Jacek Caban : ntdll: Reimplement _allrem using 32-bit arithmetic.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 0547da64a3c431ffbc8a9304aaeb1dec3b448612
URL:    https://source.winehq.org/git/wine.git/?a=commit;h=0547da64a3c431ffbc8a9304a...

Author: Jacek Caban <jacek(a)codeweavers.com>
Date:   Mon Jun  8 18:12:27 2020 +0200

ntdll: Reimplement _allrem using 32-bit arithmetic.

Based on compiler-rt.

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

---

 dlls/ntdll/large_int.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/dlls/ntdll/large_int.c b/dlls/ntdll/large_int.c
index 5f53a3f404..7114b8c2d9 100644
--- a/dlls/ntdll/large_int.c
+++ b/dlls/ntdll/large_int.c
@@ -777,7 +777,13 @@ LONGLONG WINAPI _allmul( LONGLONG a, LONGLONG b )
  */
 LONGLONG WINAPI _allrem( LONGLONG a, LONGLONG b )
 {
-    return a % b;
+    LONGLONG s = b >> 63;          /* s = b < 0 ? -1 : 0 */
+    ULONGLONG r;
+    b = (b ^ s) - s;               /* negate if s == -1 */
+    s = a >> 63;                   /* s = a < 0 ? -1 : 0 */
+    a = (a ^ s) - s;               /* negate if s == -1 */
+    udivmod(a, b, &r);
+    return ((LONGLONG)r ^ s) - s;  /* negate if s == -1 */
 }