7 |
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/* |
8 |
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* Fast malloc for memory hogs and VM environments. |
9 |
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* Performs a minimum of searching through free lists. |
10 |
– |
* bmalloc() doesn't keep track of free lists -- it's basically |
11 |
– |
* just a buffered call to sbrk(). |
12 |
– |
* bfree() puts memory from any source into malloc() free lists. |
10 |
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* malloc(), realloc() and free() use buckets |
11 |
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* containing blocks in powers of two, similar to CIT routines. |
12 |
+ |
* bfree() puts memory from any source into malloc free lists. |
13 |
+ |
* bmalloc() doesn't keep track of free lists -- it's usually |
14 |
+ |
* just a buffered call to sbrk(2). However, bmalloc will |
15 |
+ |
* call mscrounge() if sbrk fails. |
16 |
+ |
* mscrounge() returns whatever memory it can find to satisfy the |
17 |
+ |
* request along with the number of bytes (modified). |
18 |
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* |
19 |
|
* Greg Ward Lawrence Berkeley Laboratory |
20 |
|
*/ |
21 |
|
|
22 |
+ |
#include <errno.h> |
23 |
+ |
|
24 |
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#define NULL 0 |
25 |
|
|
26 |
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#ifndef ALIGN |
28 |
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#endif |
29 |
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#define BYTES_WORD sizeof(ALIGN) |
30 |
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|
31 |
+ |
#define MAXINCR (1<<18) /* largest sbrk(2) increment */ |
32 |
+ |
|
33 |
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#ifdef NOVMEM |
34 |
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#define getpagesize() BYTES_WORD |
35 |
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#endif |
29 |
– |
|
36 |
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/* malloc free lists */ |
37 |
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typedef union m_head { |
38 |
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union m_head *next; |
47 |
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|
48 |
|
|
49 |
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char * |
50 |
+ |
mscrounge(np) /* search free lists to satisfy request */ |
51 |
+ |
register unsigned *np; |
52 |
+ |
{ |
53 |
+ |
char *p; |
54 |
+ |
register int bucket; |
55 |
+ |
register unsigned bsiz; |
56 |
+ |
|
57 |
+ |
for (bucket = FIRSTBUCKET, bsiz = 1<<FIRSTBUCKET; |
58 |
+ |
bucket < NBUCKETS; bucket++, bsiz <<= 1) |
59 |
+ |
if (free_list[bucket] != NULL && bsiz+sizeof(M_HEAD) >= *np) { |
60 |
+ |
*np = bsiz+sizeof(M_HEAD); |
61 |
+ |
p = (char *)free_list[bucket]; |
62 |
+ |
free_list[bucket] = free_list[bucket]->next; |
63 |
+ |
return(p); |
64 |
+ |
} |
65 |
+ |
*np = 0; |
66 |
+ |
return(NULL); |
67 |
+ |
} |
68 |
+ |
|
69 |
+ |
|
70 |
+ |
char * |
71 |
|
bmalloc(n) /* allocate a block of n bytes, sans header */ |
72 |
|
register unsigned n; |
73 |
|
{ |
74 |
|
extern char *sbrk(); |
75 |
< |
static int pagesz = 0; |
76 |
< |
static int amnt; |
75 |
> |
static unsigned pagesz = 0; |
76 |
> |
static unsigned amnt; |
77 |
|
static char *bpos; |
78 |
< |
static int nrem; |
78 |
> |
static unsigned nrem; |
79 |
> |
unsigned thisamnt; |
80 |
|
register char *p; |
81 |
|
|
82 |
|
if (pagesz == 0) { /* initialize */ |
91 |
|
n = (n+(BYTES_WORD-1))&~(BYTES_WORD-1); /* word align rqst. */ |
92 |
|
|
93 |
|
if (n > nrem) { /* need more core */ |
94 |
< |
if (n > amnt) /* increase amount */ |
95 |
< |
amnt = (n+(pagesz-1))&~(pagesz-1); |
96 |
< |
p = sbrk(amnt); |
97 |
< |
if ((int)p == -1) |
70 |
< |
return(NULL); |
71 |
< |
if (p != bpos+nrem) { /* someone called sbrk()! */ |
