+++ /dev/null
-------------------------------------------------------------------------------
--- --
--- GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS --
--- --
--- S Y S T E M . T A S K I N G . P R O T E C T E D _ O B J E C T S . --
--- S I N G L E _ E N T R Y --
--- --
--- S p e c --
--- --
--- $Revision: 1.1 $
--- --
--- Copyright (C) 1991-1999 Florida State University --
--- --
--- GNARL is free software; you can redistribute it and/or modify it under --
--- terms of the GNU General Public License as published by the Free Soft- --
--- ware Foundation; either version 2, or (at your option) any later ver- --
--- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
--- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
--- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
--- for more details. You should have received a copy of the GNU General --
--- Public License distributed with GNARL; see file COPYING. If not, write --
--- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
--- MA 02111-1307, USA. --
--- --
--- As a special exception, if other files instantiate generics from this --
--- unit, or you link this unit with other files to produce an executable, --
--- this unit does not by itself cause the resulting executable to be --
--- covered by the GNU General Public License. This exception does not --
--- however invalidate any other reasons why the executable file might be --
--- covered by the GNU Public License. --
--- --
--- GNARL was developed by the GNARL team at Florida State University. It is --
--- now maintained by Ada Core Technologies Inc. in cooperation with Florida --
--- State University (http://www.gnat.com). --
--- --
-------------------------------------------------------------------------------
-
--- This package provides an optimized version of Protected_Objects.Operations
--- and Protected_Objects.Entries making the following assumptions:
---
--- PO have only one entry
--- There is only one caller at a time (No_Entry_Queue)
--- There is no dynamic priority support (No_Dynamic_Priorities)
--- No Abort Statements
--- (No_Abort_Statements, Max_Asynchronous_Select_Nesting => 0)
--- PO are at library level
--- None of the tasks will terminate (no need for finalization)
---
--- This interface is intended to be used in the ravenscar profile, the
--- compiler is responsible for ensuring that the conditions mentioned above
--- are respected, except for the No_Entry_Queue restriction that is checked
--- dynamically in this package, since the check cannot be performed at compile
--- time, and is relatively cheap (see body).
---
--- This package is part of the high level tasking interface used by the
--- compiler to expand Ada 95 tasking constructs into simpler run time calls
--- (aka GNARLI, GNU Ada Run-time Library Interface)
---
--- Note: the compiler generates direct calls to this interface, via Rtsfind.
--- Any changes to this interface may require corresponding compiler changes
--- in exp_ch9.adb and possibly exp_ch7.adb
-
-package System.Tasking.Protected_Objects.Single_Entry is
- pragma Elaborate_Body;
-
- ---------------------------------
- -- Compiler Interface (GNARLI) --
- ---------------------------------
-
- -- The compiler will expand in the GNAT tree the following construct:
- --
- -- protected PO is
- -- entry E;
- -- procedure P;
- -- private
- -- Open : Boolean := False;
- -- end PO;
- --
- -- protected body PO is
- -- entry E when Open is
- -- ...variable declarations...
- -- begin
- -- ...B...
- -- end E;
- --
- -- procedure P is
- -- ...variable declarations...
- -- begin
- -- ...C...
- -- end P;
- -- end PO;
- --
- -- as follows:
- --
- -- protected type poT is
- -- entry e;
- -- procedure p;
- -- private
- -- open : boolean := false;
- -- end poT;
- -- type poTV is limited record
- -- open : boolean := false;
- -- _object : aliased protection_entry;
- -- end record;
- -- procedure poPT__E1s (O : address; P : address; E :
- -- protected_entry_index);
- -- function poPT__B2s (O : address; E : protected_entry_index) return
- -- boolean;
- -- procedure poPT__pN (_object : in out poTV);
- -- procedure poPT__pP (_object : in out poTV);
- -- poTA : aliased entry_body := (
- -- barrier => poPT__B2s'unrestricted_access,
- -- action => poPT__E1s'unrestricted_access);
- -- freeze poTV [
- -- procedure _init_proc (_init : in out poTV) is
- -- begin
- -- _init.open := false;
- -- _init_proc (_init._object);
- -- initialize_protection_entry (_init._object'unchecked_access,
- -- unspecified_priority, _init'address, poTA'
- -- unrestricted_access);
- -- return;
- -- end _init_proc;
- -- ]
- -- po : poT;
- -- _init_proc (poTV!(po));
- --
- -- function poPT__B2s (O : address; E : protected_entry_index) return
- -- boolean is
- -- type poTVP is access poTV;
- -- _object : poTVP := poTVP!(O);
- -- poR : protection_entry renames _object._object;
- -- openP : boolean renames _object.open;
- -- begin
- -- return open;
- -- end poPT__B2s;
- --
- -- procedure poPT__E1s (O : address; P : address; E :
- -- protected_entry_index) is
- -- type poTVP is access poTV;
- -- _object : poTVP := poTVP!(O);
- -- begin
- -- B1b : declare
- -- poR : protection_entry renames _object._object;
- -- openP : boolean renames _object.open;
- -- ...variable declarations...
- -- begin
- -- ...B...
- -- end B1b;
- -- complete_single_entry_body (_object._object'unchecked_access);
- -- return;
- -- exception
- -- when all others =>
- -- exceptional_complete_single_entry_body (_object._object'
- -- unchecked_access, get_gnat_exception);
- -- return;
- -- end poPT__E1s;
- --
- -- procedure poPT__pN (_object : in out poTV) is
- -- poR : protection_entry renames _object._object;
- -- openP : boolean renames _object.open;
- -- ...variable declarations...
