modulo(p1)
x.modulo(y) means x-y*(x/y).floor
Equivalent to num.divmod(numeric)[1].
See Numeric#divmod.
static VALUE num_modulo(VALUE x, VALUE y) { return rb_funcall(x, '-', 1, rb_funcall(y, '*', 1, rb_funcall(x, rb_intern("div"), 1, y))); }