Piotr Caban : msvcrt: Fix Pi constants while computing acosf.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 80eec636ee64e7f59d1b701a9b9e3011343a4677
URL:    https://source.winehq.org/git/wine.git/?a=commit;h=80eec636ee64e7f59d1b701a9...

Author: Piotr Caban <piotr(a)codeweavers.com>
Date:   Wed Jan 19 16:20:12 2022 +0100

msvcrt: Fix Pi constants while computing acosf.

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

---

 dlls/msvcrt/math.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/dlls/msvcrt/math.c b/dlls/msvcrt/math.c
index 14afad5fb45..9bb3e26570f 100644
--- a/dlls/msvcrt/math.c
+++ b/dlls/msvcrt/math.c
@@ -798,6 +798,7 @@ static float asinf_R(float z)
 float CDECL acosf( float x )
 {
     static const double pio2_lo = 6.12323399573676603587e-17;
+    static const double pio2_hi = 1.57079632679489655800e+00;
 
     float z, w, s, c, df;
     unsigned int hx, ix;
@@ -818,13 +819,13 @@ float CDECL acosf( float x )
     if (ix < 0x3f000000) {
         if (ix <= 0x32800000) /* |x| < 2**-26 */
             return M_PI_2;
-        return M_PI_2 - (x - (pio2_lo - x * asinf_R(x * x)));
+        return pio2_hi - (x - (pio2_lo - x * asinf_R(x * x)));
     }
     /* x < -0.5 */
     if (hx >> 31) {
         z = (1 + x) * 0.5f;
         s = sqrtf(z);
-        return M_PI - 2 * (s + ((double)s * asinf_R(z)));
+        return 2*(pio2_hi - (s + (asinf_R(z) * s - pio2_lo)));
     }
     /* x > 0.5 */
     z = (1 - x) * 0.5f;