-- RefCountsImpl.Mesa
-- Last Edited by: Willie-Sue, December 10, 1982 11:48 am
-- Last Edited by: Paul Rovner, May 17, 1983 11:08 am
-- Last Edited by: Levin, August 8, 1983 5:13 pm


DIRECTORY
  PrincOpsUtils USING[BITXOR, BITSHIFT, LowHalf, HighHalf],
  RefCounts USING[],  -- exports only
  RTMicrocode USING[DUMPINDEX],
  RTRefCounts USING[nRCEntry, ProbeIndex, GCState, rcAbsent, Residue, MapRcePiRef];

RefCountsImpl: MONITOR  -- protects dump area in GCState
    IMPORTS PrincOpsUtils, RTMicrocode, RTRefCounts
    EXPORTS RefCounts
= BEGIN OPEN PrincOpsUtils;
  
GetCount: PUBLIC ENTRY PROC[ref: LONG POINTER--loopholed REF--]
      RETURNS[count: NAT _ RTRefCounts.rcAbsent, markedAsOnStack: BOOL _ FALSE] =
  { ENABLE UNWIND => NULL;
    pi: RTRefCounts.ProbeIndex;
    res: RTRefCounts.Residue;
    npi: CARDINAL;
    [pi, res] _ MapRefPiRes[LOOPHOLE[ref]];
    npi _ RTMicrocode.DUMPINDEX[pi];
    FOR i: CARDINAL IN [0..npi)
      DO e: RTRefCounts.nRCEntry = LOOPHOLE[RTRefCounts.GCState.dumpTable[i]];
          IF e.res = res THEN RETURN[e.rc, (e.onStack = true)];
     ENDLOOP;
  };

  -- BEWARE Enumerate is UNSAFE. See Paul Rovner before using it. ref arg may be invalid!
  -- (ref = NIL) => not stopped
Enumerate: PUBLIC ENTRY PROC
           [proc: PROC[ref: REF ANY, count: NAT, markedAsOnStack: BOOL] RETURNS[stop: BOOL]]
      RETURNS[ref: REF ANY _ NIL, count: NAT _ 0, markedAsOnStack: BOOL _ FALSE] =
  { ENABLE UNWIND => NULL;
    FOR pi: RTRefCounts.ProbeIndex IN RTRefCounts.ProbeIndex
      DO
        n: CARDINAL = RTMicrocode.DUMPINDEX[pi];
        FOR i: CARDINAL IN [0..n)
          DO e: RTRefCounts.nRCEntry = LOOPHOLE[RTRefCounts.GCState.dumpTable[i]];
              ref _ RTRefCounts.MapRcePiRef[e, pi];
              IF proc[ref, e.rc, (e.onStack = true)]
               THEN RETURN[ref: ref,
                                 count: e.rc,
                                 markedAsOnStack: (e.onStack = true)];
         ENDLOOP;
     ENDLOOP;
  };


MapRefPiRes: PROC[ref: REF]
      RETURNS[pi: RTRefCounts.ProbeIndex, res: RTRefCounts.Residue] =
  {res _ MapRefRes[ref];
    pi_ BITXOR[BITSHIFT[LowHalf[LOOPHOLE[ref, LONG POINTER]], -1], res]};

MapRefRes: PROC[ref: REF] RETURNS[RTRefCounts.Residue] =
 {RETURN[HighHalf[LOOPHOLE[ref, LONG POINTER]]]};

 END.