1 files changed, 66 insertions, 0 deletions
diff --git a/npc/functions/bitwise.txt b/npc/functions/bitwise.txt
new file mode 100644
index 00000000..a2e57587
--- /dev/null
+++ b/npc/functions/bitwise.txt
@@ -0,0 +1,66 @@
+/**
+ * Gets a bitmasked value in from an integer. If the shift is omitted, it will
+ * be deduced from the mask.
+ *
+ * @arg 0 - the variable
+ * @arg 1 - mask
+ * @arg 2 - shift
+ */
+function	script	bitwise_get	{
+    .@shift = getarg(2, 0);
+
+    if (getargcount() < 3) {
+        // guess the shift from the mask:
+        for (.@shift = 0; .@shift < 32; ++.@shift) {
+            if ((getarg(1) & (1 << .@shift)) != 0) {
+                break;
+            }
+        }
+    }
+
+    return (getarg(0) & getarg(1)) >> .@shift;
+}
+
+/**
+ * sets a bitmasked value in a variable
+ *
+ * @arg 0 - the target variable
+ * @arg 1 - mask
+ * @arg 2 - shift
+ * @arg 3 - new value
+ * @return a reference to the variable
+ */
+function	script	bitwise_set	{
+    if (getargcount() < 4) {
+        // guess the shift from the mask:
+        for (.@shift = 0; .@shift < 32; ++.@shift) {
+            if ((getarg(1) & (1 << .@shift)) != 0) {
+                break;
+            }
+        }
+
+        return set(getarg(0), (getarg(0) & ~(getarg(1))) | (getarg(2, 0) << .@shift));
+    }
+
+    return set(getarg(0), (getarg(0) & ~(getarg(1))) | (getarg(3, 0) << getarg(2, 0)));
+}
+
+
+// bitmask_count(<int>)
+//    returns the number of bits set in <int> (up to 4096?)
+function	script	bitmask_count	{
+    .@n = getarg(0); // Number evaluated
+    .@p=0; // Bits set/unset
+    .@s=0; // Stack and Check
+    .@m=0; // Memory
+
+    // Loop only as needed
+    while (.@s < .@n) {
+        .@s=2**.@m;
+        if (.@n & .@s)
+            .@p++;
+        .@m++;
+    }
+    return .@p;
+}
+