80C186EC/80C188EC Microprocessor User's Manual

INSTRUCTION SET DESCRIPTIONS
Table C-4. Instruction Set (Continued)
Name Description Operation
SBB
NOTE:
Subtract With Borrow:
SBB dest, src
Subtracts the source from the destination,
subtracts one if CF is set, and
returns the result to the destination
operand. Both operands may be bytes
or words. Both operands may be
signed or unsigned binary numbers
(see AAS and DAS)
Instruction Operands:
SBB reg, reg
SBB reg, mem
SBB mem, reg
SBB accum, immed
SBB reg, immed
SBB mem, immed
if
(CF) = 1
then
(dest) = (dest) – (src) – 1
else
(dest) ← (dest) – (src)
The three symbols used in the Flags Affected column are defined as follows:
– the contents of the flag remain unchanged after the instruction is executed
the contents of the flag is undefined after the instruction is executed
üthe flag is updated after the instruction is executed
Flags
Affected
AF ü
CF ü
DF –
IF –
OF ü
PF ü
SF ü
TF –
ZF ü
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