Initial revision

lib/float/add_ext.c

@@ -0,0 +1,56 @@
+/*
+  (c) copyright 1988 by the Vrije Universiteit, Amsterdam, The Netherlands.
+  See the copyright notice in the ACK home directory, in the file "Copyright".
+*/
+
+/* $Header$ */
+
+/*
+	ADD TWO EXTENDED FORMAT NUMBERS
+*/
+
+#include "FP_types.h"
+
+void
+add_ext(e1,e2)
+register EXTEND	*e1,*e2;
+{
+	if ((e2->m1 | e2->m2) == 0L) {
+		return;
+	}
+	if ((e1->m1 | e1->m2) == 0L) {
+		*e1 = *e2;
+		return;
+	}
+	sft_ext(e1, e2);	/* adjust mantissas to equal powers */
+	if (e1->sign != e2->sign) {
+		/* e1 + e2 = e1 - (-e2) */
+		if (e2->m1 > e1->m1 ||
+                    (e2->m1 == e1->m1 && e2->m2 > e1->m2)) {
+                	/*      abs(e2) > abs(e1) */
+			EXTEND x;
+
+			x = *e1;
+			*e1 = *e2;
+                	if (x.m2 > e1->m2) {
+                        	e1->m1 -= 1;    /* carry in */
+                	}
+                	e1->m1 -= x.m1;
+                	e1->m2 -= x.m2;
+        	}
+        	else {
+                	if (e2->m2 > e1->m2)
+                        	e1->m1 -= 1;    /* carry in */
+                	e1->m1 -= e2->m1;
+                	e1->m2 -= e2->m2;
+        	}
+	}
+	else {
+		if (b64_add(&e1->mantissa,&e2->mantissa)) {	/* addition carry */
+			b64_rsft(&e1->mantissa);	/* shift mantissa one bit RIGHT */
+			e1->m1 |= 0x80000000L;	/* set max bit	*/
+			e1->exp++;		/* increase the exponent */
+		}
+	}
+	nrm_ext(e1);
+}