4.3BSD - /usr/src/bin/sh/blok.c

   1: #ifndef lint
   2: static char sccsid[] = "@(#)blok.c	4.2 8/11/83";
   3: #endif
   4: 
   5: #
   6: /*
   7:  *	UNIX shell
   8:  *
   9:  *	S. R. Bourne
  10:  *	Bell Telephone Laboratories
  11:  *
  12:  */
  13: 
  14: #include    "defs.h"
  15: 
  16: 
  17: /*
  18:  *	storage allocator
  19:  *	(circular first fit strategy)
  20:  */
  21: 
  22: #define BUSY 01
  23: #define busy(x) (Rcheat((x)->word)&BUSY)
  24: 
  25: POS     brkincr=BRKINCR;
  26: BLKPTR      blokp;          /*current search pointer*/
  27: BLKPTR      bloktop=BLK(end);   /*top of arena (last blok)*/
  28: 
  29: 
  30: 
  31: ADDRESS alloc(nbytes)
  32:     POS     nbytes;
  33: {
  34:     REG POS     rbytes = round(nbytes+BYTESPERWORD,BYTESPERWORD);
  35: 
  36:     LOOP    INT     c=0;
  37:         REG BLKPTR  p = blokp;
  38:         REG BLKPTR  q;
  39:         REP IF !busy(p)
  40:             THEN    WHILE !busy(q = p->word) DO p->word = q->word OD
  41:                 IF ADR(q)-ADR(p) >= rbytes
  42:                 THEN    blokp = BLK(ADR(p)+rbytes);
  43:                     IF q > blokp
  44:                     THEN    blokp->word = p->word;
  45:                     FI
  46:                     p->word=BLK(Rcheat(blokp)|BUSY);
  47:                     return(ADR(p+1));
  48:                 FI
  49:             FI
  50:             q = p; p = BLK(Rcheat(p->word)&~BUSY);
  51:         PER p>q ORF (c++)==0 DONE
  52:         addblok(rbytes);
  53:     POOL
  54: }
  55: 
  56: VOID    addblok(reqd)
  57:     POS     reqd;
  58: {
  59:     IF stakbas!=staktop
  60:     THEN    REG STKPTR  rndstak;
  61:         REG BLKPTR  blokstak;
  62: 
  63:         pushstak(0);
  64:         rndstak=round(staktop,BYTESPERWORD);
  65:         blokstak=BLK(stakbas)-1;
  66:         blokstak->word=stakbsy; stakbsy=blokstak;
  67:         bloktop->word=BLK(Rcheat(rndstak)|BUSY);
  68:         bloktop=BLK(rndstak);
  69:     FI
  70:     reqd += brkincr; reqd &= ~(brkincr-1);
  71:     blokp=bloktop;
  72:     bloktop=bloktop->word=BLK(Rcheat(bloktop)+reqd);
  73:     bloktop->word=BLK(ADR(end)+1);
  74:     BEGIN
  75:        REG STKPTR stakadr=STK(bloktop+2);
  76:        staktop=movstr(stakbot,stakadr);
  77:        stakbas=stakbot=stakadr;
  78:     END
  79: }
  80: 
  81: VOID    free(ap)
  82:     BLKPTR      ap;
  83: {
  84:     REG BLKPTR  p;
  85: 
  86:     IF (p=ap) ANDF p<bloktop
  87:     THEN    Lcheat((--p)->word) &= ~BUSY;
  88:     FI
  89: }
  90: 
  91: #ifdef DEBUG
  92: chkbptr(ptr)
  93:     BLKPTR  ptr;
  94: {
  95:     INT     exf=0;
  96:     REG BLKPTR  p = end;
  97:     REG BLKPTR  q;
  98:     INT     us=0, un=0;
  99: 
 100:     LOOP
 101:        q = Rcheat(p->word)&~BUSY;
 102:        IF p==ptr THEN exf++ FI
 103:        IF q<end ORF q>bloktop THEN abort(3) FI
 104:        IF p==bloktop THEN break FI
 105:        IF busy(p)
 106:        THEN us += q-p;
 107:        ELSE un += q-p;
 108:        FI
 109:        IF p>=q THEN abort(4) FI
 110:        p=q;
 111:     POOL
 112:     IF exf==0 THEN abort(1) FI
 113:     prn(un); prc(SP); prn(us); prc(NL);
 114: }
 115: #endif

Defined functions

Defined variables

Defined macros