fix trap handling

[cpc.git] / src / native / linux / 486 / System / Mod / Kernel.cp

MODULE Kernel;

  IMPORT S := SYSTEM, stdlib := PosixCstdlib, stdio := PosixCstdio,
    time := PosixCtime, wctype := PosixCwctype, sysmman := PosixCsys_mman,
    dlfcn := PosixCdlfcn, types := PosixCtypes, fcntl := PosixCfcntl,
    unistd := PosixCunistd, signal := PosixCsignal, setjmp := PosixCsetjmp;

  (* init fpu? *)
  (* add signal blocking to avoid race conditions in Try/Trap/TrapHandler *)
  (* add BeepHook for Beep *)

  CONST
    nameLen* = 256;

    littleEndian* = TRUE;
    timeResolution* = 1000; (* ticks per second *)

    processor* = 1;  (* generic c *)

    objType* = "ocf"; (* file types *)
    symType* = "osf";
    docType* = "odc";

    (* loader constants *)
    done* = 0;
    fileNotFound* = 1;
    syntaxError* = 2;
    objNotFound* = 3;
    illegalFPrint* = 4;
    cyclicImport* = 5;
    noMem* = 6;
    commNotFound* = 7;
    commSyntaxError* = 8;
    moduleNotFound* = 9;

    any = 1000000;

    CX = 1;
    SP = 4; (* register number of stack pointer *)
    FP = 5; (* register number of frame pointer *)
    ML = 3; (* register which holds the module list at program start *)

    strictStackSweep = FALSE;
    N = 128 DIV 16; (* free lists *)

    (* kernel flags in module desc *)
    init = 16; dyn = 17; dll = 24; iptrs = 30;

    (* meta interface consts *)
    mConst = 1; mTyp = 2; mVar = 3; mProc = 4; mField = 5;

  TYPE
    Name* = ARRAY nameLen OF CHAR;
    Utf8Name* = ARRAY nameLen OF SHORTCHAR;
    Command* = PROCEDURE;

    Module* = POINTER TO RECORD [untagged]
      next-: Module;
      opts-: SET; (* 0..15: compiler opts, 16..31: kernel flags *)
      refcnt-: INTEGER; (* <0: module invalidated *)
      compTime-, loadTime-: ARRAY 6 OF SHORTINT;
      ext-: INTEGER;  (* currently not used *)
      term-: Command; (* terminator *)
      nofimps-, nofptrs-: INTEGER;
      csize-, dsize-, rsize-: INTEGER;
      code-, data-, refs-: INTEGER;
      procBase-, varBase-: INTEGER; (* meta base addresses *)
      names-: POINTER TO ARRAY [untagged] OF SHORTCHAR; (* names[0] = 0X *)
      ptrs-: POINTER TO ARRAY [untagged] OF INTEGER;
      imports-: POINTER TO ARRAY [untagged] OF Module;
      export-: Directory; (* exported objects (name sorted) *)
      name-: Utf8Name
    END;

    Type* = POINTER TO RECORD [untagged]
      (* record: ptr to method n at offset - 4 * (n+1) *)
      size-: INTEGER; (* record: size, array: #elem, dyn array: 0, proc: sigfp *)
      mod-: Module;
      id-: INTEGER; (* name idx * 256 + lev * 16 + attr * 4 + form *)
      base-: ARRAY 16 OF Type;  (* signature if form = ProcTyp *)
      fields-: Directory; (* new fields (declaration order) *)
      ptroffs-: ARRAY any OF INTEGER  (* array of any length *)
    END;

    Object* = POINTER TO ObjDesc;

    ObjDesc* = RECORD [untagged]
      fprint-: INTEGER;
      offs-: INTEGER; (* pvfprint for record types *)
      id-: INTEGER; (* name idx * 256 + vis * 16 + mode *)
      struct-: Type (* id of basic type or pointer to typedesc/signature *)
    END;

    Directory* = POINTER TO RECORD [untagged]
      num-: INTEGER;  (* number of entries *)
      obj-: ARRAY any OF ObjDesc  (* array of any length *)
    END;
    
    Signature* = POINTER TO RECORD [untagged]
      retStruct-: Type; (* id of basic type or pointer to typedesc or 0 *)
      num-: INTEGER;  (* number of parameters *)
      par-: ARRAY any OF RECORD [untagged]  (* parameters *)
        id-: INTEGER; (* name idx * 256 + kind *)
        struct-: Type (* id of basic type or pointer to typedesc *)
      END
    END;

    Handler* = PROCEDURE;

    Reducer* = POINTER TO ABSTRACT RECORD
      next: Reducer
    END;

    Identifier* = ABSTRACT RECORD
      typ*: INTEGER;
      obj-: ANYPTR
    END;

    TrapCleaner* = POINTER TO ABSTRACT RECORD
      next: TrapCleaner
    END;

    TryHandler* = PROCEDURE (a, b, c: INTEGER);

    (* meta extension suport *)

    ItemExt* = POINTER TO ABSTRACT RECORD END;

    ItemAttr* = RECORD
      obj*, vis*, typ*, adr*: INTEGER;
      mod*: Module;
      desc*: Type;
      ptr*: S.PTR;
      ext*: ItemExt
    END;

    Hook* = POINTER TO ABSTRACT RECORD END;

    LoaderHook* = POINTER TO ABSTRACT RECORD (Hook) 
      res*: INTEGER;
      importing*, imported*, object*: ARRAY 256 OF CHAR
    END;

    Block = POINTER TO RECORD [untagged]
      tag: Type;
      last: INTEGER;    (* arrays: last element *)
      actual: INTEGER;  (* arrays: used during mark phase *)
      first: INTEGER    (* arrays: first element *)
    END;

    FreeBlock = POINTER TO FreeDesc;

    FreeDesc = RECORD [untagged]
      tag: Type;    (* f.tag = ADR(f.size) *)
      size: INTEGER;
      next: FreeBlock
    END;

    Cluster = POINTER TO RECORD [untagged]
      size: INTEGER;  (* total size *)
      next: Cluster;
      max: INTEGER  (* exe: reserved size, dll: original address *)
      (* start of first block *)
    END;

    FList = POINTER TO RECORD
      next: FList;
      blk: Block;
      iptr, aiptr: BOOLEAN
    END;

    CList = POINTER TO RECORD
      next: CList;
      do: Command;
      trapped: BOOLEAN
    END;


    PtrType = RECORD v: S.PTR END;  (* used for array of pointer *)
    Char8Type = RECORD v: SHORTCHAR END;
    Char16Type = RECORD v: CHAR END;
    Int8Type = RECORD v: BYTE END;
    Int16Type = RECORD v: SHORTINT END;
    Int32Type = RECORD v: INTEGER END;
    Int64Type = RECORD v: LONGINT END;
    BoolType = RECORD v: BOOLEAN END;
    SetType = RECORD v: SET END;
    Real32Type = RECORD v: SHORTREAL END;
    Real64Type = RECORD v: REAL END;
    ProcType = RECORD v: PROCEDURE END;
    UPtrType = RECORD v: INTEGER END;
    StrPtr = POINTER TO ARRAY [untagged] OF SHORTCHAR;

    ArrStrPtr = POINTER TO ARRAY [untagged] OF StrPtr;

    ADDRESS* = types.Pvoid;

  VAR
    baseStack: INTEGER;
    root: Cluster;
    modList-: Module;
    trapCount-: INTEGER;
    err-, pc-, sp-, fp-, stack-, val-: INTEGER;

    isTry, checkReadable: BOOLEAN;
    startEnv, checkReadableEnv: setjmp.sigjmp_buf;
    tryEnv: setjmp.jmp_buf;

    argc-: INTEGER;
    argv-: ArrStrPtr;
    pagesize: unistd.long;

    free: ARRAY N OF FreeBlock; (* free list *)
    sentinelBlock: FreeDesc;
    sentinel: FreeBlock;
    candidates: ARRAY 1024 OF INTEGER;
    nofcand: INTEGER;
    allocated: INTEGER; (* bytes allocated on BlackBox heap *)
    total: INTEGER; (* current total size of BlackBox heap *)
    used: INTEGER;  (* bytes allocated on system heap *)
    finalizers: FList;
    hotFinalizers: FList;
    cleaners: CList;
    reducers: Reducer;
    trapStack: TrapCleaner;
    actual: Module; (* valid during module initialization *)

    trapViewer, trapChecker: Handler;
    trapped, guarded, secondTrap: BOOLEAN;
    interrupted: BOOLEAN;
    static, inDll, terminating: BOOLEAN;
    restart: Command;

    loader: LoaderHook;
    loadres: INTEGER;

    wouldFinalize: BOOLEAN;

    watcher*: PROCEDURE (event: INTEGER); (* for debugging *)

    intTrap*: BOOLEAN;

  PROCEDURE Erase (adr, words: INTEGER);
  BEGIN
    ASSERT(words >= 0, 20);
    WHILE words > 0 DO
      S.PUT(adr, 0);
      INC(adr, 4);
      DEC(words)
    END
  END Erase;


  PROCEDURE (VAR id: Identifier) Identified* (): BOOLEAN, NEW, ABSTRACT;
  PROCEDURE (r: Reducer) Reduce* (full: BOOLEAN), NEW, ABSTRACT;
  PROCEDURE (c: TrapCleaner) Cleanup*,  NEW, EMPTY;

  (* meta extension suport *)

