NEGATE

Multiply the operand by -1.

Opcode	Bytes	Cycles	Form	Example
$37	2	3	negate b:_	negate b:1
$38	2	3	negate p:_	negate p:2
$39	2	3	negate i:_	negate i:4

Condition flag	Output
zero (ZF)	If the result is zero, this flag is 1; otherwise it is 0.
negative (NF)	If the result is negative, this flag is 1; otherwise it is 0.
overflow (OF)	If the negated value exceeds the register's signed range, this flag is 1; otherwise it is 0.
carry (CF)	This flag is always 0.

Notes

• This operation is equivalent to subtracting the operand from 0 using subtract.

• Replaces the value of the operand with its two's complement.

• Two's complement has one extra negative value, for example pair values range from -32768 ($8000) to 32767 ($7fff). For these overflow cases, negate will leave the value unchanged, setting OF to 1 to indicate the overflow.