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f6227721 SL |
1 | #ifndef lint |
2 | static char sccsid[] = "@(#)blok.c 4.2 %G%"; | |
3 | #endif | |
1d90e24b KM |
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 |