*-----------------------------------------------------------
Title[DMesaReclaim.mc..December 16, 1981  10:17 AM..WSH];
*-----------------------------------------------------------
** PILOT ONLY version
*-----------------------------------------------------------
   top level;

*-----------------------------------------------------------
* ReclaimedRef[ref] RETURNS ref or NIL
*-----------------------------------------------------------
ReclaimedRef: MiscTable[60];   * placement
   rbase_ rbase[rcv], Stack&-1;
   call[MapRefPiRes];
    branch[.+2, r>=0], probe, membase_ gcMapPiRce;
    Stack&+1, IFUNext0;		* ref = NIL, do nothing

   fetch_ probe;
   entry_ Md;
    branch[rrentry, R>=0], entry, T_ ResidueField[entry];
    branch[rrof, R even], entry;
    Stack&+1, IFUNext0;			* not in table, return ref
rrentry: pd_ T XOR (residue);
    branch[.+2, alu=0], T_ RefCtField[entry];
    Stack&+1, IFUNext0;			* not in table, return ref
* found as normal entry, so do a deleteref on the entry if not pinned
   pd_ T;
    branch[.+2, alu#0], pd_ T XOR (lastRefCt);
    branch[cats4];		* OldRefCt = 0
    branch[.+2, alu#0], pd_ T XOR (rcFinalize);
      Stack&+1_ T - T, branch[rr0n];
    branch[.+2, alu#0], entry_ (entry) + (reclaimedRefDelta);
    rcFnzCount_ (rcFnzCount) - 1;		*RfCntOld = rcFinalize
   entry_ (entry) AND (nrceMask);
   T_ RefCtStkField[entry];
   pd_ T XOR (becameEmpty);
    branch[rrempty, alu=0], T_ entry;
rre1: store_ probe, dbuf_ T;
rr0: Stack&+1_ T - (Q_ T);
   call[RefCtDec];
rr0n: Stack_ T - T;
   IFUNext0;

rrempty: store_ probe, T_ dbuf_ rceEmpty;
   Q_ T;
   call[HTCellDec];
   branch[rr0n], Stack&+1_ T - T;

* found an overflow entry in MapPiRce
    knowrbase[rcv];
rrof: membase_ gcStateBR, oiPrev1_ T - T;
      rme[oiCurrent, entry];
rrLoop: oiCurrent_ T_ (fetch_ oiCurrent) + 1;
   gcTemp_ Md, fetch_ T;
    branch[.+2, R>=0], T_ ResidueField[gcTemp];
     branch[cats1];
   pd_ T XOR (residue);
    branch[rr1, alu=0], gcTemp2_ Md;
    branch[rr2, R<0], gcTemp2, T_ ResidueField[gcTemp2];
   pd_ T XOR (residue);
    branch[.+2, alu=0], T_ RefCtField[gcTemp2];
    Stack&+1, IFUNext0;			* not found, return ref
   pd_ T;
    branch[.+2, alu#0], pd_ T XOR (lastRefCt);
     branch[cats4];		* OldRefCt = 0
    branch[.+2, alu#0], pd_ T XOR (rcFinalize);
    branch[rr0n], Stack&+1_ T-T;			* found, return NIL, no decrement done
    branch[.+2, alu#0], gcTemp2_ (gcTemp2) + (reclaimedRefDelta);
    rcFnzCount_ (rcFnzCount) - 1;		*RfCntOld = rcFinalize
   gcTemp2_ (gcTemp2) AND (nrceMask);
   T_ RefCtStkField[gcTemp2];
   pd_ T XOR (becameEmpty);
    branch[rr0x, alu=0], T_ gcTemp2;
    store_ oiCurrent, dbuf_ T, branch[rr0];

* second entry at end of chain became empty
rr0x: call[FreeOi], T_ (oiCurrent) - 1;
    branch[.+2, R<0], T_ oiPrev1;
     membase_ gcMapPiRce, T_ probe;
   store_ T, T_ dbuf_ gcTemp, branch[rr0];   

