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lustrec / src / backends / EMF / EMF_backend.ml @ 2475c9e8

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(* EMF backend *)
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(* This backup is initially motivated by the need to express Spacer computed
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   invariants as Matlab Simulink executable evidences.
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   Therefore the input language is more restricted. We do not expect fancy
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   datastructure, complex function calls, etc.
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   In case of error, use -node foo -inline to eliminate function calls that are
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   not seriously handled yet.
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   In terms of algorithm, the process was initially based on printing normalized
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   code. We now rely on machine code printing. The old code is available in old
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   commits (eg in dd71e482a9d0).
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   A (normalized) node becomes a JSON struct
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   node foo (in1, in2: int) returns (out1, out2: int);
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   var x : int;
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   let
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   x = bar(in1, in2); -- a stateful node
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   out1 = x;
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   out2 = in2;
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   tel
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   Since foo contains a stateful node, it is stateful itself. Its prototype is 
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   extended with a reset input. When the node is reset, each of its "pre" expression
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   is reset as well as all calls to stateful node it contains. 
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   will produce the following JSON struct:
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   "foo": {"kind":  "stateful",
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   inputs:  [{name: "in1", type: "int"}, 
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   {name: "in2", type: "int"}, 
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   ],
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   outputs: [{name: "out1", type: "int"}, {name: "out2", type: "int"}],
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   locals:  [{name: "x", type: "int"}],
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   instrs:  {
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   def_x: { lhs: ["x"], 
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   rhs: {type: "statefulcall", name: "bar", 
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   args: [in1, in2], reset: [ni4_reset] } 
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   }
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   def_out1: { lhs: "out1", rhs: "x" } ,
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   def_out2: { lhs: "out2", rhs: "in2"}
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   }
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   }
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   Basically we have the following different definitions
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   1. local assign of a variable to another one:
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   def_out1: { kind: "local_assign", lhs: "out1", rhs: "x" },
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   2. pre construct over a variable (this is a state assign):
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   def_pre_x: { kind: "pre", lhs: "pre_x", rhs: "x" },
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   3. arrow constructs, while there is not specific input, it could be reset 
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   by a specific signal. We register it as a fresh rhs var:
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   def_arrow: { kind: "arrow", name: "ni4", lhs: "is_init", rhs: "reset_ni4"}
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   2. call to a stateless function, typically an operator
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   def_x: { kind: "statelesscall", lhs: ["x"], 
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   name: "bar", rhs: [in1, in2]} 
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   or in the operator version 
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   def_x: { kind: "operator", lhs: ["x"], 
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   name: "+", rhs: [in1, in2]} 
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   In Simulink this should introduce a subsystem in the first case or a 
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   regular block in the second with card(lhs) outputs and card{args} inputs.
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   3. call to a stateful node. It is similar to the stateless above, 
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   with the addition of the reset argument
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   { def_x: { kind: "statefulcall", lhs: ["x"], 
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   name: "bar", rhs: [in1, in2], reset: [ni4_reset] } 
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   }
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   In lustrec compilation phases, a unique id is associated to this specific
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   instance of stateful node "bar", here ni4. 
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   Instruction such as reset(ni4) or noreset(ni4) may -- or not -- reset this 
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   specific node. This corresponds to "every c" suffix of a node call in lustre.
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   In Simulink this should introduce a subsystem that has this extra reset input.  
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   The reset should be defined as an "OR" over (1) the input reset of the parent 
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   node, __reset in the present example and (2) any occurence of reset(ni4) in 
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   the instructions.
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   4. branching construct: (guard expr, (tag, instr list) list)
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   "merge_XX": { type: "branch", guard: "var_guard", 
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   inputs:   ["varx", "vary"],
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   outputs:  ["vark", "varz"],
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   branches: {"tag1": {liste_of_definitions (1-4)}, ...}
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   }
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   In Simulink, this should become one IF block to produce enable ports 
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   "var_guard == tag1", "var_guard == tag2", .... as well as one action 
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   block per branch: each of these action block shall  
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*)
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open LustreSpec
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open Machine_code
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open Format 
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open EMF_common
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exception Unhandled of string
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module ISet = Utils.ISet
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let fprintf_list = Utils.fprintf_list
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(**********************************************)
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(*   Utility functions: arrow and lustre expr *)
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(**********************************************)
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(* detect whether the instruction i represents an ARROW, ie an arrow with true
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   -> false *)
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let is_arrow_fun m i =
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  match Corelang.get_instr_desc i with
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  | MStep ([var], i, vl) -> (
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    try
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      let name = (Machine_code.get_node_def i m).node_id in
