adding GNU dc ("desk calculator")

[unix-history] / gnu / usr.bin / gcc1 / gnulib / longlong / adddi3.c

#include "longlong.h"

static int badd ();

long long 
__adddi3 (u, v)
    long long u, v;
{
 long a[2], b[2], c[2];
 long_long w;
 long_long uu, vv;

 uu.ll = u;
 vv.ll = v;

 a[HIGH] = uu.s.high;
 a[LOW] = uu.s.low;
 b[HIGH] = vv.s.high;
 b[LOW] = vv.s.low;

 badd (a, b, c, sizeof c);

 w.s.high = c[HIGH];
 w.s.low = c[LOW];
 return w.ll;
}

static int 
badd (a, b, c, n)
    unsigned short *a, *b, *c;
    size_t n;
{
 unsigned long acc;
 int i;

 n /= sizeof *c;

 acc = 0;
 for (i = little_end (n); is_not_msd (i, n); i = next_msd (i))
   {
     /* Widen before adding to avoid loss of high bits.  */
     acc += (unsigned long) a[i] + b[i];
     c[i] = acc & low16;
     acc = acc >> 16;
   }
 return acc;
}