Function xsum_small_div_unsigned

xs/sources/xsum.c:2033–2186

/* FIND RESULT OF DIVIDING SMALL ACCUMULATOR BY UNSIGNED INTEGER. */

xsum_flt xsum_small_div_unsigned
           (xsum_small_accumulator *restrict sacc, unsigned div)
{
  xsum_flt result;
  unsigned rem;
  double fltv;
  int sign;
  int i, j;

  if (xsum_debug) c_printf("\nDIVIDE SMALL ACCUMULATOR BY UNSIGNED INTEGER\n");

  /* Return NaN or an Inf if that's what's in the superaccumulator. */

  if (sacc->NaN != 0)
  { COPY64(fltv, sacc->NaN);
    return fltv;
  }

  if (sacc->Inf != 0)
  { COPY64 (fltv, sacc->Inf);
    return fltv;
  }

  /* Make a copy of the superaccumulator, so we can change it here without
     changing *sacc. */

  xsum_small_accumulator tacc = *sacc;

  /* Carry propagate in the temporary copy of the superaccumulator.
     Sets 'i' to the index of the topmost nonzero chunk. */

  i = xsum_carry_propagate(&tacc);

  /* Check for division by zero, and if so, return +Inf, -Inf, or NaN,
     depending on whether the superaccumulator is positive, negative,
     or zero. */

  if (div == 0)
  { if (xsum_debug)
    { c_printf("divide by zero, top chunk has index %d, value %lld\n",
              i, tacc.chunk[i]);
    }
    return tacc.chunk[i] > 0 ? INFINITY : tacc.chunk[i] < 0 ? -INFINITY : NAN;
  }

  /* Record sign of accumulator, and if it's negative, negate and
     re-propagate so that it will be positive. */

  sign = +1;

  if (tacc.chunk[i] < 0)
  { xsum_small_negate(&tacc);
    i = xsum_carry_propagate(&tacc);
    if (xsum_debug)
    { c_printf("Negated accumulator to make it non-negative\n");
      if (tacc.chunk[i] < 0) c_abort();
    }
    sign = -1;