From: Akinobu Mita <akinobu.mita@gmail.com>
Date: Fri, 23 Mar 2012 22:02:04 +0000 (-0700)
Subject: bitops: introduce for_each_clear_bit()
X-Git-Tag: upstream/snapshot3+hdmi~7886^2~106
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=03f4a8226c2f9c14361f75848d1e93139bab90c4;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git

bitops: introduce for_each_clear_bit()

Introduce for_each_clear_bit() and for_each_clear_bit_from().  They are
similar to for_each_set_bit() and list_for_each_set_bit_from(), but they
iterate over all the cleared bits in a memory region.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Stefano Panella <stefano.panella@csr.com>
Cc: David Vrabel <david.vrabel@csr.com>
Cc: Sergei Shtylyov <sshtylyov@mvista.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index 348b1dc..a3b6b82 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -32,6 +32,17 @@ extern unsigned long __sw_hweight64(__u64 w);
 	     (bit) < (size);					\
 	     (bit) = find_next_bit((addr), (size), (bit) + 1))
 
+#define for_each_clear_bit(bit, addr, size) \
+	for ((bit) = find_first_zero_bit((addr), (size));	\
+	     (bit) < (size);					\
+	     (bit) = find_next_zero_bit((addr), (size), (bit) + 1))
+
+/* same as for_each_clear_bit() but use bit as value to start with */
+#define for_each_clear_bit_from(bit, addr, size) \
+	for ((bit) = find_next_zero_bit((addr), (size), (bit));	\
+	     (bit) < (size);					\
+	     (bit) = find_next_zero_bit((addr), (size), (bit) + 1))
+
 static __inline__ int get_bitmask_order(unsigned int count)
 {
 	int order;