105 lines
2.6 KiB
C
105 lines
2.6 KiB
C
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/* $NetBSD: sum.c,v 1.2 2008/03/21 23:13:48 christos Exp $ */
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/****************************************************************
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The author of this software is David M. Gay.
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Copyright (C) 1998 by Lucent Technologies
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All Rights Reserved
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Permission to use, copy, modify, and distribute this software and
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its documentation for any purpose and without fee is hereby
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granted, provided that the above copyright notice appear in all
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copies and that both that the copyright notice and this
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permission notice and warranty disclaimer appear in supporting
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documentation, and that the name of Lucent or any of its entities
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not be used in advertising or publicity pertaining to
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distribution of the software without specific, written prior
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permission.
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LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
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INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
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IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
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SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
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IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
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ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
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THIS SOFTWARE.
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****************************************************************/
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/* Please send bug reports to David M. Gay (dmg at acm dot org,
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* with " at " changed at "@" and " dot " changed to "."). */
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#include "gdtoaimp.h"
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Bigint *
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#ifdef KR_headers
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sum(a, b) Bigint *a; Bigint *b;
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#else
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sum(Bigint *a, Bigint *b)
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#endif
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{
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Bigint *c;
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ULong carry, *xc, *xa, *xb, *xe, y;
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#ifdef Pack_32
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ULong z;
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#endif
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if (a->wds < b->wds) {
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c = b; b = a; a = c;
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}
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c = Balloc(a->k);
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if (c == NULL)
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return NULL;
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c->wds = a->wds;
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carry = 0;
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xa = a->x;
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xb = b->x;
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xc = c->x;
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xe = xc + b->wds;
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#ifdef Pack_32
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do {
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y = (*xa & 0xffff) + (*xb & 0xffff) + carry;
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carry = (y & 0x10000) >> 16;
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z = (*xa++ >> 16) + (*xb++ >> 16) + carry;
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carry = (z & 0x10000) >> 16;
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Storeinc(xc, z, y);
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}
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while(xc < xe);
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xe += a->wds - b->wds;
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while(xc < xe) {
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y = (*xa & 0xffff) + carry;
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carry = (y & 0x10000) >> 16;
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z = (*xa++ >> 16) + carry;
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carry = (z & 0x10000) >> 16;
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Storeinc(xc, z, y);
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}
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#else
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do {
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y = *xa++ + *xb++ + carry;
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carry = (y & 0x10000) >> 16;
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*xc++ = y & 0xffff;
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}
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while(xc < xe);
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xe += a->wds - b->wds;
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while(xc < xe) {
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y = *xa++ + carry;
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carry = (y & 0x10000) >> 16;
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*xc++ = y & 0xffff;
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}
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#endif
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if (carry) {
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if (c->wds == c->maxwds) {
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b = Balloc(c->k + 1);
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if (b == NULL)
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return NULL;
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Bcopy(b, c);
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Bfree(c);
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c = b;
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}
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c->x[c->wds++] = 1;
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}
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return c;
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}
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