Number of parameters: 4

Usage:
	signed_multiply <overflow> <result> <value0> <value1>

Effect:
	Performs the signed multiplication <value0>*<value1>, storing the integer result in <result> and any overflowing bits into <overflow>

Exceptions:
	None

Flags:
	Sets the overflow flag if <overflow>:<result> != <result>
	Carry flag is never set