- Be) dem len va dem xu6ng CTUD (Counter Up/Down).
Mota ho~d dqng:
5.5 CHU'C NANG TOAN HOC
Cac l~nh s6 hQC dung dA thl!C hi~n cac phep tinh s6 hQC trong chU'O'ng trinh. Trong LAD, bfin hqp toan (math box) thl!c hi~n cac phep tinh cqng, tru 16-bit va 32-bit. Hqp nhan (multiply box) nhan hai s6 nguyen 16-bit va kijt qua la mqt s6 nguyen 32-bit. Hqp chia (divide box) chia hai s6 16-bit, thLI'O'ng la mqt s6 16-bit va
dU' cung 16-bit dU'Q'C n~p vao tu ngay trU'O'C. Niju l~p trinh bang LAD, c6 thA tiijt ki~m 6 nh6' bang each Sll' d1:1ng d§u vao IN1 d6ng thO'i cung la d§u ra OUT.
Trong STL, l~nh thl!C hi~n bfin phep tinh s6 hqc dU'Q'C qui djnh cho toan h~ng 16-bit va 32-bit. Hqp nhan thl!c hi~n phep nhan hai s6 nguyen 16-bit va tich s6 la
mqt s6 nguyen 32-bit. L~nh chia thl!c hi~n phep chia mqt s6 nguyen 16-bit v6'i 16-
bit cu6i cua mqt s6 nguyen 32-bit. Kijt qua la mqt gia trj tu kep (32-bit) trong d6 tu
th§p (tu bit o dijn bit 15) la thU'O'ng s6 va tu cao (tu bit 16 dijn 31 bit) la s6 dU' cua phep tinh~
Phep CQng
ADD_I (LAD)
+I (STL)
L~nh thl!c hi~n phep cqng cac s6 nguyen 16-bit IN1 va IN2. Trong LAD kijt qua la mqt s6 nguyen 16-bit dU'Q'C ghi vao OUT, t(pc la IN1 + IN2 = OUT.
Trong STL, kijt qua cung la mqt gia trj 16-bit nhU'ng dU'Q'C ghi l~i vao IN2, t(pc la IN1 + IN2 = IN2.
Phep trer
SUB_I (LAD) -I (STL)
L~nh thl!c hi~n phep tru cac s6 nguyen 16-bit IN1 va IN2. Trong LAD kijt qua la
mqt s6 nguyen 16-bit va dU'Q'C ghi vao OUT, tll'C la IN1 - IN2 = OUT.
Trong STL, kijt qua cung la mqt gia trj 16-bit nhU'ng dU'Q'C ghi l~i vao IN2, t(pc la