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Instruction Set
3-62
RISC 16−Bit CPU
* SBC[.W] Subtract source and borrow/.NOT. carry from destination
* SBC.B Subtract source and borrow/.NOT. carry 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: 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, reset otherwise.
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 Implementation.
The borrow is treated as a .NOT. carry : Borrow Carry bit
Yes 0
No 1