* in middle of chain, continue following
rr2: oiPrev1_ oiCurrent;
   oiCurrent_ Md, branch[rrLoop];
   
* oiCurrent.rce.res = res
rr1: T_ RefCtField[gcTemp];
    pd_ T;
     branch[.+2, alu#0], pd_ T XOR (lastRefCt);
     branch[cats4];		* OldRefCt = 0
    branch[.+2, alu#0], pd_ T XOR (rcFinalize);
    branch[rr0n], Stack&+1_ T-T;			* found, return NIL
    branch[.+2, alu#0], gcTemp_ (gcTemp) + (reclaimedRefDelta);
    rcFnzCount_ (rcFnzCount) - 1;		*RfCntOld = rcFinalize
   gcTemp_ (gcTemp) AND (nrceMask);
   T_ RefCtStkField[gcTemp];
   pd_ T XOR (becameEmpty);
    branch[.+2, alu=0], T_ (oiCurrent) - 1;
    store_ T, T_ dbuf_ gcTemp, branch[rr0];
* oiCurrent.rce became empty, Md still has oiCurrent.oe1
   gcTemp_ Md, branch[rr0x];
   
*-----------------------------------------------------------
* RTSETUP[flag, GCStateHi] RETURNS uVersion

* if flag<0 => full setup, refetch all of GCState Info
* if flag>=0 => fetch gcstateMask and gcProcNum, store FreeList and nOiFree
*-----------------------------------------------------------

RTSetup: MiscTable[63], Stack&-3;   * placement, make stack empty?
   T_ TIOA&StkP;
   T_ T AND (377C), StkP+2;	* restore two args
   T_ Stack&-1, branch[rtsOK, alu=0];
   T_ 1C;
   StkP_ T;
** stack depth was > 2 => wrong software for this microcode
   Stack_ WrongUVersion, IFUNext0;

rtsOK: membase_ gcStateBR;		* T has gcStateHi
    rbase_ rbase[gcTemp], branch[rts2, R>=0], Stack;
   gcTemp_ (BrHi_ T) - T;
   BrLo_ gcTemp;   * BrLo_ 0
   fetch_ 14S;
   fetch_ 0s, rcFnzCount_ Md;
   fetch_ 1s, oiFreeList_ Md;
   fetch_ 2s, nOiFree_ Md;
   fetch_ 3s, gcStateMask_ Md;
   membase_ gcMapPiRce, gcProcNum_ Md;
   gcProcNum_ LSH[gcProcNum, 2];	* microcode keeps procNum*4
   BrHi_ T;
   T_ (mapPiRceOffset);
   BrLo_ T;
   Stack_ UVersion, IFUNext0;
*
 rts2: T_ (fetch_ 2s) + 1;
   fetch_ T, gcStateMask_ Md;
   gcProcNum_ Md;
   gcProcNum_ LSH[gcProcNum, 2];	* microcode keeps procNum*4
   store_ 14s, dbuf_ rcFnzCount;
   store_ 0s, dbuf_ oiFreeList;
   store_ 1S, dbuf_ nOiFree, IFUNext0;	** need not return UVersion

*-----------------------------------------------------------
* ResetSTKBits[probe] RETURNS nothing
*-----------------------------------------------------------
ResetSTKBits: MiscTable[62];		** placement
  rbase_ rbase[rcv], Stack&-1;
rstkLoop: membase_ gcMapPiRce, Stack, branch[.+2, R>=0] ;
    Stack&-1, IFUNext0;		* done
  fetch_ Stack;
  entry_ Md;
   branch[rstkx, R>=0], pd_ (entry) AND (emptyRefCtMask);
   branch[rstkx1, R EVEN], entry;
 rstkL1: dblbranch[rstkLoop, rstkResched, Reschedule'], Stack_ (Stack) + 1;
 rstkResched: branch[MesaReschedTrap], b_ Md;

*  normal entry, check for becoming absent
rstkx: branch[.+2, alu=0], T_ (entry) AND (undoStackBit);
  store_ Stack, dbuf_ T, branch[rstkL1];
  store_ Stack, dbuf_ rceEmpty;
rstkAcct: membase_ gcStateBR;
   call[RstkCellAcct];
  branch[rstkL1];

