linux-kernel - [PATCH 21/30] ACPICA: Utilities: Add ACPI_IS_POWER_OF

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Date:	Thu, 24 Mar 2016 09:40:56 +0800
From:	Lv Zheng <lv.zheng@...el.com>
To:	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Len Brown <len.brown@...el.com>
Cc:	Lv Zheng <lv.zheng@...el.com>, Lv Zheng <zetalog@...il.com>,
	<linux-kernel@...r.kernel.org>, linux-acpi@...r.kernel.org,
	Bob Moore <robert.moore@...el.com>
Subject: [PATCH 21/30] ACPICA: Utilities: Add ACPI_IS_POWER_OF_TWO()

ACPICA commit cbcb77565c5032dd48e19b3a8a8b8704c5f29faf

This patch adds a macro ACPI_IS_POWER_OF_TWO, which can be used to
detect if a number is a power of two. Lv Zheng.

Link: https://github.com/acpica/acpica/commit/cbcb7756
Signed-off-by: Lv Zheng <lv.zheng@...el.com>
Signed-off-by: Bob Moore <robert.moore@...el.com>
---
 drivers/acpi/acpica/acmacros.h |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/acpi/acpica/acmacros.h b/drivers/acpi/acpica/acmacros.h
index 411c18b..b461f55 100644
--- a/drivers/acpi/acpica/acmacros.h
+++ b/drivers/acpi/acpica/acmacros.h
@@ -260,6 +260,10 @@
 
 #define ACPI_IS_MISALIGNED(value)           (((acpi_size) value) & (sizeof(acpi_size)-1))
 
+/* Generic (power-of-two) rounding */
+
+#define ACPI_IS_POWER_OF_TWO(a)             (((a) & ((a) - 1)) == 0)
+
 /*
  * Bitmask creation
  * Bit positions start at zero.
-- 
1.7.10