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 } 84