[Oberon] PO2013 - Show Heap Blocks

[Tomas Kral]

Hi Andreas,

It seems, I do not receive your posts, although they appear on
https://lists.inf.ethz.ch/

  PROCEDURE GenericScan*();
    ...
    IF mark > 0 THEN (*marked*) SYSTEM.PUT(p+4, 0);
    ...
    INC(p, size)
    UNTIL p >= heapLim
  END GenericScan;

In your code above, unmark with 0 [PUT(p+4, 0)], while for freed put -1. 
0 - to be freed, -1 freed, >0 still used?

Can we actually do heap scan without Kernel.Mark()?
I attempted in this code, which does not really see any mark >0 blocks.

  MODULE Heap; (*TK 14.6.2020 show heap blocks*)
  IMPORT S := SYSTEM, Out;
  VAR heapOrg, MemLim, heapLim: INTEGER;

  PROCEDURE Show*;
    VAR p, q, mark, tag, size, used, free: LONGINT;
  BEGIN p := heapOrg; used := 0; free := 0;
    REPEAT S.GET(p+4, mark); (*mark: 0 to be freed, -1 freed, >0 still used*)
      IF mark = -1 THEN S.GET(p, size)
      ELSE S.GET(p, tag); S.GET(tag, size) END ;
      IF (*size = 14H*) (size MOD 32 # 0) & (size MOD 64 # 0) & (size MOD 128 # 0) & (size MOD 256 # 0) THEN
        Out.Hex(p); Out.Hex(size); Out.Hex(mark); Out.Ln (*** WHY this reports a free block??? ***) 
      END ;
      IF mark > 0 THEN INC(used, size) (*none*)
      ELSIF mark = 0 THEN INC(free, size)
      ELSIF mark = -1 THEN INC(free, size) END ;
      INC(p, size)
    UNTIL p >= heapLim(*-30000H*) ;
    Out.Hex(used); Out.Hex(free);Out.Ln

  END Show;

  BEGIN S.GET(12, MemLim); S.GET(24, heapOrg); heapLim := MemLim
  END Heap.

Heap.Show

-- 
Tomas Kral <thomas.kral at email.cz>