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libsepol: optimize ebitmap_not

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Iterate on nodes instead of single bits to save node resolution for each
single bit.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Acked-by: James Carter <jwcart2@gmail.com>
This commit is contained in:
Christian Göttsche 2022-07-19 17:30:41 +02:00 committed by James Carter
parent bc8f7b502b
commit 12a8a00bf2
1 changed files with 42 additions and 6 deletions
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48
libsepol/src/ebitmap.c
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@ -101,14 +101,50 @@ int ebitmap_xor(ebitmap_t *dst, const ebitmap_t *e1, const ebitmap_t *e2)
int ebitmap_not(ebitmap_t *dst, const ebitmap_t *e1, unsigned int maxbit)
{
unsigned int i;
const ebitmap_node_t *n;
ebitmap_node_t *new, *prev = NULL;
uint32_t startbit, cur_startbit;
MAPTYPE map;
ebitmap_init(dst);
for (i=0; i < maxbit; i++) {
int val = ebitmap_get_bit(e1, i);
int rc = ebitmap_set_bit(dst, i, !val);
if (rc < 0)
return rc;
n = e1->node;
for (cur_startbit = 0; cur_startbit < maxbit; cur_startbit += MAPSIZE) {
if (n && n->startbit == cur_startbit) {
startbit = n->startbit;
map = ~n->map;
n = n->next;
} else {
startbit = cur_startbit;
map = ~((MAPTYPE) 0);
}
if (maxbit - cur_startbit < MAPSIZE)
map &= (((MAPTYPE)1) << (maxbit - cur_startbit)) - 1;
if (map != 0) {
new = malloc(sizeof(ebitmap_node_t));
if (!new) {
ebitmap_destroy(dst);
return -ENOMEM;
}
new->startbit = startbit;
new->map = map;
new->next = NULL;
if (prev)
prev->next = new;
else
dst->node = new;
prev = new;
}
}
if (prev)
dst->highbit = prev->startbit + MAPSIZE;
return 0;
}