msvcrt: Import modff implementation from musl.

Signed-off-by: Piotr Caban <piotr@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>

dlls/msvcrt/math.c

@@ -922,10 +922,40 @@ float CDECL frexpf( float x, int *exp )
 
 /*********************************************************************
  *      modff (MSVCRT.@)
+ *
+ * Copied from musl: src/math/modff.c
  */
 float CDECL modff( float x, float *iptr )
 {
-  return unix_funcs->modff( x, iptr );
+    union {float f; UINT32 i;} u = {x};
+    UINT32 mask;
+    int e = (u.i >> 23 & 0xff) - 0x7f;
+
+    /* no fractional part */
+    if (e >= 23) {
+        *iptr = x;
+        if (e == 0x80 && u.i << 9 != 0) { /* nan */
+            return x;
+        }
+        u.i &= 0x80000000;
+        return u.f;
+    }
+    /* no integral part */
+    if (e < 0) {
+        u.i &= 0x80000000;
+        *iptr = u.f;
+        return x;
+    }
+
+    mask = 0x007fffff >> e;
+    if ((u.i & mask) == 0) {
+        *iptr = x;
+        u.i &= 0x80000000;
+        return u.f;
+    }
+    u.i &= ~mask;
+    *iptr = u.f;
+    return x - u.f;
 }
 
 #endif

dlls/msvcrt/unixlib.c

@@ -459,14 +459,6 @@ static float CDECL unix_logbf( float x )
     return logbf( x );
 }
 
-/*********************************************************************
- *      modff
- */
-static float CDECL unix_modff( float x, float *iptr )
-{
-    return modff( x, iptr );
-}
-
 /*********************************************************************
  *      pow
  */
@@ -666,7 +658,6 @@ static const struct unix_funcs funcs =
     unix_log2f,
     unix_logb,
     unix_logbf,
-    unix_modff,
     unix_pow,
     unix_powf,
     unix_remainder,

dlls/msvcrt/unixlib.h

@@ -62,7 +62,6 @@ struct unix_funcs
     float           (CDECL *log2f)(float x);
     double          (CDECL *logb)(double x);
     float           (CDECL *logbf)(float x);
-    float           (CDECL *modff)(float x, float *iptr);
     double          (CDECL *pow)(double x, double y);
     float           (CDECL *powf)(float x, float y);
     double          (CDECL *remainder)(double x, double y);