* overflow entry
rstkx1: membase_ gcStateBr, oiPrev1_ T - T;
  oiPrev0_ T - T;
     rme[oiCurrent, entry];
rstk0: T_ (fetch_ oiCurrent) + 1;
  gcTemp_ Md;			* oiCurrent.rce
   branch[.+2, R>=0], pd_ (gcTemp) AND (emptyRefCtMask);
     branch[cats1];
   branch[rstk1, alu=0], T_ gcTemp_ (gcTemp) AND (undoStackBit);
*   oiCurrent.rce # absent
  oiCurrent_ (store_ oiCurrent) + 1, dbuf_ T;
  fetch_ oiCurrent;		* oiCurrent.oe1
  gcTemp2_ Md;
   branch[rstkMidChain, R<0], pd_ (gcTemp2) AND (emptyRefCtMask);

* end of the chain, oiCurrent.oe1 (gcTemp2) is a normal entry
   branch[.+2, alu=0], T_ (gcTemp2) AND (undoStackBit);
   store_ oiCurrent, dbuf_ T, branch[rstkL1];	*oiCurrent.oe1 was not empty

* oiCurrent.oe1 => empty, move oiCurrent.rce (gcTemp) to oiPrev1 or MapPiRce
  call[FreeOi], T_ (oiCurrent) - 1;
   dblbranch[rstk2, rstk2x, R<0], oiPrev1, T_ oiPrev1;
 
* oiPrev1 = 0 => move gcTemp into MapPiRce
rstk2x: membase_ gcMapPiRce, T_ Stack;

* oiPrev # 0 => oiPrev.oe1_ gcTemp
rstk2:  store_ T, dbuf_ gcTemp, branch[rstkL1];

rstkMidChain: oiPrev0_ oiPrev1;
  oiPrev1_ oiCurrent;
  oiCurrent_ Md, branch[rstk0];

* oiCurrent.rce became empty, must check oiCurrent.oe1
rstk1: T_ (oiCurrent) + 1;
  T_ (fetch_ T) - 1;
  gcTemp_ Md, call[FreeOi];
   branch[rstk3, R<0], pd_ (gcTemp) AND (emptyRefCtMask);
* this is the end of the overflow chain
   branch[rstk4, alu=0], T_ gcTemp_ (gcTemp) AND (undoStackBit);
* oiCurrent.oe1 did not become empty
   dblbranch[rstk2, rstk2x, R<0], oiPrev1, T_ oiPrev1;

* entry in the middle of a chain became empty; oiCurrent has been freed
* gcTemp has the link to the next entry
rstk3: branch[rstk3x, R<0], T_ oiPrev1;
* oiPrev1 = 0, => make MapPiRce point to next entry
  membase_ gcMapPiRce, T_ gcTemp;	* pointer to next on chain
  store_ Stack, dbuf_ T;
  membase_ gcStateBR, branch[rstk0], oiCurrent_ T;		* continue chaining

* oiPrev1 # 0, => oiPrev1.oe1_ gcTemp
rstk3x: store_ T, T_ dbuf_ gcTemp;
  oiCurrent_ T, branch[rstk0];
  
** most complicated case - both entries at the end of the chain became empty
* if there was only one overflow entry, then MapPiRce_ rceEmpty
* otherwise, we must look at the entry previous to the previous one (oiPrev0)

rstk4: branch[rstk5, R<0], T_ (oiPrev1) - 1;
* no previous entry, make MapPiRce entry vacant
  membase_ gcMapPiRce;
  store_ Stack, dbuf_ rceEmpty;
  branch[rstkAcct];

*  free the Oi at oiPrev1, after fetching its rce, then use oiPrev0 to decide where
** to store oiPrev1.rce
rstk5: fetch_ T;
  gcTemp_ Md, call[FreeOi];
  dblbranch[rstk2, rstk2x, R<0], T_ oiPrev0;

