mirror of
https://github.com/autc04/Retro68.git
synced 2024-09-10 03:54:48 +00:00
126 lines
2.9 KiB
C
126 lines
2.9 KiB
C
/* Generic unsigned 32 bit division implementation.
|
|
Copyright (C) 2009-2016 Free Software Foundation, Inc.
|
|
Contributed by Embecosm on behalf of Adapteva, Inc.
|
|
|
|
This file is part of GCC.
|
|
|
|
This file is free software; you can redistribute it and/or modify it
|
|
under the terms of the GNU General Public License as published by the
|
|
Free Software Foundation; either version 3, or (at your option) any
|
|
later version.
|
|
|
|
This file is distributed in the hope that it will be useful, but
|
|
WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
General Public License for more details.
|
|
|
|
Under Section 7 of GPL version 3, you are granted additional
|
|
permissions described in the GCC Runtime Library Exception, version
|
|
3.1, as published by the Free Software Foundation.
|
|
|
|
You should have received a copy of the GNU General Public License and
|
|
a copy of the GCC Runtime Library Exception along with this program;
|
|
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
|
|
<http://www.gnu.org/licenses/>. */
|
|
|
|
typedef union { unsigned int i; float f; } fu;
|
|
|
|
unsigned int __udivsi3 (unsigned int a, unsigned int b);
|
|
|
|
unsigned int
|
|
__udivsi3 (unsigned int a, unsigned int b)
|
|
{
|
|
unsigned int d, t, s0, s1, s2, r0, r1;
|
|
fu u0, u1, u2, u1b, u2b;
|
|
|
|
if (b > a)
|
|
return 0;
|
|
if ((int) b < 0)
|
|
return 1;
|
|
|
|
/* Assuming B is nonzero, compute S0 such that 0 <= S0,
|
|
(B << S0+1) does not overflow,
|
|
A < 4.01 * (B << S0), with S0 chosen as small as possible
|
|
without taking to much time calculating. */
|
|
#ifdef CONVERT_UNSIGNED
|
|
u0.f = a;
|
|
u1.f = b;
|
|
#else /* !CONVERT_UNSIGNED */
|
|
u0.f = (int) a;
|
|
u1.f = (int) b;
|
|
#ifdef CONCISE
|
|
if ((int) a < 0)
|
|
u0.i = (a >> 8) - 0x00800000 + 0x3f800000 + (31 << 23);
|
|
#else /* To use flag setting / cmove, this can be written as: */
|
|
{
|
|
unsigned c = 0xff800000 - 0x4f000000;
|
|
t = (int)a >> 8;
|
|
if (t >= c)
|
|
u0.i = (t - c);
|
|
}
|
|
#endif
|
|
#endif /* !CONVERT_UNSIGNED */
|
|
s0 = u0.i + 1 /* Compensate for rounding errors. */
|
|
- 0x00800000 /* adjust by one */ ;
|
|
s0 = s0 - u1.i;
|
|
s0 = (int)s0 >= 0 ? s0 : 0;
|
|
s0 >>= 23;
|
|
|
|
b <<= s0;
|
|
r1 = 0;
|
|
|
|
r0 = 1 << s0;
|
|
a = ((t=a) - b);
|
|
if (a <= t)
|
|
{
|
|
r1 += r0;
|
|
a = ((t=a) - b);
|
|
if (a <= t)
|
|
do {
|
|
r1 += r0;
|
|
a = ((t=a) - b);
|
|
} while (a <= t);
|
|
}
|
|
a += b;
|
|
d = b - 1;
|
|
|
|
#define STEP(n) case n: a += a; t = a - d; if (t <= a) a = t;
|
|
switch (s0)
|
|
{
|
|
STEP (31)
|
|
STEP (30)
|
|
STEP (29)
|
|
STEP (28)
|
|
STEP (27)
|
|
STEP (26)
|
|
STEP (25)
|
|
STEP (24)
|
|
STEP (23)
|
|
STEP (22)
|
|
STEP (21)
|
|
STEP (20)
|
|
STEP (19)
|
|
STEP (18)
|
|
STEP (17)
|
|
STEP (16)
|
|
STEP (15)
|
|
STEP (14)
|
|
STEP (13)
|
|
STEP (12)
|
|
STEP (11)
|
|
STEP (10)
|
|
STEP (9)
|
|
STEP (8)
|
|
STEP (7)
|
|
STEP (6)
|
|
STEP (5)
|
|
STEP (4)
|
|
STEP (3)
|
|
STEP (2)
|
|
STEP (1)
|
|
case 0: ;
|
|
}
|
|
r0 = r1 | (r0-1 & a);
|
|
return r0;
|
|
}
|