Commit | Line | Data |
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1d90e24b KM |
1 | /* blok.c 4.1 82/05/07 */ |
2 | ||
3 | # | |
4 | /* | |
5 | * UNIX shell | |
6 | * | |
7 | * S. R. Bourne | |
8 | * Bell Telephone Laboratories | |
9 | * | |
10 | */ | |
11 | ||
12 | #include "defs.h" | |
13 | ||
14 | ||
15 | /* | |
16 | * storage allocator | |
17 | * (circular first fit strategy) | |
18 | */ | |
19 | ||
20 | #define BUSY 01 | |
21 | #define busy(x) (Rcheat((x)->word)&BUSY) | |
22 | ||
23 | POS brkincr=BRKINCR; | |
24 | BLKPTR blokp; /*current search pointer*/ | |
25 | BLKPTR bloktop=BLK(end); /*top of arena (last blok)*/ | |
26 | ||
27 | ||
28 | ||
29 | ADDRESS alloc(nbytes) | |
30 | POS nbytes; | |
31 | { | |
32 | REG POS rbytes = round(nbytes+BYTESPERWORD,BYTESPERWORD); | |
33 | ||
34 | LOOP INT c=0; | |
35 | REG BLKPTR p = blokp; | |
36 | REG BLKPTR q; | |
37 | REP IF !busy(p) | |
38 | THEN WHILE !busy(q = p->word) DO p->word = q->word OD | |
39 | IF ADR(q)-ADR(p) >= rbytes | |
40 | THEN blokp = BLK(ADR(p)+rbytes); | |
41 | IF q > blokp | |
42 | THEN blokp->word = p->word; | |
43 | FI | |
44 | p->word=BLK(Rcheat(blokp)|BUSY); | |
45 | return(ADR(p+1)); | |
46 | FI | |
47 | FI | |
48 | q = p; p = BLK(Rcheat(p->word)&~BUSY); | |
49 | PER p>q ORF (c++)==0 DONE | |
50 | addblok(rbytes); | |
51 | POOL | |
52 | } | |
53 | ||
54 | VOID addblok(reqd) | |
55 | POS reqd; | |
56 | { | |
57 | IF stakbas!=staktop | |
58 | THEN REG STKPTR rndstak; | |
59 | REG BLKPTR blokstak; | |
60 | ||
61 | pushstak(0); | |
62 | rndstak=round(staktop,BYTESPERWORD); | |
63 | blokstak=BLK(stakbas)-1; | |
64 | blokstak->word=stakbsy; stakbsy=blokstak; | |
65 | bloktop->word=BLK(Rcheat(rndstak)|BUSY); | |
66 | bloktop=BLK(rndstak); | |
67 | FI | |
68 | reqd += brkincr; reqd &= ~(brkincr-1); | |
69 | blokp=bloktop; | |
70 | bloktop=bloktop->word=BLK(Rcheat(bloktop)+reqd); | |
71 | bloktop->word=BLK(ADR(end)+1); | |
72 | BEGIN | |
73 | REG STKPTR stakadr=STK(bloktop+2); | |
74 | staktop=movstr(stakbot,stakadr); | |
75 | stakbas=stakbot=stakadr; | |
76 | END | |
77 | } | |
78 | ||
79 | VOID free(ap) | |
80 | BLKPTR ap; | |
81 | { | |
82 | REG BLKPTR p; | |
83 | ||
84 | IF (p=ap) ANDF p<bloktop | |
85 | THEN Lcheat((--p)->word) &= ~BUSY; | |
86 | FI | |
87 | } | |
88 | ||
89 | #ifdef DEBUG | |
90 | chkbptr(ptr) | |
91 | BLKPTR ptr; | |
92 | { | |
93 | INT exf=0; | |
94 | REG BLKPTR p = end; | |
95 | REG BLKPTR q; | |
96 | INT us=0, un=0; | |
97 | ||
98 | LOOP | |
99 | q = Rcheat(p->word)&~BUSY; | |
100 | IF p==ptr THEN exf++ FI | |
101 | IF q<end ORF q>bloktop THEN abort(3) FI | |
102 | IF p==bloktop THEN break FI | |
103 | IF busy(p) | |
104 | THEN us += q-p; | |
105 | ELSE un += q-p; | |
106 | FI | |
107 | IF p>=q THEN abort(4) FI | |
108 | p=q; | |
109 | POOL | |
110 | IF exf==0 THEN abort(1) FI | |
111 | prn(un); prc(SP); prn(us); prc(NL); | |
112 | } | |
113 | #endif |