minix/lib/float/cfi.c

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2005-04-21 16:53:53 +02:00
/*
(c) copyright 1988 by the Vrije Universiteit, Amsterdam, The Netherlands.
See the copyright notice in the ACK home directory, in the file "Copyright".
*/
/* $Header$ */
/*
CONVERT FLOAT TO SIGNED (CFI m n)
N.B. The caller must know what it is getting.
A LONG is always returned. If it is an
integer the high byte is cleared first.
*/
#include "FP_trap.h"
#include "FP_types.h"
#include "FP_shift.h"
long
cfi(ds,ss,src)
int ds; /* destination size (2 or 4) */
int ss; /* source size (4 or 8) */
DOUBLE src; /* assume worst case */
{
EXTEND buf;
long new;
short max_exp;
extend(&src.d[0],&buf,ss); /* get extended format */
if (buf.exp < 0) { /* no conversion needed */
src.d[ss == 8] = 0L;
return(0L);
}
max_exp = (ds << 3) - 2; /* signed numbers */
/* have more limited max_exp */
if (buf.exp > max_exp) {
if (buf.exp == max_exp+1 && buf.sign && buf.m1 == NORMBIT &&
buf.m2 == 0L) {
}
else {
trap(EIOVFL); /* integer overflow */
buf.exp %= max_exp; /* truncate */
}
}
new = buf.m1 >> (31-buf.exp);
if (buf.sign)
new = -new;
done:
src.d[ss == 8] = new;
return(new);
}