72 |
< |
bfree(bpos, nrem); |
73 |
< |
bpos = p; |
74 |
< |
nrem = amnt; |
94 |
> |
if (n > amnt) { /* big chunk */ |
95 |
> |
thisamnt = (n+(pagesz-1))&~(pagesz-1); |
96 |
> |
if (thisamnt <= MAXINCR) /* increase amnt */ |
97 |
> |
amnt = thisamnt; |
98 |
|
} else |
99 |
< |
nrem += amnt; |
99 |
> |
thisamnt = amnt; |
100 |
> |
p = sbrk(thisamnt); |
101 |
> |
if ((int)p == -1) { /* uh-oh, ENOMEM */ |
102 |
> |
thisamnt = n; /* search free lists */ |
103 |
> |
p = mscrounge(&thisamnt); |
104 |
> |
if (p == NULL) /* we're really out */ |
105 |
> |
return(NULL); |
106 |
> |
} |
107 |
> |
if (p != bpos+nrem) { /* not an increment */ |
108 |
> |
bfree(bpos, nrem); /* free what we have */ |
109 |
> |
bpos = p; |
110 |
> |
nrem = thisamnt; |
111 |
> |
} else /* otherwise tack on */ |
112 |
> |
nrem += thisamnt; |
113 |
|
} |
114 |
|
p = bpos; |
115 |
|
bpos += n; /* advance */ |
124 |
|
{ |
125 |
|
register int bucket; |
126 |
|
register unsigned bsiz; |
127 |
< |
/* find largest bucket */ |
128 |
< |
bucket = 0; |
129 |
< |
for (bsiz = 1; bsiz+sizeof(M_HEAD) <= n; bsiz <<= 1) |
130 |
< |
bucket++; |
131 |
< |
while (bucket > FIRSTBUCKET) { |
96 |
< |
bsiz >>= 1; |
97 |
< |
bucket--; |
98 |
< |
if (n < bsiz+sizeof(M_HEAD)) /* nothing for this bucket */ |
99 |
< |
continue; |
100 |
< |
((M_HEAD *)p)->next = free_list[bucket]; |
101 |
< |
free_list[bucket] = (M_HEAD *)p; |
102 |
< |
p += bsiz+sizeof(M_HEAD); |
103 |
< |
n -= bsiz+sizeof(M_HEAD); |
127 |
> |
/* align pointer */ |
128 |
> |
bsiz = BYTES_WORD - ((unsigned)p&(BYTES_WORD-1)); |
129 |
> |
if (bsiz < BYTES_WORD) { |
130 |
> |
p += bsiz; |
131 |
> |
n -= bsiz; |
132 |
|
} |
133 |
+ |
/* fill big buckets first */ |
134 |
+ |
for (bucket = NBUCKETS-1, bsiz = 1<<(NBUCKETS-1); |
135 |
+ |
bucket >= FIRSTBUCKET; bucket--, bsiz >>= 1) |
136 |
+ |
if (n >= bsiz+sizeof(M_HEAD)) { |
137 |
+ |
((M_HEAD *)p)->next = free_list[bucket]; |
138 |
+ |
free_list[bucket] = (M_HEAD *)p; |
139 |
+ |
p += bsiz+sizeof(M_HEAD); |
140 |
+ |
n -= bsiz+sizeof(M_HEAD); |
141 |
+ |
} |
142 |
|
} |
143 |
|
|
144 |
|
|
146 |
|
malloc(n) /* allocate n bytes of memory */ |
147 |
|
unsigned n; |
148 |
|
{ |
149 |
+ |
extern int errno; |
150 |
|
register M_HEAD *mp; |
151 |
|
register int bucket; |
152 |
|
register unsigned bsiz; |
154 |
|
if (n == 0) |
155 |
|
return(NULL); |
156 |
|
/* find first bucket that fits */ |
157 |
< |
bucket = FIRSTBUCKET; |
158 |
< |
for (bsiz = 1<<FIRSTBUCKET; bsiz < n; bsiz <<= 1) |
159 |
< |
bucket++; |
160 |
< |
if (free_list[bucket] == NULL) { |
157 |
> |
for (bucket = FIRSTBUCKET, bsiz = 1<<FIRSTBUCKET; |
158 |
> |
bucket < NBUCKETS; bucket++, bsiz <<= 1) |
159 |
> |
if (bsiz >= n) |
160 |
> |
break; |
161 |
> |
if (bucket >= NBUCKETS) { |
162 |
> |
errno = EINVAL; |
163 |
> |
return(NULL); |
164 |
> |
} |
165 |
> |
if (free_list[bucket] == NULL) { /* need more core */ |
166 |
|
mp = (M_HEAD *)bmalloc(bsiz+sizeof(M_HEAD)); |
167 |
|
if (mp == NULL) |
168 |
|
return(NULL); |
169 |
< |
} else { |
169 |
> |
} else { /* got it */ |
170 |
|
mp = free_list[bucket]; |
171 |
|
free_list[bucket] = mp->next; |
172 |
|
} |
173 |
< |
mp->bucket = bucket; |
173 |
> |
mp->bucket = bucket; /* tag block */ |
174 |
|
return((char *)(mp+1)); |
175 |
|
} |
176 |
|
|
177 |
|
|
178 |
|
char * |
179 |
|
realloc(op, n) /* reallocate memory using malloc() */ |
180 |
< |
char *op; |
180 |
> |
register char *op; |
181 |
|
unsigned n; |
182 |
|
{ |
183 |
< |
register char *p; |
183 |
> |
char *p; |
184 |
|
register unsigned on; |
185 |
< |
|
185 |
> |
/* get old size */ |
186 |
|
if (op != NULL) |
187 |
|
on = 1 << ((M_HEAD *)op-1)->bucket; |
188 |
|
else |
189 |
|
on = 0; |
190 |
< |
if (n <= on && n > on>>1) |
190 |
> |
if (n <= on && (n > on>>1 || on == 1<<FIRSTBUCKET)) |
191 |
|
return(op); /* same bucket */ |
192 |
|
p = malloc(n); |
193 |
|
if (p != NULL) |