1 files changed, 42 insertions, 0 deletions
diff --git a/ext/rational/rational.c b/ext/rational/rational.c
new file mode 100644
index 0000000000..18024e9497
--- /dev/null
+++ b/ext/rational/rational.c
@@ -0,0 +1,42 @@
+#include "ruby.h"
+
+/*
+ * call-seq:
+ *    fixnum.gcd(fixnum)  ->  fixnum
+ *
+ * Fixnum-specific optimized version of Integer#gcd.  Delegates to
+ * Integer#gcd as necessary.
+ */
+static VALUE
+fix_gcd(self, other)
+    VALUE self, other;
+{
+    long a, b, min, max;
+
+    /*
+     * Note: Cannot handle values <= FIXNUM_MIN here due to overflow during negation.
+     */
+    if (!FIXNUM_P(other) ||
+	(a = FIX2LONG(self)) <= FIXNUM_MIN ||
+	(b = FIX2LONG(other)) <= FIXNUM_MIN ) {
+	/* Delegate to Integer#gcd */
+	return rb_call_super(1, &other);
+    }
+
+    min = a < 0 ? -a : a;
+    max = b < 0 ? -b : b;
+
+    while (min > 0) {
+	long tmp = min;
+	min = max % min;
+	max = tmp;
+    }
+
+    return LONG2FIX(max);
+}
+
+void
+Init_rational()
+{
+    rb_define_method(rb_cFixnum, "gcd", fix_gcd, 1);
+}