- -- begin
- -- ...C...
- -- return;
- -- end poPT__pN;
- --
- -- procedure poPT__pP (_object : in out poTV) is
- -- procedure _clean is
- -- begin
- -- service_entry (_object._object'unchecked_access);
- -- unlock_entry (_object._object'unchecked_access);
- -- return;
- -- end _clean;
- -- begin
- -- lock_entry (_object._object'unchecked_access);
- -- B5b : begin
- -- poPT__pN (_object);
- -- at end
- -- _clean;
- -- end B5b;
- -- return;
- -- end poPT__pP;
-
- type Protection_Entry is limited private;
- -- This type contains the GNARL state of a protected object. The
- -- application-defined portion of the state (i.e. private objects)
- -- is maintained by the compiler-generated code.
-
- type Protection_Entry_Access is access all Protection_Entry;
-
- procedure Initialize_Protection_Entry
- (Object : Protection_Entry_Access;
- Ceiling_Priority : Integer;
- Compiler_Info : System.Address;
- Entry_Body : Entry_Body_Access);
- -- Initialize the Object parameter so that it can be used by the run time
- -- to keep track of the runtime state of a protected object.
-
- procedure Lock_Entry (Object : Protection_Entry_Access);
- -- Lock a protected object for write access. Upon return, the caller
- -- owns the lock to this object, and no other call to Lock or
- -- Lock_Read_Only with the same argument will return until the
- -- corresponding call to Unlock has been made by the caller.
-
- procedure Lock_Read_Only_Entry
- (Object : Protection_Entry_Access);
- -- Lock a protected object for read access. Upon return, the caller
- -- owns the lock for read access, and no other calls to Lock
- -- with the same argument will return until the corresponding call
- -- to Unlock has been made by the caller. Other cals to Lock_Read_Only
- -- may (but need not) return before the call to Unlock, and the
- -- corresponding callers will also own the lock for read access.
-
- procedure Unlock_Entry (Object : Protection_Entry_Access);
- -- Relinquish ownership of the lock for the object represented by
- -- the Object parameter. If this ownership was for write access, or
- -- if it was for read access where there are no other read access
- -- locks outstanding, one (or more, in the case of Lock_Read_Only)
- -- of the tasks waiting on this lock (if any) will be given the
- -- lock and allowed to return from the Lock or Lock_Read_Only call.
-
- procedure Service_Entry (Object : Protection_Entry_Access);
- -- Service the entry queue of the specified object, executing the
- -- corresponding body of any queued entry call that is waiting on True
- -- barrier. This is used when the state of a protected object may have
- -- changed, in particular after the execution of the statement sequence of
- -- a protected procedure.
- -- This must be called with abortion deferred and with the corresponding
- -- object locked.
-
- procedure Protected_Single_Entry_Call
- (Object : Protection_Entry_Access;
- Uninterpreted_Data : System.Address;
- Mode : Call_Modes);
- -- Make a protected entry call to the specified object.
- -- Pend a protected entry call on the protected object represented
- -- by Object. A pended call is not queued; it may be executed immediately
- -- or queued, depending on the state of the entry barrier.
- --
- -- Uninterpreted_Data
- -- This will be returned by Next_Entry_Call when this call is serviced.
- -- It can be used by the compiler to pass information between the
- -- caller and the server, in particular entry parameters.
- --
- -- Mode
- -- The kind of call to be pended
-
- procedure Timed_Protected_Single_Entry_Call
- (Object : Protection_Entry_Access;
- Uninterpreted_Data : System.Address;
- Timeout : Duration;
- Mode : Delay_Modes;
- Entry_Call_Successful : out Boolean);
- -- Same as the Protected_Entry_Call but with time-out specified.
- -- This routine is used to implement timed entry calls.
-
- procedure Complete_Single_Entry_Body
- (Object : Protection_Entry_Access);
- pragma Inline (Complete_Single_Entry_Body);
- -- Called from within an entry body procedure, indicates that the
- -- corresponding entry call has been serviced.
-
- procedure Exceptional_Complete_Single_Entry_Body
- (Object : Protection_Entry_Access;
- Ex : Ada.Exceptions.Exception_Id);
- -- Perform all of the functions of Complete_Entry_Body. In addition,
- -- report in Ex the exception whose propagation terminated the entry
- -- body to the runtime system.
-
- function Protected_Count_Entry (Object : Protection_Entry)
- return Natural;
- -- Return the number of entry calls on Object (0 or 1).
-
- function Protected_Single_Entry_Caller (Object : Protection_Entry)
- return Task_ID;
- -- Return value of E'Caller, where E is the protected entry currently
- -- being handled. This will only work if called from within an
- -- entry body, as required by the LRM (C.7.1(14)).
-
-private
- type Protection_Entry is record
- L : aliased Task_Primitives.Lock;
- Compiler_Info : System.Address;
- Call_In_Progress : Entry_Call_Link;
- Ceiling : System.Any_Priority;
- Entry_Body : Entry_Body_Access;
- Entry_Queue : Entry_Call_Link;
- end record;
- pragma Volatile (Protection_Entry);
- for Protection_Entry'Alignment use Standard'Maximum_Alignment;
- -- Use maximum alignement so that one can convert a protection_entry_access
- -- to a task_id.
-
-end System.Tasking.Protected_Objects.Single_Entry;
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