From d67be61ebe5efaf9c4c11bf168781d678854c966 Mon Sep 17 00:00:00 2001
From: Trent Piepho <xyzzy@speakeasy.org>
Date: Wed, 11 Jul 2007 20:28:44 -0300
Subject: [PATCH] V4L/DVB (5832): ir-common: optimize bit extract function
New code is simpler, shorter, compiles to about half the size, and is 2
to 4 times faster depending on how many bits in the mask are set.
Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
---
drivers/media/common/ir-functions.c | 23 +++++++++++------------
1 file changed, 11 insertions(+), 12 deletions(-)
diff --git a/drivers/media/common/ir-functions.c b/drivers/media/common/ir-functions.c
index fcb194135627..fe447a06e24e 100644
--- a/drivers/media/common/ir-functions.c
+++ b/drivers/media/common/ir-functions.c
@@ -107,21 +107,20 @@ void ir_input_keydown(struct input_dev *dev, struct ir_input_state *ir,
}
/* -------------------------------------------------------------------------- */
-
+/* extract mask bits out of data and pack them into the result */
u32 ir_extract_bits(u32 data, u32 mask)
{
- int mbit, vbit;
- u32 value;
+ u32 vbit = 1, value = 0;
+
+ do {
+ if (mask&1) {
+ if (data&1)
+ value |= vbit;
+ vbit<<=1;
+ }
+ data>>=1;
+ } while (mask>>=1);
- value = 0;
- vbit = 0;
- for (mbit = 0; mbit < 32; mbit++) {
- if (!(mask & ((u32)1 << mbit)))
- continue;
- if (data & ((u32)1 << mbit))
- value |= (1 << vbit);
- vbit++;
- }
return value;
}