Visual Prolog provides six predicates for bit-level operations; bitor, bitand, bitnot, bitxor, bitleft, and bitright. These predicates have one flow variant each, operate on unsigned integers, and must be used in prefix notation.
(1) bitnot/2
bitnot performs a bit-wise logical NOT.
bitnot(X, Z) /* (i,o) */
With X bound to some integral value, Z will be bound to the bit-wise negation of X.
|
Operator |
X |
Z |
|
bitnot |
1 0 |
0 1 |
(2) bitand/3
bitand performs a bit-wise AND.
bitand(X, Y, Z) /* (i,i,o) */
With X and Y bound to some integral values, Z will be bound to the result of bit-wise ANDing the corresponding bits of X and Y.
|
Operator |
X |
Y |
Z |
|
bitand |
1 1 0 0 |
1 0 1 0 |
1 0 0 0 |
(3) bitor/3
bitor performs a bit-wise OR.
bitor(X, Y, Z) /* (i,i,o) */
With X and Y bound to some integral values, Z will be bound to the result of bit-wise ORing the corresponding bits of X and Y.
|
Operator |
X |
Y |
Z |
|
bitor |
1 1 0 0 |
1 0 1 0 |
1 1 1 0 |
(4) bitxor/3
bitxor performs a bit-wise XOR.
bitxor(X, Y, Z) /* (i,i,o) */
With X and Y bound to some integral values, Z will be bound to the result of bit-wise XORing the corresponding bits of X and Y.
|
Operator |
X |
Y |
Z |
|
bitxor |
1 1 0 0 |
1 0 1 0 |
0 1 1 0 |
(5) bitleft/3
bitleft performs a bit-wise left shift.
bitleft(X, N, Y) /* (i,i,o) */
With X and N are bound to some integral values, Y is bound to the result of shifting the bit-wise representation of X N places to the left. The new bits will be zero-filled.
(6) bitright/3
bitright performs a bit-wise right shift.
bitright(X, N, Y) /* (i,i,o) */
With X and N are bound to some integral values, Y is bound to the result of shifting the bit-wise representation of X N places to the right. The new bits will be zero-filled.
(7) Exercise
Write a Visual Prolog program to test the theory that
myxor(A, B, Result) :-
bitnot(B, NotB), bitand(A, NotB, AandNotB),
bitnot(A, NotA), bitand(NotA, B, NotAandB),
bitor(AandNotB, NotAandB, Result).
behaves like
bitxor(A, B, Result)