Initial revision

lib/float/mul_ext.c

@@ -0,0 +1,98 @@
+/*
+  (c) copyright 1988 by the Vrije Universiteit, Amsterdam, The Netherlands.
+  See the copyright notice in the ACK home directory, in the file "Copyright".
+*/
+
+/* $Header$ */
+
+/*
+	ROUTINE TO MULTIPLY TWO EXTENDED FORMAT NUMBERS
+*/
+
+# include "FP_bias.h"
+# include "FP_trap.h"
+# include "FP_types.h"
+# include "FP_shift.h"
+
+void
+mul_ext(e1,e2)
+EXTEND	*e1,*e2;
+{
+	register int	i,j;		/* loop control	*/
+	unsigned short	mp[4];		/* multiplier */
+	unsigned short	mc[4];		/* multipcand */
+	unsigned short	result[8];	/* result */
+	register unsigned short *pres;
+
+	/* first save the sign (XOR)			*/
+	e1->sign ^= e2->sign;
+
+	/* compute new exponent */
+	e1->exp += e2->exp + 1;
+	/* 128 bit multiply of mantissas			*/
+
+		/* assign unknown long formats		*/
+		/* to known unsigned word formats	*/
+	mp[0] = e1->m1 >> 16;
+	mp[1] = (unsigned short) e1->m1;
+	mp[2] = e1->m2 >> 16;
+	mp[3] = (unsigned short) e1->m2;
+	mc[0] = e2->m1 >> 16;
+	mc[1] = (unsigned short) e2->m1;
+	mc[2] = e2->m2 >> 16;
+	mc[3] = (unsigned short) e2->m2;
+	for (i = 8; i--;) {
+		result[i] = 0;
+	}
+	/*
+	 *	fill registers with their components
+	 */
+	for(i=4, pres = &result[4];i--;pres--) if (mp[i]) {
+		unsigned short k = 0;
+		unsigned long mpi = mp[i];
+		for(j=4;j--;) {
+			unsigned long tmp = (unsigned long)pres[j] + k;
+			if (mc[j]) tmp += mpi * mc[j];
+			pres[j] = tmp;
+			k = tmp >> 16;
+		}
+		pres[-1] = k;
+	}
+        if (! (result[0] & 0x8000)) {
+                e1->exp--;
+                for (i = 0; i <= 3; i++) {
+                        result[i] <<= 1;
+                        if (result[i+1]&0x8000) result[i] |= 1;
+                }
+                result[4] <<= 1;
+        }
+
+	/*
+	 *	combine the registers to a total
+	 */
+	e1->m1 = ((unsigned long)(result[0]) << 16) + result[1];
+	e1->m2 = ((unsigned long)(result[2]) << 16) + result[3];
+	if (result[4] & 0x8000) {
+		if (++e1->m2 == 0)
+			if (++e1->m1 == 0) {
+				e1->m1 = NORMBIT;
+				e1->exp++;
+			}
+	}
+
+					/* check for overflow	*/
+	if (e1->exp >= EXT_MAX)	{
+		trap(EFOVFL);
+			/* if caught 			*/
+			/* return signed infinity	*/
+		e1->exp = EXT_MAX;
+infinity:	e1->m1 = e1->m2 =0L;
+		return;
+	}
+				/* check for underflow	*/
+	if (e1->exp < EXT_MIN)	{
+		trap(EFUNFL);
+		e1->exp = EXT_MIN;
+		goto infinity;
+	}
+}