  PROCEDURE (e: ItemExt) Lookup* (name: ARRAY OF CHAR; VAR i: ANYREC), NEW, ABSTRACT;
  PROCEDURE (e: ItemExt) Index* (index: INTEGER; VAR elem: ANYREC), NEW, ABSTRACT;
  PROCEDURE (e: ItemExt) Deref* (VAR ref: ANYREC), NEW, ABSTRACT;

  PROCEDURE (e: ItemExt) Valid* (): BOOLEAN, NEW, ABSTRACT;
  PROCEDURE (e: ItemExt) Size* (): INTEGER, NEW, ABSTRACT;
  PROCEDURE (e: ItemExt) BaseTyp* (): INTEGER, NEW, ABSTRACT;
  PROCEDURE (e: ItemExt) Len* (): INTEGER, NEW, ABSTRACT;

  PROCEDURE (e: ItemExt) Call* (OUT ok: BOOLEAN), NEW, ABSTRACT;
  PROCEDURE (e: ItemExt) BoolVal* (): BOOLEAN, NEW, ABSTRACT;
  PROCEDURE (e: ItemExt) PutBoolVal* (x: BOOLEAN), NEW, ABSTRACT;
  PROCEDURE (e: ItemExt) CharVal* (): CHAR, NEW, ABSTRACT;
  PROCEDURE (e: ItemExt) PutCharVal* (x: CHAR), NEW, ABSTRACT;
  PROCEDURE (e: ItemExt) IntVal* (): INTEGER, NEW, ABSTRACT;
  PROCEDURE (e: ItemExt) PutIntVal* (x: INTEGER), NEW, ABSTRACT;
  PROCEDURE (e: ItemExt) LongVal* (): LONGINT, NEW, ABSTRACT;
  PROCEDURE (e: ItemExt) PutLongVal* (x: LONGINT), NEW, ABSTRACT;
  PROCEDURE (e: ItemExt) RealVal* (): REAL, NEW, ABSTRACT;
  PROCEDURE (e: ItemExt) PutRealVal* (x: REAL), NEW, ABSTRACT;
  PROCEDURE (e: ItemExt) SetVal* (): SET, NEW, ABSTRACT;
  PROCEDURE (e: ItemExt) PutSetVal* (x: SET), NEW, ABSTRACT;
  PROCEDURE (e: ItemExt) PtrVal* (): ANYPTR, NEW, ABSTRACT;
  PROCEDURE (e: ItemExt) PutPtrVal* (x: ANYPTR), NEW, ABSTRACT;
  PROCEDURE (e: ItemExt) GetSStringVal* (OUT x: ARRAY OF SHORTCHAR;
                                  OUT ok: BOOLEAN), NEW, ABSTRACT;
  PROCEDURE (e: ItemExt) PutSStringVal* (IN x: ARRAY OF SHORTCHAR;
                                  OUT ok: BOOLEAN), NEW, ABSTRACT;
  PROCEDURE (e: ItemExt) GetStringVal* (OUT x: ARRAY OF CHAR; OUT ok: BOOLEAN), NEW, ABSTRACT;
  PROCEDURE (e: ItemExt) PutStringVal* (IN x: ARRAY OF CHAR; OUT ok: BOOLEAN), NEW, ABSTRACT;

  (* -------------------- miscellaneous tools -------------------- *)

  PROCEDURE IsUpper* (ch: CHAR): BOOLEAN;
  BEGIN
    RETURN wctype.iswupper(ORD(ch)) # 0
  END IsUpper;

  PROCEDURE Upper* (ch: CHAR): CHAR;
  BEGIN
    RETURN CHR(wctype.towupper(ORD(ch)))
  END Upper;

  PROCEDURE IsLower* (ch: CHAR): BOOLEAN;
  BEGIN
    RETURN wctype.iswlower(ORD(ch)) # 0
  END IsLower;

  PROCEDURE Lower* (ch: CHAR): CHAR;
  BEGIN
    RETURN CHR(wctype.towlower(ORD(ch)))
  END Lower;

  PROCEDURE IsAlpha* (ch: CHAR): BOOLEAN;
  BEGIN
    RETURN wctype.iswalpha(ORD(ch)) # 0
  END IsAlpha;

  PROCEDURE Utf8ToString* (IN in: ARRAY OF SHORTCHAR; OUT out: ARRAY OF CHAR;  OUT res: INTEGER);
    VAR i, j, val, max: INTEGER; ch: SHORTCHAR;
    
    PROCEDURE FormatError();
    BEGIN out := in$; res := 2 (*format error*)
    END FormatError;
    
  BEGIN
    ch := in[0]; i := 1; j := 0; max := LEN(out) - 1;
    WHILE (ch # 0X) & (j < max) DO
      IF ch < 80X THEN
        out[j] := ch; INC(j)
      ELSIF ch < 0E0X THEN
        val := ORD(ch) - 192;
        IF val < 0 THEN FormatError; RETURN END ;
        ch := in[i]; INC(i); val := val * 64 + ORD(ch) - 128;
        IF (ch < 80X) OR (ch >= 0E0X) THEN FormatError; RETURN END ;
        out[j] := CHR(val); INC(j)
      ELSIF ch < 0F0X THEN 
        val := ORD(ch) - 224;
        ch := in[i]; INC(i); val := val * 64 + ORD(ch) - 128;
        IF (ch < 80X) OR (ch >= 0E0X) THEN FormatError; RETURN END ;
        ch := in[i]; INC(i); val := val * 64 + ORD(ch) - 128;
        IF (ch < 80X) OR (ch >= 0E0X) THEN FormatError; RETURN END ;
        out[j] := CHR(val); INC(j)
      ELSE
        FormatError; RETURN
      END ;
      ch := in[i]; INC(i)
    END;
    out[j] := 0X;
    IF ch = 0X THEN res := 0 (*ok*) ELSE res := 1 (*truncated*) END
  END Utf8ToString;

  PROCEDURE StringToUtf8* (IN in: ARRAY OF CHAR; OUT out: ARRAY OF SHORTCHAR; OUT res: INTEGER);
    VAR i, j, val, max: INTEGER;
  BEGIN
    i := 0; j := 0; max := LEN(out) - 3;
    WHILE (in[i] # 0X) & (j < max) DO
      val := ORD(in[i]); INC(i);
      IF val < 128 THEN
        out[j] := SHORT(CHR(val)); INC(j)
      ELSIF val < 2048 THEN
        out[j] := SHORT(CHR(val DIV 64 + 192)); INC(j);
        out[j] := SHORT(CHR(val MOD 64 + 128)); INC(j)
      ELSE
        out[j] := SHORT(CHR(val DIV 4096 + 224)); INC(j); 
        out[j] := SHORT(CHR(val DIV 64 MOD 64 + 128)); INC(j);
        out[j] := SHORT(CHR(val MOD 64 + 128)); INC(j)
      END;
    END;
    out[j] := 0X;
    IF in[i] = 0X THEN res := 0 (*ok*) ELSE res :=  1 (*truncated*) END
  END StringToUtf8;

  PROCEDURE SplitName* (name: ARRAY OF CHAR; VAR head, tail: ARRAY OF CHAR);
    (* portable *)
    VAR i, j: INTEGER; ch, lch: CHAR;
  BEGIN
    i := 0; ch := name[0];
    IF ch # 0X THEN
      REPEAT
        head[i] := ch; lch := ch; INC(i); ch := name[i]
      UNTIL (ch = 0X) OR (ch = ".") OR IsUpper(ch) & ~IsUpper(lch);
      IF ch = "." THEN i := 0; ch := name[0] END;
      head[i] := 0X; j := 0;
      WHILE ch # 0X DO tail[j] := ch; INC(i); INC(j); ch := name[i] END;
      tail[j] := 0X;
      IF tail = "" THEN tail := head$; head := "" END
    ELSE head := ""; tail := ""
    END
  END SplitName;

  PROCEDURE MakeFileName* (VAR name: ARRAY OF CHAR; type: ARRAY OF CHAR);
    VAR i, j: INTEGER; ext: ARRAY 8 OF CHAR; ch: CHAR;
  BEGIN
    i := 0;
    WHILE (name[i] # 0X) & (name[i] # ".") DO INC(i) END;
    IF name[i] = "." THEN
      IF name[i + 1] = 0X THEN name[i] := 0X END
    ELSE
      IF type = "" THEN ext := docType ELSE ext := type$ END;
      IF i < LEN(name) - LEN(ext$) - 1 THEN
        name[i] := "."; INC(i); j := 0; ch := ext[0];
        WHILE ch # 0X DO
          name[i] := Lower(ch); INC(i); INC(j); ch := ext[j]
        END;
        name[i] := 0X
      END
    END
  END MakeFileName;

  PROCEDURE Time* (): LONGINT;
    VAR res: time.int; tp: time.struct_timespec;
  BEGIN
    ASSERT(timeResolution >= 1);
    ASSERT(timeResolution <= 1000000000);
    res := time.clock_gettime(time.CLOCK_MONOTONIC, tp);
    ASSERT(res = 0, 100);
    RETURN tp.tv_sec * LONG(timeResolution) + tp.tv_nsec DIV LONG(1000000000 DIV timeResolution)
  END Time;

  PROCEDURE Beep*;
    (* !!! *)
  END Beep;

  PROCEDURE SearchProcVar* (var: INTEGER; VAR m: Module; VAR adr: INTEGER);
  BEGIN
    adr := var; m := NIL;
    IF var # 0 THEN
      m := modList;
      WHILE (m # NIL) & ((var < m.code) OR (var >= m.code + m.csize)) DO m := m.next END;
      IF m # NIL THEN DEC(adr, m.code) END
    END
  END SearchProcVar;

