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ntdll: Reimplement _aulldiv using 32-bit arithmetic. 

Based on compiler-rt.

Signed-off-by: Jacek Caban <jacek@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>
This commit is contained in:
Jacek Caban 2020-06-08 18:12:01 +02:00 committed by Alexandre Julliard
parent 2618162e89
commit d53672c6ec
1 changed files with 178 additions and 1 deletions
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179
dlls/ntdll/large_int.c
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@ -545,6 +545,183 @@ NTSTATUS WINAPI RtlInt64ToUnicodeString(
#ifdef __i386__
static ULONGLONG udivmod(ULONGLONG a, ULONGLONG b, ULONGLONG *rem)
{
const ULARGE_INTEGER n = { .QuadPart = a };
const ULARGE_INTEGER d = { .QuadPart = b };
DWORD sr, carry, index;
ULARGE_INTEGER q, r;
const unsigned n_uword_bits = 32;
const unsigned n_udword_bits = 64;
/* special cases, X is unknown, K != 0 */
if (n.u.HighPart == 0)
{
if (d.u.HighPart == 0)
{
/* 0 X / 0 X */
if (rem) *rem = n.u.LowPart % d.u.LowPart;
return n.u.LowPart / d.u.LowPart;
}
/* 0 X / K X */
if (rem) *rem = n.u.LowPart;
return 0;
}
/* n.u.HighPart != 0 */
if (d.u.LowPart == 0)
{
if (d.u.HighPart == 0)
{
/* K X / 0 0 */
if (rem) *rem = n.u.HighPart % d.u.LowPart;
return n.u.HighPart / d.u.LowPart;
}
/* d.u.HighPart != 0 */
if (n.u.LowPart == 0) {
/* K 0 / K 0 */
if (rem)
{
r.u.HighPart = n.u.HighPart % d.u.HighPart;
r.u.LowPart = 0;
*rem = r.QuadPart;
}
return n.u.HighPart / d.u.HighPart;
}
/* K K / K 0 */
if ((d.u.HighPart & (d.u.HighPart - 1)) == 0) /* if d is a power of 2 */
{
if (rem)
{
r.u.LowPart = n.u.LowPart;
r.u.HighPart = n.u.HighPart & (d.u.HighPart - 1);
*rem = r.QuadPart;
}
BitScanForward(&index, d.u.HighPart);
return n.u.HighPart >> index;
}
/* K K / K 0 */
BitScanReverse(&index, d.u.HighPart);
BitScanReverse(&sr, n.u.HighPart);
sr -= index;
/* 0 <= sr <= n_uword_bits - 2 or sr large */
if (sr > n_uword_bits - 2)
{
if (rem) *rem = n.QuadPart;
return 0;
}
++sr;
/* 1 <= sr <= n_uword_bits - 1 */
/* q.QuadPart = n.QuadPart << (n_udword_bits - sr); */
q.u.LowPart = 0;
q.u.HighPart = n.u.LowPart << (n_uword_bits - sr);
/* r.QuadPart = n.QuadPart >> sr; */
r.u.HighPart = n.u.HighPart >> sr;
r.u.LowPart = (n.u.HighPart << (n_uword_bits - sr)) | (n.u.LowPart >> sr);
}
else /* d.u.LowPart != 0 */
{
if (d.u.HighPart == 0)
{
/* K X / 0 K */
if ((d.u.LowPart & (d.u.LowPart - 1)) == 0) /* if d is a power of 2 */
{
if (rem) *rem = n.u.LowPart & (d.u.LowPart - 1);
if (d.u.LowPart == 1) return n.QuadPart;
BitScanForward(&sr, d.u.LowPart);
q.u.HighPart = n.u.HighPart >> sr;
q.u.LowPart = (n.u.HighPart << (n_uword_bits - sr)) | (n.u.LowPart >> sr);