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      match name, vl with
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      | "_arrow", [v1; v2] -> (
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	match v1.value_desc, v2.value_desc with
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	| Cst c1, Cst c2 ->
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	   if c1 = Corelang.const_of_bool true && c2 = Corelang.const_of_bool false then
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	     true
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	   else
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	     assert false (* only handle true -> false *)
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	| _ -> assert false
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      )
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      | _ -> false
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    with
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    | Not_found -> false (* Not declared (should have been detected now, or imported node *)
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  )
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  | _ -> false
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(**********************************************)
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(*   Printing machine code as EMF             *)
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(**********************************************)
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let branch_cpt = ref 0
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let get_instr_id fmt i =
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  match Corelang.get_instr_desc i with
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  | MLocalAssign(lhs,_) | MStateAssign (lhs, _) -> Printers.pp_var_name fmt lhs
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  | MReset i | MNoReset i -> fprintf fmt "%s" (reset_name i)
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  | MBranch (g, _) -> incr branch_cpt; fprintf fmt "branch_%i" !branch_cpt
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  | MStep (outs, id, _) -> fprintf fmt "%a_%s" (fprintf_list ~sep:"_" Printers.pp_var_name) outs id
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  | _ -> () (* No name *)
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let rec branch_block_vars il =
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  List.fold_left
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    (fun (accu_def, accu_read) i ->
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      let defined_vars, read_vars = branch_instr_vars i in
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      ISet.union accu_def defined_vars, VSet.union accu_read read_vars)
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    (ISet.empty, VSet.empty) il
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and branch_instr_vars i =
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  match Corelang.get_instr_desc i with
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  | MLocalAssign (var,expr) 
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  | MStateAssign (var,expr) -> ISet.singleton var.var_id, get_expr_vars expr
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  | MStep (vars, _, args)  ->
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     ISet.of_list (List.map (fun v -> v.var_id) vars),
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    List.fold_left (fun accu v -> VSet.union accu (get_expr_vars v)) VSet.empty args
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  | MBranch (g,(_,hd_il)::tl)     -> (* We focus on variables defined in all branches *)
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     let read_guard = get_expr_vars g in
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     let def_vars_hd, read_vars_hd = branch_block_vars hd_il in
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     let def_vars, read_vars =
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       List.fold_left
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	 (fun (def_vars, read_vars) (_, il) ->
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	 (* We accumulate reads but intersect writes *)
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	   let writes_il, reads_il = branch_block_vars il in
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	   ISet.inter def_vars writes_il,
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	 VSet.union read_vars reads_il
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	 )
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	 (def_vars_hd, read_vars_hd)
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	 tl
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     in
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     def_vars, VSet.union read_guard read_vars
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  | MBranch _ -> assert false (* branch instruction should admit at least one case *)
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  | MReset ni           
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  | MNoReset ni -> ISet.singleton (reset_name ni), VSet.empty
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  | MComment _ -> assert false (* not  available for EMF output *)
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let rec pp_emf_instr m fmt i =
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  let pp_content fmt i =
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    match Corelang.get_instr_desc i with
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    | MLocalAssign(lhs, expr)
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    -> (
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      (match expr.value_desc with
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      | Fun (fun_id, vl) -> (
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	(* Thanks to normalization, vl shall only contain constant or
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	   local/state vars but not calls to other functions *)
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	fprintf fmt "\"kind\": \"operator\",@ ";
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	fprintf fmt "\"lhs\": \"%a\",@ " Printers.pp_var_name lhs;
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	fprintf fmt "\"name\": \"%s\",@ \"args\": [@[%a@]]"
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	  fun_id
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	  pp_emf_cst_or_var_list vl
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      )	 
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      | Array _ | Access _ | Power _ -> assert false (* No array expression allowed yet *)
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      | Cst _ 
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      | LocalVar _
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      | StateVar _ -> (
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	fprintf fmt "\"kind\": \"local_assign\",@ \"lhs\": \"%a\",@ \"rhs\": %a"
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	  Printers.pp_var_name lhs
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	  pp_emf_cst_or_var expr
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      ))    )
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  | MStateAssign(lhs, expr) (* a Pre construct Shall only be defined by a
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			       variable or a constant, no function anymore! *)
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    -> (
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      fprintf fmt "\"kind\": \"pre\",@ \"lhs\": \"%a\",@ \"rhs\": %a"
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	Printers.pp_var_name lhs
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	pp_emf_cst_or_var expr
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    )
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  | MReset id           
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    -> (
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      fprintf fmt "\"kind\": \"reset\",@ \"lhs\": \"%s\",@ \"rhs\": \"true\""
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	(reset_name id)
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    )
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  | MNoReset id           
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    -> (
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      fprintf fmt "\"kind\": \"reset\",@ \"lhs\": \"%s\",@ \"rhs\": \"false\""
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	(reset_name id)
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    )
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  | MBranch (g, hl) -> (
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    let outputs, inputs = branch_instr_vars i in
