Piotr Caban : msvcrt: Import cos implementation from musl.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: ef91a7c02c8431a09edb1c1954cacda8b5f8958c
URL:    https://source.winehq.org/git/wine.git/?a=commit;h=ef91a7c02c8431a09edb1c195...

Author: Piotr Caban <piotr(a)codeweavers.com>
Date:   Thu May 20 23:04:58 2021 +0200

msvcrt: Import cos implementation from musl.

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

---

 dlls/msvcrt/math.c | 35 ++++++++++++++++++++++++++++++++---
 1 file changed, 32 insertions(+), 3 deletions(-)

diff --git a/dlls/msvcrt/math.c b/dlls/msvcrt/math.c
index d89a4c7f5bc..7643f39fde7 100644
--- a/dlls/msvcrt/math.c
+++ b/dlls/msvcrt/math.c
@@ -1802,12 +1802,41 @@ static double __cos(double x, double y)
 
 /*********************************************************************
  *		cos (MSVCRT.@)
+ *
+ * Copied from musl: src/math/cos.c
  */
 double CDECL cos( double x )
 {
-  double ret = unix_funcs->cos( x );
-  if (!isfinite(x)) return math_error(_DOMAIN, "cos", x, 0, ret);
-  return ret;
+    double y[2];
+    UINT32 ix;
+    unsigned n;
+
+    ix = *(ULONGLONG*)&x >> 32;
+    ix &= 0x7fffffff;
+
+    /* |x| ~< pi/4 */
+    if (ix <= 0x3fe921fb) {
+        if (ix < 0x3e46a09e) { /* |x| < 2**-27 * sqrt(2) */
+            /* raise inexact if x!=0 */
+            fp_barrier(x + 0x1p120f);
+            return 1.0;
+        }
+        return __cos(x, 0);
+    }
+
+    /* cos(Inf or NaN) is NaN */
+    if (isinf(x)) return math_error(_DOMAIN, "cos", x, 0, x - x);
+    if (ix >= 0x7ff00000)
+        return x - x;
+
+    /* argument reduction */
+    n = __rem_pio2(x, y);
+    switch (n & 3) {
+    case 0: return __cos(y[0], y[1]);
+    case 1: return -__sin(y[0], y[1], 1);
+    case 2: return -__cos(y[0], y[1]);
+    default: return __sin(y[0], y[1], 1);
+    }
 }
 
 /*********************************************************************