Commit | Line | Data |
---|---|---|
7a10d9ad BJ |
1 | /* Copyright (c) 1979 Regents of the University of California */ |
2 | #include "sh.local.h" | |
3 | #ifdef debug | |
4 | #define ASSERT(p) if(!(p))botch("p");else | |
5 | botch(s) | |
6 | char *s; | |
7 | { | |
8 | printf("assertion botched: %s\n",s); | |
9 | abort(); | |
10 | } | |
11 | #else | |
12 | #define ASSERT(p) | |
13 | #endif | |
14 | ||
15 | /* avoid break bug */ | |
16 | #ifdef pdp11 | |
17 | #define GRANULE 64 | |
18 | #else | |
19 | #define GRANULE 0 | |
20 | #endif | |
21 | /* C storage allocator | |
22 | * circular first-fit strategy | |
23 | * works with noncontiguous, but monotonically linked, arena | |
24 | * each block is preceded by a ptr to the (pointer of) | |
25 | * the next following block | |
26 | * blocks are exact number of words long | |
27 | * aligned to the data type requirements of ALIGN | |
28 | * pointers to blocks must have BUSY bit 0 | |
29 | * bit in ptr is 1 for busy, 0 for idle | |
30 | * gaps in arena are merely noted as busy blocks | |
31 | * last block of arena (pointed to by alloct) is empty and | |
32 | * has a pointer to first | |
33 | * idle blocks are coalesced during space search | |
34 | * | |
35 | * a different implementation may need to redefine | |
36 | * ALIGN, NALIGN, BLOCK, BUSY, INT | |
37 | * where INT is integer type to which a pointer can be cast | |
38 | */ | |
39 | #define INT int | |
40 | #define ALIGN int | |
41 | #define NALIGN 1 | |
42 | #define WORD sizeof(union store) | |
43 | #define BLOCK 1024 /* a multiple of WORD*/ | |
44 | #define BUSY 1 | |
45 | #define NULL 0 | |
46 | #define testbusy(p) ((INT)(p)&BUSY) | |
47 | #define setbusy(p) (union store *)((INT)(p)|BUSY) | |
48 | #define clearbusy(p) (union store *)((INT)(p)&~BUSY) | |
49 | ||
50 | union store { union store *ptr; | |
51 | ALIGN dummy[NALIGN]; | |
52 | int calloc; /*calloc clears an array of integers*/ | |
53 | }; | |
54 | ||
55 | static union store allocs[2]; /*initial arena*/ | |
56 | static union store *allocp; /*search ptr*/ | |
57 | static union store *alloct; /*arena top*/ | |
58 | static union store *allocx; /*for benefit of realloc*/ | |
59 | char *sbrk(); | |
60 | ||
61 | char * | |
62 | malloc(nbytes) | |
63 | unsigned nbytes; | |
64 | { | |
65 | register union store *p, *q; | |
66 | register nw; | |
67 | static temp; /*coroutines assume no auto*/ | |
68 | ||
69 | if(allocs[0].ptr==0) { /*first time*/ | |
70 | allocs[0].ptr = setbusy(&allocs[1]); | |
71 | allocs[1].ptr = setbusy(&allocs[0]); | |
72 | alloct = &allocs[1]; | |
73 | allocp = &allocs[0]; | |
74 | } | |
75 | nw = (nbytes+WORD+WORD-1)/WORD; | |
76 | ASSERT(allocp>=allocs && allocp<=alloct); | |
77 | ASSERT(allock()); | |
78 | for(p=allocp; ; ) { | |
79 | for(temp=0; ; ) { | |
80 | if(!testbusy(p->ptr)) { | |
81 | while(!testbusy((q=p->ptr)->ptr)) { | |
82 | ASSERT(q>p&&q<alloct); | |
83 | p->ptr = q->ptr; | |
84 | } | |
85 | if(q>=p+nw && p+nw>=p) | |
86 | goto found; | |
87 | } | |
88 | q = p; | |
89 | p = clearbusy(p->ptr); | |
90 | if(p>q) | |
91 | ASSERT(p<=alloct); | |
92 | else if(q!=alloct || p!=allocs) { | |
93 | ASSERT(q==alloct&&p==allocs); | |
94 | return(NULL); | |
95 | } else if(++temp>1) | |
96 | break; | |
97 | } | |
98 | temp = ((nw+BLOCK/WORD)/(BLOCK/WORD))*(BLOCK/WORD); | |
