Concurrency::precise_math::signbit(), and only as of VS 2012 runtimes. This is an awfully high bar for such a simple function.<div> </div><div> <div class="gmail_quote">On Mon, Sep 24, 2012 at 1:43 PM, Matt Turner <<a href="mailto:mattst88@gmail.com" target="_blank">mattst88@gmail.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">On Mon, Sep 24, 2012 at 11:02 AM, Brian Paul <<a href="mailto:brianp@vmware.com">brianp@vmware.com</a>> wrote: > On 09/24/2012 10:49 AM, Matt Turner wrote: >> >> Module: Mesa >> Branch: master >> Commit: 0f3ba405eada72e1ab4371948315b28608903927 >> URL: >> <a href="http://cgit.freedesktop.org/mesa/mesa/commit/?id=0f3ba405eada72e1ab4371948315b28608903927" target="_blank">http://cgit.freedesktop.org/mesa/mesa/commit/?id=0f3ba405eada72e1ab4371948315b28608903927</a> >> >> Author: Matt Turner<<a href="mailto:mattst88@gmail.com">mattst88@gmail.com</a>> >> Date: Fri Sep 14 16:04:40 2012 -0700 >> >> Use signbit() in IS_NEGATIVE and DIFFERENT_SIGNS >> >> signbit() appears to be available everywhere (even MSVC according to >> MSDN), so let's use it instead of open-coding some messy and confusing >> bit twiddling macros. >> >> Bugzilla: <a href="https://bugs.freedesktop.org/show_bug.cgi?id=54805" target="_blank">https://bugs.freedesktop.org/show_bug.cgi?id=54805</a> >> Reviewed-by: Paul Berry<<a href="mailto:stereotype441@gmail.com">stereotype441@gmail.com</a>> >> Suggested-by: Ian Romanick<<a href="mailto:ian.d.romanick@intel.com">ian.d.romanick@intel.com</a>> >> >> --- >> >> <a href="http://configure.ac" target="_blank">configure.ac</a> | 7 +++++++ >> src/mesa/main/macros.h | 21 ++------------------- >> 2 files changed, 9 insertions(+), 19 deletions(-) >> >> diff --git a/<a href="http://configure.ac" target="_blank">configure.ac</a> b/<a href="http://configure.ac" target="_blank">configure.ac</a> >> index 4193496..cb65467 100644 >> --- a/<a href="http://configure.ac" target="_blank">configure.ac</a> >> +++ b/<a href="http://configure.ac" target="_blank">configure.ac</a> >> @@ -499,6 +499,13 @@ AC_SUBST([DLOPEN_LIBS]) >> dnl See if posix_memalign is available >> AC_CHECK_FUNC([posix_memalign], [DEFINES="$DEFINES >> -DHAVE_POSIX_MEMALIGN"]) >> >> +dnl signbit() is a macro in glibc's math.h, so AC_CHECK_FUNC fails. To >> handle >> +dnl this, use AC_CHECK_DECLS and fallback to AC_CHECK_FUNC in case it >> fails. >> +AC_CHECK_DECLS([signbit],[], >> + AC_CHECK_FUNC([signbit],[], >> + AC_MSG_ERROR([could not find signbit()])), >> + [#include<math.h>]) >> + >> dnl SELinux awareness. >> AC_ARG_ENABLE([selinux], >> [AS_HELP_STRING([--enable-selinux], >> diff --git a/src/mesa/main/macros.h b/src/mesa/main/macros.h >> index 04d59d7..7b7fd1b 100644 >> --- a/src/mesa/main/macros.h >> +++ b/src/mesa/main/macros.h >> @@ -693,31 +693,14 @@ NORMALIZE_3FV(GLfloat v[3]) >> static inline GLboolean >> IS_NEGATIVE(float x) >> { >> -#if defined(USE_IEEE) >> - fi_type fi; >> - fi.f = x; >> - return fi.i< 0; >> -#else >> - return x< 0.0F; >> -#endif >> + return signbit(x) != 0; >> } >> >> - >> /** Test two floats have opposite signs */ >> static inline GLboolean >> DIFFERENT_SIGNS(GLfloat x, GLfloat y) >> { >> -#if defined(USE_IEEE) >> - fi_type xfi, yfi; >> - xfi.f = x; >> - yfi.f = y; >> - return !!((xfi.i ^ yfi.i)& (1u<< 31)); >> -#else >> - /* Could just use (x*y<0) except for the flatshading requirements. >> - * Maybe there's a better way? >> - */ >> - return ((x) * (y)<= 0.0F&& (x) - (y) != 0.0F); >> -#endif >> + return signbit(x) != signbit(y); >> } >> >> > > Looks like we don't have signbit() on Windows. We build with scons there so > the autoconf check isn't applicable. I'll post a patch in a bit. > > -Brian MSDN claims that Windows does have signbit(): <a href="http://msdn.microsoft.com/en-us/library/hh308342.aspx" target="_blank">http://msdn.microsoft.com/en-us/library/hh308342.aspx</a> _______________________________________________ mesa-dev mailing list <a href="mailto:mesa-dev@lists.freedesktop.org">mesa-dev@lists.freedesktop.org</a> <a href="http://lists.freedesktop.org/mailman/listinfo/mesa-dev" target="_blank">http://lists.freedesktop.org/mailman/listinfo/mesa-dev</a> </blockquote></div> </div>