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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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} |