Initial revision

modules/src/flt_arith/flt_mul.c

@@ -0,0 +1,83 @@
+/*
+  (c) copyright 1988 by the Vrije Universiteit, Amsterdam, The Netherlands.
+  See the copyright notice in the ACK home directory, in the file "Copyright".
+*/
+
+/* $Header$ */
+
+#include "misc.h"
+
+flt_mul(e1,e2,e3)
+	register flt_arith *e1,*e2,*e3;
+{
+	/*	Multiply the extended numbers e1 and e2, and put the
+		result in e3.
+	*/
+	register int	i,j;		/* loop control	*/
+	unsigned short	mp[4];
+	unsigned short	mc[4];
+	unsigned short	result[8];	/* result */
+
+	register unsigned short *pres;
+
+	flt_status = 0;
+
+	/* first save the sign (XOR)			*/
+	e3->flt_sign = e1->flt_sign ^ e2->flt_sign;
+
+	/* compute new exponent */
+	e3->flt_exp = e1->flt_exp + e2->flt_exp + 1;
+
+	/* 128 bit multiply of mantissas	*/
+
+	/* assign unknown long formats		*/
+	/* to known unsigned word formats	*/
+	mp[0] = (e1->m1 >> 16) & 0xFFFF;
+	mp[1] = e1->m1 & 0xFFFF;
+	mp[2] = (e1->m2 >> 16) & 0xFFFF;
+	mp[3] = e1->m2 & 0xFFFF;
+	mc[0] = (e2->m1 >> 16) & 0xFFFF;
+	mc[1] = e2->m1 & 0xFFFF;
+	mc[2] = (e2->m2 >> 16) & 0xFFFF;
+	mc[3] = e2->m2 & 0xFFFF;
+	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;
+		long mpi = mp[i];
+		for(j=4;j--;) {
+			long tmp = (long)pres[j] + k;
+			if (mc[j]) tmp += mpi * mc[j];
+			pres[j] = tmp & 0xFFFF;
+			k = (tmp >> 16) & 0xFFFF;
+		}
+		pres[-1] = k;
+	}
+
+	if (! (result[0] & 0x8000)) {
+		e3->flt_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
+	 */
+	e3->m1 = ((long)result[0] << 16) + result[1];
+	e3->m2 = ((long)result[2] << 16) + result[3];
+	if (result[4] & 0x8000) {
+		if (++e3->m2 == 0) {
+			if (++e3->m1 == 0) {
+				e3->m1 = 0x80000000;
+				e3->flt_exp++;
+			}
+		}
+	}
+	flt_chk(e3);
+}