  (* -------------------- system memory management --------------------- *)

  PROCEDURE AllocMem (size: sysmman.size_t; VAR max: sysmman.size_t): ADDRESS;
    VAR fd, flags, res: fcntl.int; ptr: ADDRESS;
  BEGIN
    max := (size + pagesize - 1) DIV pagesize * pagesize;
    fd := fcntl.open("/dev/zero", fcntl.O_RDWR, 0);
    IF fd # -1 THEN
      flags := sysmman.PROT_READ + sysmman.PROT_WRITE;
      ptr := sysmman.mmap(0, max, flags, sysmman.MAP_PRIVATE, fd, 0);
      IF ptr = sysmman.MAP_FAILED THEN ptr := 0 END;
      res := unistd.close(fd);
      ASSERT(res = 0, 100)
    ELSE
      ptr := 0
    END;
    RETURN ptr
  END AllocMem;

  PROCEDURE FreeMem (adr: ADDRESS; size: sysmman.size_t);
    VAR res: types.int;
  BEGIN
    size := (size + pagesize - 1) DIV pagesize * pagesize;
    res := sysmman.munmap(adr, size);
    ASSERT(res = 0, 100)
  END FreeMem;

  PROCEDURE AllocHeapMem (size: INTEGER; VAR c: Cluster);
    CONST N = 65536;  (* cluster size for dll *)
    VAR adr, allocated, newsize: INTEGER;
  BEGIN
    INC(size, 16);
    ASSERT(size > 0, 100); adr := 0;
    IF size < N THEN
      adr := AllocMem(N, newsize);
      allocated := newsize
    END;
    IF adr = 0 THEN
      adr := AllocMem(size, newsize);
      allocated := newsize
    END;
    IF adr = 0 THEN c := NIL
    ELSE
      c := S.VAL(Cluster, (adr + 15) DIV 16 * 16); c.max := adr;
      c.size := allocated - (S.VAL(INTEGER, c) - adr);
      INC(used, c.size); INC(total, c.size)
    END;
    ASSERT((adr = 0) OR (adr MOD 16 = 0) & (c.size >= size), 101);
    (* post: (c = NIL) OR (c MOD 16 = 0) & (c.size >= size) *)
  END AllocHeapMem;

  PROCEDURE FreeHeapMem (c: Cluster);
  BEGIN
    DEC(used, c.size); DEC(total, c.size);
    FreeMem(S.VAL(ADDRESS, c.max), c.size)
  END FreeHeapMem;

  PROCEDURE HeapFull (size: INTEGER): BOOLEAN;
  BEGIN
    RETURN TRUE
  END HeapFull;

  PROCEDURE AllocModMem* (descSize, modSize: INTEGER; VAR descAdr, modAdr: INTEGER);
  BEGIN
    descAdr := 0; modAdr := 0;
    descAdr := AllocMem(descSize, descSize);
    IF descAdr # 0 THEN
      modAdr := AllocMem(modSize, modSize);
      IF modAdr = 0 THEN
        FreeMem(descAdr, descSize)
      ELSE
        INC(used, descSize + modSize)
      END
    END
  END AllocModMem;

  PROCEDURE DeallocModMem* (descSize, modSize, descAdr, modAdr: INTEGER);
  BEGIN
    FreeMem(descAdr, descSize);
    FreeMem(modAdr, modSize);
    DEC(used, descSize + modSize)
  END DeallocModMem;

  PROCEDURE InvalModMem (modSize, modAdr: INTEGER);
  BEGIN
    FreeMem(modAdr, modSize)
  END InvalModMem;

  PROCEDURE IsReadable* (from, to: INTEGER): BOOLEAN;
    VAR r: BOOLEAN; jmp: setjmp.sigjmp_buf; res: setjmp.int; i: INTEGER; x: BYTE;
  BEGIN
    r := checkReadable;
    jmp := checkReadableEnv;
    checkReadable := TRUE;
    res := setjmp.sigsetjmp(checkReadableEnv, 1);
    IF res = 0 THEN
      IF from <= to THEN
        FOR i := from TO to DO
          S.GET(i, x)
        END
      ELSE
        FOR i := to TO from BY -1 DO
          S.GET(i, x)
        END
      END
    END;
    checkReadableEnv := jmp;
    checkReadable := r;
    RETURN res = 0
  END IsReadable;

  (* --------------------- NEW implementation (portable) -------------------- *)

  PROCEDURE^ NewBlock (size: INTEGER): Block;

  PROCEDURE NewRec* (typ: INTEGER): INTEGER;  (* implementation of NEW(ptr) *)
    VAR size, adr: INTEGER; b: Block; tag: Type; l: FList;
  BEGIN
    IF ~ODD(typ) THEN
      tag := S.VAL(Type, typ);
      b := NewBlock(tag.size);
      IF b # NIL THEN
        b.tag := tag;
        S.GET(typ - 4, size);
        IF size # 0 THEN (* record uses a finalizer *)
          l := S.VAL(FList, S.ADR(b.last)); (* anchor new object! *)
          l := S.VAL(FList, NewRec(S.TYP(FList)));  (* NEW(l) *)
          l.blk := b; l.next := finalizers; finalizers := l
        END;
        adr := S.ADR(b.last)
      ELSE
        adr := 0
      END
    ELSE
      HALT(100)  (* COM interface pointers not supported *)
    END;
    RETURN adr
  END NewRec;

  PROCEDURE NewArr* (eltyp, nofelem, nofdim: INTEGER): INTEGER; (* impl. of NEW(ptr, dim0, dim1, ...) *)
    VAR b: Block; size, headSize: INTEGER; t: Type;
  BEGIN
    CASE eltyp OF
    | -1: HALT(100)  (* COM interface pointers not supported *)
    | 0: eltyp := S.ADR(PtrType)
    | 1: eltyp := S.ADR(Char8Type)
    | 2: eltyp := S.ADR(Int16Type)
    | 3: eltyp := S.ADR(Int8Type)
    | 4: eltyp := S.ADR(Int32Type)
    | 5: eltyp := S.ADR(BoolType)
    | 6: eltyp := S.ADR(SetType)
    | 7: eltyp := S.ADR(Real32Type)
    | 8: eltyp := S.ADR(Real64Type)
    | 9: eltyp := S.ADR(Char16Type)
    | 10: eltyp := S.ADR(Int64Type)
    | 11: eltyp := S.ADR(ProcType)
    | 12: HALT(101)  (* COM interface pointers not supported *)
    ELSE
      ASSERT(~ODD(eltyp), 102)  (* COM interface pointers not supported *)
    END;
    t := S.VAL(Type, eltyp);
    headSize := 4 * nofdim + 12;
    size := headSize + nofelem * t.size;
    b := NewBlock(size);
    IF b # NIL THEN
      b.tag := S.VAL(Type, eltyp + 2);  (* tag + array mark *)
      b.last := S.ADR(b.last) + size - t.size;  (* pointer to last elem *)
      b.first := S.ADR(b.last) + headSize;  (* pointer to first elem *)
      RETURN S.ADR(b.last)
    ELSE
      RETURN 0
    END;
  END NewArr;

  (* -------------------- handler installation (portable) --------------------- *)

  PROCEDURE ThisFinObj* (VAR id: Identifier): ANYPTR;
    VAR l: FList;
  BEGIN
    ASSERT(id.typ # 0, 100);
    l := finalizers;
    WHILE l # NIL DO
      IF S.VAL(INTEGER, l.blk.tag) = id.typ THEN
        id.obj := S.VAL(ANYPTR, S.ADR(l.blk.last));
        IF id.Identified() THEN RETURN id.obj END
      END;
      l := l.next
    END;
    RETURN NIL
  END ThisFinObj;

  PROCEDURE InstallReducer* (r: Reducer);
  BEGIN
    r.next := reducers; reducers := r
  END InstallReducer;

  PROCEDURE InstallTrapViewer* (h: Handler);
  BEGIN
    trapViewer := h
  END InstallTrapViewer;

  PROCEDURE InstallTrapChecker* (h: Handler);
  BEGIN
    trapChecker := h
  END InstallTrapChecker;

  PROCEDURE PushTrapCleaner* (c: TrapCleaner);
    VAR t: TrapCleaner;
  BEGIN
    t := trapStack; WHILE (t # NIL) & (t # c) DO t := t.next END;
    ASSERT(t = NIL, 20);
    c.next := trapStack; trapStack := c
  END PushTrapCleaner;

  PROCEDURE PopTrapCleaner* (c: TrapCleaner);
    VAR t: TrapCleaner;
  BEGIN
    t := NIL;
    WHILE (trapStack # NIL) & (t # c) DO
      t := trapStack; trapStack := trapStack.next
    END
  END PopTrapCleaner;

  PROCEDURE InstallCleaner* (p: Command);
    VAR c: CList;
  BEGIN
    c := S.VAL(CList, NewRec(S.TYP(CList)));  (* NEW(c) *)
    c.do := p; c.trapped := FALSE; c.next := cleaners; cleaners := c
  END InstallCleaner;

  PROCEDURE RemoveCleaner* (p: Command);
    VAR c0, c: CList;
  BEGIN
    c := cleaners; c0 := NIL;
    WHILE (c # NIL) & (c.do # p) DO c0 := c; c := c.next END;
    IF c # NIL THEN
      IF c0 = NIL THEN cleaners := cleaners.next ELSE c0.next := c.next END
    END
  END RemoveCleaner;

