Piotr Caban : msvcrt: Import modf implementation from musl.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 9984a5d661ff45b5e273dedaea9f80f0c1479ee6
URL:    https://source.winehq.org/git/wine.git/?a=commit;h=9984a5d661ff45b5e273dedaea9f80f0c1479ee6

Author: Piotr Caban <piotr at codeweavers.com>
Date:   Tue May 18 19:08:37 2021 +0200

msvcrt: Import modf implementation from musl.

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

---

 dlls/msvcrt/math.c    | 32 +++++++++++++++++++++++++++++++-
 dlls/msvcrt/unixlib.c |  9 ---------
 dlls/msvcrt/unixlib.h |  1 -
 3 files changed, 31 insertions(+), 11 deletions(-)

diff --git a/dlls/msvcrt/math.c b/dlls/msvcrt/math.c
index de0db9cca50..a860dfc3d2b 100644
--- a/dlls/msvcrt/math.c
+++ b/dlls/msvcrt/math.c
@@ -2000,10 +2000,40 @@ double CDECL frexp( double x, int *exp )
 
 /*********************************************************************
  *		modf (MSVCRT.@)
+ *
+ * Copied from musl: src/math/modf.c
  */
 double CDECL modf( double x, double *iptr )
 {
-  return unix_funcs->modf( x, iptr );
+    union {double f; UINT64 i;} u = {x};
+    UINT64 mask;
+    int e = (u.i >> 52 & 0x7ff) - 0x3ff;
+
+    /* no fractional part */
+    if (e >= 52) {
+        *iptr = x;
+        if (e == 0x400 && u.i << 12 != 0) /* nan */
+            return x;
+        u.i &= 1ULL << 63;
+        return u.f;
+    }
+
+    /* no integral part*/
+    if (e < 0) {
+        u.i &= 1ULL << 63;
+        *iptr = u.f;
+        return x;
+    }
+
+    mask = -1ULL >> 12 >> e;
+    if ((u.i & mask) == 0) {
+        *iptr = x;
+        u.i &= 1ULL << 63;
+        return u.f;
+    }
+    u.i &= ~mask;
+    *iptr = u.f;
+    return x - u.f;
 }
 
 /**********************************************************************
diff --git a/dlls/msvcrt/unixlib.c b/dlls/msvcrt/unixlib.c
index a2bae9c6e5e..2a3d8ed4090 100644
--- a/dlls/msvcrt/unixlib.c
+++ b/dlls/msvcrt/unixlib.c
@@ -459,14 +459,6 @@ static float CDECL unix_logbf( float x )
     return logbf( x );
 }
 
-/*********************************************************************
- *      modf
- */
-static double CDECL unix_modf( double x, double *iptr )
-{
-    return modf( x, iptr );
-}
-
 /*********************************************************************
  *      modff
  */
@@ -674,7 +666,6 @@ static const struct unix_funcs funcs =
     unix_log2f,
     unix_logb,
     unix_logbf,
-    unix_modf,
     unix_modff,
     unix_pow,
     unix_powf,
diff --git a/dlls/msvcrt/unixlib.h b/dlls/msvcrt/unixlib.h
index edb9e99d3e4..080c9da9d08 100644
--- a/dlls/msvcrt/unixlib.h
+++ b/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);
-    double          (CDECL *modf)(double x, double *iptr);
     float           (CDECL *modff)(float x, float *iptr);
     double          (CDECL *pow)(double x, double y);
     float           (CDECL *powf)(float x, float y);