144 lines
3.2 KiB
C
144 lines
3.2 KiB
C
/* Half-float conversion routines.
|
|
|
|
Copyright (C) 2008-2013 Free Software Foundation, Inc.
|
|
Contributed by CodeSourcery.
|
|
|
|
This file is free software; you can redistribute it and/or modify it
|
|
under the terms of the GNU General Public License as published by the
|
|
Free Software Foundation; either version 3, or (at your option) any
|
|
later version.
|
|
|
|
This file is distributed in the hope that it will be useful, but
|
|
WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
General Public License for more details.
|
|
|
|
Under Section 7 of GPL version 3, you are granted additional
|
|
permissions described in the GCC Runtime Library Exception, version
|
|
3.1, as published by the Free Software Foundation.
|
|
|
|
You should have received a copy of the GNU General Public License and
|
|
a copy of the GCC Runtime Library Exception along with this program;
|
|
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
|
|
<http://www.gnu.org/licenses/>. */
|
|
|
|
static inline unsigned short
|
|
__gnu_f2h_internal(unsigned int a, int ieee)
|
|
{
|
|
unsigned short sign = (a >> 16) & 0x8000;
|
|
int aexp = (a >> 23) & 0xff;
|
|
unsigned int mantissa = a & 0x007fffff;
|
|
unsigned int mask;
|
|
unsigned int increment;
|
|
|
|
if (aexp == 0xff)
|
|
{
|
|
if (!ieee)
|
|
return sign;
|
|
return sign | 0x7e00 | (mantissa >> 13);
|
|
}
|
|
|
|
if (aexp == 0 && mantissa == 0)
|
|
return sign;
|
|
|
|
aexp -= 127;
|
|
|
|
/* Decimal point between bits 22 and 23. */
|
|
mantissa |= 0x00800000;
|
|
if (aexp < -14)
|
|
{
|
|
mask = 0x00ffffff;
|
|
if (aexp >= -25)
|
|
mask >>= 25 + aexp;
|
|
}
|
|
else
|
|
mask = 0x00001fff;
|
|
|
|
/* Round. */
|
|
if (mantissa & mask)
|
|
{
|
|
increment = (mask + 1) >> 1;
|
|
if ((mantissa & mask) == increment)
|
|
increment = mantissa & (increment << 1);
|
|
mantissa += increment;
|
|
if (mantissa >= 0x01000000)
|
|
{
|
|
mantissa >>= 1;
|
|
aexp++;
|
|
}
|
|
}
|
|
|
|
if (ieee)
|
|
{
|
|
if (aexp > 15)
|
|
return sign | 0x7c00;
|
|
}
|
|
else
|
|
{
|
|
if (aexp > 16)
|
|
return sign | 0x7fff;
|
|
}
|
|
|
|
if (aexp < -24)
|
|
return sign;
|
|
|
|
if (aexp < -14)
|
|
{
|
|
mantissa >>= -14 - aexp;
|
|
aexp = -14;
|
|
}
|
|
|
|
/* We leave the leading 1 in the mantissa, and subtract one
|
|
from the exponent bias to compensate. */
|
|
return sign | (((aexp + 14) << 10) + (mantissa >> 13));
|
|
}
|
|
|
|
unsigned int
|
|
__gnu_h2f_internal(unsigned short a, int ieee)
|
|
{
|
|
unsigned int sign = (unsigned int)(a & 0x8000) << 16;
|
|
int aexp = (a >> 10) & 0x1f;
|
|
unsigned int mantissa = a & 0x3ff;
|
|
|
|
if (aexp == 0x1f && ieee)
|
|
return sign | 0x7f800000 | (mantissa << 13);
|
|
|
|
if (aexp == 0)
|
|
{
|
|
int shift;
|
|
|
|
if (mantissa == 0)
|
|
return sign;
|
|
|
|
shift = __builtin_clz(mantissa) - 21;
|
|
mantissa <<= shift;
|
|
aexp = -shift;
|
|
}
|
|
|
|
return sign | (((aexp + 0x70) << 23) + (mantissa << 13));
|
|
}
|
|
|
|
unsigned short
|
|
__gnu_f2h_ieee(unsigned int a)
|
|
{
|
|
return __gnu_f2h_internal(a, 1);
|
|
}
|
|
|
|
unsigned int
|
|
__gnu_h2f_ieee(unsigned short a)
|
|
{
|
|
return __gnu_h2f_internal(a, 1);
|
|
}
|
|
|
|
unsigned short
|
|
__gnu_f2h_alternative(unsigned int x)
|
|
{
|
|
return __gnu_f2h_internal(x, 0);
|
|
}
|
|
|
|
unsigned int
|
|
__gnu_h2f_alternative(unsigned short a)
|
|
{
|
|
return __gnu_h2f_internal(a, 0);
|
|
}
|