  PROCEDURE Cleanup*;
    VAR c, c0: CList;
  BEGIN
    c := cleaners; c0 := NIL;
    WHILE c # NIL DO
      IF ~c.trapped THEN
        c.trapped := TRUE; c.do; c.trapped := FALSE; c0 := c
      ELSE
        IF c0 = NIL THEN cleaners := cleaners.next
        ELSE c0.next := c.next
        END
      END;
      c := c.next
    END
  END Cleanup;

  (* -------------------- meta information (portable) --------------------- *)

  PROCEDURE (h: LoaderHook) ThisMod* (IN name: ARRAY OF CHAR): Module, NEW, ABSTRACT;

  PROCEDURE SetLoaderHook*(h: LoaderHook);
  BEGIN
    loader := h
  END SetLoaderHook;

  PROCEDURE InitModule (mod: Module); (* initialize linked modules *)
    VAR body: Command;
  BEGIN
    IF ~(dyn IN mod.opts) & (mod.next # NIL) & ~(init IN mod.next.opts) THEN InitModule(mod.next) END;
    IF ~(init IN mod.opts) THEN
      body := S.VAL(Command, mod.code);
      INCL(mod.opts, init);
      actual := mod;
      body(); actual := NIL
    END
  END InitModule;

  PROCEDURE ThisLoadedMod* (IN name: ARRAY OF CHAR): Module;  (* loaded modules only *)
    VAR m: Module; res: INTEGER; n: Utf8Name;
  BEGIN
    StringToUtf8(name, n, res); ASSERT(res = 0);
    loadres := done;
    m := modList;
    WHILE (m # NIL) & ((m.name # n) OR (m.refcnt < 0)) DO m := m.next END;
    IF (m # NIL) & ~(init IN m.opts) THEN InitModule(m) END;
    IF m = NIL THEN loadres := moduleNotFound END;
    RETURN m
  END ThisLoadedMod;

  PROCEDURE ThisMod* (IN name: ARRAY OF CHAR): Module;
  BEGIN
    IF loader # NIL THEN
      loader.res := done;
      RETURN loader.ThisMod(name)
    ELSE
      RETURN ThisLoadedMod(name)
    END
  END ThisMod;

  PROCEDURE LoadMod* (IN name: ARRAY OF CHAR);
    VAR m: Module;
  BEGIN
    m := ThisMod(name)
  END LoadMod;

  PROCEDURE GetLoaderResult* (OUT res: INTEGER; OUT importing, imported, object: ARRAY OF CHAR);
  BEGIN
    IF loader # NIL THEN
      res := loader.res;
      importing := loader.importing$;
      imported := loader.imported$;
      object := loader.object$
    ELSE
      res := loadres;
      importing := "";
      imported := "";
      object := ""
    END
  END GetLoaderResult;

  PROCEDURE ThisObject* (mod: Module; IN name: ARRAY OF CHAR): Object;
    VAR l, r, m, res: INTEGER; p: StrPtr; n: Utf8Name;
  BEGIN
    StringToUtf8(name, n, res); ASSERT(res = 0);
    l := 0; r := mod.export.num;
    WHILE l < r DO  (* binary search *)
      m := (l + r) DIV 2;
      p := S.VAL(StrPtr, S.ADR(mod.names[mod.export.obj[m].id DIV 256]));
      IF p^ = n THEN RETURN S.VAL(Object, S.ADR(mod.export.obj[m])) END;
      IF p^ < n THEN l := m + 1 ELSE r := m END
    END;
    RETURN NIL
  END ThisObject;

  PROCEDURE ThisDesc* (mod: Module; fprint: INTEGER): Object;
    VAR i, n: INTEGER;
  BEGIN
    i := 0; n := mod.export.num;
    WHILE (i < n) & (mod.export.obj[i].id DIV 256 = 0) DO 
      IF mod.export.obj[i].offs = fprint THEN RETURN S.VAL(Object, S.ADR(mod.export.obj[i])) END;
      INC(i)
    END;
    RETURN NIL
  END ThisDesc;

  PROCEDURE ThisField* (rec: Type; IN name: ARRAY OF CHAR): Object;
    VAR n, res: INTEGER; p: StrPtr; obj: Object; m: Module; nn: Utf8Name;
  BEGIN
    StringToUtf8(name, nn, res); ASSERT(res = 0);
    m := rec.mod;
    obj := S.VAL(Object, S.ADR(rec.fields.obj[0])); n := rec.fields.num;
    WHILE n > 0 DO
      p := S.VAL(StrPtr, S.ADR(m.names[obj.id DIV 256]));
      IF p^ = nn THEN RETURN obj END;
      DEC(n); INC(S.VAL(INTEGER, obj), 16)
    END;
    RETURN NIL
  END ThisField;

  PROCEDURE ThisCommand* (mod: Module; IN name: ARRAY OF CHAR): Command;
    VAR x: Object; sig: Signature;
  BEGIN
    x := ThisObject(mod, name);
    IF (x # NIL) & (x.id MOD 16 = mProc) THEN
      sig := S.VAL(Signature, x.struct);
      IF (sig.retStruct = NIL) & (sig.num = 0) THEN RETURN S.VAL(Command, mod.procBase + x.offs) END
    END;
    RETURN NIL
  END ThisCommand;

  PROCEDURE ThisType* (mod: Module; IN name: ARRAY OF CHAR): Type;
    VAR x: Object;
  BEGIN
    x := ThisObject(mod, name);
    IF (x # NIL) & (x.id MOD 16 = mTyp) & (S.VAL(INTEGER, x.struct) DIV 256 # 0) THEN
      RETURN x.struct
    ELSE
      RETURN NIL
    END
  END ThisType;

  PROCEDURE TypeOf* (IN rec: ANYREC): Type;
  BEGIN
    RETURN S.VAL(Type, S.TYP(rec))
  END TypeOf;

  PROCEDURE LevelOf* (t: Type): SHORTINT;
  BEGIN
    RETURN SHORT(t.id DIV 16 MOD 16)
  END LevelOf;

  PROCEDURE NewObj* (VAR o: S.PTR; t: Type);
    VAR i: INTEGER;
  BEGIN
    IF t.size = -1 THEN o := NIL
    ELSE
      i := 0; WHILE t.ptroffs[i] >= 0 DO INC(i) END;
      IF t.ptroffs[i+1] >= 0 THEN INC(S.VAL(INTEGER, t)) END; (* with interface pointers *)
      o := S.VAL(S.PTR, NewRec(S.VAL(INTEGER, t)))  (* generic NEW *)
    END
  END NewObj;

  PROCEDURE GetModName* (mod: Module; OUT name: Name);
    VAR res: INTEGER;
  BEGIN
    Utf8ToString(mod.name, name, res); ASSERT(res = 0)
  END GetModName;

  PROCEDURE GetObjName* (mod: Module; obj: Object; OUT name: Name);
    VAR p: StrPtr; res: INTEGER;
  BEGIN
    p := S.VAL(StrPtr, S.ADR(mod.names[obj.id DIV 256]));
    Utf8ToString(p^$, name, res); ASSERT(res = 0)
  END GetObjName;

  PROCEDURE GetTypeName* (t: Type; OUT name: Name);
    VAR p: StrPtr; res: INTEGER;
  BEGIN
    p := S.VAL(StrPtr, S.ADR(t.mod.names[t.id DIV 256]));
    Utf8ToString(p^$, name, res); ASSERT(res = 0)
  END GetTypeName;

  PROCEDURE RegisterMod* (mod: Module);
    VAR i: INTEGER; epoch: time.time_t; tm: time.struct_tm; ptm: time.Pstruct_tm;
  BEGIN
    mod.next := modList; modList := mod; mod.refcnt := 0; INCL(mod.opts, dyn); i := 0;
    WHILE i < mod.nofimps DO
      IF mod.imports[i] # NIL THEN INC(mod.imports[i].refcnt) END;
      INC(i)
    END;
    epoch := time.time(NIL);
    ptm := time.localtime_r(epoch, tm);
    IF ptm # NIL THEN
      mod.loadTime[0] := SHORT(tm.tm_year + 1900);
      mod.loadTime[1] := SHORT(tm.tm_mon + 1);
      mod.loadTime[2] := SHORT(tm.tm_mday);
      mod.loadTime[3] := SHORT(tm.tm_hour);
      mod.loadTime[4] := SHORT(tm.tm_min);
      mod.loadTime[5] := SHORT(tm.tm_sec)
    ELSE
      mod.loadTime[0] := 0;
      mod.loadTime[1] := 0;
      mod.loadTime[2] := 0;
      mod.loadTime[3] := 0;
      mod.loadTime[4] := 0;
      mod.loadTime[5] := 0
    END;
    IF ~(init IN mod.opts) THEN InitModule(mod) END
  END RegisterMod;

  PROCEDURE^ Collect*;

  PROCEDURE UnloadMod* (mod: Module);
    VAR i: INTEGER; t: Command;
  BEGIN
    IF mod.refcnt = 0 THEN
      t := mod.term; mod.term := NIL;
      IF t # NIL THEN t() END;  (* terminate module *)
      i := 0;
      WHILE i < mod.nofptrs DO  (* release global pointers *)
        S.PUT(mod.varBase + mod.ptrs[i], 0); INC(i)
      END;
      Collect;  (* call finalizers *)
      i := 0;
      WHILE i < mod.nofimps DO  (* release imported modules *)
        IF mod.imports[i] # NIL THEN DEC(mod.imports[i].refcnt) END;
        INC(i)
      END;
      mod.refcnt := -1;
      IF dyn IN mod.opts THEN (* release memory *)
        InvalModMem(mod.data + mod.dsize - mod.refs, mod.refs)
      END
    END
  END UnloadMod;

