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Use signbit() in IS_NEGATIVE and DIFFERENT_SIGNS

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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: https://bugs.freedesktop.org/show_bug.cgi?id=54805
Reviewed-by: Paul Berry <stereotype441@gmail.com>
Suggested-by: Ian Romanick <ian.d.romanick@intel.com>
This commit is contained in:
Matt Turner 2012-09-14 16:04:40 -07:00
parent 959fe586fb
commit 0f3ba405ea
2 changed files with 9 additions and 19 deletions
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7
configure.ac
View file

@ -499,6 +499,13 @@ AC_SUBST([DLOPEN_LIBS])
dnl See if posix_memalign is available dnl See if posix_memalign is available
AC_CHECK_FUNC([posix_memalign], [DEFINES="$DEFINES -DHAVE_POSIX_MEMALIGN"]) AC_CHECK_FUNC([posix_memalign], [DEFINES="$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. dnl SELinux awareness.
AC_ARG_ENABLE([selinux], AC_ARG_ENABLE([selinux],
[AS_HELP_STRING([--enable-selinux], [AS_HELP_STRING([--enable-selinux],

21
src/mesa/main/macros.h
View file

@ -693,31 +693,14 @@ NORMALIZE_3FV(GLfloat v[3])
static inline GLboolean static inline GLboolean
IS_NEGATIVE(float x) IS_NEGATIVE(float x)
{ {
#if defined(USE_IEEE) return signbit(x) != 0;
fi_type fi;
fi.f = x;
return fi.i < 0;
#else
return x < 0.0F;
#endif
} }
/** Test two floats have opposite signs */ /** Test two floats have opposite signs */
static inline GLboolean static inline GLboolean
DIFFERENT_SIGNS(GLfloat x, GLfloat y) DIFFERENT_SIGNS(GLfloat x, GLfloat y)
{ {
#if defined(USE_IEEE) return signbit(x) != signbit(y);
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
} }