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(* SYSTEM.mod implement the ISO SYSTEM specification.
Copyright (C) 2004-2023 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/>. *)
IMPLEMENTATION MODULE SYSTEM ;
FROM libc IMPORT memcpy, memcpy, memset ;
CONST
BitsPerBitset = MAX(BITSET)+1 ;
(*
Max - returns the maximum of a and b.
*)
PROCEDURE Max (a, b: CARDINAL) : CARDINAL ;
BEGIN
IF a>b
THEN
RETURN a
ELSE
RETURN b
END
END Max ;
(*
Min - returns the minimum of a and b.
*)
PROCEDURE Min (a, b: CARDINAL) : CARDINAL ;
BEGIN
IF a<b
THEN
RETURN a
ELSE
RETURN b
END
END Min ;
(*
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) ;
VAR
a: ADDRESS ;
BEGIN
IF ShiftCount>0
THEN
ShiftCount := ShiftCount MOD VAL(INTEGER, SetSizeInBits) ;
ShiftLeft(s, d, SetSizeInBits, ShiftCount)
ELSIF ShiftCount<0
THEN
ShiftCount := (-ShiftCount) MOD VAL(INTEGER, SetSizeInBits) ;
ShiftRight(s, d, SetSizeInBits, ShiftCount)
ELSE
a := memcpy(ADR(d), ADR(s), (HIGH(d)+1)*SIZE(BITSET))
END
END ShiftVal ;
(*
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) ;
VAR
lo, hi : BITSET ;
i, j, h: CARDINAL ;
a : ADDRESS ;
BEGIN
h := HIGH(s)+1 ;
IF ShiftCount MOD BitsPerBitset=0
THEN
i := ShiftCount DIV BitsPerBitset ;
a := ADR(d[i]) ;
a := memcpy(a, ADR(s), (h-i)*SIZE(BITSET)) ;
a := memset(ADR(d), 0, i*SIZE(BITSET))
ELSE
i := h ;
WHILE i>0 DO
DEC(i) ;
lo := SHIFT(s[i], ShiftCount MOD BitsPerBitset) ;
hi := SHIFT(s[i], -(BitsPerBitset - (ShiftCount MOD BitsPerBitset))) ;
d[i] := BITSET{} ;
j := i + ShiftCount DIV BitsPerBitset ;
IF j<h
THEN
d[j] := d[j] + lo ;
INC(j) ;
IF j<h
THEN
d[j] := d[j] + hi
END
END
END
END
END ShiftLeft ;
(*
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) ;
VAR
lo, hi : BITSET ;
j, i, h: INTEGER ;
a : ADDRESS ;
BEGIN
h := HIGH(s)+1 ;
IF ShiftCount MOD BitsPerBitset=0
THEN
i := ShiftCount DIV BitsPerBitset ;
a := ADR(s[i]) ;
j := h-i ;
a := memcpy(ADR(d), a, j * VAL (INTEGER, SIZE (BITSET))) ;
a := ADR(d[j]) ;
a := memset(a, 0, i * VAL (INTEGER, SIZE (BITSET)))
ELSE
i := 0 ;
WHILE i<h DO
lo := SHIFT(s[i], BitsPerBitset - (ShiftCount MOD BitsPerBitset)) ;
hi := SHIFT(s[i], -(ShiftCount MOD BitsPerBitset)) ;
d[i] := BITSET{} ;
j := i - VAL(INTEGER, ShiftCount DIV BitsPerBitset) ;
IF j>=0
THEN
d[j] := d[j] + hi ;
DEC(j) ;
IF j>=0
THEN
d[j] := d[j] + lo
END
END ;
INC(i)
END
END
END ShiftRight ;
(*
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) ;
VAR
a: ADDRESS ;
BEGIN
IF RotateCount>0
THEN
RotateCount := RotateCount MOD VAL(INTEGER, SetSizeInBits)
ELSIF RotateCount<0
THEN
RotateCount := -VAL(INTEGER, VAL(CARDINAL, -RotateCount) MOD SetSizeInBits)
END ;
IF RotateCount>0
THEN
RotateLeft(s, d, SetSizeInBits, RotateCount)
ELSIF RotateCount<0
THEN
RotateRight(s, d, SetSizeInBits, -RotateCount)
ELSE
(* no rotate required, but we must copy source to dest. *)
a := memcpy(ADR(d), ADR(s), (HIGH(d)+1)*SIZE(BITSET))
END
END RotateVal ;
(*
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) ;
VAR
lo, hi : BITSET ;
b, i, j, h: CARDINAL ;
BEGIN
h := HIGH(s) ;
(* firstly we set d := {} *)
i := 0 ;
WHILE i<=h DO
d[i] := BITSET{} ;
INC(i)
END ;
i := h+1 ;
RotateCount := RotateCount MOD SetSizeInBits ;
b := SetSizeInBits MOD BitsPerBitset ;
IF b=0
THEN
b := BitsPerBitset
END ;
WHILE i>0 DO
DEC(i) ;
lo := SHIFT(s[i], RotateCount MOD BitsPerBitset) ;
hi := SHIFT(s[i], -(b - (RotateCount MOD BitsPerBitset))) ;
j := ((i*BitsPerBitset + RotateCount) MOD
SetSizeInBits) DIV BitsPerBitset ;
d[j] := d[j] + lo ;
j := (((i+1)*BitsPerBitset + RotateCount) MOD
SetSizeInBits) DIV BitsPerBitset ;
d[j] := d[j] + hi ;
b := BitsPerBitset
END
END RotateLeft ;
(*
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) ;
BEGIN
RotateLeft(s, d, SetSizeInBits, SetSizeInBits-RotateCount)
END RotateRight ;
END SYSTEM.
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