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| author | Werner Koch <wk@gnupg.org> | 2015-01-15 10:04:43 +0100 |
|---|---|---|
| committer | Werner Koch <wk@gnupg.org> | 2015-01-15 10:37:53 +0100 |
| commit | 9d2a22c94ae99f9301321082c4fb8d73f4085fda (patch) | |
| tree | bd06e3f0b580cf0676e4eca798620414f61e1240 /configure.ac | |
| parent | 27a91a93d101ef080f71e5d7e50c3cbf3dbb2e39 (diff) | |
| download | libgcrypt-9d2a22c94ae99f9301321082c4fb8d73f4085fda.tar.gz | |
Add functions to count trailing zero bits in a word.
* cipher/bithelp.h (_gcry_ctz, _gcry_ctz64): New.
* configure.ac (HAVE_BUILTIN_CTZ): Add new test.
--
Note that these functions return the number of bits in the word when
passing 0.
Signed-off-by: Werner Koch <wk@gnupg.org>
Diffstat (limited to 'configure.ac')
| -rw-r--r-- | configure.ac | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/configure.ac b/configure.ac index 4cfebe7b..4bbd686c 100644 --- a/configure.ac +++ b/configure.ac @@ -827,6 +827,21 @@ fi # +# Check for __builtin_ctz intrinsic. +# +AC_CACHE_CHECK(for __builtin_ctz, + [gcry_cv_have_builtin_ctz], + [gcry_cv_have_builtin_ctz=no + AC_LINK_IFELSE([AC_LANG_PROGRAM([], + [unsigned int x = 0; int y = __builtin_ctz(x); return y;])], + [gcry_cv_have_builtin_ctz=yes])]) +if test "$gcry_cv_have_builtin_ctz" = "yes" ; then + AC_DEFINE(HAVE_BUILTIN_CTZ, 1, + [Defined if compiler has '__builtin_ctz' intrinsic]) +fi + + +# # Check for VLA support (variable length arrays). # AC_CACHE_CHECK(whether the variable length arrays are supported, |