1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * Simple pointer stack |
4 | * |
5 | * (c) 2010 Arnaldo Carvalho de Melo <acme@redhat.com> |
6 | */ |
7 | |
8 | #include "pstack.h" |
9 | #include "debug.h" |
10 | #include <linux/kernel.h> |
11 | #include <linux/zalloc.h> |
12 | #include <stdlib.h> |
13 | #include <string.h> |
14 | |
15 | struct pstack { |
16 | unsigned short top; |
17 | unsigned short max_nr_entries; |
18 | void *entries[]; |
19 | }; |
20 | |
21 | struct pstack *pstack__new(unsigned short max_nr_entries) |
22 | { |
23 | struct pstack *pstack = zalloc((sizeof(*pstack) + |
24 | max_nr_entries * sizeof(void *))); |
25 | if (pstack != NULL) |
26 | pstack->max_nr_entries = max_nr_entries; |
27 | return pstack; |
28 | } |
29 | |
30 | void pstack__delete(struct pstack *pstack) |
31 | { |
32 | free(pstack); |
33 | } |
34 | |
35 | bool pstack__empty(const struct pstack *pstack) |
36 | { |
37 | return pstack->top == 0; |
38 | } |
39 | |
40 | void pstack__remove(struct pstack *pstack, void *key) |
41 | { |
42 | unsigned short i = pstack->top, last_index = pstack->top - 1; |
43 | |
44 | while (i-- != 0) { |
45 | if (pstack->entries[i] == key) { |
46 | if (i < last_index) |
47 | memmove(pstack->entries + i, |
48 | pstack->entries + i + 1, |
49 | (last_index - i) * sizeof(void *)); |
50 | --pstack->top; |
51 | return; |
52 | } |
53 | } |
54 | pr_err("%s: %p not on the pstack!\n" , __func__, key); |
55 | } |
56 | |
57 | void pstack__push(struct pstack *pstack, void *key) |
58 | { |
59 | if (pstack->top == pstack->max_nr_entries) { |
60 | pr_err("%s: top=%d, overflow!\n" , __func__, pstack->top); |
61 | return; |
62 | } |
63 | pstack->entries[pstack->top++] = key; |
64 | } |
65 | |
66 | void *pstack__pop(struct pstack *pstack) |
67 | { |
68 | void *ret; |
69 | |
70 | if (pstack->top == 0) { |
71 | pr_err("%s: underflow!\n" , __func__); |
72 | return NULL; |
73 | } |
74 | |
75 | ret = pstack->entries[--pstack->top]; |
76 | pstack->entries[pstack->top] = NULL; |
77 | return ret; |
78 | } |
79 | |
80 | void *pstack__peek(struct pstack *pstack) |
81 | { |
82 | if (pstack->top == 0) |
83 | return NULL; |
84 | return pstack->entries[pstack->top - 1]; |
85 | } |
86 | |