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