Merge release-5-0 into master

[alexxy/gromacs.git] / src / gromacs / utility / real.h

diff --git a/src/gromacs/utility/real.h b/src/gromacs/utility/real.h
index a8fb5a52deec970017af31f1f15437b9bc0fccb8..e8a3ae18e7702dc765c24ddc2564438e8a875b67 100644 (file)
--- a/src/gromacs/utility/real.h
+++ b/src/gromacs/utility/real.h
@@ -62,6 +62,24 @@
 /*! \brief Minimum single precision value */
 #define GMX_FLOAT_MIN    1.175494351E-38F
 
+#ifdef __PGI
+/* The portland group x86 C/C++ compilers do not treat negative zero initializers
+ * correctly, but "optimizes" them to positive zero, so we implement it explicitly.
+ * These constructs are optimized to simple loads at compile time. If you want to
+ * use them on other compilers those have to support gcc preprocessor extensions.
+ * Note: These initializers might be sensitive to the endianness (which can
+ * be different for byte and word order), so check that it works for your platform
+ * and add a separate section if necessary before adding to the ifdef above.
+ */
+#    define GMX_DOUBLE_NEGZERO  ({ const union { int  di[2]; double d; } _gmx_dzero = {0, -2147483648}; _gmx_dzero.d; })
+#    define GMX_FLOAT_NEGZERO   ({ const union { int  fi; float f; } _gmx_fzero = {-2147483648}; _gmx_fzero.f; })
+#else
+/*! \brief Negative zero in double */
+#    define GMX_DOUBLE_NEGZERO  (-0.0)
+
+/*! \brief Negative zero in float */
+#    define GMX_FLOAT_NEGZERO   (-0.0f)
+#endif
 
 /*! \typedef real
  * \brief Precision-dependent \Gromacs floating-point type.
@@ -81,6 +99,9 @@
 /*! \def GMX_REAL_MAX
  * \brief Largest finite value for `real`.
  */
+/*! \def GMX_REAL_NEGZERO
+ * \brief Negative zero for `real`.
+ */
 /*! \def gmx_real_fullprecision_pfmt
  * \brief Format string for full `real` precision.
  */
@@ -91,10 +112,11 @@ typedef double      real;
 #define HAVE_REAL
 #endif
 
-#define GMX_MPI_REAL    MPI_DOUBLE
-#define GMX_REAL_EPS    GMX_DOUBLE_EPS
-#define GMX_REAL_MIN    GMX_DOUBLE_MIN
-#define GMX_REAL_MAX    GMX_DOUBLE_MAX
+#define GMX_MPI_REAL      MPI_DOUBLE
+#define GMX_REAL_EPS      GMX_DOUBLE_EPS
+#define GMX_REAL_MIN      GMX_DOUBLE_MIN
+#define GMX_REAL_MAX      GMX_DOUBLE_MAX
+#define GMX_REAL_NEGZERO  GMX_DOUBLE_NEGZERO
 #define gmx_real_fullprecision_pfmt "%21.14e"
 
 #else /* GMX_DOUBLE */
@@ -104,10 +126,11 @@ typedef float           real;
 #define HAVE_REAL
 #endif
 
-#define GMX_MPI_REAL    MPI_FLOAT
-#define GMX_REAL_EPS    GMX_FLOAT_EPS
-#define GMX_REAL_MIN    GMX_FLOAT_MIN
-#define GMX_REAL_MAX    GMX_FLOAT_MAX
+#define GMX_MPI_REAL      MPI_FLOAT
+#define GMX_REAL_EPS      GMX_FLOAT_EPS
+#define GMX_REAL_MIN      GMX_FLOAT_MIN
+#define GMX_REAL_MAX      GMX_FLOAT_MAX
+#define GMX_REAL_NEGZERO  GMX_FLOAT_NEGZERO
 #define gmx_real_fullprecision_pfmt "%14.7e"
 
 #endif /* GMX_DOUBLE */