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/* Half-float conversion routines.
Copyright (C) 2008, 2009 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 = 0x007fffff;
if (aexp < -25)
aexp = -26;
else if (aexp != -25)
mask >>= 24 + 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);
}
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