1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
|
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// long double __gcc_qdiv(long double x, long double y);
// This file implements the PowerPC 128-bit double-double division operation.
// This implementation is shamelessly cribbed from Apple's DDRT, circa 1993(!)
#include "DD.h"
long double __gcc_qdiv(long double a, long double b)
{
static const uint32_t infinityHi = UINT32_C(0x7ff00000);
DD dst = { .ld = a }, src = { .ld = b };
register double x = dst.hi, x1 = dst.lo,
y = src.hi, y1 = src.lo;
double yHi, yLo, qHi, qLo;
double yq, tmp, q;
q = x / y;
// Detect special cases
if (q == 0.0) {
dst.hi = q;
dst.lo = 0.0;
return dst.ld;
}
const doublebits qBits = { .d = q };
if (((uint32_t)(qBits.x >> 32) & infinityHi) == infinityHi) {
dst.hi = q;
dst.lo = 0.0;
return dst.ld;
}
yHi = high26bits(y);
qHi = high26bits(q);
yq = y * q;
yLo = y - yHi;
qLo = q - qHi;
tmp = LOWORDER(yq, yHi, yLo, qHi, qLo);
tmp = (x - yq) - tmp;
tmp = ((tmp + x1) - y1 * q) / y;
x = q + tmp;
dst.lo = (q - x) + tmp;
dst.hi = x;
return dst.ld;
}
|
