tools/perf/util/pstack.c

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