Manual merge to 5.1.

2 files changed, 33 insertions, 11 deletions

diff --git a/include/config-win.h b/include/config-win.h
index ab0926af864..3a21551ebbb 100644
--- a/include/config-win.h
+++ b/include/config-win.h
@@ -33,7 +33,6 @@ functions */
 
 #include <sys/locking.h>
 #include <winsock2.h>
-#include <math.h>			/* Because of rint() */
 #include <fcntl.h>
 #include <io.h>
 #include <malloc.h>
@@ -223,13 +222,6 @@ typedef uint rf_SetTimer;
 #define inline __inline
 #endif /* __cplusplus */
 
-inline double rint(double nr)
-{
-  double f = floor(nr);
-  double c = ceil(nr);
-  return (((c-nr) >= (nr-f)) ? f :c);
-}
-
 #ifdef _WIN64
 #define ulonglong2double(A) ((double) (ulonglong) (A))
 #define my_off_t2double(A)  ((double) (my_off_t) (A))
@@ -284,7 +276,6 @@ inline ulonglong double2ulonglong(double d)
 #define HAVE_FLOAT_H
 #define HAVE_LIMITS_H
 #define HAVE_STDDEF_H
-#define HAVE_RINT		/* defined in this file */
 #define NO_FCNTL_NONBLOCK	/* No FCNTL */
 #define HAVE_ALLOCA
 #define HAVE_STRPBRK
diff --git a/include/my_global.h b/include/my_global.h
index 8c25cbf802e..5250d24d0e1 100644
--- a/include/my_global.h
+++ b/include/my_global.h
@@ -578,8 +578,39 @@ typedef unsigned short ushort;
 #define set_bits(type, bit_count) (sizeof(type)*8 <= (bit_count) ? ~(type) 0 : ((((type) 1) << (bit_count)) - (type) 1))
 #define array_elements(A) ((uint) (sizeof(A)/sizeof(A[0])))
 #ifndef HAVE_RINT
-#define rint(A) floor((A)+(((A) < 0)? -0.5 : 0.5))
-#endif
+/**
+   All integers up to this number can be represented exactly as double precision
+   values (DBL_MANT_DIG == 53 for IEEE 754 hardware).
+*/
+#define MAX_EXACT_INTEGER ((1LL << DBL_MANT_DIG) - 1)
+
+/**
+   rint(3) implementation for platforms that do not have it.
+   Always rounds to the nearest integer with ties being rounded to the nearest
+   even integer to mimic glibc's rint() behavior in the "round-to-nearest"
+   FPU mode. Hardware-specific optimizations are possible (frndint on x86).
+   Unlike this implementation, hardware will also honor the FPU rounding mode.
+*/
+
+static inline double rint(double x)
+{
+  double f, i;
+  f = modf(x, &i);
+  /*
+    All doubles with absolute values > MAX_EXACT_INTEGER are even anyway,
+    no need to check it.
+  */
+  if (x > 0.0)
+    i += (double) ((f > 0.5) || (f == 0.5 &&
+                                 i <= (double) MAX_EXACT_INTEGER &&
+                                 (longlong) i % 2));
+  else
+    i -= (double) ((f < -0.5) || (f == -0.5 &&
+                                  i >= (double) -MAX_EXACT_INTEGER &&
+                                  (longlong) i % 2));
+  return i;
+}
+#endif /* HAVE_RINT */
 
 /* Define some general constants */
 #ifndef TRUE