1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT COMPILER COMPONENTS                         --
4--                                                                          --
5--              S Y S T E M . E X C E P T I O N S . M A C H I N E           --
6--                                                                          --
7--                                 S p e c                                  --
8--                                                                          --
9--          Copyright (C) 2013-2020, Free Software Foundation, Inc.          --
10--                                                                          --
11-- GNAT is free software;  you can  redistribute it  and/or modify it under --
12-- terms of the  GNU General Public License as published  by the Free Soft- --
13-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
14-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
15-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
16-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
17--                                                                          --
18-- As a special exception under Section 7 of GPL version 3, you are granted --
19-- additional permissions described in the GCC Runtime Library Exception,   --
20-- version 3.1, as published by the Free Software Foundation.               --
21--                                                                          --
22-- You should have received a copy of the GNU General Public License and    --
23-- a copy of the GCC Runtime Library Exception along with this program;     --
24-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
25-- <http://www.gnu.org/licenses/>.                                          --
26--                                                                          --
27-- GNAT was originally developed  by the GNAT team at  New York University. --
28-- Extensive contributions were provided by Ada Core Technologies Inc.      --
29--                                                                          --
30------------------------------------------------------------------------------
31
32--  Declaration of the machine exception and some associated facilities. The
33--  machine exception is the object that is propagated by low level routines
34--  and that contains the Ada exception occurrence.
35
36--  This is the version using the ARM EHABI mechanism
37
38with Ada.Unchecked_Conversion;
39with Ada.Exceptions;
40
41package System.Exceptions.Machine is
42   pragma Preelaborate;
43
44   ------------------------------------------------
45   -- Entities to interface with the GCC runtime --
46   ------------------------------------------------
47
48   --  Return codes from GCC runtime functions used to propagate an exception
49
50   type Unwind_Reason_Code is
51     (URC_OK,
52      URC_FOREIGN_EXCEPTION_CAUGHT,
53      URC_Unused2,
54      URC_Unused3,
55      URC_Unused4,
56      URC_Unused5,
57      URC_HANDLER_FOUND,
58      URC_INSTALL_CONTEXT,
59      URC_CONTINUE_UNWIND,
60      URC_FAILURE);
61   pragma Convention (C, Unwind_Reason_Code);
62
63   pragma Unreferenced
64     (URC_OK,
65      URC_FOREIGN_EXCEPTION_CAUGHT,
66      URC_Unused2,
67      URC_Unused3,
68      URC_Unused4,
69      URC_Unused5,
70      URC_HANDLER_FOUND,
71      URC_INSTALL_CONTEXT,
72      URC_CONTINUE_UNWIND,
73      URC_FAILURE);
74
75   --  ARM Unwinding State
76
77   type uint32_t is mod 2**32;
78   pragma Convention (C, uint32_t);
79
80   type uint32_t_array is array (Natural range <>) of uint32_t;
81   pragma Convention (C, uint32_t_array);
82
83   type Unwind_State is new uint32_t;
84   pragma Convention (C, Unwind_State);
85
86   US_VIRTUAL_UNWIND_FRAME  : constant Unwind_State := 0;
87   US_UNWIND_FRAME_STARTING : constant Unwind_State := 1;
88   US_UNWIND_FRAME_RESUME   : constant Unwind_State := 2;
89
90   pragma Unreferenced
91     (US_VIRTUAL_UNWIND_FRAME,
92      US_UNWIND_FRAME_STARTING,
93      US_UNWIND_FRAME_RESUME);
94
95   --  Mandatory common header for any exception object handled by the
96   --  GCC unwinding runtime.
97
98   type Exception_Class is array (0 .. 7) of Character;
99
100   GNAT_Exception_Class : constant Exception_Class := "GNU-Ada" & ASCII.NUL;
101   --  "GNU-Ada\0"
102
103   type Unwinder_Cache_Type is record
104      Reserved1 : uint32_t;
105      Reserved2 : uint32_t;
106      Reserved3 : uint32_t;
107      Reserved4 : uint32_t;
108      Reserved5 : uint32_t;
109   end record;
110
111   type Barrier_Cache_Type is record
112      Sp         : uint32_t;
113      Bitpattern : uint32_t_array (0 .. 4);
114   end record;
115
116   type Cleanup_Cache_Type is record
117     Bitpattern : uint32_t_array (0 .. 3);
118   end record;
119
120   type Pr_Cache_Type is record
121      Fnstart    : uint32_t;
122      Ehtp       : System.Address;
123      Additional : uint32_t;
124      Reserved1  : uint32_t;
125   end record;
126
127   type Unwind_Control_Block is record
128      Class   : Exception_Class;
129      Cleanup : System.Address;
130
131      --  Caches
132      Unwinder_Cache : Unwinder_Cache_Type;
133      Barrier_Cache  : Barrier_Cache_Type;
134      Cleanup_Cache  : Cleanup_Cache_Type;
135      Pr_Cache       : Pr_Cache_Type;
136   end record;
137   pragma Convention (C, Unwind_Control_Block);
138   for Unwind_Control_Block'Alignment use 8;
139   --  Map the GCC struct used for exception handling
140
141   type Unwind_Control_Block_Access is access all Unwind_Control_Block;
142   subtype GCC_Exception_Access is Unwind_Control_Block_Access;
143   --  Pointer to a UCB
144
145   procedure Unwind_DeleteException
146     (Ucbp : not null Unwind_Control_Block_Access);
147   pragma Import (C, Unwind_DeleteException, "_Unwind_DeleteException");
148   --  Procedure to free any GCC exception
149
150   --------------------------------------------------------------
151   -- GNAT Specific Entities To Deal With The GCC EH Circuitry --
152   --------------------------------------------------------------
153
154   --  A GNAT exception object to be dealt with by the personality routine
155   --  called by the GCC unwinding runtime.
156
157   type GNAT_GCC_Exception is record
158      Header : Unwind_Control_Block;
159      --  ABI Exception header first
160
161      Occurrence : aliased Ada.Exceptions.Exception_Occurrence;
162      --  The Ada occurrence
163   end record;
164
165   pragma Convention (C, GNAT_GCC_Exception);
166
167   type GNAT_GCC_Exception_Access is access all GNAT_GCC_Exception;
168
169   function To_GCC_Exception is new
170     Ada.Unchecked_Conversion (System.Address, GCC_Exception_Access);
171
172   function To_GNAT_GCC_Exception is new
173     Ada.Unchecked_Conversion
174     (GCC_Exception_Access, GNAT_GCC_Exception_Access);
175
176   function New_Occurrence return GNAT_GCC_Exception_Access;
177   --  Allocate and initialize a machine occurrence
178
179end System.Exceptions.Machine;
180