1 (* Bitmatch persistent patterns.
2 * Copyright (C) 2008 Red Hat Inc., Richard W.M. Jones
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2 of the License, or (at your option) any later version.
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with this library; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
27 type patt = Camlp4.PreCast.Syntax.Ast.patt
28 type expr = Camlp4.PreCast.Syntax.Ast.expr
29 type loc_t = Camlp4.PreCast.Syntax.Ast.Loc.t
31 (* Field. In bitmatch (patterns) the type is [patt field]. In
32 * BITSTRING (constructor) the type is [expr field].
35 field : 'a; (* field ('a is either patt or expr) *)
36 flen : expr; (* length in bits, may be non-const *)
37 endian : endian_expr; (* endianness *)
38 signed : bool; (* true if signed, false if unsigned *)
39 t : field_type; (* type *)
40 _loc : Loc.t; (* location in source code *)
41 offset : expr option; (* offset expression *)
43 (* Turn the field into a string. This used to be a function,
44 * but that would prevent this structure from being marshalled.
45 * This is unsatisfactory at the moment because it means we
46 * can't print out the 'a field.
50 and field_type = Int | String | Bitstring (* field type *)
52 | ConstantEndian of Bitmatch.endian (* a constant little/big/nativeendian *)
53 | EndianExpr of expr (* an endian expression *)
54 and printer_t = PattPrinter | ExprPrinter | NoPrinter
56 type pattern = patt field list
58 type constructor = expr field list
60 type named = string * alt
63 | Constructor of constructor
65 (* Work out if an expression is an integer constant.
67 * Returns [Some i] if so (where i is the integer value), else [None].
69 * Fairly simplistic algorithm: we can only detect simple constant
70 * expressions such as [k], [k+c], [k-c] etc.
72 let rec expr_is_constant = function
73 | <:expr< $int:i$ >> -> (* Literal integer constant. *)
74 Some (int_of_string i)
75 | <:expr< $a$ + $b$ >> -> (* Addition of constants. *)
76 (match expr_is_constant a, expr_is_constant b with
77 | Some a, Some b -> Some (a+b)
79 | <:expr< $a$ - $b$ >> -> (* Subtraction. *)
80 (match expr_is_constant a, expr_is_constant b with
81 | Some a, Some b -> Some (a-b)
83 | <:expr< $a$ * $b$ >> -> (* Multiplication. *)
84 (match expr_is_constant a, expr_is_constant b with
85 | Some a, Some b -> Some (a*b)
87 | <:expr< $a$ / $b$ >> -> (* Division. *)
88 (match expr_is_constant a, expr_is_constant b with
89 | Some a, Some b -> Some (a/b)
91 | <:expr< $a$ lsl $b$ >> -> (* Shift left. *)
92 (match expr_is_constant a, expr_is_constant b with
93 | Some a, Some b -> Some (a lsl b)
95 | <:expr< $a$ lsr $b$ >> -> (* Shift right. *)
96 (match expr_is_constant a, expr_is_constant b with
97 | Some a, Some b -> Some (a lsr b)
99 | _ -> None (* Anything else is not constant. *)
101 let string_of_field_type = function
104 | Bitstring -> "bitstring"
106 let patt_printer = function
107 | <:patt< $lid:id$ >> -> id
108 | <:patt< _ >> -> "_"
111 let expr_printer = function
112 | <:expr< $lid:id$ >> -> id
113 | <:expr< $int:i$ >> -> i
114 | _ -> "[expression]"
116 let string_of_field { field = field; flen = flen;
117 endian = endian; signed = signed; t = t;
121 match expr_is_constant flen with
122 | Some i -> string_of_int i
123 | None -> "[non-const-len]" in
126 | ConstantEndian endian -> Bitmatch.string_of_endian endian
127 | EndianExpr _ -> "endian [expr]" in
128 let signed = if signed then "signed" else "unsigned" in
129 let t = string_of_field_type t in
130 let loc_fname = Loc.file_name _loc in
131 let loc_line = Loc.start_line _loc in
132 let loc_char = Loc.start_off _loc - Loc.start_bol _loc in
134 sprintf "[field] : %s : %s, %s, %s @ (%S, %d, %d)"
135 (*printer field*) flen t endian signed loc_fname loc_line loc_char
137 let string_of_pattern pattern =
138 "{ " ^ String.concat ";\n " (List.map string_of_field pattern) ^ " }\n"
140 let string_of_constructor constructor =
141 "{ " ^ String.concat ";\n " (List.map string_of_field constructor) ^ " }\n"
143 let named_to_channel chan n = Marshal.to_channel chan n []
145 let named_to_string n = Marshal.to_string n []
147 let named_to_buffer str ofs len n = Marshal.to_buffer str ofs len n []
149 let named_from_channel = Marshal.from_channel
151 let named_from_string = Marshal.from_string
153 let create_pattern_field _loc =
155 field = <:patt< _ >>;
156 flen = <:expr< 32 >>;
157 endian = ConstantEndian Bitmatch.BigEndian;
161 printer = PattPrinter;
165 let set_lident_patt field id =
166 let _loc = field._loc in
167 { field with field = <:patt< $lid:id$ >> }
168 let set_int_patt field i =
169 let _loc = field._loc in
170 { field with field = <:patt< $`int:i$ >> }
171 let set_string_patt field str =
172 let _loc = field._loc in
173 { field with field = <:patt< $str:str$ >> }
174 let set_unbound_patt field =
175 let _loc = field._loc in
176 { field with field = <:patt< _ >> }
177 let set_patt field patt = { field with field = patt }
178 let set_length_int field flen =
179 let _loc = field._loc in
180 { field with flen = <:expr< $`int:flen$ >> }
181 let set_length field flen = { field with flen = flen }
182 let set_endian field endian = { field with endian = ConstantEndian endian }
183 let set_endian_expr field expr = { field with endian = EndianExpr expr }
184 let set_signed field signed = { field with signed = signed }
185 let set_type_int field = { field with t = Int }
186 let set_type_string field = { field with t = String }
187 let set_type_bitstring field = { field with t = Bitstring }
188 let set_location field loc = { field with _loc = loc }
189 let set_offset_int field i =
190 let _loc = field._loc in
191 { field with offset = Some <:expr< $`int:i$ >> }
192 let set_offset field expr = { field with offset = Some expr }
193 let set_no_offset field = { field with offset = None }
195 let create_constructor_field _loc =
197 field = <:expr< 0 >>;
198 flen = <:expr< 32 >>;
199 endian = ConstantEndian Bitmatch.BigEndian;
203 printer = ExprPrinter;
207 let set_lident_expr field id =
208 let _loc = field._loc in
209 { field with field = <:expr< $lid:id$ >> }
210 let set_int_expr field i =
211 let _loc = field._loc in
212 { field with field = <:expr< $`int:i$ >> }
213 let set_string_expr field str =
214 let _loc = field._loc in
215 { field with field = <:expr< $str:str$ >> }
216 let set_expr field expr =
217 let _loc = field._loc in
218 { field with field = expr }
220 let get_patt field = field.field
221 let get_expr field = field.field
222 let get_length field = field.flen
223 let get_endian field = field.endian
224 let get_signed field = field.signed
225 let get_type field = field.t
226 let get_location field = field._loc
227 let get_offset field = field.offset