*-----------------------------------------------------------
* ISPIRECLAIMABLE[pi: ProbeIndex] RETURNS[pi: ProbeIndex, npi: CARDINAL]
**  code checks for ReSchedule every time around the loop

** stores possibly reclaimable rce's in GCState.rceToReclaim and
** returns the number of rce's it stored for a particular probeIndex
**  when npi is returned as 0, the loop is finished
** an rce is a possibly reclaimable REF if rce.rc <= rcFinalize and onStack is not set
*-----------------------------------------------------------
ISPIRECLAIMABLE: MiscTable[65],    * IsPiReclaimable
   Stack&-1_ A0;    * preset npi to 0 - used as counter
   rbase_ rbase[rcv];	* placement
   rcv_ rceReclaimOffset;
   membase_ gcMapPiRce, T_ pd_ Stack;
* one extra fetch beyond MapPiRce is ok - that is MapOiOe
 ipLoop: fetch_ T, branch[.+2, alu>=0];	* finished when T < 0
    Stack&+1, b_ Md, IFUNext0;
   Stack_ T;
   entry_ Md;
   entry_ RefCtStkField[entry], branch[isprn, R>=0];
   entry_ Md;
    branch[isprof, R EVEN], entry;	* branch if overflow entry
    T_ (Stack) + 1, dblbranch[ipLoop, iplResched, ReSchedule'];

 *---------------------------- normal entry
isprn: branch[ipl2, r Odd], pd_ (entry) - (rcFinalize1);  * branch if onStack set
   branch[.+2, alu<0];  * skip if possibly reclaimable
     T_ (Stack) + 1, dblbranch[ipLoop, iplResched, ReSchedule'];

   membase_ GCStateBR, Stack&+1;
   store_ rcv, dbuf_ Md;   * might be reclaimable
   Stack_ (Stack) + 1, b_ Md, IFUNext0;
*---------------------------- check for pending interrupts
*--------- update Stack (can't before because of page faults)
  ipL2: dblbranch[ipLoop, iplResched, ReSchedule'], T_ (Stack) + 1;
*---------------------------- must look at an overflow chain of entries
isprof:
   membase_ GCStateBR;	   * Md has MapPiRce[pi]
   T_ (fetch_ entry) + 1;    * fetch rce part of overflow entry
 ispr1: T_ gcTemp_ Md, fetch_ T;
    branch[.+2, R>=0], gcTemp_ RefCtStkField[gcTemp];
     branch[cats1];
    branch[.+2, r even], pd_ (gcTemp) - (rcFinalize1); 
    branch[ispr2], gcTemp_ Md;   * onStack was set
   branch[ispr2, alu>=0], gcTemp_ Md;
**-------------- store entry in GCState.rceToReclaim[rcv]
   rcv_ (store_ rcv) + 1, dbuf_ T;
ispr2: branch[.+2, R>=0], gcTemp_ RefCtStkField[gcTemp];
   T_ (fetch_ Md) + 1, branch[ispr1];	* Md has second entry, follow chain
** end of chain, check second entry (gcTemp)
    branch[ispr3, R odd], pd_ (gcTemp) - (rcFinalize1);	* onStack was set
    branch[ispr3x, alu>=0], T_ (rcv) - (rceReclaimOffset);
    rcv_ (store_ rcv) + 1, dbuf_ Md, branch[ispr4];
    
**-------------- check if anything was stored in GCState.rceToReclaim
ispr3: T_ (rcv) - (rceReclaimOffset);   * test if npi = 0
ispr3x: branch[ispr4x, alu#0], membase_ gcMapPiRce;
 * go looking for more
    dblBranch[ipLoop, iplResched, ReSchedule'], T_ (Stack) + 1;
ispr4: T_ (rcv) - (rceReclaimOffset);
ispr4x: Stack+1_ T, b_ Md, IFUNext0;    ** did find something
*---------------------------- allow other processes to run
iplResched:  b_ Md, rbase_ rbase[rtemp0];
  branch[MesaReschedTrap];

*-------------------------------------------------------- 
cats1: branch[cats], T_ 1C;
cats4: branch[cats], T_ 4C;