innov
/
xiuos
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Find order faster in KBuddyPagesAlloc when using GCC.

This commit is contained in:
Flower Black 2024-12-04 11:16:36 +08:00 committed by SJTUqizhenlin
parent 157c622d1f
commit 5f47b92255
1 changed files with 5 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
Ubiquitous/XiZi_AIoT/softkernel/memory/buddy.c
View File

@ -77,8 +77,13 @@ static struct KPage* KBuddyPagesAlloc(struct KBuddy* pbuddy, int nPages)
int i = 0, order = 0; int i = 0, order = 0;
// find order // 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++) for (order = 0; (FREE_LIST_INDEX(order)) < nPages; order++)
; ;
#endif
// find the free page list // find the free page list
for (i = order; i < MAX_BUDDY_ORDER; i++) { for (i = order; i < MAX_BUDDY_ORDER; i++) {