2.2.40 (1) NEG (B)
NEG (NEGate)
Negate Binary Signed
Operation
0 – Rd
→
Rd
Assembly-Language Format
NEG.B
Rd
Operand Size
Byte
Condition Code
H: Set to 1 if there is a borrow at bit 3;
otherwise cleared to 0.
N: Set to 1 if the result is negative; otherwise
cleared to 0.
Z: Set to 1 if the result is zero; otherwise
cleared to 0.
V: Set to 1 if an overflow occurs; otherwise
cleared to 0.
C: Set to 1 if there is a borrow at bit 7;
otherwise cleared to 0.
I
UI
H
U
N
Z
V
C
—
—
↕
—
↕
↕
↕
↕
Description
This instruction takes the two’s complement of the contents of an 8-bit register Rd (destination
operand) and stores the result in the 8-bit register Rd (subtracting the register contents from H'00).
If the original contents of Rd was H'80, however, the result remains H'80.
Available Registers
Rd: R0L to R7L, R0H to R7H
Operand Format and Number of States Required for Execution
Notes
An overflow occurs if the previous contents of Rd was H'80.
Instruction Format
1st byte
2nd byte
3rd byte
4th byte
Register direct
NEG.B
Rd
1
7
8
rd
2
No. of
States
Addressing
Mode
Mnemonic
Operands
132