From 29e99741d94517b1b17b300a0c7b85a1c0806a00 Mon Sep 17 00:00:00 2001
From: Piotr Caban <piotr@codeweavers.com>
Date: Tue, 18 May 2021 19:08:44 +0200
Subject: [PATCH] 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    | 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 a860dfc3d2b..fab505abfb5 100644
--- a/dlls/msvcrt/math.c
+++ b/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
diff --git a/dlls/msvcrt/unixlib.c b/dlls/msvcrt/unixlib.c
index 2a3d8ed4090..62c6a5ae189 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 );
 }
 
-/*********************************************************************
- *      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,
diff --git a/dlls/msvcrt/unixlib.h b/dlls/msvcrt/unixlib.h
index 080c9da9d08..69f4e02f321 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);
-    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);