IMPLEMENTATION MODULE Memory ;

FROM SYSTEM IMPORT ADR ;

TYPE
  SlotRec = RECORD CASE : BOOLEAN OF
              | TRUE: b : ARRAY [0..7] OF CHAR ;
              | FALSE: q : LONGCARD ;
            END ;
          END ;
  WordRec = RECORD CASE : BOOLEAN OF
              | TRUE: b : ARRAY [0..3] OF CHAR ;
              | FALSE: w : CARDINAL ;
            END ;
          END ;
  LongRec = RECORD CASE : BOOLEAN OF
              | TRUE: b : ARRAY [0..7] OF CHAR ;
              | FALSE: l : LONGINT ;
            END ;
          END ;

VAR
  ms : ARRAY [0 .. MaxMem - 1] OF CHAR ;
  arenaBase : LONGCARD ;

PROCEDURE Init ;
BEGIN
  arenaBase := 1048576 ;
  heapPointer := TopOfMemory () ;
END Init ;

PROCEDURE ArenaBase () : LONGCARD ;
BEGIN
  RETURN arenaBase ;
END ArenaBase ;

PROCEDURE TopOfMemory () : LONGCARD ;
BEGIN
  RETURN VAL (LONGCARD, MaxMem) ;
END TopOfMemory ;

PROCEDURE ReadByte (a: LONGCARD) : CARDINAL ;
BEGIN
  RETURN ORD (ms [VAL (CARDINAL, a)]) ;
END ReadByte ;

PROCEDURE WriteByte (a: LONGCARD; b: CARDINAL) ;
BEGIN
  ms [VAL (CARDINAL, a)] := CHR (b MOD 256) ;
END WriteByte ;

PROCEDURE ReadSlot (a: LONGCARD) : LONGCARD ;
VAR sr: SlotRec ; i: CARDINAL ;
BEGIN
  sr.q := 0 ;
  FOR i := 0 TO 7 DO
    sr.b [i] := ms [VAL (CARDINAL, a) + i] ;
  END ;
  RETURN sr.q ;
END ReadSlot ;

PROCEDURE WriteSlot (a: LONGCARD; v: LONGCARD) ;
VAR sr: SlotRec ; i: CARDINAL ;
BEGIN
  sr.q := v ;
  FOR i := 0 TO 7 DO
    ms [VAL (CARDINAL, a) + i] := sr.b [i] ;
  END ;
END WriteSlot ;

PROCEDURE ReadWord (a: LONGCARD) : CARDINAL ;
VAR wr: WordRec ; i: CARDINAL ;
BEGIN
  wr.w := 0 ;
  FOR i := 0 TO 3 DO
    wr.b [i] := ms [VAL (CARDINAL, a) + i] ;
  END ;
  RETURN wr.w ;
END ReadWord ;

PROCEDURE WriteWord (a: LONGCARD; v: CARDINAL) ;
VAR wr: WordRec ; i: CARDINAL ;
BEGIN
  wr.w := v ;
  FOR i := 0 TO 3 DO
    ms [VAL (CARDINAL, a) + i] := wr.b [i] ;
  END ;
END WriteWord ;

PROCEDURE ReadLong (a: LONGCARD) : LONGINT ;
VAR lr: LongRec ; i: CARDINAL ;
BEGIN
  lr.l := 0 ;
  FOR i := 0 TO 7 DO
    lr.b [i] := ms [VAL (CARDINAL, a) + i] ;
  END ;
  RETURN lr.l ;
END ReadLong ;

PROCEDURE WriteLong (a: LONGCARD; v: LONGINT) ;
VAR lr: LongRec ; i: CARDINAL ;
BEGIN
  lr.l := v ;
  FOR i := 0 TO 7 DO
    ms [VAL (CARDINAL, a) + i] := lr.b [i] ;
  END ;
END WriteLong ;

PROCEDURE CopyBytes (src, dst: LONGCARD; n: LONGCARD) ;
VAR i: LONGCARD ;
BEGIN
  i := 0 ;
  WHILE i < n DO
    ms [VAL (CARDINAL, dst + i)] := ms [VAL (CARDINAL, src + i)] ;
    i := i + 1 ;
  END ;
END CopyBytes ;

PROCEDURE FillBytes (dst: LONGCARD; n: LONGCARD; b: CARDINAL) ;
VAR i: LONGCARD ;
BEGIN
  i := 0 ;
  WHILE i < n DO
    ms [VAL (CARDINAL, dst + i)] := CHR (b MOD 256) ;
    i := i + 1 ;
  END ;
END FillBytes ;

PROCEDURE LoadImage (VAR data: ARRAY OF CHAR; off: CARDINAL; dst: LONGCARD; n: CARDINAL) ;
VAR i: CARDINAL ; j: LONGCARD ;
BEGIN
  i := 0 ; j := 0 ;
  WHILE i < n DO
    ms [VAL (CARDINAL, dst + j)] := data [off + i] ;
    INC (i) ; j := j + 1 ;
  END ;
END LoadImage ;

END Memory.