+ offset++;
+ tmp >>= 1;
+ }
+
+ return offset;
+}
diff -uNrp /warthog/kernels/linux-2.6.10-rc1-mm3/lib/Makefile linux-2.6.10-rc1-mm3-frv/lib/Makefile
--- /warthog/kernels/linux-2.6.10-rc1-mm3/lib/Makefile 2004-11-05 13:15:52.000000000 +0000
+++ linux-2.6.10-rc1-mm3-frv/lib/Makefile 2004-11-05 14:13:04.574439103 +0000
@@ -14,6 +14,7 @@ endif

lib-$(CONFIG_RWSEM_GENERIC_SPINLOCK) += rwsem-spinlock.o
lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o
+lib-$(CONFIG_GENERIC_FIND_NEXT_BIT) += find_next_bit.o
obj-$(CONFIG_LOCK_KERNEL) += kernel_lock.o

ifneq ($(CONFIG_HAVE_DEC_LOCK),y)
-
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