Zilog Z8F0130 - Manual (Page 235)

eZ8
™
CPU Core
User Manual
UM012820-0810 SBCX Instruction
220
SBCX
Definition
Subtract with Carry using Extended Addressing.
Syntax
SBCX dst, src
Operation
dst
 dst - src - C
Description
This new eZ8 extended addressing instruction subtracts the source oper-
and and the Carry (C) flag from the destination. The destination stores the
result. The contents of the source 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 per-
mits the carry (borrow) from the subtraction of low-order operands to be
subtracted 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 the result is negative; 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