This is an automated email from the git hooks/post-receive script.
ppm-guest pushed a commit to annotated tag v0.36
in repository libmath-prime-util-perl.
commit c54a1285b7b8b166e162ad879e2c8beaae4f8ba2
Author: Dana Jacobsen <d...@acm.org>
Date: Thu Jan 9 14:59:00 2014 -0800
More clz,ctz,log2floor changes
---
util.h | 53 ++++++++++++++++++++++++++++++++++-------------------
1 file changed, 34 insertions(+), 19 deletions(-)
diff --git a/util.h b/util.h
index 1c65466..59c1da3 100644
--- a/util.h
+++ b/util.h
@@ -119,28 +119,40 @@ static int is_perfect_square(UV n)
}
#endif
-/* clz gives floor(log2(n)). ctz gives number of times divisible by 2 */
-#if defined(FUNC_clz) || defined(FUNC_ctz)
+#if defined(FUNC_clz) || defined(FUNC_ctz) || defined(FUNC_log2floor)
+/* log2floor(n) gives the location of the first set bit (starting from left)
+ * ctz(n) gives the number of times n is divisible by 2
+ * clz(n) gives the number of zeros on the left */
#ifdef __GNUC__
#if BITS_PER_WORD == 64
- #define ctz(n) ((n)?__builtin_ctzll(n):64)
- #define clz(n) ((n)?__builtin_clzll(n):64)
+ #define ctz(n) ((n) ? __builtin_ctzll(n) : 64)
+ #define clz(n) ((n) ? __builtin_clzll(n) : 64)
+ #define log2floor(n) ((n) ? 63-__builtin_clzll(n) : 0)
#else
- #define ctz(n) ((n)?__builtin_ctzl(n):32)
- #define clz(n) ((n)?__builtin_clzl(n):32)
+ #define ctz(n) ((n) ? __builtin_ctzl(n) : 32)
+ #define clz(n) ((n) ? __builtin_clzl(n) : 32)
+ #define log2floor(n) ((n) ? 31-__builtin_clzl(n) : 0)
#endif
#elif defined (_MSC_VER)
#include <intrin.h>
#ifdef FUNC_ctz
static int ctz(UV n) {
UV tz = 0;
- if (_BitScanForward(&tz, n)) return tz; else return BITS_PER_WORD;
+ #ifdef BITS_PER_WORD == 64
+ if (_BitScanForward64(&tz, n)) return tz; else return 64;
+ #else
+ if (_BitScanForward(&tz, n)) return tz; else return 32;
+ #endif
}
#endif
- #ifdef FUNC_clz
- static int clz(UV n) {
+ #if defined(FUNC_clz) || defined(FUNC_log2floor)
+ static int log2floor(UV n) {
UV lz = 0;
- if (_BitScanReverse(&lz, n)) return BITS_PER_WORD-1-lz; else return
BITS_PER_WORD;
+ #ifdef BITS_PER_WORD == 64
+ if (_BitScanReverse64(&lz, n)) return lz; else return 0;
+ #else
+ if (_BitScanReverse(&lz, n)) return lz; else return 0;
+ #endif
}
#endif
#elif BITS_PER_WORD == 64
@@ -153,12 +165,12 @@ static int is_perfect_square(UV n)
return n ? _debruijn64[((n & -n)*UVCONST(0x07EDD5E59A4E28C2)) >> 58] : 64;
}
#endif
- #ifdef FUNC_clz
- static unsigned int clz(UV n) {
- if (n == 0) return 64;
+ #if defined(FUNC_clz) || defined(FUNC_log2floor)
+ static unsigned int log2floor(UV n) {
+ if (n == 0) return 0;
n |= n >> 1; n |= n >> 2; n |= n >> 4;
n |= n >> 8; n |= n >> 16; n |= n >> 32;
- return 63 - _debruijn64[((n-(n>>1))*UVCONST(0x07EDD5E59A4E28C2)) >> 58];
+ return _debruijn64[((n-(n>>1))*UVCONST(0x07EDD5E59A4E28C2)) >> 58];
}
#endif
#else
@@ -170,17 +182,20 @@ static int is_perfect_square(UV n)
return n ? _trail_debruijn32[((n & -n) * UVCONST(0x077CB531)) >> 27] : 32;
}
#endif
- #ifdef FUNC_clz
+ #if defined(FUNC_clz) || defined(FUNC_log2floor)
static const unsigned char _lead_debruijn32[32] = {
0, 9, 1, 10, 13, 21, 2, 29, 11, 14, 16, 18, 22, 25, 3, 30,
8, 12, 20, 28, 15, 17, 24, 7, 19, 27, 23, 6, 26, 5, 4, 31 };
- static unsigned int clz(UV n) {
- if (n == 0) return 32;
+ static unsigned int log2floor(UV n) {
+ if (n == 0) return 0;
n |= n >> 1; n |= n >> 2; n |= n >> 4; n |= n >> 8; n |= n >> 16;
- return 31 - _lead_debruijn32[(n * UVCONST(0x07C4ACDD)) >> 27];
+ return _lead_debruijn32[(n * UVCONST(0x07C4ACDD)) >> 27];
}
#endif
#endif
-#endif /* End of clz and ctz */
+#if defined(FUNC_clz) && !defined(clz)
+ #define clz(n) ( (n) ? BITS_PER_WORD-1-log2floor(n) : BITS_PER_WORD )
+#endif
+#endif /* End of log2floor, clz, and ctz */
#endif
--
Alioth's /usr/local/bin/git-commit-notice on
/srv/git.debian.org/git/pkg-perl/packages/libmath-prime-util-perl.git
_______________________________________________
Pkg-perl-cvs-commits mailing list
Pkg-perl-cvs-commits@lists.alioth.debian.org
http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/pkg-perl-cvs-commits
