------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- SYSTEM.MACHINE_STATE_OPERATIONS -- -- -- -- S p e c -- -- -- -- Copyright (C) 1999-2005 Free Software Foundation, Inc. -- -- -- -- GNAT 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. GNAT 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 GNAT; see file COPYING. If not, write -- -- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, -- -- Boston, MA 02110-1301, 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. -- -- -- -- GNAT was originally developed by the GNAT team at New York University. -- -- Extensive contributions were provided by Ada Core Technologies Inc. -- -- -- ------------------------------------------------------------------------------ pragma Polling (Off); -- We must turn polling off for this unit, because otherwise we get -- elaboration circularities with System.Exception_Tables. with System.Storage_Elements; package System.Machine_State_Operations is subtype Code_Loc is System.Address; -- Code location used in building exception tables and for call -- addresses when propagating an exception (also traceback table) -- Values of this type are created by using Label'Address or -- extracted from machine states using Get_Code_Loc. type Machine_State is new System.Address; -- The table based exception handling approach (see a-except.adb) isolates -- the target dependent aspects using an abstract data type interface -- to the type Machine_State, which is represented as a System.Address -- value (presumably implemented as a pointer to an appropriate record -- structure). function Machine_State_Length return System.Storage_Elements.Storage_Offset; -- Function to determine the length of the Storage_Array needed to hold -- a machine state. The machine state will always be maximally aligned. -- The value returned is a constant that will be used to allocate space -- for a machine state value. function Allocate_Machine_State return Machine_State; -- Allocate the required space for a Machine_State procedure Free_Machine_State (M : in out Machine_State); -- Free the dynamic memory taken by Machine_State -- The initial value of type Machine_State is created by the low level -- routine that actually raises an exception using the special builtin -- _builtin_machine_state. This value will typically encode the value -- of the program counter, and relevant registers. The following -- operations are defined on Machine_State values: function Get_Code_Loc (M : Machine_State) return Code_Loc; -- This function extracts the program counter value from a machine -- state, which the caller uses for searching the exception tables, -- and also for recording entries in the traceback table. The call -- returns a value of Null_Loc if the machine state represents the -- outer level, or some other frame for which no information can be -- provided. procedure Pop_Frame (M : Machine_State); -- This procedure pops the machine state M so that it represents the -- call point, as though the current subprogram had returned. It -- changes only the value referenced by M, and does not affect -- the current stack environment. function Fetch_Code (Loc : Code_Loc) return Code_Loc; -- Some architectures (notably VMS) use a descriptor to describe -- a subprogram address. This function computes the actual starting -- address of the code from Loc. -- Do not add pragma Inline, see 9116-002. -- ??? This function will go away when 'Code_Address is fixed on VMS. procedure Set_Machine_State (M : Machine_State); -- This routine sets M from the current machine state. It is called -- when an exception is initially signalled to initialize the state. end System.Machine_State_Operations;