(* SYSTEM.def provides access to COROUTINE primitives and underlying system.
Copyright (C) 2002-2025 Free Software Foundation, Inc.
Contributed by Gaius Mulley <gaius.mulley@southwales.ac.uk>.
This file is part of GNU Modula-2.
GNU Modula-2 is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
GNU Modula-2 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
General Public License for more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. *)
DEFINITION MODULE SYSTEM ;
(* This module is designed to be used on a native operating system
rather than an embedded system as it implements the coroutine
primitives TRANSFER, IOTRANSFER and
NEWPROCESS through the GNU Pthread library. *)
FROM COROUTINES IMPORT PROTECTION ;
EXPORT QUALIFIED (* the following are built into the compiler: *)
ADDRESS, WORD, BYTE, CSIZE_T, CSSIZE_T, COFF_T, (* @SYSTEM_DATATYPES@ *)
ADR, TSIZE, ROTATE, SHIFT, THROW, TBITSIZE,
(* SIZE is exported depending upon -fpim2 and
-fpedantic. *)
(* The rest are implemented in SYSTEM.mod. *)
PROCESS, TRANSFER, NEWPROCESS, IOTRANSFER,
LISTEN,
ListenLoop, TurnInterrupts,
(* Internal GM2 compiler functions. *)
ShiftVal, ShiftLeft, ShiftRight,
RotateVal, RotateLeft, RotateRight ;
TYPE
PROCESS = RECORD
context: INTEGER ;
END ;
(* Note that the full list of system and sized datatypes include:
LOC, WORD, BYTE, ADDRESS,
(and the non language standard target types)
INTEGER8, INTEGER16, INTEGER32, INTEGER64,
CARDINAL8, CARDINAL16, CARDINAL32, CARDINAL64,
WORD16, WORD32, WORD64, BITSET8, BITSET16,
BITSET32, REAL32, REAL64, REAL128, COMPLEX32,
COMPLEX64, COMPLEX128, CSIZE_T, CSSIZE_T.
Also note that the non-standard data types will
move into another module in the future. *)
(* The following types are supported on this target:
@SYSTEM_TYPES@
*)
(*
TRANSFER - save the current volatile environment into, p1.
Restore the volatile environment from, p2.
*)
PROCEDURE TRANSFER (VAR p1: PROCESS; p2: PROCESS) ;
(*
NEWPROCESS - p is a parameterless procedure, a, is the origin of
the workspace used for the process stack and containing
the volatile environment of the process. StackSize, is
the maximum size of the stack in bytes which can be used
by this process. new, is the new process.
*)
PROCEDURE NEWPROCESS (p: PROC; a: ADDRESS; StackSize: CARDINAL; VAR new: PROCESS) ;
(*
IOTRANSFER - saves the current volatile environment into, First,
and restores volatile environment, Second.
When an interrupt, InterruptNo, is encountered then
the reverse takes place. (The then current volatile
environment is shelved onto Second and First is resumed).
NOTE: that upon interrupt the Second might not be the
same process as that before the original call to
IOTRANSFER.
*)
PROCEDURE IOTRANSFER (VAR First, Second: PROCESS; InterruptNo: CARDINAL) ;
(*
LISTEN - briefly listen for any interrupts.
*)
PROCEDURE LISTEN ;
(*
ListenLoop - should be called instead of users writing:
LOOP
LISTEN
END
It performs the same function but yields
control back to the underlying operating system
via a call to pth_select.
It also checks for deadlock.
This function returns when an interrupt occurs ie
a file descriptor becomes ready or a time event
expires. See the module RTint.
*)
PROCEDURE ListenLoop ;
(*
TurnInterrupts - switches processor interrupts to the protection
level, to. It returns the old value.
*)
PROCEDURE TurnInterrupts (to: PROTECTION) : PROTECTION ;
(*
all the functions below are declared internally to gm2
====================================================
PROCEDURE ADR (VAR v: <anytype>): ADDRESS;
(* Returns the address of variable v. *)
PROCEDURE SIZE (v: <type>) : ZType;
(* Returns the number of BYTES used to store a v of
any specified <type>. Only available if -fpim2 is used.
