1*7c3d14c8STreehugger Robot /* This file is distributed under the University of Illinois Open Source
2*7c3d14c8STreehugger Robot * License. See LICENSE.TXT for details.
3*7c3d14c8STreehugger Robot */
4*7c3d14c8STreehugger Robot
5*7c3d14c8STreehugger Robot /* long double __gcc_qdiv(long double x, long double y);
6*7c3d14c8STreehugger Robot * This file implements the PowerPC 128-bit double-double division operation.
7*7c3d14c8STreehugger Robot * This implementation is shamelessly cribbed from Apple's DDRT, circa 1993(!)
8*7c3d14c8STreehugger Robot */
9*7c3d14c8STreehugger Robot
10*7c3d14c8STreehugger Robot #include "DD.h"
11*7c3d14c8STreehugger Robot
__gcc_qdiv(long double a,long double b)12*7c3d14c8STreehugger Robot long double __gcc_qdiv(long double a, long double b)
13*7c3d14c8STreehugger Robot {
14*7c3d14c8STreehugger Robot static const uint32_t infinityHi = UINT32_C(0x7ff00000);
15*7c3d14c8STreehugger Robot DD dst = { .ld = a }, src = { .ld = b };
16*7c3d14c8STreehugger Robot
17*7c3d14c8STreehugger Robot register double x = dst.s.hi, x1 = dst.s.lo,
18*7c3d14c8STreehugger Robot y = src.s.hi, y1 = src.s.lo;
19*7c3d14c8STreehugger Robot
20*7c3d14c8STreehugger Robot double yHi, yLo, qHi, qLo;
21*7c3d14c8STreehugger Robot double yq, tmp, q;
22*7c3d14c8STreehugger Robot
23*7c3d14c8STreehugger Robot q = x / y;
24*7c3d14c8STreehugger Robot
25*7c3d14c8STreehugger Robot /* Detect special cases */
26*7c3d14c8STreehugger Robot if (q == 0.0) {
27*7c3d14c8STreehugger Robot dst.s.hi = q;
28*7c3d14c8STreehugger Robot dst.s.lo = 0.0;
29*7c3d14c8STreehugger Robot return dst.ld;
30*7c3d14c8STreehugger Robot }
31*7c3d14c8STreehugger Robot
32*7c3d14c8STreehugger Robot const doublebits qBits = { .d = q };
33*7c3d14c8STreehugger Robot if (((uint32_t)(qBits.x >> 32) & infinityHi) == infinityHi) {
34*7c3d14c8STreehugger Robot dst.s.hi = q;
35*7c3d14c8STreehugger Robot dst.s.lo = 0.0;
36*7c3d14c8STreehugger Robot return dst.ld;
37*7c3d14c8STreehugger Robot }
38*7c3d14c8STreehugger Robot
39*7c3d14c8STreehugger Robot yHi = high26bits(y);
40*7c3d14c8STreehugger Robot qHi = high26bits(q);
41*7c3d14c8STreehugger Robot
42*7c3d14c8STreehugger Robot yq = y * q;
43*7c3d14c8STreehugger Robot yLo = y - yHi;
44*7c3d14c8STreehugger Robot qLo = q - qHi;
45*7c3d14c8STreehugger Robot
46*7c3d14c8STreehugger Robot tmp = LOWORDER(yq, yHi, yLo, qHi, qLo);
47*7c3d14c8STreehugger Robot tmp = (x - yq) - tmp;
48*7c3d14c8STreehugger Robot tmp = ((tmp + x1) - y1 * q) / y;
49*7c3d14c8STreehugger Robot x = q + tmp;
50*7c3d14c8STreehugger Robot
51*7c3d14c8STreehugger Robot dst.s.lo = (q - x) + tmp;
52*7c3d14c8STreehugger Robot dst.s.hi = x;
53*7c3d14c8STreehugger Robot
54*7c3d14c8STreehugger Robot return dst.ld;
55*7c3d14c8STreehugger Robot }
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