msvcrt: Make the tanh function NAN preserving.

Signed-off-by: Martin Storsjo <martin@martin.st> Signed-off-by: Piotr Caban <piotr@codeweavers.com> Signed-off-by: Alexandre Julliard <julliard@winehq.org>

msvcrt: Make the tanh function NAN preserving.
07ec052e · Martin Storsjo · Alexandre Julliard · 11166aa0 · 07ec052e
Commit 07ec052e authored Jul 28, 2021 by Martin Storsjo Committed by Alexandre Julliard Jul 28, 2021
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Showing with 7 additions and 4 deletions

math.c dlls/msvcrt/math.c +7 -4

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--- a/dlls/msvcrt/math.c
+++ b/dlls/msvcrt/math.c
@@ -4336,12 +4336,11 @@ double CDECL tan( double x )
 double CDECL tanh( double x )
 {
    UINT64 ui = *(UINT64*)&x;
+    UINT64 sign = ui & 0x8000000000000000ULL;
    UINT32 w;
-    int sign;
    double t;

    /* x = |x| */
-    sign = ui >> 63;
    ui &= (UINT64)-1 / 2;
    x = *(double*)&ui;
    w = ui >> 32;
@@ -4349,11 +4348,15 @@ double CDECL tanh( double x )
    if (w > 0x3fe193ea) {
        /* |x| > log(3)/2 ~= 0.5493 or nan */
        if (w > 0x40340000) {
+            if (ui > 0x7ff0000000000000ULL) {
+                *(UINT64*)&x = ui | sign | 0x0008000000000000ULL;
 #if _MSVCR_VER < 140
-            if (isnan(x))
                return math_error(_DOMAIN, "tanh", x, 0, x);
+#else
+                return x;
 #endif
-            /* |x| > 20 or nan */
+            }
+            /* |x| > 20 */
            /* note: this branch avoids raising overflow */
            fp_barrier(x + 0x1p120f);
            t = 1 - 0 / x;