(6.2.1.2) The result of converting an integer to a shorter signed integer, or the result of converting an unsigned integer to a signed integer of equal length, if the value cannot be represented:

When an integer is converted to a shorter signed integer, the low order bits are copied from the longer integer to the shorter signed integer. The result may be negative.

When an unsigned integer is converted to a signed integer of equal size, the low order bits are copied from the unsigned integer to the signed integer. The result may be negative.