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    fprintf fmt "\"kind\": \"branch\",@ ";
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    fprintf fmt "\"guard\": %a,@ " pp_emf_cst_or_var g; (* it has to be a variable or a constant *)
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    fprintf fmt "\"outputs\": [%a],@ " (fprintf_list ~sep:", " pp_var_string) (ISet.elements outputs);
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    fprintf fmt "\"inputs\": [%a],@ " pp_emf_vars_decl
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      (* (let guard_inputs = get_expr_vars g in
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	  VSet.elements (VSet.diff inputs guard_inputs)) -- previous version to
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	 remove guard's variable from inputs *)
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      (VSet.elements inputs)
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    ;
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    fprintf fmt "@[<v 2>\"branches\": {@ %a@]}@ "
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      (fprintf_list ~sep:",@ "
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	 (fun fmt (tag, instrs_tag) ->
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	   let (*branch_outputs*) _, branch_inputs = branch_block_vars instrs_tag in    	   
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	   fprintf fmt "@[<v 2>\"%s\": {@ " tag;
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	   fprintf fmt "\"inputs\": [%a],@ " pp_emf_vars_decl (VSet.elements branch_inputs); 
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	   fprintf fmt "@[<v 2>\"instrs\": {@ ";
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	   fprintf_list ~sep:",@ " (pp_emf_instr m) fmt instrs_tag;
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	   fprintf fmt "@]}@ ";
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	   fprintf fmt "@]}"
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	 )
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      )
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      hl
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   )
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  | MStep ([var], f, _) when is_arrow_fun m i -> (* Arrow case *) (
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    fprintf fmt "\"kind\": \"arrow\",@ \"name\": \"%s\",@ \"lhs\": \"%a\",@ \"rhs\": \"%s\""
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      f
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      Printers.pp_var_name var
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      (reset_name f)
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  )
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  | MStep (outputs, f, inputs) when not (is_imported_node f m) -> (
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    let node_f = Machine_code.get_node_def f m in
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    let is_stateful = List.mem_assoc f m.minstances in 
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    fprintf fmt "\"kind\": \"%s\",@ \"name\": \"%s\",@ \"id\": \"%s\",@ "
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      (if is_stateful then "statefulcall" else "statelesscall")
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      (node_f.node_id) 
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      f;
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    fprintf fmt "\"lhs\": [@[%a@]],@ \"args\": [@[%a@]]"
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      (fprintf_list ~sep:",@ " (fun fmt v -> fprintf fmt "\"%a\"" Printers.pp_var_name v)) outputs
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      pp_emf_cst_or_var_list inputs;
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    if is_stateful then fprintf fmt ",@ \"reset\": \"%s\"" (reset_name f) else fprintf fmt "@ "
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  )
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  | MStep(outputs, f, inputs ) -> (* This is an imported node *)
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        EMF_library_calls.pp_call fmt m f outputs inputs
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  | MComment _ 
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    -> Format.eprintf "unhandled comment in EMF@.@?"; assert false
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  (* not  available for EMF output *)
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  in
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  fprintf fmt "@[ @[<v 2>\"%a\": {@ " get_instr_id i;
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  fprintf fmt "%a@ " pp_content i;
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  fprintf fmt "}@]"
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let pp_machine fmt m =
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  try
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    fprintf fmt "@[<v 2>\"%s\": {@ "
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      m.mname.node_id;
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    fprintf fmt "\"kind\": %t,@ \"inputs\": [%a],@ \"outputs\": [%a],@ \"locals\": [%a],@ "
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      (fun fmt -> if not ( snd (get_stateless_status m) )
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	then fprintf fmt "\"stateful\""
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	else fprintf fmt "\"stateless\"")
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      pp_emf_vars_decl m.mstep.step_inputs
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      pp_emf_vars_decl m.mstep.step_outputs
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      pp_emf_vars_decl m.mstep.step_locals
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    ;
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    fprintf fmt "\"instrs\": {@[<v 0> %a@]@ }"
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      (fprintf_list ~sep:",@ " (pp_emf_instr m)) m.mstep.step_instrs;
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    fprintf fmt "@]@ }"
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  with Unhandled msg -> (
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    eprintf "[Error] @[<v 0>EMF backend@ Issues while translating node %s@ "
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      m.mname.node_id;
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    eprintf "%s@ " msg;
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    eprintf "node skipped - no output generated@ @]@."
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  )
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(****************************************************)
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(* Main function: iterates over node and print them *)
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(****************************************************)
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let pp_meta fmt basename =
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  fprintf fmt "\"meta\": @[<v 0>{@ ";
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  Utils.fprintf_list ~sep:",@ "
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    (fun fmt (k, v) -> fprintf fmt "\"%s\": \"%s\"" k v)
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    fmt
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    ["compiler-name", (Filename.basename Sys.executable_name);
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     "compiler-version", Version.number;
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     "command", (String.concat " " (Array.to_list Sys.argv));
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     "source_file", basename
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    ]
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  ;
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  fprintf fmt "@ @]},@ "
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let translate fmt basename prog machines =
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  fprintf fmt "@[<v 0>{@ ";
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  pp_meta fmt basename;
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  fprintf fmt "\"nodes\": @[<v 0>{@ ";
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  (* Previous alternative: mapping normalized lustre to EMF: 
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     fprintf_list ~sep:",@ " pp_decl fmt prog; *)
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  fprintf_list ~sep:",@ " pp_machine fmt (List.rev machines);
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  fprintf fmt "@ @]}";
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  fprintf fmt "@ @]}"
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(* Local Variables: *)
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(* compile-command: "make -C ../.." *)
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(* End: *)