Intel 8253 - Page 554

XA User Guide 6-154 4/17/98
SEXT Sign Extend
Syntax: SEXT Rd
Operation: if N = 1
then (Rd) <-- FF in byte mode or FFFF in word mode
if N = 0
then (Rd) <-- 00 in byte mode or 0000 in word mode
Description: Copies the N flag (the sign bit of the last ALU operation) into the destination register.
The destination register may be a byte or word register.
Example:
SEXT.b R1
if the result of the previous operation left the N flag set, then R1 <-- FF
Size: Byte, word
Flags Updated: none
Bytes:2
Clocks:3
Encoding:
d d d d 1 0 0 1
1 0 0 1 SZ 0 0 0