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* [newlib-cygwin] bitset: add BIT_FFS_AT() for finding the first bit set greater than a start bit
@ 2022-06-24 5:42 Sebastian Huber
0 siblings, 0 replies; only message in thread
From: Sebastian Huber @ 2022-06-24 5:42 UTC (permalink / raw)
To: newlib-cvs
https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=4c5b7bec977b31bf626bcbe3012ee5e7a5956cc8
commit 4c5b7bec977b31bf626bcbe3012ee5e7a5956cc8
Author: D Scott Phillips <scottph@FreeBSD.org>
Date: Wed Aug 26 02:07:46 2020 +0000
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
Diff:
---
newlib/libc/sys/rtems/include/sys/bitset.h | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)
diff --git a/newlib/libc/sys/rtems/include/sys/bitset.h b/newlib/libc/sys/rtems/include/sys/bitset.h
index 9ff18f4f3..2e00dab7b 100644
--- a/newlib/libc/sys/rtems/include/sys/bitset.h
+++ b/newlib/libc/sys/rtems/include/sys/bitset.h
@@ -210,21 +210,32 @@
(f)->__bits[__i]); \
} 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; \
+ long __mask; \
int __bit; \
\
+ __mask = ~0UL << ((start) % _BITSET_BITS); \
__bit = 0; \
- for (__i = 0; __i < __bitset_words((_s)); __i++) { \
- if ((p)->__bits[__i] != 0) { \
- __bit = ffsl((p)->__bits[__i]); \
+ for (__i = __bitset_word((_s), (start)); \
+ __i < __bitset_words((_s)); \
+ __i++) { \
+ if (((p)->__bits[__i] & __mask) != 0) { \
+ __bit = ffsl((p)->__bits[__i] & __mask); \
__bit += __i * _BITSET_BITS; \
break; \
} \
+ __mask = ~0UL; \
} \
__bit; \
})
+#define BIT_FFS(_s, p) BIT_FFS_AT((_s), (p), 0)
+
#define BIT_FLS(_s, p) __extension__ ({ \
__size_t __i; \
int __bit; \
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