  (* -------------------- dynamic procedure call  --------------------- *)

  PROCEDURE [code] PUSH (p: INTEGER) 050H;  (* push AX *)
  PROCEDURE [code] CALL (a: INTEGER) 0FFH, 0D0H;  (* call AX *)
  PROCEDURE [code] RETI (): LONGINT;
  PROCEDURE [code] RETR (): REAL;

  (*
    type           par
    32 bit scalar  value
    64 bit scalar  low hi
    var scalar     address
    record         address tag
    array          address size
    open array     length_N-1 .. length_0
  *)

  PROCEDURE Call* (adr: INTEGER; sig: Signature; IN par: ARRAY OF INTEGER; n: INTEGER): LONGINT;
    VAR p, kind, sp, size: INTEGER; typ: Type; r: REAL;
  BEGIN
    p := sig.num;
    WHILE p > 0 DO  (* push parameters from right to left *)
      DEC(p);
      typ := sig.par[p].struct;
      kind := sig.par[p].id MOD 16;
      IF (S.VAL(INTEGER, typ) DIV 256 = 0) OR (typ.id MOD 4 IN {0, 3}) THEN (* scalar, ANYREC *)
        IF (kind = 10) & ((S.VAL(INTEGER, typ) = 8) OR (S.VAL(INTEGER, typ) = 10)) THEN (* 64 bit *)
          DEC(n); PUSH(par[n])  (* push hi word *)
        ELSIF S.VAL(INTEGER, typ) = 11 THEN   (* ANYREC *)
          ASSERT(kind # 10); (* not a value par, also checked by compiler *)
          DEC(n); PUSH(par[n]) (* push tag *)
        END;
        DEC(n); PUSH(par[n])  (* push value/address *)
      ELSIF typ.id MOD 4 = 1 THEN (* record *)
        IF kind # 10 THEN (* var par *)
          DEC(n); PUSH(par[n]); (* push tag *)
          DEC(n); PUSH(par[n])  (* push address *)
        ELSE
          DEC(n, 2);  (* skip tag *)
          S.GETREG(SP, sp); sp := (sp - typ.size) DIV 4 * 4; S.PUTREG(SP, sp);  (* allocate space *)
          S.MOVE(par[n], sp, typ.size)  (* copy to stack *)
        END
      ELSIF typ.size = 0 THEN (* open array *)
        size := typ.id DIV 16 MOD 16; (* number of open dimensions *)
        WHILE size > 0 DO
          DEC(size); DEC(n); PUSH(par[n]) (* push length *)
        END;
        DEC(n); PUSH(par[n])  (* push address *)
      ELSE  (* fix array *)
        IF kind # 10 THEN (* var par *)
          DEC(n, 2); PUSH(par[n]) (* push address *)
        ELSE
          DEC(n); size := par[n]; DEC(n);
          S.GETREG(SP, sp); sp := (sp - size) DIV 4 * 4; S.PUTREG(SP, sp);  (* allocate space *)
          S.MOVE(par[n], sp, size)  (* copy to stack *)
        END
      END
    END;
    ASSERT(n = 0);
    IF S.VAL(INTEGER, sig.retStruct) = 7 THEN (* shortreal *)
      CALL(adr);
      RETURN S.VAL(INTEGER, SHORT(RETR()))  (* return value in fpu register *)
    ELSIF S.VAL(INTEGER, sig.retStruct) = 8 THEN  (* real *)
      CALL(adr); r := RETR();
      RETURN S.VAL(LONGINT, r)  (* return value in fpu register *)
    ELSE
      CALL(adr);
      RETURN RETI() (* return value in integer registers *)
    END
  END Call;

  (* -------------------- reference information (portable) --------------------- *)

  PROCEDURE RefCh (VAR ref: INTEGER; OUT ch: SHORTCHAR);
  BEGIN
    S.GET(ref, ch); INC(ref)
  END RefCh;

  PROCEDURE RefNum (VAR ref: INTEGER; OUT x: INTEGER);
    VAR s, n: INTEGER; ch: SHORTCHAR;
  BEGIN
    s := 0; n := 0; RefCh(ref, ch);
    WHILE ORD(ch) >= 128 DO INC(n, ASH(ORD(ch) - 128, s) ); INC(s, 7); RefCh(ref, ch) END;
    x := n + ASH(ORD(ch) MOD 64 - ORD(ch) DIV 64 * 64, s)
  END RefNum;

  PROCEDURE RefName (VAR ref: INTEGER; OUT n: Utf8Name);
    VAR i: INTEGER; ch: SHORTCHAR;
  BEGIN
    i := 0; RefCh(ref, ch);
    WHILE ch # 0X DO n[i] := ch; INC(i); RefCh(ref, ch) END;
    n[i] := 0X
  END RefName;

  PROCEDURE GetRefProc* (VAR ref: INTEGER; OUT adr: INTEGER; OUT name: Utf8Name);
    VAR ch: SHORTCHAR;
  BEGIN
    S.GET(ref, ch);
    WHILE ch >= 0FDX DO (* skip variables *)
      INC(ref); RefCh(ref, ch);
      IF ch = 10X THEN INC(ref, 4) END;
      RefNum(ref, adr); RefName(ref, name); S.GET(ref, ch)
    END;
    WHILE (ch > 0X) & (ch < 0FCX) DO  (* skip source refs *)
      INC(ref); RefNum(ref, adr); S.GET(ref, ch)
    END;
    IF ch = 0FCX THEN INC(ref); RefNum(ref, adr); RefName(ref, name)
    ELSE adr := 0
    END
  END GetRefProc;

  PROCEDURE GetRefVar* (VAR ref: INTEGER; OUT mode, form: SHORTCHAR; OUT desc: Type; OUT adr: INTEGER; OUT name: Utf8Name);
  BEGIN
    S.GET(ref, mode); desc := NIL;
    IF mode >= 0FDX THEN
      mode := SHORT(CHR(ORD(mode) - 0FCH));
      INC(ref); RefCh(ref, form);
      IF form = 10X THEN
        S.GET(ref, desc); INC(ref, 4); form := SHORT(CHR(16 + desc.id MOD 4))
      END;
      RefNum(ref, adr); RefName(ref, name)
    ELSE
      mode := 0X; form := 0X; adr := 0
    END
  END GetRefVar;

  PROCEDURE SourcePos* (mod: Module; codePos: INTEGER): INTEGER;
    VAR ref, pos, ad, d: INTEGER; ch: SHORTCHAR; name: Utf8Name;
  BEGIN
    IF mod # NIL THEN (* mf, 12.02.04 *)
      ref := mod.refs; pos := 0; ad := 0; S.GET(ref, ch);
      WHILE ch # 0X DO
        WHILE (ch > 0X) & (ch < 0FCX) DO  (* srcref: {dAdr,dPos} *)
          INC(ad, ORD(ch)); INC(ref); RefNum(ref, d);
          IF ad > codePos THEN RETURN pos END;
          INC(pos, d); S.GET(ref, ch)
        END;
        IF ch = 0FCX THEN (* proc: 0FCX,Adr,Name *)
          INC(ref); RefNum(ref, d); RefName(ref, name); S.GET(ref, ch);
          IF (d > codePos) & (pos > 0) THEN RETURN pos END 
        END;
        WHILE ch >= 0FDX DO (* skip variables: Mode, Form, adr, Name *)
          INC(ref); RefCh(ref, ch);
          IF ch = 10X THEN INC(ref, 4) END;
          RefNum(ref, d); RefName(ref, name); S.GET(ref, ch)
        END
      END;
    END;
    RETURN -1
  END SourcePos;

  PROCEDURE LoadDll* (IN name: ARRAY OF CHAR; VAR ok: BOOLEAN);
    VAR h: ADDRESS; file: Utf8Name; res: INTEGER;
  BEGIN
    StringToUtf8(name, file, res);
    IF res = 0 THEN
      h := dlfcn.dlopen(file, dlfcn.RTLD_LAZY + dlfcn.RTLD_GLOBAL);
      ok := h # 0
    ELSE
      ok := FALSE
    END
  END LoadDll;

  PROCEDURE ThisDllObj* (mode, fprint: INTEGER; IN dll, name: ARRAY OF CHAR): INTEGER;
    VAR h, p: ADDRESS; file, sym: Utf8Name; res: INTEGER; err: dlfcn.int;
  BEGIN
    StringToUtf8(dll, file, res);
    IF res = 0 THEN
      h := dlfcn.dlopen(file, dlfcn.RTLD_LAZY + dlfcn.RTLD_GLOBAL);
      IF h # 0 THEN
        StringToUtf8(name, sym, res);
        IF res = 0 THEN
          p := dlfcn.dlsym(h, sym)
        ELSE
          p := 0
        END;
        err := dlfcn.dlclose(h);
        ASSERT(err = 0, 100)
      ELSE
        p := 0
      END
    ELSE
      p := 0
    END;
    RETURN p
  END ThisDllObj;

  (* -------------------- garbage collector (portable) --------------------- *)

