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

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 8f144eb566c0bbbe925e5fb81b67873ed6b9e8bd
URL:    https://source.winehq.org/git/wine.git/?a=commit;h=8f144eb566c0bbbe925e5fb81b67873ed6b9e8bd

Author: Jacek Caban <jacek at codeweavers.com>
Date:   Mon Jun  8 18:12:21 2020 +0200

ntdll: Reimplement _alldiv using 32-bit arithmetic.

Based on compiler-rt.

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

---

 dlls/ntdll/large_int.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/dlls/ntdll/large_int.c b/dlls/ntdll/large_int.c
index e55d450e1e..5f53a3f404 100644
--- a/dlls/ntdll/large_int.c
+++ b/dlls/ntdll/large_int.c
@@ -736,7 +736,12 @@ static ULONGLONG udivmod(ULONGLONG a, ULONGLONG b, ULONGLONG *rem)
  */
 LONGLONG WINAPI _alldiv( LONGLONG a, LONGLONG b )
 {
-    return a / b;
+    LONGLONG s_a = a >> 63;                    /* s_a = a < 0 ? -1 : 0 */
+    LONGLONG s_b = b >> 63;                    /* s_b = b < 0 ? -1 : 0 */
+    a = (a ^ s_a) - s_a;                       /* negate if s_a == -1 */
+    b = (b ^ s_b) - s_b;                       /* negate if s_b == -1 */
+    s_a ^= s_b;                                /* sign of quotient */
+    return (udivmod(a, b, NULL) ^ s_a) - s_a;  /* negate if s_a == -1 */
 }