sum.c revision 112158 
1139743Simp/****************************************************************
243412Snewton
343412SnewtonThe author of this software is David M. Gay.
443412Snewton
543412SnewtonCopyright (C) 1998 by Lucent Technologies
643412SnewtonAll Rights Reserved
743412Snewton
843412SnewtonPermission to use, copy, modify, and distribute this software and
943412Snewtonits documentation for any purpose and without fee is hereby
1043412Snewtongranted, provided that the above copyright notice appear in all
1143412Snewtoncopies and that both that the copyright notice and this
1243412Snewtonpermission notice and warranty disclaimer appear in supporting
1343412Snewtondocumentation, and that the name of Lucent or any of its entities
1443412Snewtonnot be used in advertising or publicity pertaining to
1543412Snewtondistribution of the software without specific, written prior
1643412Snewtonpermission.
1743412Snewton
1843412SnewtonLUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
1943412SnewtonINCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
2043412SnewtonIN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
2143412SnewtonSPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
2243412SnewtonWHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
2343412SnewtonIN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
2443412SnewtonARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
2543412SnewtonTHIS SOFTWARE.
2643412Snewton
2749267Snewton****************************************************************/
2850477Speter
2943412Snewton/* Please send bug reports to
3043412Snewton	David M. Gay
3143412Snewton	Bell Laboratories, Room 2C-463
3243412Snewton	600 Mountain Avenue
3343412Snewton	Murray Hill, NJ 07974-0636
3443412Snewton	U.S.A.
3543412Snewton	dmg@bell-labs.com
3643412Snewton */
3743412Snewton
3843412Snewton#include "gdtoaimp.h"
3943412Snewton
4043412Snewton Bigint *
4143412Snewton#ifdef KR_headers
4243412Snewtonsum(a, b) Bigint *a; Bigint *b;
4343412Snewton#else
4443412Snewtonsum(Bigint *a, Bigint *b)
4543412Snewton#endif
4643412Snewton{
4743412Snewton	Bigint *c;
4843412Snewton	ULong carry, *xc, *xa, *xb, *xe, y;
4943412Snewton#ifdef Pack_32
5043412Snewton	ULong z;
5143412Snewton#endif
5243412Snewton
5343412Snewton	if (a->wds < b->wds) {
5443412Snewton		c = b; b = a; a = c;
5543412Snewton		}
5643412Snewton	c = Balloc(a->k);
5743412Snewton	c->wds = a->wds;
5843412Snewton	carry = 0;
5943412Snewton	xa = a->x;
6043412Snewton	xb = b->x;
6143412Snewton	xc = c->x;
6243412Snewton	xe = xc + b->wds;
6343412Snewton#ifdef Pack_32
6443412Snewton	do {
6543412Snewton		y = (*xa & 0xffff) + (*xb & 0xffff) + carry;
6643412Snewton		carry = (y & 0x10000) >> 16;
6743412Snewton		z = (*xa++ >> 16) + (*xb++ >> 16) + carry;
6843412Snewton		carry = (z & 0x10000) >> 16;
6943412Snewton		Storeinc(xc, z, y);
7043412Snewton		}
7143412Snewton		while(xc < xe);
7243412Snewton	xe += a->wds - b->wds;
7343412Snewton	while(xc < xe) {
7443412Snewton		y = (*xa & 0xffff) + carry;
75		carry = (y & 0x10000) >> 16;
76		z = (*xa++ >> 16) + carry;
77		carry = (z & 0x10000) >> 16;
78		Storeinc(xc, z, y);
79		}
80#else
81	do {
82		y = *xa++ + *xb++ + carry;
83		carry = (y & 0x10000) >> 16;
84		*xc++ = y & 0xffff;
85		}
86		while(xc < xe);
87	xe += a->wds - b->wds;
88	while(xc < xe) {
89		y = *xa++ + carry;
90		carry = (y & 0x10000) >> 16;
91		*xc++ = y & 0xffff;
92		}
93#endif
94	if (carry) {
95		if (c->wds == c->maxwds) {
96			b = Balloc(c->k + 1);
97			Bcopy(b, c);
98			Bfree(c);
99			c = b;
100			}
101		c->x[c->wds++] = 1;
102		}
103	return c;
104	}
105