COMPARE

Compare the two operands and set the flags.

Opcode	Bytes	Cycles	Form	Example
$95	3	2	compare b:_, {byte}	compare b:1, 123
$96	3	2	compare p:_, {s_byte}	compare p:2, 123
$d7	4	2	compare p:_, {pair}	compare p:2, 12345
$97	3	2	compare i:_, {s_byte}	compare i:4, 123
$d8	4	2	compare i:_, {s_pair}	compare i:4, 12345
$98	3	2	compare i:_, xhex {xint}	compare i:4, xhex $d000_0000
$99	3	2	compare b:_, b:_	compare b:1, b:2
$9a	3	2	compare p:_, p:_	compare p:2, p:4
$9b	3	2	compare i:_, i:_	compare i:4, i:8

Condition flag	Output
zero (ZF)	If the difference is zero, this flag is 1; otherwise it is 0.
negative (NF)	If the signed difference is a negative number, this flag is 1; otherwise it is 0.
overflow (OF)	If the difference exceeds the register's signed range, this flag is 1; otherwise it is 0.
carry (CF)	If the difference exceeds the register's unsigned range, this flag is 1; otherwise it is 0.

Notes

• The flag outputs are calculated exactly the same as for the subtract instruction, including the effects of the with carry instruction.

• compare is typically followed by if which acts according to the flags.