  PROCEDURE Mark (this: Block);
    VAR father, son: Block; tag: Type; flag, offset, actual: INTEGER;
  BEGIN
    IF ~ODD(S.VAL(INTEGER, this.tag)) THEN
      father := NIL;
      LOOP
        INC(S.VAL(INTEGER, this.tag));
        flag := S.VAL(INTEGER, this.tag) MOD 4;
        tag := S.VAL(Type, S.VAL(INTEGER, this.tag) - flag);
        IF flag >= 2 THEN actual := this.first; this.actual := actual
        ELSE actual := S.ADR(this.last)
        END;
        LOOP
          offset := tag.ptroffs[0];
          IF offset < 0 THEN
            INC(S.VAL(INTEGER, tag), offset + 4); (* restore tag *)
            IF (flag >= 2) & (actual < this.last) & (offset < -4) THEN  (* next array element *)
              INC(actual, tag.size); this.actual := actual
            ELSE  (* up *)
              this.tag := S.VAL(Type, S.VAL(INTEGER, tag) + flag);
              IF father = NIL THEN RETURN END;
              son := this; this := father;
              flag := S.VAL(INTEGER, this.tag) MOD 4;
              tag := S.VAL(Type, S.VAL(INTEGER, this.tag) - flag);
              offset := tag.ptroffs[0];
              IF flag >= 2 THEN actual := this.actual ELSE actual := S.ADR(this.last) END;
              S.GET(actual + offset, father); S.PUT(actual + offset, S.ADR(son.last));
              INC(S.VAL(INTEGER, tag), 4)
            END
          ELSE
            S.GET(actual + offset, son);
            IF son # NIL THEN
              DEC(S.VAL(INTEGER, son), 4);
              IF ~ODD(S.VAL(INTEGER, son.tag)) THEN (* down *)
                this.tag := S.VAL(Type, S.VAL(INTEGER, tag) + flag);
                S.PUT(actual + offset, father); father := this; this := son;
                EXIT
              END
            END;
            INC(S.VAL(INTEGER, tag), 4)
          END
        END
      END
    END
  END Mark;

  PROCEDURE MarkGlobals;
    VAR m: Module; i, p: INTEGER;
  BEGIN
    m := modList;
    WHILE m # NIL DO
      IF m.refcnt >= 0 THEN
        i := 0;
        WHILE i < m.nofptrs DO
          S.GET(m.varBase + m.ptrs[i], p); INC(i);
          IF p # 0 THEN Mark(S.VAL(Block, p - 4)) END
        END
      END;
      m := m.next
    END
  END MarkGlobals;

  PROCEDURE Next (b: Block): Block; (* next block in same cluster *)
    VAR size: INTEGER;
  BEGIN
    S.GET(S.VAL(INTEGER, b.tag) DIV 4 * 4, size);
    IF ODD(S.VAL(INTEGER, b.tag) DIV 2) THEN INC(size, b.last - S.ADR(b.last)) END;
    RETURN S.VAL(Block, S.VAL(INTEGER, b) + (size + 19) DIV 16 * 16)
  END Next;

  PROCEDURE CheckCandidates;
  (* pre: nofcand > 0 *)
    VAR i, j, h, p, end: INTEGER; c: Cluster; blk, next: Block;
  BEGIN
    (* sort candidates (shellsort) *)
    h := 1; REPEAT h := h*3 + 1 UNTIL h > nofcand;
    REPEAT h := h DIV 3; i := h;
      WHILE i < nofcand DO p := candidates[i]; j := i;
        WHILE (j >= h) & (candidates[j-h] > p) DO
          candidates[j] := candidates[j-h]; j := j-h
        END;
        candidates[j] := p; INC(i)
      END
    UNTIL h = 1;
    (* sweep *)
    c := root; i := 0;
    WHILE c # NIL DO
      blk := S.VAL(Block, S.VAL(INTEGER, c) + 12);
      end := S.VAL(INTEGER, blk) + (c.size - 12) DIV 16 * 16;
      WHILE candidates[i] < S.VAL(INTEGER, blk) DO
        INC(i);
        IF i = nofcand THEN RETURN END
      END;
      WHILE S.VAL(INTEGER, blk) < end DO
        next := Next(blk);
        IF candidates[i] < S.VAL(INTEGER, next) THEN
          IF (S.VAL(INTEGER, blk.tag) # S.ADR(blk.last))  (* not a free block *)
              & (~strictStackSweep OR (candidates[i] = S.ADR(blk.last))) THEN
            Mark(blk)
          END;
          REPEAT
            INC(i);
            IF i = nofcand THEN RETURN END
          UNTIL candidates[i] >= S.VAL(INTEGER, next)
        END;
        IF (S.VAL(INTEGER, blk.tag) MOD 4 = 0) & (S.VAL(INTEGER, blk.tag) # S.ADR(blk.last))
            & (blk.tag.base[0] = NIL) & (blk.actual > 0) THEN (* referenced interface record *)
          Mark(blk)
        END;
        blk := next
      END;
      c := c.next
    END
  END CheckCandidates;

  PROCEDURE MarkLocals;
    VAR sp, p, min, max: INTEGER; c: Cluster;
  BEGIN
    sp := S.ADR(sp); nofcand := 0; c := root;
    WHILE c.next # NIL DO c := c.next END;
    min := S.VAL(INTEGER, root); max := S.VAL(INTEGER, c) + c.size;
    WHILE sp < baseStack DO
      S.GET(sp, p);
      IF (p > min) & (p < max) & (~strictStackSweep OR (p MOD 16 = 0)) THEN
        candidates[nofcand] := p; INC(nofcand);
        IF nofcand = LEN(candidates) - 1 THEN CheckCandidates; nofcand := 0 END
      END;
      INC(sp, 4)
    END;
    candidates[nofcand] := max; INC(nofcand); (* ensure complete scan for interface mark*)
    IF nofcand > 0 THEN CheckCandidates END
  END MarkLocals;

  PROCEDURE MarkFinObj;
    VAR f: FList;
  BEGIN
    wouldFinalize := FALSE;
    f := finalizers;
    WHILE f # NIL DO
      IF ~ODD(S.VAL(INTEGER, f.blk.tag)) THEN wouldFinalize := TRUE END;
      Mark(f.blk);
      f := f.next
    END;
    f := hotFinalizers;
    WHILE f # NIL DO IF ~ODD(S.VAL(INTEGER, f.blk.tag)) THEN wouldFinalize := TRUE END;
      Mark(f.blk);
      f := f.next
    END
  END MarkFinObj;

  PROCEDURE CheckFinalizers;
    VAR f, g, h, k: FList;
  BEGIN
    f := finalizers; g := NIL;
    IF hotFinalizers = NIL THEN k := NIL
    ELSE
      k := hotFinalizers;
      WHILE k.next # NIL DO k := k.next END
    END;
    WHILE f # NIL DO
      h := f; f := f.next;
      IF ~ODD(S.VAL(INTEGER, h.blk.tag)) THEN
        IF g = NIL THEN finalizers := f ELSE g.next := f END;
        IF k = NIL THEN hotFinalizers := h ELSE k.next := h END;
        k := h; h.next := NIL
      ELSE g := h
      END
    END;
    h := hotFinalizers;
    WHILE h # NIL DO Mark(h.blk); h := h.next END
  END CheckFinalizers;

  PROCEDURE ExecFinalizer (a, b, c: INTEGER);
    VAR f: FList; fin: PROCEDURE(this: ANYPTR);
  BEGIN
    f := S.VAL(FList, a);
    S.GET(S.VAL(INTEGER, f.blk.tag) - 4, fin);  (* method 0 *)
    IF (fin # NIL) & (f.blk.tag.mod.refcnt >= 0) THEN fin(S.VAL(ANYPTR, S.ADR(f.blk.last))) END;
  END ExecFinalizer;

  PROCEDURE^ Try* (h: TryHandler; a, b, c: INTEGER);  (* COMPILER DEPENDENT *)

  PROCEDURE CallFinalizers;
    VAR f: FList;
  BEGIN
    WHILE hotFinalizers # NIL DO
      f := hotFinalizers; hotFinalizers := hotFinalizers.next;
      Try(ExecFinalizer, S.VAL(INTEGER, f), 0, 0)
    END;
    wouldFinalize := FALSE
  END CallFinalizers;

  PROCEDURE Insert (blk: FreeBlock; size: INTEGER); (* insert block in free list *)
    VAR i: INTEGER;
  BEGIN
    blk.size := size - 4; blk.tag := S.VAL(Type, S.ADR(blk.size));
    i := MIN(N - 1, (blk.size DIV 16));
    blk.next := free[i]; free[i] := blk
  END Insert;