99 | q = (union store *)sbrk(0); | |
100 | if(q+temp+GRANULE < q) { | |
101 | return(NULL); | |
102 | } | |
103 | q = (union store *)sbrk(temp*WORD); | |
104 | if((INT)q == -1) { | |
105 | return(NULL); | |
106 | } | |
107 | ASSERT(q>alloct); | |
108 | alloct->ptr = q; | |
109 | if(q!=alloct+1) | |
110 | alloct->ptr = setbusy(alloct->ptr); | |
111 | alloct = q->ptr = q+temp-1; | |
112 | alloct->ptr = setbusy(allocs); | |
113 | } | |
114 | found: | |
115 | allocp = p + nw; | |
116 | ASSERT(allocp<=alloct); | |
117 | if(q>allocp) { | |
118 | allocx = allocp->ptr; | |
119 | allocp->ptr = p->ptr; | |
120 | } | |
121 | p->ptr = setbusy(allocp); | |
122 | return((char *)(p+1)); | |
123 | } | |
124 | ||
125 | /* freeing strategy tuned for LIFO allocation | |
126 | */ | |
127 | free(ap) | |
128 | register char *ap; | |
129 | { | |
130 | register union store *p = (union store *)ap; | |
131 | ||
132 | ASSERT(p>clearbusy(allocs[1].ptr)&&p<=alloct); | |
133 | ASSERT(allock()); | |
134 | allocp = --p; | |
135 | /* ASSERT(testbusy(p->ptr)); */ | |
136 | p->ptr = clearbusy(p->ptr); | |
137 | ASSERT(p->ptr > allocp && p->ptr <= alloct); | |
138 | } | |
139 | ||
140 | /* realloc(p, nbytes) reallocates a block obtained from malloc() | |
141 | * and freed since last call of malloc() | |
142 | * to have new size nbytes, and old content | |
143 | * returns new location, or 0 on failure | |
144 | */ | |
145 | ||
146 | char * | |
147 | realloc(p, nbytes) | |
148 | register union store *p; | |
149 | unsigned nbytes; | |
150 | { | |
151 | register union store *q; | |
152 | union store *s, *t; | |
153 | register unsigned nw; | |
154 | unsigned onw; | |
155 | ||
156 | if(testbusy(p[-1].ptr)) | |
157 | free((char *)p); | |
158 | onw = p[-1].ptr - p; | |
159 | q = (union store *)malloc(nbytes); | |
160 | if(q==NULL || q==p) | |
161 | return((char *)q); | |
162 | s = p; | |
163 | t = q; | |
164 | nw = (nbytes+WORD-1)/WORD; | |
165 | if(nw<onw) | |
166 | onw = nw; | |
167 | while(onw--!=0) | |
168 | #ifdef V6 | |
169 | copy(t++, s++, sizeof (*t)); | |
170 | #else | |
171 | *t++ = *s++; | |
172 | #endif | |
173 | if(q<p && q+nw>=p) | |
174 | (q+(q+nw-p))->ptr = allocx; | |
175 | return((char *)q); | |
176 | } | |
177 | ||
178 | #ifdef debug | |
179 | allock() | |
180 | { | |
181 | #ifdef longdebug | |
182 | register union store *p; | |
183 | int x; | |
184 | x = 0; | |
185 | for(p= &allocs[0]; clearbusy(p->ptr) > p; p=clearbusy(p->ptr)) { | |
186 | if(p==allocp) | |
187 | x++; | |
188 | } | |
189 | ASSERT(p==alloct); | |
190 | return(x==1|p==allocp); | |
191 | #else | |
192 | return(1); | |
193 | #endif | |
194 | } | |
195 | #endif | |
196 | ||
197 | #ifdef debug | |
198 | showall(v) | |
199 | char **v; | |
200 | { | |
201 | register union store *p, *q; | |
202 | int used = 0, free = 0, i; | |
203 | ||
204 | for (p = clearbusy(allocs[1].ptr); p != alloct; p = q) { | |
205 | q = clearbusy(p->ptr); | |
206 | if (v[1]) | |
207 | printf("%6o %5d %s\n", p, | |
208 | ((unsigned) q - (unsigned) p), | |
209 | testbusy(p->ptr) ? "BUSY" : "FREE"); | |
210 | i = ((unsigned) q - (unsigned) p); | |
211 | if (testbusy(p->ptr)) used += i; else free += i; | |
212 | } | |
213 | printf("%d used, %d free, %l end\n", used, free, clearbusy(alloct)); | |
214 | } | |
215 | #endif |