From: Piotr Caban <piotr@codeweavers.com>
Subject: [PATCH] msvcrt: Fix logf implementation.
Message-Id: <7f07b6a8-0c92-5c3d-4099-824690fc3f3f@codeweavers.com>
Date: Mon, 7 Jun 2021 12:58:26 +0200

Wine-bug: https://bugs.winehq.org/show_bug.cgi?id=51222
Signed-off-by: Piotr Caban <piotr@codeweavers.com>
---
  dlls/msvcrt/math.c | 6 +++---
  1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/dlls/msvcrt/math.c b/dlls/msvcrt/math.c
index 0c958f538aa..a054f561a63 100644
--- a/dlls/msvcrt/math.c
+++ b/dlls/msvcrt/math.c
@@ -1254,7 +1254,7 @@ float CDECL logf( float x )
     if (ix - 0x00800000 >= 0x7f800000 - 0x00800000) {
         /* x < 0x1p-126 or inf or nan. */
         if (ix * 2 == 0)
-            return math_error(_SING, "logf", x, 0, -1.0 / x);
+            return math_error(_SING, "logf", x, 0, (ix & 0x80000000 ? 1.0 : -1.0) / x);
         if (ix == 0x7f800000) /* log(inf) == inf. */
             return x;
         if (ix * 2 > 0xff000000)
@@ -1273,7 +1273,7 @@ float CDECL logf( float x )
     tmp = ix - 0x3f330000;
     i = (tmp >> (23 - 4)) % (1 << 4);
     k = (INT32)tmp >> 23; /* arithmetic shift */
-    iz = ix - (tmp & 0xff << 23);
+    iz = ix - (tmp & (0x1ffu << 23));
     invc = T[i].invc;
     logc = T[i].logc;
     z = *(float*)&iz;
@@ -2966,7 +2966,7 @@ double CDECL log( double x )
     if (top - 0x0010 >= 0x7ff0 - 0x0010) {
         /* x < 0x1p-1022 or inf or nan. */
         if (ix * 2 == 0)
-            return math_error(_SING, "log", x, 0, -1.0 / x);
+            return math_error(_SING, "log", x, 0, (top & 0x8000 ? 1.0 : -1.0) / x);
         if (ix == 0x7ff0000000000000ULL) /* log(inf) == inf. */
             return x;
         if ((top & 0x7ff0) == 0x7ff0 && (ix & 0xfffffffffffffULL))