linux/tools/perf/util/pstack.c
Namhyung Kim c8539e3fc6 perf tools: Introduce pstack_peek()
The pstack_peek() is to get the topmost entry without removing it.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1429838133-14001-1-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2015-05-05 18:13:22 -03:00

84 lines
1.6 KiB
C

/*
* Simple pointer stack
*
* (c) 2010 Arnaldo Carvalho de Melo <acme@redhat.com>
*/
#include "util.h"
#include "pstack.h"
#include "debug.h"
#include <linux/kernel.h>
#include <stdlib.h>
struct pstack {
unsigned short top;
unsigned short max_nr_entries;
void *entries[0];
};
struct pstack *pstack__new(unsigned short max_nr_entries)
{
struct pstack *pstack = zalloc((sizeof(*pstack) +
max_nr_entries * sizeof(void *)));
if (pstack != NULL)
pstack->max_nr_entries = max_nr_entries;
return pstack;
}
void pstack__delete(struct pstack *pstack)
{
free(pstack);
}
bool pstack__empty(const struct pstack *pstack)
{
return pstack->top == 0;
}
void pstack__remove(struct pstack *pstack, void *key)
{
unsigned short i = pstack->top, last_index = pstack->top - 1;
while (i-- != 0) {
if (pstack->entries[i] == key) {
if (i < last_index)
memmove(pstack->entries + i,
pstack->entries + i + 1,
(last_index - i) * sizeof(void *));
--pstack->top;
return;
}
}
pr_err("%s: %p not on the pstack!\n", __func__, key);
}
void pstack__push(struct pstack *pstack, void *key)
{
if (pstack->top == pstack->max_nr_entries) {
pr_err("%s: top=%d, overflow!\n", __func__, pstack->top);
return;
}
pstack->entries[pstack->top++] = key;
}
void *pstack__pop(struct pstack *pstack)
{
void *ret;
if (pstack->top == 0) {
pr_err("%s: underflow!\n", __func__);
return NULL;
}
ret = pstack->entries[--pstack->top];
pstack->entries[pstack->top] = NULL;
return ret;
}
void *pstack__peek(struct pstack *pstack)
{
if (pstack->top == 0)
return NULL;
return pstack->entries[pstack->top - 1];
}