msvcrt: Import trunc implementation from musl.

configure

@@ -19643,8 +19643,7 @@ for ac_func in \
 	remquo \
 	remquof \
 	tgamma \
-	tgammaf \
-	trunc
+	tgammaf
 
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`

configure.ac

@@ -2683,8 +2683,7 @@ AC_CHECK_FUNCS(\
 	remquo \
 	remquof \
 	tgamma \
-	tgammaf \
-	trunc
+	tgammaf
 )
 LIBS="$ac_save_LIBS"
 

dlls/msvcrt/math.c

@@ -4981,10 +4981,24 @@ __int64 CDECL llroundf(float x)
 
 /*********************************************************************
  *      trunc (MSVCR120.@)
+ *
+ * Copied from musl: src/math/trunc.c
  */
 double CDECL trunc(double x)
 {
-    return unix_funcs->trunc(x);
+    union {double f; UINT64 i;} u = {x};
+    int e = (u.i >> 52 & 0x7ff) - 0x3ff + 12;
+    UINT64 m;
+
+    if (e >= 52 + 12)
+        return x;
+    if (e < 12)
+        e = 1;
+    m = -1ULL >> e;
+    if ((u.i & m) == 0)
+        return x;
+    u.i &= ~m;
+    return u.f;
 }
 
 /*********************************************************************

dlls/msvcrt/unixlib.c

@@ -637,18 +637,6 @@ static double CDECL unix_tgamma(double x)
 }
 
 /*********************************************************************
- *      trunc
- */
-static double CDECL unix_trunc(double x)
-{
-#ifdef HAVE_TRUNC
-    return trunc(x);
-#else
-    return (x > 0) ? floor(x) : ceil(x);
-#endif
-}
-
-/*********************************************************************
  *      tgammaf
  */
 static float CDECL unix_tgammaf(float x)
@@ -722,7 +710,6 @@ static const struct unix_funcs funcs =
     unix_tanhf,
     unix_tgamma,
     unix_tgammaf,
-    unix_trunc,
 };
 
 NTSTATUS CDECL __wine_init_unix_lib( HMODULE module, DWORD reason, const void *ptr_in, void *ptr_out )

dlls/msvcrt/unixlib.h

@@ -82,7 +82,6 @@ struct unix_funcs
     float           (CDECL *tanhf)(float x);
     double          (CDECL *tgamma)(double x);
     float           (CDECL *tgammaf)(float x);
-    double          (CDECL *trunc)(double x);
 };
 
 #endif /* __UNIXLIB_H */

include/config.h.in

@@ -1010,9 +1010,6 @@
 /* Define to 1 if you have the <tiffio.h> header file. */
 #undef HAVE_TIFFIO_H
 
-/* Define to 1 if you have the `trunc' function. */
-#undef HAVE_TRUNC
-
 /* Define to 1 if you have the `udev' library (-ludev). */
 #undef HAVE_UDEV