presto-main/src/main/java/io/prestosql/operator/scalar/MathFunctions.java/MathFunctions/floorLongShort
class MathFunctions:        @LiteralParameters({"p", "s", "rp"})
        @SqlType("decimal(rp,0)")
        @Constraint(variable = "rp", expression = "p - s + min(s, 1)")
        public static long floorLongShort(@LiteralParameter("s") long numScale, @SqlType("decimal(p, s)") Slice num)
        {
            return unscaledDecimalToUnscaledLong(floorLong(numScale, num));
        }