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>
diff --git a/drivers/media/common/ir-functions.c b/drivers/media/common/ir-functions.c
index fcb1941..fe447a0 100644
--- a/drivers/media/common/ir-functions.c
+++ b/drivers/media/common/ir-functions.c
@@ -107,21 +107,20 @@
}
/* -------------------------------------------------------------------------- */
-
+/* 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;
- 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++;
- }
+ do {
+ if (mask&1) {
+ if (data&1)
+ value |= vbit;
+ vbit<<=1;
+ }
+ data>>=1;
+ } while (mask>>=1);
+
return value;
}