Re: [PATCH] introduce lower_32_bits() macro

From: H. Peter Anvin
Date: Fri Jul 25 2008 - 12:07:01 EST


Joerg Roedel wrote:
The file kernel.h contains the upper_32_bits macro. This patch adds the other
part, the lower_32_bits macro. Its first use will be in the driver for AMD
IOMMU.

Signed-off-by: Joerg Roedel <joerg.roedel@xxxxxxx>
---
include/linux/kernel.h | 6 ++++++
1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index f9cd7a5..6fd2977 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -73,6 +73,12 @@ extern const char linux_proc_banner[];
*/
#define upper_32_bits(n) ((u32)(((n) >> 16) >> 16))
+/**
+ * lower_32_bits - return bits 0-31 of a number
+ * @n: the number we're accessing
+ */
+#define lower_32_bits(n) ((n) & 0xffffffffULL)
+

NAK. These are assymmetric with regards to type, which is the *last* thing we want.

The symmetric definition would be ((u32)(n)), but that's already idiomatic use, so why not use it as-is?

-hpa

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/