Home | History | Annotate | Download | only in gdtoa 
      1 /* $NetBSD: sum.c,v 1.1.1.1.14.1 2008/04/08 21:10:55 jdc Exp $ */
      2 
      3 /****************************************************************
      4 
      5 The author of this software is David M. Gay.
      6 
      7 Copyright (C) 1998 by Lucent Technologies
      8 All Rights Reserved
      9 
     10 Permission to use, copy, modify, and distribute this software and
     11 its documentation for any purpose and without fee is hereby
     12 granted, provided that the above copyright notice appear in all
     13 copies and that both that the copyright notice and this
     14 permission notice and warranty disclaimer appear in supporting
     15 documentation, and that the name of Lucent or any of its entities
     16 not be used in advertising or publicity pertaining to
     17 distribution of the software without specific, written prior
     18 permission.
     19 
     20 LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
     21 INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
     22 IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
     23 SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
     24 WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
     25 IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
     26 ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
     27 THIS SOFTWARE.
     28 
     29 ****************************************************************/
     30 
     31 /* Please send bug reports to David M. Gay (dmg at acm dot org,
     32  * with " at " changed at "@" and " dot " changed to ".").  */
     33 #include  <LibConfig.h>
     34 
     35 #include "gdtoaimp.h"
     36 
     37  Bigint *
     38 #ifdef KR_headers
     39 sum(a, b) Bigint *a; Bigint *b;
     40 #else
     41 sum(Bigint *a, Bigint *b)
     42 #endif
     43 {
     44   Bigint *c;
     45   ULong carry, *xc, *xa, *xb, *xe, y;
     46 #ifdef Pack_32
     47   ULong z;
     48 #endif
     49 
     50   if (a->wds < b->wds) {
     51     c = b; b = a; a = c;
     52     }
     53   c = Balloc(a->k);
     54   if (c == NULL)
     55     return NULL;
     56   c->wds = a->wds;
     57   carry = 0;
     58   xa = a->x;
     59   xb = b->x;
     60   xc = c->x;
     61   xe = xc + b->wds;
     62 #ifdef Pack_32
     63   do {
     64     y = (*xa & 0xffff) + (*xb & 0xffff) + carry;
     65     carry = (y & 0x10000) >> 16;
     66     z = (*xa++ >> 16) + (*xb++ >> 16) + carry;
     67     carry = (z & 0x10000) >> 16;
     68     Storeinc(xc, z, y);
     69     }
     70     while(xc < xe);
     71   xe += a->wds - b->wds;
     72   while(xc < xe) {
     73     y = (*xa & 0xffff) + carry;
     74     carry = (y & 0x10000) >> 16;
     75     z = (*xa++ >> 16) + carry;
     76     carry = (z & 0x10000) >> 16;
     77     Storeinc(xc, z, y);
     78     }
     79 #else
     80   do {
     81     y = *xa++ + *xb++ + carry;
     82     carry = (y & 0x10000) >> 16;
     83     *xc++ = y & 0xffff;
     84     }
     85     while(xc < xe);
     86   xe += a->wds - b->wds;
     87   while(xc < xe) {
     88     y = *xa++ + carry;
     89     carry = (y & 0x10000) >> 16;
     90     *xc++ = y & 0xffff;
     91     }
     92 #endif
     93   if (carry) {
     94     if (c->wds == c->maxwds) {
     95       b = Balloc(c->k + 1);
     96       if (b == NULL)
     97         return NULL;
     98       Bcopy(b, c);
     99       Bfree(c);
    100       c = b;
    101       }
    102     c->x[c->wds++] = 1;
    103     }
    104   return c;
    105   }
    106