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>

1 files 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;
 }