langs a-z

Task/Ethiopian-multiplication/PL-SQL/ethiopian-multiplication.sql

@@ -0,0 +1,58 @@
+create or replace package ethiopian is
+
+  function multiply
+    ( left    in  integer,
+      right   in  integer)
+  return integer;
+
+end ethiopian;
+/
+
+create or replace package body ethiopian is
+
+  function is_even(item  in integer) return boolean is
+  begin
+    return item mod 2 = 0;
+  end is_even;
+
+  function double(item  in integer) return integer is
+  begin
+    return item * 2;
+  end double;
+
+  function half(item  in integer) return integer is
+  begin
+    return trunc(item / 2);
+  end half;
+
+  function multiply
+    ( left   in integer,
+      right  in integer)
+    return Integer
+  is
+    temp     integer := 0;
+    plier    integer := left;
+    plicand  integer := right;
+  begin
+
+    loop
+      if not is_even(plier) then
+        temp := temp + plicand;
+      end if;
+      exit when plier <= 1;
+      plier := half(plier);
+      plicand := double(plicand);
+    end loop;
+
+    return temp;
+
+  end multiply;
+
+end ethiopian;
+/
+
+/* example call */
+begin
+  dbms_output.put_line(ethiopian.multiply(17, 34));
+end;
+/