1/* Compute remainder and a congruent to the quotient.
2   Copyright (C) 1997-2018 Free Software Foundation, Inc.
3   This file is part of the GNU C Library.
4   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997 and
5		  Jakub Jelinek <jj@ultra.linux.cz>, 1999.
6
7   The GNU C Library is free software; you can redistribute it and/or
8   modify it under the terms of the GNU Lesser General Public
9   License as published by the Free Software Foundation; either
10   version 2.1 of the License, or (at your option) any later version.
11
12   The GNU C Library is distributed in the hope that it will be useful,
13   but WITHOUT ANY WARRANTY; without even the implied warranty of
14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15   Lesser General Public License for more details.
16
17   You should have received a copy of the GNU Lesser General Public
18   License along with the GNU C Library; if not, see
19   <http://www.gnu.org/licenses/>.  */
20
21#include "quadmath-imp.h"
22
23static const __float128 zero = 0.0;
24
25
26__float128
27remquoq (__float128 x, __float128 y, int *quo)
28{
29  int64_t hx,hy;
30  uint64_t sx,lx,ly,qs;
31  int cquo;
32
33  GET_FLT128_WORDS64 (hx, lx, x);
34  GET_FLT128_WORDS64 (hy, ly, y);
35  sx = hx & 0x8000000000000000ULL;
36  qs = sx ^ (hy & 0x8000000000000000ULL);
37  hy &= 0x7fffffffffffffffLL;
38  hx &= 0x7fffffffffffffffLL;
39
40  /* Purge off exception values.  */
41  if ((hy | ly) == 0)
42    return (x * y) / (x * y); 			/* y = 0 */
43  if ((hx >= 0x7fff000000000000LL)		/* x not finite */
44      || ((hy >= 0x7fff000000000000LL)		/* y is NaN */
45	  && (((hy - 0x7fff000000000000LL) | ly) != 0)))
46    return (x * y) / (x * y);
47
48  if (hy <= 0x7ffbffffffffffffLL)
49    x = fmodq (x, 8 * y);              /* now x < 8y */
50
51  if (((hx - hy) | (lx - ly)) == 0)
52    {
53      *quo = qs ? -1 : 1;
54      return zero * x;
55    }
56
57  x  = fabsq (x);
58  y  = fabsq (y);
59  cquo = 0;
60
61  if (hy <= 0x7ffcffffffffffffLL && x >= 4 * y)
62    {
63      x -= 4 * y;
64      cquo += 4;
65    }
66  if (hy <= 0x7ffdffffffffffffLL && x >= 2 * y)
67    {
68      x -= 2 * y;
69      cquo += 2;
70    }
71
72  if (hy < 0x0002000000000000LL)
73    {
74      if (x + x > y)
75	{
76	  x -= y;
77	  ++cquo;
78	  if (x + x >= y)
79	    {
80	      x -= y;
81	      ++cquo;
82	    }
83	}
84    }
85  else
86    {
87      __float128 y_half = 0.5Q * y;
88      if (x > y_half)
89	{
90	  x -= y;
91	  ++cquo;
92	  if (x >= y_half)
93	    {
94	      x -= y;
95	      ++cquo;
96	    }
97	}
98    }
99
100  *quo = qs ? -cquo : cquo;
101
102  /* Ensure correct sign of zero result in round-downward mode.  */
103  if (x == 0)
104    x = 0;
105  if (sx)
106    x = -x;
107  return x;
108}
109