optimize byteSwap

1 files changed, 4 insertions, 12 deletions

diff --git a/bits.c b/bits.c
index 0be410f..e280f1e 100644
--- a/bits.c
+++ b/bits.c
@@ -101,19 +101,11 @@ int logtwo(int v) {
  *    Difficulty: 2
  */
 int byteSwap(int x, int n, int m) {
-  int ns = (n << 3) ;
-  int ms = (m << 3);
-  int nb = (x >> ns) & 0xFF;
-  int mb = (x >> ms) & 0xFF;
+    int ns = n << 3;
+    int ms = m << 3;
+    int diff = ((x >> ns) ^ (x >> ms)) & 0xFF;
 
-  int mask = ~((0xFF << ns) | (0xFF <<  ms));
-
-  x = x & mask;
-
-  x = x | (nb << ms);
-  x = x | (mb << ns);
-
-  return x;
+    return x ^ (diff << ns) ^ (diff << ms);
 }
 
 /*