1 /*
2 * Simple pointer stack
3 *
4 * (c) 2010 Arnaldo Carvalho de Melo <acme@redhat.com>
5 */
6
7 #include "util.h"
8 #include "pstack.h"
9 #include "debug.h"
10 #include <linux/kernel.h>
11 #include <stdlib.h>
12
13 struct pstack {
14 unsigned short top;
15 unsigned short max_nr_entries;
16 void *entries[0];
17 };
18
pstack__new(unsigned short max_nr_entries)19 struct pstack *pstack__new(unsigned short max_nr_entries)
20 {
21 struct pstack *pstack = zalloc((sizeof(*pstack) +
22 max_nr_entries * sizeof(void *)));
23 if (pstack != NULL)
24 pstack->max_nr_entries = max_nr_entries;
25 return pstack;
26 }
27
pstack__delete(struct pstack * pstack)28 void pstack__delete(struct pstack *pstack)
29 {
30 free(pstack);
31 }
32
pstack__empty(const struct pstack * pstack)33 bool pstack__empty(const struct pstack *pstack)
34 {
35 return pstack->top == 0;
36 }
37
pstack__remove(struct pstack * pstack,void * key)38 void pstack__remove(struct pstack *pstack, void *key)
39 {
40 unsigned short i = pstack->top, last_index = pstack->top - 1;
41
42 while (i-- != 0) {
43 if (pstack->entries[i] == key) {
44 if (i < last_index)
45 memmove(pstack->entries + i,
46 pstack->entries + i + 1,
47 (last_index - i) * sizeof(void *));
48 --pstack->top;
49 return;
50 }
51 }
52 pr_err("%s: %p not on the pstack!\n", __func__, key);
53 }
54
pstack__push(struct pstack * pstack,void * key)55 void pstack__push(struct pstack *pstack, void *key)
56 {
57 if (pstack->top == pstack->max_nr_entries) {
58 pr_err("%s: top=%d, overflow!\n", __func__, pstack->top);
59 return;
60 }
61 pstack->entries[pstack->top++] = key;
62 }
63
pstack__pop(struct pstack * pstack)64 void *pstack__pop(struct pstack *pstack)
65 {
66 void *ret;
67
68 if (pstack->top == 0) {
69 pr_err("%s: underflow!\n", __func__);
70 return NULL;
71 }
72
73 ret = pstack->entries[--pstack->top];
74 pstack->entries[pstack->top] = NULL;
75 return ret;
76 }
77
pstack__peek(struct pstack * pstack)78 void *pstack__peek(struct pstack *pstack)
79 {
80 if (pstack->top == 0)
81 return NULL;
82 return pstack->entries[pstack->top - 1];
83 }
84