  PROCEDURE Sweep (dealloc: BOOLEAN);
    VAR cluster, last, c: Cluster; blk, next: Block; fblk, b, t: FreeBlock; end, i: INTEGER;
  BEGIN
    cluster := root; last := NIL; allocated := 0;
    i := N;
    REPEAT DEC(i); free[i] := sentinel UNTIL i = 0;
    WHILE cluster # NIL DO
      blk := S.VAL(Block, S.VAL(INTEGER, cluster) + 12);
      end := S.VAL(INTEGER, blk) + (cluster.size - 12) DIV 16 * 16;
      fblk := NIL;
      WHILE S.VAL(INTEGER, blk) < end DO
        next := Next(blk);
        IF ODD(S.VAL(INTEGER, blk.tag)) THEN
          IF fblk # NIL THEN
            Insert(fblk, S.VAL(INTEGER, blk) - S.VAL(INTEGER, fblk));
            fblk := NIL
          END;
          DEC(S.VAL(INTEGER, blk.tag)); (* unmark *)
          INC(allocated, S.VAL(INTEGER, next) - S.VAL(INTEGER, blk))
        ELSIF fblk = NIL THEN
          fblk := S.VAL(FreeBlock, blk)
        END;
        blk := next
      END;
      IF dealloc & (S.VAL(INTEGER, fblk) = S.VAL(INTEGER, cluster) + 12) THEN (* deallocate cluster *)
        c := cluster; cluster := cluster.next;
        IF last = NIL THEN root := cluster ELSE last.next := cluster END;
        FreeHeapMem(c)
      ELSE
        IF fblk # NIL THEN Insert(fblk, end - S.VAL(INTEGER, fblk)) END;
        last := cluster; cluster := cluster.next
      END
    END;
    (* reverse free list *)
    i := N;
    REPEAT
      DEC(i);
      b := free[i]; fblk := sentinel;
      WHILE b # sentinel DO t := b; b := t.next; t.next := fblk; fblk := t END;
      free[i] := fblk
    UNTIL i = 0
  END Sweep;

  PROCEDURE Collect*;
  BEGIN
    IF root # NIL THEN
      CallFinalizers; (* trap cleanup *)
      MarkGlobals;
      MarkLocals;
      CheckFinalizers;
      Sweep(TRUE);
      CallFinalizers
    END
  END Collect;
  
  PROCEDURE FastCollect*;
  BEGIN
    IF root # NIL THEN
      MarkGlobals;
      MarkLocals;
      MarkFinObj;
      Sweep(FALSE)
    END
  END FastCollect;

  PROCEDURE WouldFinalize* (): BOOLEAN;
  BEGIN
    RETURN wouldFinalize
  END WouldFinalize;

  (* --------------------- memory allocation (portable) -------------------- *)

  PROCEDURE OldBlock (size: INTEGER): FreeBlock;  (* size MOD 16 = 0 *)
    VAR b, l: FreeBlock; s, i: INTEGER;
  BEGIN
    s := size - 4;
    i := MIN(N - 1, s DIV 16);
    WHILE (i # N - 1) & (free[i] = sentinel) DO INC(i) END;
    b := free[i]; l := NIL;
    WHILE b.size < s DO l := b; b := b.next END;
    IF b # sentinel THEN
      IF l = NIL THEN free[i] := b.next ELSE l.next := b.next END
    ELSE b := NIL
    END;
    RETURN b
  END OldBlock;

  PROCEDURE LastBlock (limit: INTEGER): FreeBlock;  (* size MOD 16 = 0 *)
    VAR b, l: FreeBlock; s, i: INTEGER;
  BEGIN
    s := limit - 4;
    i := 0;
    REPEAT
      b := free[i]; l := NIL;
      WHILE (b # sentinel) & (S.VAL(INTEGER, b) + b.size # s) DO l := b; b := b.next END;
      IF b # sentinel THEN
        IF l = NIL THEN free[i] := b.next ELSE l.next := b.next END
      ELSE b := NIL
      END;
      INC(i)
    UNTIL (b # NIL) OR (i = N);
    RETURN b
  END LastBlock;

  PROCEDURE NewBlock (size: INTEGER): Block;
    VAR tsize, a, s: INTEGER; b: FreeBlock; new, c: Cluster; r: Reducer;
  BEGIN
    ASSERT(size >= 0, 20);
    IF size > MAX(INTEGER) - 19 THEN RETURN NIL END;
    tsize := (size + 19) DIV 16 * 16;
    b := OldBlock(tsize); (* 1) search for free block *)
    IF b = NIL THEN
      FastCollect; b := OldBlock(tsize);  (* 2) collect *)
      IF b = NIL THEN
        Collect; b := OldBlock(tsize);  (* 2a) fully collect *)
      END;
      IF b = NIL THEN
        AllocHeapMem(tsize + 12, new);  (* 3) allocate new cluster *)
        IF new # NIL THEN
          IF (root = NIL) OR (S.VAL(INTEGER, new) < S.VAL(INTEGER, root)) THEN
            new.next := root; root := new
          ELSE
            c := root;
            WHILE (c.next # NIL) & (S.VAL(INTEGER, new) > S.VAL(INTEGER, c.next)) DO c := c.next END;
            new.next := c.next; c.next := new
          END;
          b := S.VAL(FreeBlock, S.VAL(INTEGER, new) + 12);
          b.size := (new.size - 12) DIV 16 * 16 - 4
        ELSE
          RETURN NIL  (* 4) give up *)
        END
      END
    END;
    (* b # NIL *)
    a := b.size + 4 - tsize;
    IF a > 0 THEN Insert(S.VAL(FreeBlock, S.VAL(INTEGER, b) + tsize), a) END;
    IF size > 0 THEN Erase(S.ADR(b.size), (size + 3) DIV 4) END;
    INC(allocated, tsize);
    RETURN S.VAL(Block, b)
  END NewBlock;

  PROCEDURE Allocated* (): INTEGER;
  BEGIN
    RETURN allocated
  END Allocated;

  PROCEDURE Used* (): INTEGER;
  BEGIN
    RETURN used
  END Used;

  PROCEDURE Root* (): INTEGER;
  BEGIN
    RETURN S.VAL(INTEGER, root)
  END Root;

  (* -------------------- Trap Handling --------------------- *)

  PROCEDURE Start* (code: Command);
    VAR res: setjmp.int;
  BEGIN
    restart := code;
    S.GETREG(SP, baseStack);
    res := setjmp.sigsetjmp(startEnv, 1);
    restart
  END Start;

  PROCEDURE Quit* (exitCode: INTEGER);
    VAR m: Module; term: Command; t: BOOLEAN;
  BEGIN
    trapViewer := NIL; trapChecker := NIL; restart := NIL;
    t := terminating; terminating := TRUE; m := modList;
    WHILE m # NIL DO  (* call terminators *)
      IF ~static OR ~t THEN
        term := m.term; m.term := NIL;
        IF term # NIL THEN term() END
      END;
      m := m.next
    END;
    CallFinalizers;
    hotFinalizers := finalizers; finalizers := NIL;
    CallFinalizers;
    stdlib.exit(exitCode)
  END Quit;

  PROCEDURE FatalError* (id: INTEGER; str: ARRAY OF CHAR);
    VAR res: stdio.int; title: ARRAY 16 OF CHAR; text: ARRAY 256 OF SHORTCHAR;
  BEGIN
    title := "Error xy";
    title[6] := CHR(id DIV 10 + ORD("0"));
    title[7] := CHR(id MOD 10 + ORD("0"));
    res := unistd.write(2, S.ADR(title), 8);
    stdlib.abort
  END FatalError;

  PROCEDURE DefaultTrapViewer;
    VAR out: ARRAY 2048 OF SHORTCHAR; a, b, c, len, ref, end: INTEGER; mod: Module;
      modName, name: Name; n: Utf8Name; res: unistd.int;

    PROCEDURE WriteString (IN s: ARRAY OF SHORTCHAR);
      VAR i: INTEGER;
    BEGIN
      i := 0;
      WHILE (len < LEN(out) - 1) & (s[i] # 0X) DO out[len] := s[i]; INC(i); INC(len) END
    END WriteString;

    PROCEDURE WriteHex (x, n: INTEGER);
      VAR i, y: INTEGER;
    BEGIN
      IF len + n < LEN(out) THEN
        i := len + n - 1;
        WHILE i >= len DO
          y := x MOD 16; x := x DIV 16;
          IF y > 9 THEN y := y + (ORD("A") - ORD("0") - 10) END;
          out[i] := SHORT(CHR(y + ORD("0"))); DEC(i)
        END;
        INC(len, n)
      END
    END WriteHex;

    PROCEDURE WriteLn;
    BEGIN
      IF len < LEN(out) - 1 THEN out[len] := 0AX; INC(len) END
    END WriteLn;

