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Find order faster in KBuddyPagesAlloc when using GCC.

This commit is contained in:
Flower Black 2024-12-04 11:16:36 +08:00
parent dd780261f3
commit 7802cd067e
1 changed files with 5 additions and 0 deletions
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5
Ubiquitous/XiZi_AIoT/softkernel/memory/buddy.c
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@ -77,8 +77,13 @@ static struct KPage* KBuddyPagesAlloc(struct KBuddy* pbuddy, int nPages)
int i = 0, order = 0;
// find order
#if defined(__GNUC__)
// see: https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html
order = nPages ? (sizeof(int) * 8 - __builtin_clz(nPages) - 1) + !!(__builtin_popcount(nPages) != 1) : 0;
#else
for (order = 0; (FREE_LIST_INDEX(order)) < nPages; order++)
;
#endif
// find the free page list
for (i = order; i < MAX_BUDDY_ORDER; i++) {