commit 4db345f322e255447c1a290d571402e52c27d8da
author Wan-Teh Chang <wtc@google.com> Wed Mar 29 17:43:01 2023 -0700
committer Wan-Teh Chang <wtc@google.com> Fri Mar 31 00:30:10 2023 +0000
tree 78f1ccf40a138ff5e8b60ba39f88a9844ac2aff0
parent 33698ab087d17513efaf96079e5fe2d830b94d2f

Minor improvement to the default get_msb function

Use `shift` as the loop index variable.

This algorithm is essentially Figure 5-13 in Hacker's Delight.

Change-Id: I4d6bf7160371c0dce7cf76f1d9fe24e2733d78c9

aom_ports/bitops.h

diff --git a/aom_ports/bitops.h b/aom_ports/bitops.h
index 9309dad..3c5b992 100644
--- a/aom_ports/bitops.h
+++ b/aom_ports/bitops.h
@@ -70,12 +70,10 @@
 static INLINE int get_msb(unsigned int n) {
   int log = 0;
   unsigned int value = n;
-  int i;
 
   assert(n != 0);
 
-  for (i = 4; i >= 0; --i) {
-    const int shift = (1 << i);
+  for (int shift = 16; shift != 0; shift >>= 1) {
     const unsigned int x = value >> shift;
     if (x != 0) {
       value = x;