msvcrt: Import round implementation from musl.

configure

@@ -19651,7 +19651,6 @@ for ac_func in \
 	remquof \
 	rint \
 	rintf \
-	round \
 	tgamma \
 	tgammaf \
 	trunc \

configure.ac

@@ -2694,7 +2694,6 @@ AC_CHECK_FUNCS(\
 	remquof \
 	rint \
 	rintf \
-	round \
 	tgamma \
 	tgammaf \
 	trunc \

dlls/msvcrt/math.c

@@ -87,6 +87,14 @@ static inline float fp_barrierf(float x)
     return y;
 }
 
+#if _MSVCR_VER>=120
+static inline double fp_barrier(double x)
+{
+    volatile double y = x;
+    return y;
+}
+#endif
+
 static inline double CDECL ret_nan( BOOL update_sw )
 {
     double x = 1.0;
@@ -4321,10 +4329,33 @@ short CDECL _dclass(double x)
 
 /*********************************************************************
  *      round (MSVCR120.@)
+ *
+ * Copied from musl: src/math/round.c
  */
 double CDECL round(double x)
 {
-    return unix_funcs->round(x);
+    static const double toint = 1 / DBL_EPSILON;
+
+    ULONGLONG llx = *(ULONGLONG*)&x;
+    int e = llx >> 52 & 0x7ff;
+    double y;
+
+    if (e >= 0x3ff + 52)
+        return x;
+    if (llx >> 63)
+        x = -x;
+    if (e < 0x3ff - 1)
+        return 0 * *(double*)&llx;
+    y = fp_barrier(x + toint) - toint - x;
+    if (y > 0.5)
+        y = y + x - 1;
+    else if (y <= -0.5)
+        y = y + x + 1;
+    else
+        y = y + x;
+    if (llx >> 63)
+        y = -y;
+    return y;
 }
 
 /*********************************************************************

dlls/msvcrt/unixlib.c

@@ -754,18 +754,6 @@ static float CDECL unix_rintf(float x)
 }
 
 /*********************************************************************
- *      round
- */
-static double CDECL unix_round(double x)
-{
-#ifdef HAVE_ROUND
-    return round(x);
-#else
-    return unix_rint(x);
-#endif
-}
-
-/*********************************************************************
  *      sin
  */
 static double CDECL unix_sin( double x )
@@ -948,7 +936,6 @@ static const struct unix_funcs funcs =
     unix_remquof,
     unix_rint,
     unix_rintf,
-    unix_round,
     unix_sin,
     unix_sinf,
     unix_sinh,

dlls/msvcrt/unixlib.h

@@ -90,7 +90,6 @@ struct unix_funcs
     float           (CDECL *remquof)(float x, float y, int *quo);
     double          (CDECL *rint)(double x);
     float           (CDECL *rintf)(float x);
-    double          (CDECL *round)(double x);
     double          (CDECL *sin)(double x);
     float           (CDECL *sinf)(float x);
     double          (CDECL *sinh)(double x);

include/config.h.in

@@ -690,9 +690,6 @@
 /* Define to 1 if you have the `rintf' function. */
 #undef HAVE_RINTF
 
-/* Define to 1 if you have the `round' function. */
-#undef HAVE_ROUND
-
 /* Define to 1 if you have the <sasl/sasl.h> header file. */
 #undef HAVE_SASL_SASL_H