NEG = Negate
| Hex | Mnemonic | Cycles |
|---|---|---|
| CE A4 | NEG A | 12 |
| CE A5 | NEG B | 12 |
| CE A6 nn | NEG [N+#nn] | 20 |
| CE A7 | NEG [HL] | 16 |
Execute
A = Register A
B = Register B
[N+#nn] = Memory: (I shl 16) or (N shl 8) or #nn
[HL] = Memory: (I shl 16) or HL
; NEG Ds
;
; Ds = Source/Destination
Ds = 0 - Ds
Description
8-Bits Destination is negated.
Conditions
Zero: Set when result is 0
Carry: Set when result is not 0
Overflow: Set when result is 0x80
Sign: Set when bit 7 of the result is 1
Examples
; A = 0x01
NEG A
; A = 0xFF (0 - 0x01 = 0xFF)
; F = (Zero=0):(Carry=1):(Overflow=0):(Sign=1)
; B = 0x00
NEG B
; B = 0x00 (0 - 0x00 = 0x00)
; F = (Zero=1):(Carry=0):(Overflow=0):(Sign=0)
; [HL] = 0x80
NEG [HL]
; [HL] = 0x80 (0 - 0x80 = 0x80)
; F = (Zero=0):(Carry=1):(Overflow=1):(Sign=1)