1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * Simple pointer stack
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * (c) 2010 Arnaldo Carvalho de Melo <acme@redhat.com>
6*4882a593Smuzhiyun */
7*4882a593Smuzhiyun
8*4882a593Smuzhiyun #include "pstack.h"
9*4882a593Smuzhiyun #include "debug.h"
10*4882a593Smuzhiyun #include <linux/kernel.h>
11*4882a593Smuzhiyun #include <linux/zalloc.h>
12*4882a593Smuzhiyun #include <stdlib.h>
13*4882a593Smuzhiyun #include <string.h>
14*4882a593Smuzhiyun
15*4882a593Smuzhiyun struct pstack {
16*4882a593Smuzhiyun unsigned short top;
17*4882a593Smuzhiyun unsigned short max_nr_entries;
18*4882a593Smuzhiyun void *entries[];
19*4882a593Smuzhiyun };
20*4882a593Smuzhiyun
pstack__new(unsigned short max_nr_entries)21*4882a593Smuzhiyun struct pstack *pstack__new(unsigned short max_nr_entries)
22*4882a593Smuzhiyun {
23*4882a593Smuzhiyun struct pstack *pstack = zalloc((sizeof(*pstack) +
24*4882a593Smuzhiyun max_nr_entries * sizeof(void *)));
25*4882a593Smuzhiyun if (pstack != NULL)
26*4882a593Smuzhiyun pstack->max_nr_entries = max_nr_entries;
27*4882a593Smuzhiyun return pstack;
28*4882a593Smuzhiyun }
29*4882a593Smuzhiyun
pstack__delete(struct pstack * pstack)30*4882a593Smuzhiyun void pstack__delete(struct pstack *pstack)
31*4882a593Smuzhiyun {
32*4882a593Smuzhiyun free(pstack);
33*4882a593Smuzhiyun }
34*4882a593Smuzhiyun
pstack__empty(const struct pstack * pstack)35*4882a593Smuzhiyun bool pstack__empty(const struct pstack *pstack)
36*4882a593Smuzhiyun {
37*4882a593Smuzhiyun return pstack->top == 0;
38*4882a593Smuzhiyun }
39*4882a593Smuzhiyun
pstack__remove(struct pstack * pstack,void * key)40*4882a593Smuzhiyun void pstack__remove(struct pstack *pstack, void *key)
41*4882a593Smuzhiyun {
42*4882a593Smuzhiyun unsigned short i = pstack->top, last_index = pstack->top - 1;
43*4882a593Smuzhiyun
44*4882a593Smuzhiyun while (i-- != 0) {
45*4882a593Smuzhiyun if (pstack->entries[i] == key) {
46*4882a593Smuzhiyun if (i < last_index)
47*4882a593Smuzhiyun memmove(pstack->entries + i,
48*4882a593Smuzhiyun pstack->entries + i + 1,
49*4882a593Smuzhiyun (last_index - i) * sizeof(void *));
50*4882a593Smuzhiyun --pstack->top;
51*4882a593Smuzhiyun return;
52*4882a593Smuzhiyun }
53*4882a593Smuzhiyun }
54*4882a593Smuzhiyun pr_err("%s: %p not on the pstack!\n", __func__, key);
55*4882a593Smuzhiyun }
56*4882a593Smuzhiyun
pstack__push(struct pstack * pstack,void * key)57*4882a593Smuzhiyun void pstack__push(struct pstack *pstack, void *key)
58*4882a593Smuzhiyun {
59*4882a593Smuzhiyun if (pstack->top == pstack->max_nr_entries) {
60*4882a593Smuzhiyun pr_err("%s: top=%d, overflow!\n", __func__, pstack->top);
61*4882a593Smuzhiyun return;
62*4882a593Smuzhiyun }
63*4882a593Smuzhiyun pstack->entries[pstack->top++] = key;
64*4882a593Smuzhiyun }
65*4882a593Smuzhiyun
pstack__pop(struct pstack * pstack)66*4882a593Smuzhiyun void *pstack__pop(struct pstack *pstack)
67*4882a593Smuzhiyun {
68*4882a593Smuzhiyun void *ret;
69*4882a593Smuzhiyun
70*4882a593Smuzhiyun if (pstack->top == 0) {
71*4882a593Smuzhiyun pr_err("%s: underflow!\n", __func__);
72*4882a593Smuzhiyun return NULL;
73*4882a593Smuzhiyun }
74*4882a593Smuzhiyun
75*4882a593Smuzhiyun ret = pstack->entries[--pstack->top];
76*4882a593Smuzhiyun pstack->entries[pstack->top] = NULL;
77*4882a593Smuzhiyun return ret;
78*4882a593Smuzhiyun }
79*4882a593Smuzhiyun
pstack__peek(struct pstack * pstack)80*4882a593Smuzhiyun void *pstack__peek(struct pstack *pstack)
81*4882a593Smuzhiyun {
82*4882a593Smuzhiyun if (pstack->top == 0)
83*4882a593Smuzhiyun return NULL;
84*4882a593Smuzhiyun return pstack->entries[pstack->top - 1];
85*4882a593Smuzhiyun }
86