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|
(*
Système Digital, cours de J.Vuillemin, 2013-2013
Alex AUVOLAT, ENS INFO 2013
Circuit Simulator, machine simulator
ASSUMPTIONS:
- Only one ROM chip
*)
open Netlist_ast
exception Error of string
exception Is_not_modified
let load_rom filename =
() (* TODO *)
type ram_prop = int * int (* addr size ; word size *)
type machine = {
p : program;
mutable vars : value Env.t;
mutable regs : value Env.t;
ram_chips : ram_prop array;
ram : value array array;
}
let rec two_to_the = function
| 0 -> 1
| n -> let k = (two_to_the (n/2)) in
if n mod 2 = 1 then 2 * k else k
let create p =
let ram_chips = Array.of_list
(List.fold_left
(fun x (_, v) -> match v with
| Eram (a, w, _, _, _, _) ->
(a, w)::x
| _ -> x)
[]
p.p_eqs) in
let vars = Env.fold
(fun k v x ->
Env.add k
(match v with
| TBit -> VBit(false)
| TBitArray(n) -> VBitArray(Array.make n false))
x)
p.p_vars
Env.empty in
{
p = p;
vars = vars;
regs = Env.empty; (* no use putting anything at the moment *)
ram_chips = ram_chips;
ram = Array.map
(fun (a, w) -> Array.make (two_to_the a) (VBitArray (Array.make w false)))
ram_chips;
}
let read_inputs m f =
List.iter
(fun n ->
m.vars <- Env.add n (f (n, Env.find n m.p.p_vars)) m.vars)
m.p.p_inputs
let step m =
let get = function
| Avar(x) ->
begin match Env.find x m.vars with
| VBit(x) -> VBit(x)
| VBitArray(u) as s ->
if Array.length u = 1 then VBit(u.(0)) else s
end
| Aconst(x) -> x
in
(* Load register values into dest variables *)
Env.iter
(fun k v ->
m.vars <- Env.add k v m.vars)
m.regs;
(* Do all the logic *)
List.iter
(fun (varname, exp) ->
let evaluate = function
| Earg(k) -> get k
| Ereg(_) -> raise Is_not_modified (* do nothing, registers are handled somewhere else *)
| Enot(k) ->
begin match get k with
| VBit(u) -> VBit (not u)
| VBitArray(u) -> VBitArray(Array.map (fun x -> not x) u)
end
| Ebinop(op, k1, k2) ->
let f = begin match op with
| Or -> (fun x y -> x || y)
| Xor -> (fun x y -> (x || y) && (not (x && y)))
| And -> (fun x y -> x && y)
| Nand -> (fun x y -> not (x && y))
end in
begin match get k1, get k2 with
| VBit(u), VBit(v) -> VBit(f u v)
| VBitArray(u), VBitArray(v) when Array.length u = Array.length v ->
let r = Array.make (Array.length u) false in
for i = 0 to Array.length u - 1 do
r.(i) <- (f u.(i) v.(i))
done; VBitArray(r)
| VBit(u), VBitArray(v) -> VBit(f u v.(0))
| VBitArray(u), VBit(v) -> VBit(f u.(0) v)
| _ -> raise (Error "Incompatible data types.")
end
| Emux (control, in0, in1) ->
begin match get control, get in0, get in1 with
| VBit(u), x, y ->
if u then y else x
| VBitArray(u), VBitArray(a), VBitArray(b)
when Array.length a = Array.length b
&& Array.length u = Array.length a ->
let r = Array.make (Array.length u) false in
for i = 0 to Array.length u - 1 do
r.(i) <- (if u.(i) then b.(i) else a.(i))
done;
VBitArray(r)
| _ -> raise (Error "Invalid data size in mux")
end
| Erom(_, w, _) -> VBitArray(Array.make w false) (* TODO *)
| Eram(_, _, _,_, _, _) -> raise Is_not_modified (* TODO *)
| Econcat(k1, k2) ->
let a1 = match get k1 with
| VBit(u) -> [|u|]
| VBitArray(u) -> u
in
let a2 = match get k2 with
| VBit(u) -> [|u|]
| VBitArray(u) -> u
in
VBitArray(Array.append a1 a2)
| Eslice (first, last, k) ->
begin match get k with
| VBit(u) when first = 0 && last = 0 -> VBit(u)
| VBitArray(u) ->
let r = Array.make (last - first) false in
for i = first to last - 1 do
r.(i - first) <- u.(i)
done;
VBitArray(u)
| _ -> raise (Error "Invalid slicing parameters")
end
| Eselect(id, k) ->
begin match get k with
| VBit(u) when id = 0 -> VBit(u)
| VBitArray(u) -> VBit(u.(id))
| _ -> raise (Error "Invalid select parameters")
end
in
try
m.vars <- Env.add varname (evaluate exp) m.vars
with Is_not_modified -> ())
m.p.p_eqs;
(* Saves register values *)
m.regs <- List.fold_left
(fun x (k, v) ->
match v with
| Ereg(n) -> Env.add k (Env.find n m.vars) x
| _ -> x)
Env.empty
m.p.p_eqs
let print_outputs m f =
List.iter
(fun n ->
f (n, Env.find n m.vars))
m.p.p_outputs
|
