Zilog Z8F0130 - Manual (Page 232)

eZ8
™
CPU Core
User Manual
UM012820-0810 SBC Instruction
217
SBC
Definition
Subtract with Carry.
Syntax
SBC dst, src
Operation
dst
 dst - src - C
Description
This instruction subtracts the source operand and the Carry (C) flag from
the destination. The destination stores the result. The contents of the
source operand are unaffected. The eZ8 CPU performs subtraction by
adding the two’s-complement of the source operand to the destination
operand. In multiple-precision arithmetic, this instruction permits the
carry (borrow) from the subtraction of low-order operands to be sub-
tracted from the subtraction of high-order operands.
Flags
C Set if a borrow is required by bit 7; reset otherwise
Z Set if the result is zero; reset otherwise
S Set if Bit 7 of the result is set; reset otherwise
V Set if an arithmetic overflow occurs; reset otherwise
D Set to 1
H Set if a borrow is required by bit 3; reset otherwise