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bitset: add BIT_FFS_AT() for finding the first bit set greater than a start bit 

Reviewed by:	kib
Approved by:	scottl (implicit)
MFC after:	1 week
Sponsored by:	Ampere Computing, Inc.
Differential Revision:	https://reviews.freebsd.org/D26128
This commit is contained in:
D Scott Phillips 2020-08-26 02:07:46 +00:00 committed by Sebastian Huber
parent 5e7a2b174a
commit 4c5b7bec97
1 changed files with 15 additions and 4 deletions
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19
newlib/libc/sys/rtems/include/sys/bitset.h
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@ -210,21 +210,32 @@
(f)->__bits[__i]); \ (f)->__bits[__i]); \
} while (0) } while (0)
#define BIT_FFS(_s, p) __extension__ ({ \ /*
* Note that `start` and the returned value from BIT_FFS_AT are
* 1-based bit indices.
*/
#define BIT_FFS_AT(_s, p, start) __extension__ ({ \
__size_t __i; \ __size_t __i; \
long __mask; \
int __bit; \ int __bit; \
\ \
__mask = ~0UL << ((start) % _BITSET_BITS); \
__bit = 0; \ __bit = 0; \
for (__i = 0; __i < __bitset_words((_s)); __i++) { \ for (__i = __bitset_word((_s), (start)); \
if ((p)->__bits[__i] != 0) { \ __i < __bitset_words((_s)); \
__bit = ffsl((p)->__bits[__i]); \ __i++) { \
if (((p)->__bits[__i] & __mask) != 0) { \
__bit = ffsl((p)->__bits[__i] & __mask); \
__bit += __i * _BITSET_BITS; \ __bit += __i * _BITSET_BITS; \
break; \ break; \
} \ } \
__mask = ~0UL; \
} \ } \
__bit; \ __bit; \
}) })
#define BIT_FFS(_s, p) BIT_FFS_AT((_s), (p), 0)
#define BIT_FLS(_s, p) __extension__ ({ \ #define BIT_FLS(_s, p) __extension__ ({ \
__size_t __i; \ __size_t __i; \
int __bit; \ int __bit; \