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(*
Copyright (c) 2000
Cambridge University Technical Services Limited
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*)
(*
TODO: This duplicates some of the Word structure although it adds certain
"unsafe" and Poly-specific functions. It probably should be rewritten now
that we have the standard basis library. DCJM June 2000.
*)
structure Address :>
(*****************************************************************************)
(* Address export signature *)
(*****************************************************************************)
sig
type machineWord
type address
type handler
type short = Word.word
val wordEq : 'a * 'a -> bool
val isShort : 'a -> bool
exception Cast of string;
val unsafeCast: 'a -> 'b
val toMachineWord : 'a -> machineWord
val toShort : 'a -> short
val toAddress : 'a -> address
val loadByte: (address * Word.word) -> Word8.word
val loadWord: (address * Word.word) -> machineWord
val assignByte: (address * Word.word * Word8.word) -> unit
val assignWord: (address * Word.word * machineWord) -> unit
val alloc: (short * Word8.word * machineWord) -> address
val lock: address -> unit
val length: address -> short
val flags: address -> Word8.word
val setFlags: address * Word8.word -> unit
val getFlags: address -> Word8.word
val wordSize: int
val F_words : Word8.word
val F_bytes : Word8.word
val F_code : Word8.word
val F_stack : Word8.word
val F_negative : Word8.word
val F_mutable : Word8.word
val F_gc : Word8.word;
val isWords : address -> bool;
val isBytes : address -> bool;
val isCode : address -> bool;
val isStack : address -> bool;
val isMutable:address -> bool;
val call: (address * machineWord) -> machineWord
val isIoAddress : address -> bool
(* The following function is VERY unsafe and should only be *)
(* used by the Poly/ML code generator (ML version). *)
val offsetAddr : address * short -> handler
end =
let
open RuntimeCalls;
in
(*****************************************************************************)
(* Address structure body *)
(*****************************************************************************)
struct
type machineWord = word (* a legal ML object (tag = 0 or 1) *)
and address = word (* a normal pointer (tag = 0) *)
and handler = word (* pointer to exception handler (tag = 2!) *)
and short = word; (* a 31/63-bit int (tag = 1) *)
(* pointer equality *)
val wordEq = PolyML.pointerEq
val unsafeCast : 'a -> 'b = RunCall.unsafeCast;
local
val short : machineWord->bool = RunCall.run_call1 POLY_SYS_is_short
in
fun isShort (x:'a): bool = unsafeCast short x
end
(* The following cast is always safe *)
val toMachineWord : 'a -> machineWord = unsafeCast;
(* The following casts need checking *)
exception Cast of string;
fun toShort (w:'a) : short =
if isShort w then unsafeCast w else raise Cast "toShort";
fun toAddress (w:'a) : address =
if isShort w then raise Cast "toAddress" else unsafeCast w;
(* Note:
assignByte should *not* be used with word-objects
(we might copy half a pointer into the object,
then call the garbage collector)
loadWord should *not* be used with byte-objects
(we might load something that's not a valid ML value,
then call the garbage collector)
Violating these assertions may corrupt the heap and cause unpredictable
behaviour.
It's safe to use assignWord with a byte-object or loadByte
with a word-object but it may not do what you expect.
One difference is that loadWord / assignWord leave the tag bits
unchanged but loadByte / assignByte strip and replace them.
Another difference is that the offset for the
"Word" functions is in words, whereas the offset for the
"Byte" functions is in bytes.
*)
val loadByte: (address * Word.word) -> Word8.word =
RunCall.run_call2 POLY_SYS_load_byte;
val loadWord: (address * Word.word) -> machineWord =
RunCall.run_call2 POLY_SYS_load_word;
val assignByte: (address * Word.word * Word8.word) -> unit =
RunCall.run_call3 POLY_SYS_assign_byte;
val assignWord: (address * Word.word * machineWord) -> unit =
RunCall.run_call3 POLY_SYS_assign_word;
val alloc: (short * Word8.word * machineWord) -> address =
RunCall.run_call3 POLY_SYS_alloc_store;
val lock: address -> unit =
RunCall.run_call1 POLY_SYS_lockseg;
val getFlags: address -> Word8.word =
RunCall.run_call1 POLY_SYS_get_flags;
val setFlags: address * Word8.word -> unit =
RunCall.run_call2 POLY_SYS_code_flags;
val wordSize: int =
RunCall.run_call0 POLY_SYS_bytes_per_word ();
val length: address -> Word.word =
RunCall.run_call1 POLY_SYS_get_length;
val flags: address -> Word8.word =
RunCall.run_call1 POLY_SYS_get_flags;
(* "call" added SPF 7/7/94, corrected 13/7/94, 8/9/94 *)
(* call takes the address of the code of a function [N.B. *NOT* *)
(* the closure for the function] that uses Poly parameter *)
(* conventions (values in registers e.g. an ML secondary entry *)
(* point) and applies it to the address of a single ML tuple. *)
(* N.B. it MUST be a tuple, even if there's only one parameter. *)
(* However, since unit is a "short" not an "address", the type *)
(* of the second parameter has to be "word" (not "address"). *)
(* The run-time system functions all use Poly convention. *)
val call: (address * machineWord) -> machineWord =
RunCall.run_call1 POLY_SYS_callcode_tupled;
val F_words : Word8.word = 0wx00;
val F_bytes : Word8.word = 0wx01;
val F_code : Word8.word = 0wx02;
val F_stack : Word8.word = 0wx03;
val F_negative : Word8.word = 0wx20;
val F_mutable : Word8.word = 0wx40;
val F_gc : Word8.word = 0wx80;
local
val doCall: int*address -> bool
= RunCall.run_call2 RuntimeCalls.POLY_SYS_process_env
in
fun isIoAddress (a: address) : bool = doCall(102, a)
end
(* The following function is VERY unsafe and should only be *)
(* used by the Poly/ML code generator (ML version). *)
val offsetAddr : address * short -> handler =
RunCall.run_call2 POLY_SYS_offset_address;
local
val typeMask : Word8.word = 0wx03;
fun isType (t: Word8.word) (a: address):bool =
Word8.andb(flags a, typeMask) = t
in
val isWords = isType F_words;
val isBytes = isType F_bytes;
val isCode = isType F_code;
val isStack = isType F_stack;
(* The mutable flag may be used with any of the others. *)
fun isMutable a = Word8.andb(flags a, F_mutable) = F_mutable
end;
end
end; (* open RuntimeCalls *)
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