8 |
|
* Fast malloc for memory hogs and VM environments. |
9 |
|
* 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. |
11 |
> |
* just a buffered call to sbrk(2). However, bmalloc will |
12 |
> |
* call mscrounge() if sbrk fails. |
13 |
> |
* bfree() puts memory from any source into malloc free lists. |
14 |
|
* malloc(), realloc() and free() use buckets |
15 |
|
* containing blocks in powers of two, similar to CIT routines. |
16 |
+ |
* mscrounge() returns whatever memory it can find to satisfy the |
17 |
+ |
* request along with the number of bytes (modified). |
18 |
|
* |
19 |
|
* Greg Ward Lawrence Berkeley Laboratory |
20 |
|
*/ |
26 |
|
#endif |
27 |
|
#define BYTES_WORD sizeof(ALIGN) |
28 |
|
|
29 |
+ |
#define MAXINCR (1<<18) /* largest sbrk(2) increment */ |
30 |
+ |
|
31 |
|
#ifdef NOVMEM |
32 |
|
#define getpagesize() BYTES_WORD |
33 |
|
#endif |
29 |
– |
|
34 |
|
/* malloc free lists */ |
35 |
|
typedef union m_head { |
36 |
|
union m_head *next; |
45 |
|
|
46 |
|
|
47 |
|
char * |
48 |
+ |
mscrounge(np) /* search free lists trying to satisfy request */ |
49 |
+ |
register unsigned *np; |
50 |
+ |
{ |
51 |
+ |
char *p; |
52 |
+ |
register int bucket; |
53 |
+ |
register unsigned bsiz; |
54 |
+ |
|
55 |
+ |
for (bucket = FIRSTBUCKET, bsiz = 1<<FIRSTBUCKET; |
56 |
+ |
bucket < NBUCKETS; bucket++, bsiz <<= 1) |
57 |
+ |
if (free_list[bucket] != NULL && bsiz+sizeof(M_HEAD) >= *np) { |
58 |
+ |
*np = bsiz+sizeof(M_HEAD); |
59 |
+ |
p = (char *)free_list[bucket]; |
60 |
+ |
free_list[bucket] = free_list[bucket]->next; |
61 |
+ |
return(p); |
62 |
+ |
} |
63 |
+ |
*np = 0; |
64 |
+ |
return(NULL); |
65 |
+ |
} |
66 |
+ |
|
67 |
+ |
|
68 |
+ |
char * |
69 |
|
bmalloc(n) /* allocate a block of n bytes, sans header */ |
70 |
|
register unsigned n; |
71 |
|
{ |
72 |
|
extern char *sbrk(); |
73 |
< |
static int pagesz = 0; |
74 |
< |
static int amnt; |
73 |
> |
static unsigned pagesz = 0; |
74 |
> |
static unsigned amnt; |
75 |
|
static char *bpos; |
76 |
< |
static int nrem; |
76 |
> |
static unsigned nrem; |
77 |
> |
unsigned thisamnt; |
78 |
|
register char *p; |
79 |
|
|
80 |
|
if (pagesz == 0) { /* initialize */ |
89 |
|
n = (n+(BYTES_WORD-1))&~(BYTES_WORD-1); /* word align rqst. */ |
90 |
|
|
91 |
|
if (n > nrem) { /* need more core */ |
92 |
< |
if (n > amnt) /* increase amount */ |
93 |
< |
amnt = (n+(pagesz-1))&~(pagesz-1); |
94 |
< |
p = sbrk(amnt); |
95 |
< |
if ((int)p == -1) |
96 |
< |
return(NULL); |
97 |
< |
if (p != bpos+nrem) { /* someone called sbrk()! */ |
92 |
> |
if (n > amnt) { /* big chunk */ |
93 |
> |
thisamnt = (n+(pagesz-1))&~(pagesz-1); |
94 |
> |
if (thisamnt <= MAXINCR) /* increase amnt */ |
95 |
> |
amnt = thisamnt; |
96 |
> |
} else |
97 |
> |
thisamnt = amnt; |
98 |
> |
p = sbrk(thisamnt); |
99 |
> |
if ((int)p == -1) { /* uh-oh */ |
100 |
> |
thisamnt = n; /* search free lists */ |
101 |
> |
p = mscrounge(&thisamnt); |
102 |
> |
if (p == NULL) /* we're really out */ |
103 |
> |
return(NULL); |
104 |
> |
} |
105 |
> |
if (p != bpos+nrem) { /* not an increment */ |
106 |
|
bfree(bpos, nrem); |
107 |
|
bpos = p; |
108 |
< |
nrem = amnt; |
108 |
> |
nrem = thisamnt; |
109 |
|
} else |
110 |
< |
nrem += amnt; |
110 |
> |
nrem += thisamnt; |
111 |
|
} |
112 |
|
p = bpos; |
113 |
|
bpos += n; /* advance */ |