Simplify base 2 logarithm computation

1 files changed, 9 insertions, 23 deletions

diff --git a/npc/functions/math.txt b/npc/functions/math.txt
index 22cf88159..d54558352 100644
--- a/npc/functions/math.txt
+++ b/npc/functions/math.txt
@@ -40,31 +40,17 @@ function	script	lognbaselvl	{
 }
 
 // log2(<int>)
-//    returns the log base 2 of the passed integer, up to 20 (2**20=1.048.576) (round down always)
-
+//   returns the base 2 logarithm of the passed integer
+// Note: Negative values are first converted to positive.
+//       For 0, -1 is returned instead
+//       (as if passed value == 0.5, but that is not possible for integers).
 function	script	log2	{
-    .@v=abs(getarg(0));
-    .@ok=0;
-    .@i=0;
-    if (.@v < 1)
-        return -1;
-
-    freeloop(true);
-    while (!.@ok) {
-        // exact match
-        if (2**.@i == .@v) {
-            .@ok=1;
-        // inexact match, or limit exceeded
-        } else if (2**.@i >= .@v || .@i > 20) {
-            .@ok=1;
-            .@i-=1; // round down
-        // not yet
-        } else {
-            .@i+=1;
-        }
+    .@v = abs(getarg(0));
+    .@i = -1;
+    while (.@v > 0) {
+        .@i += 1;
+        .@v >>= 1;
     }
-    freeloop(false);
-
     return .@i;
 }