projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| a8f68b84 TL |
1 | # |
| 2 | /* | |
| 3 | * UNIX shell | |
| 4 | * | |
| 5 | * S. R. Bourne | |
| 6 | * Bell Telephone Laboratories | |
| 7 | * | |
| 8 | */ | |
| 9 | ||
| 10 | #include "defs.h" | |
| 11 | ||
| 12 | ||
| 13 | /* | |
| 14 | * storage allocator | |
| 15 | * (circular first fit strategy) | |
| 16 | */ | |
| 17 | ||
| 18 | #define BUSY 01 | |
| 19 | #define busy(x) (Rcheat((x)->word)&BUSY) | |
| 20 | ||
| 21 | POS brkincr=BRKINCR; | |
| 22 | BLKPTR blokp; /*current search pointer*/ | |
| 23 | BLKPTR bloktop=BLK(end); /*top of arena (last blok)*/ | |
| 24 | ||
| 25 | ||
| 26 | ||
| 27 | ADDRESS alloc(nbytes) | |
| 28 | POS nbytes; | |
| 29 | { | |
| 30 | REG POS rbytes = round(nbytes+BYTESPERWORD,BYTESPERWORD); | |
| 31 | ||
| 32 | LOOP INT c=0; | |
| 33 | REG BLKPTR p = blokp; | |
| 34 | REG BLKPTR q; | |
| 35 | REP IF !busy(p) | |
| 36 | THEN WHILE !busy(q = p->word) DO p->word = q->word OD | |
| 37 | IF ADR(q)-ADR(p) >= rbytes | |
| 38 | THEN blokp = BLK(ADR(p)+rbytes); | |
| 39 | IF q > blokp | |
| 40 | THEN blokp->word = p->word; | |
| 41 | FI | |
| 42 | p->word=BLK(Rcheat(blokp)|BUSY); | |
| 43 | return(ADR(p+1)); | |
| 44 | FI | |
| 45 | FI | |
| 46 | q = p; p = BLK(Rcheat(p->word)&~BUSY); | |
| 47 | PER p>q ORF (c++)==0 DONE | |
| 48 | addblok(rbytes); | |
| 49 | POOL | |
| 50 | } | |
| 51 | ||
| 52 | VOID addblok(reqd) | |
| 53 | POS reqd; | |
| 54 | { | |
| 55 | IF stakbas!=staktop | |
| 56 | THEN REG STKPTR rndstak; | |
| 57 | REG BLKPTR blokstak; | |
| 58 | ||
| 59 | pushstak(0); | |
| 60 | rndstak=round(staktop,BYTESPERWORD); | |
| 61 | blokstak=BLK(stakbas)-1; | |
| 62 | blokstak->word=stakbsy; stakbsy=blokstak; | |
| 63 | bloktop->word=BLK(Rcheat(rndstak)|BUSY); | |
| 64 | bloktop=BLK(rndstak); | |
| 65 | FI | |
| 66 | reqd += brkincr; reqd &= ~(brkincr-1); | |
| 67 | blokp=bloktop; | |
| 68 | bloktop=bloktop->word=BLK(Rcheat(bloktop)+reqd); | |
| 69 | bloktop->word=BLK(ADR(end)+1); | |
| 70 | BEGIN | |
| 71 | REG STKPTR stakadr=STK(bloktop+2); | |
| 72 | staktop=movstr(stakbot,stakadr); | |
| 73 | stakbas=stakbot=stakadr; | |
| 74 | END | |
| 75 | } | |
| 76 | ||
| 77 | VOID free(ap) | |
| 78 | BLKPTR ap; | |
| 79 | { | |
| 80 | REG BLKPTR p; | |
| 81 | ||
| 82 | IF (p=ap) ANDF p<bloktop | |
| 83 | THEN Lcheat((--p)->word) &= ~BUSY; | |
| 84 | FI | |
| 85 | } | |
| 86 | ||
| 87 | #ifdef DEBUG | |
| 88 | chkbptr(ptr) | |
| 89 | BLKPTR ptr; | |
| 90 | { | |
| 91 | INT exf=0; | |
| 92 | REG BLKPTR p = end; | |
| 93 | REG BLKPTR q; | |
| 94 | INT us=0, un=0; | |
| 95 | ||
| 96 | LOOP | |
| 97 | q = Rcheat(p->word)&~BUSY; | |
| 98 | IF p==ptr THEN exf++ FI | |
| 99 | IF q<end ORF q>bloktop THEN abort(3) FI | |
| 100 | IF p==bloktop THEN break FI | |
| 101 | IF busy(p) | |
| 102 | THEN us += q-p; | |
| 103 | ELSE un += q-p; | |
| 104 | FI | |
| 105 | IF p>=q THEN abort(4) FI | |
| 106 | p=q; | |
| 107 | POOL | |
| 108 | IF exf==0 THEN abort(1) FI | |
| 109 | prn(un); prc(SP); prn(us); prc(NL); | |
| 110 | } | |
| 111 | #endif |