*)
PROCEDURE TSIZE (<type>) : CARDINAL;
(* Returns the number of BYTES used to store a value of the
specified <type>.
*)
PROCEDURE ROTATE (val: <a set type>;
num: INTEGER): <type of first parameter>;
(* Returns a bit sequence obtained from val by rotating up or down
(left or right) by the absolute value of num. The direction is
down if the sign of num is negative, otherwise the direction is up.
*)
PROCEDURE SHIFT (val: <a set type>;
num: INTEGER): <type of first parameter>;
(* Returns a bit sequence obtained from val by shifting up or down
(left or right) by the absolute value of num, introducing
zeros as necessary. The direction is down if the sign of
num is negative, otherwise the direction is up.
*)
PROCEDURE THROW (i: INTEGER) <* noreturn *> ;
(*
THROW is a GNU extension and was not part of the PIM or ISO
standards. It throws an exception which will be caught by the EXCEPT
block (assuming it exists). This is a compiler builtin function which
interfaces to the GCC exception handling runtime system.
GCC uses the term throw, hence the naming distinction between
the GCC builtin and the Modula-2 runtime library procedure Raise.
The later library procedure Raise will call SYSTEM.THROW after
performing various housekeeping activities.
*)
PROCEDURE TBITSIZE (<type>) : CARDINAL ;
(* Returns the minimum number of bits necessary to represent
<type>. This procedure function is only useful for determining
the number of bits used for any type field within a packed RECORD.
It is not particularly useful elsewhere since <type> might be
optimized for speed, for example a BOOLEAN could occupy a WORD.
*)
*)
(* The following procedures are invoked by GNU Modula-2 to
shift non word sized set types. They are not strictly part
of the core PIM Modula-2, however they are used
to implement the SHIFT procedure defined above,
which are in turn used by the Logitech compatible libraries.
Users will access these procedures by using the procedure
SHIFT above and GNU Modula-2 will map SHIFT onto one of
the following procedures.
*)
(*
ShiftVal - is a runtime procedure whose job is to implement
the SHIFT procedure of ISO SYSTEM. GNU Modula-2 will
inline a SHIFT of a single WORD sized set and will
only call this routine for larger sets.
*)
PROCEDURE ShiftVal (VAR s, d: ARRAY OF BITSET;
SetSizeInBits: CARDINAL;
ShiftCount: INTEGER) ;
(*
ShiftLeft - performs the shift left for a multi word set.
This procedure might be called by the back end of
GNU Modula-2 depending whether amount is known at
compile time.
*)
PROCEDURE ShiftLeft (VAR s, d: ARRAY OF BITSET;
SetSizeInBits: CARDINAL;
ShiftCount: CARDINAL) ;
(*
ShiftRight - performs the shift left for a multi word set.
This procedure might be called by the back end of
GNU Modula-2 depending whether amount is known at
compile time.
*)
PROCEDURE ShiftRight (VAR s, d: ARRAY OF BITSET;
SetSizeInBits: CARDINAL;
ShiftCount: CARDINAL) ;
(*
RotateVal - is a runtime procedure whose job is to implement
the ROTATE procedure of ISO SYSTEM. GNU Modula-2 will
inline a ROTATE of a single WORD (or less)
sized set and will only call this routine for
larger sets.
*)
PROCEDURE RotateVal (VAR s, d: ARRAY OF BITSET;
SetSizeInBits: CARDINAL;
RotateCount: INTEGER) ;
(*
RotateLeft - performs the rotate left for a multi word set.
This procedure might be called by the back end of
GNU Modula-2 depending whether amount is known
at compile time.
*)
PROCEDURE RotateLeft (VAR s, d: ARRAY OF BITSET;
SetSizeInBits: CARDINAL;
RotateCount: CARDINAL) ;
(*
RotateRight - performs the rotate right for a multi word set.
This procedure might be called by the back end of
GNU Modula-2 depending whether amount is known at
compile time.
*)
PROCEDURE RotateRight (VAR s, d: ARRAY OF BITSET;
SetSizeInBits: CARDINAL;
RotateCount: CARDINAL) ;
END SYSTEM.