File psl-1983/tests/p-allocators.red artifact ba8756dcc0 part of check-in 3af273af29

%
% ALLOCATORS.RED - Low level storage management
% 
% Author:      Eric Benson
%              Computer Science Dept.
%              University of Utah
% Date:        27 August 1981
% Copyright (c) 1981 University of Utah

% Revisions, MLG, 20 Feb 1983
% 	Moved space declarations to XXX-HEADER.RED
%  <PSL.KERNEL>ALLOCATORS.RED.4, 10-Jan-83 15:50:50, Edit by PERDUE
%  	Added GtEVect

on SysLisp;

external Wvar HeapLowerBound,
	      HeapUpperBound,
	      HeapLast,
	      HeapPreviousLast,
	      NextBPS,
	      LastBPS;

% NextSymbol is in GLOBAL-DATA.RED

syslsp procedure GtHEAP N;		
%  get heap block of N words
if null N then (HeapUpperBound - HeapLast) / AddressingUnitsPerItem else
<<  HeapPreviousLast := HeapLast;
    HeapLast := HeapLast + N*AddressingUnitsPerItem;
    if HeapLast > HeapUpperBound then
    <<  !%Reclaim();
	HeapPreviousLast := HeapLast;
	HeapLast := HeapLast + N*AddressingUnitsPerItem;
	if HeapLast > HeapUpperBound then
	    FatalError "Heap space exhausted" >>;
    HeapPreviousLast >>;

syslsp procedure DelHeap(LowPointer, HighPointer);
    if HighPointer eq HeapLast then HeapLast := LowPointer;

syslsp procedure GtSTR N;		
%  Allocate space for a string N chars
begin scalar S, NW;
    S := GtHEAP((NW := STRPack N) + 1);
    @S := MkItem(HBytes, N);
    S[NW] := 0;				% clear last word, including last byte
    return S;
end;

syslsp procedure GtConstSTR N;	 
%  allocate un-collected string for print name
begin scalar S, NW;			% same as GtSTR, but uses BPS, not heap
    S := GtBPS((NW := STRPack N) + 1);
    @S := N;
    S[NW] := 0;				% clear last word, including last byte
    return S;
end;

syslsp procedure GtHalfWords N;		
%  Allocate space for N halfwords
begin scalar S, NW;
    S := GtHEAP((NW := HalfWordPack N) + 1);
    @S := MkItem(HHalfWords, N);
    return S;
end;

syslsp procedure GtVECT N;		
%  Allocate space for a vector N items
begin scalar V;
    V := GtHEAP(VECTPack N + 1);
    @V := MkItem(HVECT, N);
    return V;
end;

syslsp procedure GtEVECT N;		
%  Allocate space for a Evector N items
begin scalar V;
    V := GtHEAP(VECTPack N + 1);
    @V := MkItem(HVECT, N);
    return V;
end;

syslsp procedure GtWRDS N;		
%  Allocate space for N untraced words
begin scalar W;
    W := GtHEAP(WRDPack N + 1);
    @W := MkItem(HWRDS, N);
    return W;
end;


syslsp procedure GtFIXN();		
%  allocate space for a fixnum
begin scalar W;
    W := GtHEAP(WRDPack 0 + 1);
    @W := MkItem(HWRDS, 0);
    return W;
end;

syslsp procedure GtFLTN();		
%  allocate space for a float
begin scalar W;
    W := GtHEAP(WRDPack 1 + 1);
    @W := MkItem(HWRDS, 1);
    return W;
end;

syslsp procedure GtID();		
%  Allocate a new ID
%
% IDs are allocated as a linked free list through the SymNam cell,
% with a 0 to indicate the end of the list.
%
begin scalar U;
    if NextSymbol = 0 then 
    <<  Reclaim();
	if NextSymbol = 0 then
	    return FatalError "Ran out of ID space" >>;
    U := NextSymbol;
    NextSymbol := SymNam U;
    return U;
end;


syslsp procedure GtBPS N;		
%  Allocate N words for binary code
begin scalar B;
    if null N then return((LastBPS - NextBPS)/AddressingUnitsPerItem);
					% GTBPS NIL returns # left
    B := NextBPS;
    NextBPS := NextBPS + N*AddressingUnitsPerItem;
    return if NextBPS > LastBPS then
	StdError '"Ran out of binary program space"
    else B;
end;

syslsp procedure DelBPS(Bottom, Top);	
%  Return space to BPS
    if NextBPS eq Top then NextBPS := Bottom;

syslsp procedure GtWArray N;	
%  Allocate N words for WVar/WArray/WString
begin scalar B;
    if null N then return((LastBPS - NextBPS)/AddressingUnitsPerItem);
					% GtWArray NIL returns # left
    B := LastBPS - N*AddressingUnitsPerItem;
    return if NextBPS > B then
	StdError '"Ran out of WArray space"
    else
	LastBPS := B;
end;

syslsp procedure DelWArray(Bottom, Top);	
%  Return space for WArray
    if LastBPS eq Bottom then LastBPS := Top;

off SysLisp;

END;