Initial revision

lib/float/cfi.c

@@ -0,0 +1,52 @@
+/*
+  (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);
+}