Category : C Source Code
Archive   : JPL-C2.ZIP
Filename : FINT.C

/* 1.0 06-27-85 (fint.c)
************************************************************************
* Robert C. Tausworthe *
* Jet Propulsion Laboratory *
* Pasadena, CA 91009 1985 *
************************************************************************/

#include "defs.h"
#include "stdtyp.h"

/************************************************************************/
double
fint(x) /* return integer part of x as double */

/*----------------------------------------------------------------------*/
double x;
{
int i, ex2, byte;
BITS bitmask;
TBITS *xp;
LOCAL TBITS mask[8] =
{0, 0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfe};

xp = (char *) &x;

#ifdef ECOSOFT
ex2 = (((int) xp[0]) - 0x80);/* implied normalized bit, but sign is */
byte = ex2 / 8 + 1; /* in the normalized place */
bitmask = mask[ex2 & 7]; /* i.e., % 8 */
#endif

#ifdef AZTEC
ex2 = (((int) (xp[0] & 0x7f)) - 0x40); /* base 256 */
byte = 1 + ex2;
bitmask = 0;
#endif

#ifdef CPM86
ex2 = (((int) (((xp[7] << 4) + (xp[6] >> 4)) & 0x7ff)) - 0x3fe + 3);
byte = 6 - ex2 / 8; /* has implied normalized bit */
bitmask = mask[ex2 & 7];
#endif

#ifdef UNIVERSE
ex2 = (((int)(((*xp << 1) + (xp[1] &0x80 ? 1 : 0)) & 0xff)) - 0x80);
byte = 1 + ex2 / 8; /* has normalized bit, but extended exponent */
bitmask = mask[ex2 & 7];
#endif
/*\p*/

#ifdef SUN
ex2 = (int)(((*xp & 0x7f)<<4) + ((xp[1]>>4) & 0xf) - 0x3fe);
byte = (i = ex2 + 11) / 8; /* i is location of dec. pt. */
bitmask = mask[i & 7];
#endif

if (ex2 < 1)
return 0.0;

#ifdef CPM86
if (byte > -1)
{ xp[byte] &= bitmask;
for (i = --byte; i > -1; i--)
xp[i] = 0;
}
#else
if (byte < 8)
{ xp[byte] &= bitmask;
for (i = ++byte; i < 8; i++)
xp[i] = 0;
}
#endif
return x;
}