kolibrios/contrib/kolibri-libc/source/math/frexp.c
Magomed Kostoev (mkostoevr) 1f4d74f500 Relocate kolibri-libc from GitHub
git-svn-id: svn://kolibrios.org@8622 a494cfbc-eb01-0410-851d-a64ba20cac60
2021-03-02 17:58:11 +00:00

27 lines
583 B
C

/* Copyright (C) 1994 DJ Delorie, see COPYING.DJ for details */
#include <math.h>
double
frexp(double x, int *exptr)
{
union {
double d;
unsigned char c[8];
} u;
u.d = x;
/*
* The format of the number is:
* Sign, 12 exponent bits, 51 mantissa bits
* The exponent is 1023 biased and there is an implicit zero.
* We get the exponent from the upper bits and set the exponent
* to 0x3fe (1022).
*/
*exptr = (int)(((u.c[7] & 0x7f) << 4) | (u.c[6] >> 4)) - 1022;
u.c[7] &= 0x80;
u.c[7] |= 0x3f;
u.c[6] &= 0x0f;
u.c[6] |= 0xe0;
return u.d;
}