Four bit adder: Difference between revisions
→{{header|OCaml}}: slight simplification, and n-bit adder
(4-bit adder in ocaml) |
(→{{header|OCaml}}: slight simplification, and n-bit adder) |
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Line 1,136:
let sub nin nout where = { nin=nin; nout=nout; apply=function
bits -> Array.sub bits where nout };;
let transpose n p v =
if n*p <> Array.length v
then failwith "bad dim"
else
let w = Array.copy v in
for i=0 to n-1 do
for j=0 to p-1 do
let r = i*p+j and s = j*n+i in
w.(r) <- v.(s)
done
done;
w;;
(* line mixing (a special permutation)
mix 4 2 : 0,1,2,3, 4,5,6,7 -> 0,4, 1,5, 2,6, 3,7
unmix: inverse operation *)
let mix n p = perm (transpose n p (Array.init (n*p) (function x -> x)));;
let unmix n p = perm (transpose p n (Array.init (n*p) (function x -> x)));;
(* basic blocks
Line 1,193 ⟶ 1,214:
(* 4-bit adder *)
let add4 = block_array serial [|
assoc (const false 1) (
assoc full_adder (pass 6);
assoc (assoc (pass 1) full_adder) (pass 4);
Line 1,227 ⟶ 1,248:
# plus 0 0;;
- : int * int = (0, 0)
</lang>
An extension : n-bit adder, for n <= 64 (n could be greater, but we use Int64 for I/O)
<lang ocaml>
(* general adder (n bits with n <= 64) *)
let gen_adder n = block_array serial [|
assoc (const false 1) (mix n 2);
assoc full_adder (pass (2*n-2));
block_array serial (Array.init (n-2) (function k ->
assoc (assoc (pass (k+1)) full_adder) (pass (2*(n-k-2)))));
assoc (pass (n-1)) full_adder |];;
let gadd_io n = assoc (gen_adder n) (const false (n-1));;
let gen_plus n a b =
let v = Array.map Int64.to_int
(eval (gadd_io n) n n (Array.map Int64.of_int [| a; b |])) in
v.(0), v.(1);;
</lang>
And a test
<lang ocaml>
# gen_plus 7 100 100;;
- : int * int = (72, 1)
# gen_plus 8 100 100;;
- : int * int = (200, 0)
</lang>
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