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