  BEGIN
    len := 0;
    WriteString("====== ");
    IF err = 129 THEN WriteString("invalid with")
    ELSIF err = 130 THEN WriteString("invalid case")
    ELSIF err = 131 THEN WriteString("function without return")
    ELSIF err = 132 THEN WriteString("type guard")
    ELSIF err = 133 THEN WriteString("implied type guard")
    ELSIF err = 134 THEN WriteString("value out of range")
    ELSIF err = 135 THEN WriteString("index out of range")
    ELSIF err = 136 THEN WriteString("string too long")
    ELSIF err = 137 THEN WriteString("stack overflow")
    ELSIF err = 138 THEN WriteString("integer overflow")
    ELSIF err = 139 THEN WriteString("division by zero")
    ELSIF err = 140 THEN WriteString("infinite real result")
    ELSIF err = 141 THEN WriteString("real underflow")
    ELSIF err = 142 THEN WriteString("real overflow")
    ELSIF err = 143 THEN WriteString("undefined real result")
    ELSIF err = 144 THEN WriteString("not a number")
    ELSIF err = 200 THEN WriteString("keyboard interrupt")
    ELSIF err = 201 THEN WriteString("NIL dereference")
    ELSIF err = 202 THEN WriteString("illegal instruction:  ");
      WriteHex(val, 4)
    ELSIF err = 203 THEN WriteString("illegal memory read [ad = ");
      WriteHex(val, 8); WriteString("]")
    ELSIF err = 204 THEN WriteString("illegal memory write [ad = ");
      WriteHex(val, 8); WriteString("]")
    ELSIF err = 205 THEN WriteString("illegal execution [ad = ");
      WriteHex(val, 8); WriteString("]")
    ELSIF err = 257 THEN WriteString("out of memory")
    ELSIF err = 10001H THEN WriteString("bus error")
    ELSIF err = 10002H THEN WriteString("address error")
    ELSIF err = 10007H THEN WriteString("fpu error")
    ELSIF err < 0 THEN WriteString("exception #"); WriteHex(-err, 2)
    ELSE err := err DIV 100 * 256 + err DIV 10 MOD 10 * 16 + err MOD 10;
      WriteString("trap #"); WriteHex(err, 3)
    END;
    WriteString(" ======");
    a := pc; b := fp; c := 12;
    REPEAT
      WriteLn; WriteString("- ");
      mod := modList;
      WHILE (mod # NIL) & ((a < mod.code) OR (a >= mod.code + mod.csize)) DO mod := mod.next END;
      IF mod # NIL THEN
        DEC(a, mod.code);
        IF mod.refcnt >= 0 THEN
          GetModName(mod, modName); WriteString(SHORT(modName)); ref := mod.refs;
          REPEAT GetRefProc(ref, end, n) UNTIL (end = 0) OR (a < end);
          IF a < end THEN
            Utf8ToString(n, name, res); WriteString("."); WriteString(SHORT(name))
          END
        ELSE
          GetModName(mod, modName); WriteString("("); WriteString(SHORT(modName)); WriteString(")")
        END;
        WriteString("  ")
      END;
      WriteString("(pc="); WriteHex(a, 8);
      WriteString(", fp="); WriteHex(b, 8); WriteString(")");
      IF (b >= sp) & (b < stack) THEN
        S.GET(b+4, a);  (* stacked pc *)
        S.GET(b, b);  (* dynamic link *)
        DEC(c)
      ELSE c := 0
      END
    UNTIL c = 0;
    out[len] := 0X;
    res := unistd.write(2, S.ADR(out), len)
  END DefaultTrapViewer;

  PROCEDURE TrapCleanup;
    VAR t: TrapCleaner;
  BEGIN
    WHILE trapStack # NIL DO
      t := trapStack; trapStack := trapStack.next; t.Cleanup
    END;
    IF (trapChecker # NIL) & (err # 128) THEN trapChecker END
  END TrapCleanup;

  PROCEDURE SetTrapGuard* (on: BOOLEAN);
  BEGIN
    guarded := on
  END SetTrapGuard;

  PROCEDURE Try* (h: TryHandler; a, b, c: INTEGER);
    VAR oldIsTry: BOOLEAN; oldTryEnv: setjmp.jmp_buf; res: setjmp.int;
  BEGIN
    oldIsTry := isTry; oldTryEnv := tryEnv;
    isTry := TRUE;
    res := setjmp._setjmp(tryEnv);
    IF res = 0 THEN h(a, b, c) END;
    isTry := oldIsTry; tryEnv := oldTryEnv
  END Try;

  PROCEDURE Trap* (n: INTEGER);
  BEGIN
    IF trapped THEN
      DefaultTrapViewer;
      IF ~secondTrap THEN trapped := FALSE; secondTrap := TRUE END
    END;
    IF n >= 0 THEN err := n
    ELSE err := -n + 128
    END;
    pc := 0; sp := 0; fp := 0; stack := 0; val := 0;
    INC(trapCount);
    (* !!! InitFPU *)
    TrapCleanup;
    IF isTry THEN
      setjmp._longjmp(tryEnv, 1)
    END;
    IF (err = 128) OR (err = 200) & ~intTrap THEN (* do nothing *)
    ELSIF (trapViewer # NIL) & (restart # NIL) & ~trapped & ~guarded THEN
      trapped := TRUE; trapViewer()
    ELSE DefaultTrapViewer
    END;
    trapped := FALSE; secondTrap := FALSE;
    IF restart # NIL THEN
      setjmp.siglongjmp(startEnv, 1)
    END;
    stdlib.abort
  END Trap;

  PROCEDURE [ccall] TrapHandler (signo: signal.int; IN info: signal.siginfo_t; context: ADDRESS);
    VAR res: signal.int; uc: signal.Pucontext_t;
  BEGIN
    IF checkReadable THEN
      setjmp.siglongjmp(checkReadableEnv, 1)
    END;
    IF trapped THEN
      DefaultTrapViewer;
      IF ~secondTrap THEN trapped := FALSE; secondTrap := TRUE END
    END;
    err := -signo;
    uc := S.VAL(signal.Pucontext_t, context);
    pc := uc.uc_mcontext.gregs[14]; (* %eip *)
    sp := uc.uc_mcontext.gregs[7]; (* %esp *)
    fp := uc.uc_mcontext.gregs[6]; (* %ebp *)
    stack := baseStack;
    val := info.info.sigsegv.si_addr;
    CASE signo OF
    | signal.SIGFPE:
        val := info.si_code;
        pc := info.info.sigfpe.si_addr;
        CASE info.si_code OF
        | signal.FPE_INTDIV: err := 139 (* division by zero *)
        | signal.FPE_INTOVF: err := 138 (* integer overflow *)
        | signal.FPE_FLTDIV: err := 140 (* fpu: division by zero *)
        | signal.FPE_FLTOVF: err := 142 (* fpu: overflow *)
        | signal.FPE_FLTUND: err := 141 (* fpu: underflow *)
        (* !!! | signal.FPE_FLTRES: err := ??? (* fpu: *) *)
        | signal.FPE_FLTINV: err := 143 (* val := opcode *) (* fpu: invalid op *)
        (* !!! | signal.FPE_FLTSUB: err := ??? (* fpu: *) *)
        ELSE (* unknown *)
        END
    | signal.SIGINT:
        val := info.si_code;
        err := 200 (* keyboard interrupt *)
    | signal.SIGSEGV:
        val := info.info.sigsegv.si_addr;
        err := 203 (* illigal read *)
    | signal.SIGBUS:
        val := info.info.sigbus.si_addr;
        err := 10001H (* bus error *)
    | signal.SIGILL:
        pc := info.info.sigill.si_addr;
        err := 202; (* illigal instruction *)
        IF IsReadable(pc, pc + 4) THEN
          S.GET(pc, val);
          IF val MOD 100H = 8DH THEN (* lea reg,reg *)
            IF val DIV 100H MOD 100H = 0F0H THEN
              err := val DIV 10000H MOD 100H (* trap *)
            ELSIF val DIV 1000H MOD 10H = 0EH THEN
              err := 128 + val DIV 100H MOD 10H (* run time error *)
            END
          END
        END;
    ELSE (* unknown *)
    END;
    INC(trapCount);
    (* !!! InitFPU *)
    TrapCleanup;
    IF isTry THEN
      setjmp._longjmp(tryEnv, 1)
    END;
    IF (err = 128) OR (err = 200) & ~intTrap THEN (* do nothing *)
    ELSIF (trapViewer # NIL) & (restart # NIL) & ~trapped & ~guarded THEN
      trapped := TRUE; trapViewer()
    ELSE DefaultTrapViewer
    END;
    trapped := FALSE; secondTrap := FALSE;
    IF restart # NIL THEN
      setjmp.siglongjmp(startEnv, 1)
    END;
    stdlib.abort
  END TrapHandler;

  (* -------------------- Initialization --------------------- *)

  PROCEDURE InstallTrap (signo: signal.int);
    VAR act: signal.struct_sigaction; res: signal.int;
  BEGIN
    act.handler.sa_handler := NIL;
    res := signal.sigemptyset(act.sa_mask);
    act.sa_flags := signal.SA_NODEFER + signal.SA_SIGINFO;
    act.handler.sa_sigaction := TrapHandler;
    res := signal.sigaction(signo, act, NIL);
  END InstallTrap;

  PROCEDURE InstallTrapVectors;
  BEGIN
    InstallTrap(signal.SIGFPE);
    InstallTrap(signal.SIGINT);
    InstallTrap(signal.SIGSEGV);
    InstallTrap(signal.SIGBUS);
    InstallTrap(signal.SIGILL)
  END InstallTrapVectors;

  PROCEDURE RemoveTrapVectors;
  END RemoveTrapVectors;

  PROCEDURE Init;
    VAR i: INTEGER;
  BEGIN
    intTrap := TRUE;
    pagesize := unistd.sysconf(unistd._SC_PAGESIZE);

    (* init heap *)
    allocated := 0; total := 0; used := 0;
    sentinelBlock.size := MAX(INTEGER);
    sentinel := S.ADR(sentinelBlock);
    i := N;
    REPEAT DEC(i); free[i] := sentinel UNTIL i = 0;

    IF ~inDll THEN
      InstallTrapVectors
    END;

    (* !!! InitFPU *)
    IF ~static THEN
      InitModule(modList);
      IF ~inDll THEN Quit(1) END
    END
  END Init;

BEGIN
  IF modList = NIL THEN (* only once *)
    S.GETREG(SP, baseStack);
    S.GET(baseStack + 16, argc);
    argv := S.VAL(ArrStrPtr, baseStack + 20);
    S.GETREG(ML, modList);  (* linker loads module list to BX *)
    static := init IN modList.opts;
    inDll := dll IN modList.opts;
    Init
  END
CLOSE
  IF ~terminating THEN
    terminating := TRUE;
    Quit(0)
  END
END Kernel.