| 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 | |
| 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 | |
| 28 | void pstack__delete(struct pstack *pstack) |
| 29 | { |
| 30 | free(pstack); |
| 31 | } |
| 32 | |
| 33 | bool pstack__empty(const struct pstack *pstack) |
| 34 | { |
| 35 | return pstack->top == 0; |
| 36 | } |
| 37 | |
| 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 | |
| 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 | |
| 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 | |
| 78 | void *pstack__peek(struct pstack *pstack) |
| 79 | { |
| 80 | if (pstack->top == 0) |
| 81 | return NULL; |
| 82 | return pstack->entries[pstack->top - 1]; |
| 83 | } |