1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
|
/*
A pooled string allocator intended to cut down on the
memory overhead of many small string allocations.
Andrew Whitwham, September 2010.
*/
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include "string_alloc.h"
#define MIN_STR_SIZE 1024
/* creates the string pool. max_length is the initial size
a single string can be. Tha max_length can grow as
needed */
string_alloc_t *string_pool_create(size_t max_length) {
string_alloc_t *a_str;
if (NULL == (a_str = (string_alloc_t *)malloc(sizeof(*a_str)))) {
return NULL;
}
if (max_length < MIN_STR_SIZE) max_length = MIN_STR_SIZE;
a_str->nstrings = 0;
a_str->max_length = max_length;
a_str->strings = NULL;
return a_str;
}
/* internal function to do the actual memory allocation */
static string_t *new_string_pool(string_alloc_t *a_str) {
string_t *str;
str = realloc(a_str->strings, (a_str->nstrings + 1) * sizeof(*a_str->strings));
if (NULL == str) return NULL;
a_str->strings = str;
str = &a_str->strings[a_str->nstrings];
str->str = malloc(a_str->max_length);;
if (NULL == str->str) return NULL;
str->used = 0;
a_str->nstrings++;
return str;
}
/* free allocated memory */
void string_pool_destroy(string_alloc_t *a_str) {
size_t i;
for (i = 0; i < a_str->nstrings; i++) {
free(a_str->strings[i].str);
}
free(a_str->strings);
free(a_str);
}
/* allocate space for a string */
char *string_alloc(string_alloc_t *a_str, size_t length) {
string_t *str;
char *ret;
if (length <= 0) return NULL;
// add to last string pool if we have space
if (a_str->nstrings) {
str = &a_str->strings[a_str->nstrings - 1];
if (str->used + length < a_str->max_length) {
ret = str->str + str->used;
str->used += length;
return ret;
}
}
// increase the max length if needs be
if (length > a_str->max_length) a_str->max_length = length;
// need a new string pool
str = new_string_pool(a_str);
if (NULL == str) return NULL;
str->used = length;
return str->str;
}
/* equivalent to strdup */
char *string_dup(string_alloc_t *a_str, char *instr) {
char *str;
size_t len = strlen(instr);
if (len > a_str->max_length) len = a_str->max_length - 1;
str = string_alloc(a_str, len + 1);
if (NULL == str) return NULL;
strncpy(str, instr, len + 1);
return str;
}
|