return q.QuadPart;
}
BitScanReverse(&index, d.u.LowPart);
BitScanReverse(&sr, n.u.HighPart);
sr = 1 + n_uword_bits + sr - index;
/* 2 <= sr <= n_udword_bits - 1
* q.QuadPart = n.QuadPart << (n_udword_bits - sr);
* r.QuadPart = n.QuadPart >> sr; */
if (sr == n_uword_bits)
{
q.u.LowPart = 0;
q.u.HighPart = n.u.LowPart;
r.u.HighPart = 0;
r.u.LowPart = n.u.HighPart;
}
else if (sr < n_uword_bits) /* 2 <= sr <= n_uword_bits - 1 */
{
q.u.LowPart = 0;
q.u.HighPart = n.u.LowPart << (n_uword_bits - sr);
r.u.HighPart = n.u.HighPart >> sr;
r.u.LowPart = (n.u.HighPart << (n_uword_bits - sr)) | (n.u.LowPart >> sr);
}
else /* n_uword_bits + 1 <= sr <= n_udword_bits - 1 */
{
q.u.LowPart = n.u.LowPart << (n_udword_bits - sr);
q.u.HighPart = (n.u.HighPart << (n_udword_bits - sr)) |
(n.u.LowPart >> (sr - n_uword_bits));
r.u.HighPart = 0;
r.u.LowPart = n.u.HighPart >> (sr - n_uword_bits);
}
}
else
{
/* K X / K K */
BitScanReverse(&index, d.u.HighPart);
BitScanReverse(&sr, n.u.HighPart);
sr -= index;
/* 0 <= sr <= n_uword_bits - 1 or sr large */
if (sr > n_uword_bits - 1)
{
if (rem) *rem = n.QuadPart;
return 0;
}
++sr;
/* 1 <= sr <= n_uword_bits
* q.QuadPart = n.QuadPart << (n_udword_bits - sr); */
q.u.LowPart = 0;
if (sr == n_uword_bits)
{
q.u.HighPart = n.u.LowPart;
r.u.HighPart = 0;
r.u.LowPart = n.u.HighPart;
}
else
{
q.u.HighPart = n.u.LowPart << (n_uword_bits - sr);
r.u.HighPart = n.u.HighPart >> sr;
r.u.LowPart = (n.u.HighPart << (n_uword_bits - sr)) | (n.u.LowPart >> sr);
}
}
}
/* Not a special case
* q and r are initialized with:
* q.QuadPart = n.QuadPart << (n_udword_bits - sr);
* r.QuadPart = n.QuadPart >> sr;
* 1 <= sr <= n_udword_bits - 1 */
carry = 0;
for (; sr > 0; --sr)
{
LONGLONG s;
/* r:q = ((r:q) << 1) | carry */
r.u.HighPart = (r.u.HighPart << 1) | (r.u.LowPart >> (n_uword_bits - 1));
r.u.LowPart = (r.u.LowPart << 1) | (q.u.HighPart >> (n_uword_bits - 1));
q.u.HighPart = (q.u.HighPart << 1) | (q.u.LowPart >> (n_uword_bits - 1));
q.u.LowPart = (q.u.LowPart << 1) | carry;
/* if (r.QuadPart >= d.QuadPart)
* {
* r.QuadPart -= d.QuadPart;
* carry = 1;
* }
*/
s = (LONGLONG)(d.QuadPart - r.QuadPart - 1) >> (n_udword_bits - 1);
carry = s & 1;
r.QuadPart -= d.QuadPart & s;
}
q.QuadPart = (q.QuadPart << 1) | carry;
if (rem) *rem = r.QuadPart;
return q.QuadPart;
}
/******************************************************************************
* _alldiv (NTDLL.@)
*
@ -613,7 +790,7 @@ LONGLONG WINAPI _allrem( LONGLONG a, LONGLONG b )
*/
ULONGLONG WINAPI _aulldiv( ULONGLONG a, ULONGLONG b )
{
return a / b;
return udivmod(a, b, NULL);
}
/******************************************************************************