minix/lib/ack/libfp/fif8.fc

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/*
(c) copyright 1988 by the Vrije Universiteit, Amsterdam, The Netherlands.
See the copyright notice in the ACK home directory, in the file "Copyright".
*/
/* $Header$ */
/*
MULTIPLY AND DISMEMBER PARTS (FIF 8)
*/
#include "FP_types.h"
#include "FP_shift.h"
void
fif8(p,x,y)
DOUBLE x,y;
struct fif8_returns *p;
{
EXTEND e1,e2;
extend(&y.d[0],&e1,sizeof(DOUBLE));
extend(&x.d[0],&e2,sizeof(DOUBLE));
/* do a multiply */
mul_ext(&e1,&e2);
e2 = e1;
compact(&e2, &y.d[0], sizeof(DOUBLE));
if (e1.exp < 0) {
p->ipart.d[0] = 0;
p->ipart.d[1] = 0;
p->fpart = y;
return;
}
if (e1.exp > 62 - DBL_M1LEFT) {
p->ipart = y;
p->fpart.d[0] = 0;
p->fpart.d[1] = 0;
return;
}
b64_sft(&e1.mantissa, 63 - e1.exp);
b64_sft(&e1.mantissa, e1.exp - 63); /* "loose" low order bits */
compact(&e1, &(p->ipart.d[0]), sizeof(DOUBLE));
extend(&(p->ipart.d[0]), &e2, sizeof(DOUBLE));
extend(&y.d[0], &e1, sizeof(DOUBLE));
sub_ext(&e1, &e2);
compact(&e1, &(p->fpart.d[0]), sizeof(DOUBLE));
}