Texas Instruments MSP430x4xx User Manual

Page 100

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Instruction Set

3-66

RISC 16−Bit CPU

SUB[.W]

Subtract source from destination

SUB.B

Subtract source from destination

Syntax

SUB

src,dst

or

SUB.W

src,dst

SUB.B

src,dst

Operation

dst + .NOT.src + 1 −> dst
or
[(dst − src −> dst)]

Description

The source operand is subtracted from the destination operand by adding the
source operand’s 1s complement and the constant 1. The source operand is
not affected. The previous contents of the destination are lost.

Status Bits

N: Set if result is negative, reset if positive
Z: Set if result is zero, reset otherwise
C: Set if there is a carry from the MSB of the result, reset otherwise.

Set to 1 if no borrow, reset if borrow.

V: Set if an arithmetic overflow occurs, otherwise reset

Mode Bits

OSCOFF, CPUOFF, and GIE are not affected.

Example

See example at the SBC instruction.

Example

See example at the SBC.B instruction.

Note:

Borrow Is Treated as a .NOT.

The borrow is treated as a .NOT. carry :

Borrow

Carry bit

Yes

0

No

1

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