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/**********************************************************************
safe_double.h: small abstraction for storing double without endianess
problems
Copyright (C) 2006 Vincent Fourmond
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Library Public License as published
by the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program 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 Library General Public License for more details.
You should have received a copy of the GNU Library General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
**********************************************************************/
/* This file provides two functions: store_double and get_double, which
can be used in a 'safe' way to store doubles and retrive them
in a hopefully platform-independent form. However, it just
stores it without regards to that if ieee754.h isn't found...
*/
#ifndef _DOUBLE_H
#define _DOUBLE_H
#define STORE_LOWER_BYTE(a,p) do {\
*(p++) = (a) & 0xFF; (a) >>= 8; }\
while(0)
#define STORE_UNSIGNED(a,p) for(i = 0; i < 4; i++) STORE_LOWER_BYTE(a,p);
#define GET_UNSIGNED(a,p) do { a = 0; for(i = 0; i < 4; i++) \
(a) |= *(p++) << (i * 8); } while (0)
#ifdef HAVE_IEEE754_H
#include <ieee754.h>
static inline void store_double(double a, unsigned char * p)
{
unsigned int tmp;
int i;
union ieee754_double d;
d.d = a;
/* we store it with lower bytes firts */
tmp = d.ieee.mantissa1;
STORE_UNSIGNED(tmp, p);
tmp = d.ieee.negative << 31 |
d.ieee.exponent << 20 |
d.ieee.mantissa0;
STORE_UNSIGNED(tmp, p);
}
static inline double get_double(const unsigned char * p)
{
unsigned int tmp;
int i;
union ieee754_double d;
GET_UNSIGNED(tmp, p);
d.ieee.mantissa1 = tmp;
GET_UNSIGNED(tmp, p);
d.ieee.mantissa0 = tmp & 0xFFFFF;
d.ieee.exponent = (tmp >> 20) & 0x7FF;
d.ieee.negative = (tmp >> 31) & 0x1;
return d.d;
}
#else
union basic_double{
double d;
struct {
unsigned int a:32;
unsigned int b:32;
} i;
};
static inline void store_double(double a, unsigned char * p)
{
union basic_double d;
int i;
d.d = a;
STORE_UNSIGNED(d.i.a, p);
STORE_UNSIGNED(d.i.b, p);
}
static inline double get_double(const unsigned char * p)
{
union basic_double d;
int i;
GET_UNSIGNED(d.i.a, p);
GET_UNSIGNED(d.i.b, p);
return d.d;
}
#endif /* HAVE_IEEE754_H */
#endif /* _DOUBLE_H */
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