1/* Half-float conversion routines.
2
3   Copyright (C) 2008-2015 Free Software Foundation, Inc.
4   Contributed by CodeSourcery.
5
6   This file is free software; you can redistribute it and/or modify it
7   under the terms of the GNU General Public License as published by the
8   Free Software Foundation; either version 3, or (at your option) any
9   later version.
10
11   This file is distributed in the hope that it will be useful, but
12   WITHOUT ANY WARRANTY; without even the implied warranty of
13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14   General Public License for more details.
15
16   Under Section 7 of GPL version 3, you are granted additional
17   permissions described in the GCC Runtime Library Exception, version
18   3.1, as published by the Free Software Foundation.
19
20   You should have received a copy of the GNU General Public License and
21   a copy of the GCC Runtime Library Exception along with this program;
22   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
23   <http://www.gnu.org/licenses/>.  */
24
25static inline unsigned short
26__gnu_f2h_internal(unsigned int a, int ieee)
27{
28  unsigned short sign = (a >> 16) & 0x8000;
29  int aexp = (a >> 23) & 0xff;
30  unsigned int mantissa = a & 0x007fffff;
31  unsigned int mask;
32  unsigned int increment;
33
34  if (aexp == 0xff)
35    {
36      if (!ieee)
37	return sign;
38      return sign | 0x7e00 | (mantissa >> 13);
39    }
40
41  if (aexp == 0 && mantissa == 0)
42    return sign;
43
44  aexp -= 127;
45
46  /* Decimal point between bits 22 and 23.  */
47  mantissa |= 0x00800000;
48  if (aexp < -14)
49    {
50      mask = 0x00ffffff;
51      if (aexp >= -25)
52        mask >>= 25 + aexp;
53    }
54  else
55    mask = 0x00001fff;
56
57  /* Round.  */
58  if (mantissa & mask)
59    {
60      increment = (mask + 1) >> 1;
61      if ((mantissa & mask) == increment)
62	increment = mantissa & (increment << 1);
63      mantissa += increment;
64      if (mantissa >= 0x01000000)
65       	{
66	  mantissa >>= 1;
67	  aexp++;
68	}
69    }
70
71  if (ieee)
72    {
73      if (aexp > 15)
74	return sign | 0x7c00;
75    }
76  else
77    {
78      if (aexp > 16)
79	return sign | 0x7fff;
80    }
81
82  if (aexp < -24)
83    return sign;
84
85  if (aexp < -14)
86    {
87      mantissa >>= -14 - aexp;
88      aexp = -14;
89    }
90
91  /* We leave the leading 1 in the mantissa, and subtract one
92     from the exponent bias to compensate.  */
93  return sign | (((aexp + 14) << 10) + (mantissa >> 13));
94}
95
96unsigned int
97__gnu_h2f_internal(unsigned short a, int ieee)
98{
99  unsigned int sign = (unsigned int)(a & 0x8000) << 16;
100  int aexp = (a >> 10) & 0x1f;
101  unsigned int mantissa = a & 0x3ff;
102
103  if (aexp == 0x1f && ieee)
104    return sign | 0x7f800000 | (mantissa << 13);
105
106  if (aexp == 0)
107    {
108      int shift;
109
110      if (mantissa == 0)
111	return sign;
112
113      shift = __builtin_clz(mantissa) - 21;
114      mantissa <<= shift;
115      aexp = -shift;
116    }
117
118  return sign | (((aexp + 0x70) << 23) + (mantissa << 13));
119}
120
121unsigned short
122__gnu_f2h_ieee(unsigned int a)
123{
124  return __gnu_f2h_internal(a, 1);
125}
126
127unsigned int
128__gnu_h2f_ieee(unsigned short a)
129{
130  return __gnu_h2f_internal(a, 1);
131}
132
133unsigned short
134__gnu_f2h_alternative(unsigned int x)
135{
136  return __gnu_f2h_internal(x, 0);
137}
138
139unsigned int
140__gnu_h2f_alternative(unsigned short a)
141{
142  return __gnu_h2f_internal(a, 0);
143}
144