Texas Instruments MSP430x1xx - Manual (Page 402)

Instruction Set Overview
B-52
* SBC[.W] Subtract (borrow *) from destination
* SBC.B Subtract (borrow *) from destination
Syntax SBC dst or SBC.W dst
SBC.B dst
Operation dst + 0FFFFh + C –> dst
dst + 0FFh + C –> dst
Emulation SUBC #0,dst
SUBC.B #0,dst
Description The carry bit (C) is added to the destination operand minus one. 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: Reset if dst was decremented from 0000 to 0FFFFh, set otherwise
Reset if dst was decremented from 00 to 0FFh, set otherwise
V: Set if initially C = 0 and dst = 08000h
Set if initially C = 0 and dst = 080h
Mode Bits OscOff, CPUOff, and GIE are not affected.
Example The 16-bit counter pointed to by R13 is subtracted from a 32-bit counter
pointed to by R12.
SUB @R13,0(R12) ; Subtract LSDs
SBC 2(R12) ; Subtract carry from MSD
Example The 8-bit counter pointed to by R13 is subtracted from a 16-bit counter pointed
to by R12.
SUB.B @R13,0(R12) ; Subtract LSDs
SBC.B 1(R12) ; Subtract carry from MSD
Note: Borrow Is Treated as a .NOT.
The borrow is treated as a .NOT. carry : Borrow Carry bit
Yes 0
No 1