1 /* This file is distributed under the University of Illinois Open Source
2 * License. See LICENSE.TXT for details.
3 */
4
5 /* long double __gcc_qdiv(long double x, long double y);
6 * This file implements the PowerPC 128-bit double-double division operation.
7 * This implementation is shamelessly cribbed from Apple's DDRT, circa 1993(!)
8 */
9
10 #include "DD.h"
11
__gcc_qdiv(long double a,long double b)12 long double __gcc_qdiv(long double a, long double b)
13 {
14 static const uint32_t infinityHi = UINT32_C(0x7ff00000);
15 DD dst = { .ld = a }, src = { .ld = b };
16
17 register double x = dst.s.hi, x1 = dst.s.lo,
18 y = src.s.hi, y1 = src.s.lo;
19
20 double yHi, yLo, qHi, qLo;
21 double yq, tmp, q;
22
23 q = x / y;
24
25 /* Detect special cases */
26 if (q == 0.0) {
27 dst.s.hi = q;
28 dst.s.lo = 0.0;
29 return dst.ld;
30 }
31
32 const doublebits qBits = { .d = q };
33 if (((uint32_t)(qBits.x >> 32) & infinityHi) == infinityHi) {
34 dst.s.hi = q;
35 dst.s.lo = 0.0;
36 return dst.ld;
37 }
38
39 yHi = high26bits(y);
40 qHi = high26bits(q);
41
42 yq = y * q;
43 yLo = y - yHi;
44 qLo = q - qHi;
45
46 tmp = LOWORDER(yq, yHi, yLo, qHi, qLo);
47 tmp = (x - yq) - tmp;
48 tmp = ((tmp + x1) - y1 * q) / y;
49 x = q + tmp;
50
51 dst.s.lo = (q - x) + tmp;
52 dst.s.hi = x;
53
54 return dst.ld;
55 }
56