#include "libm.h"

#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
long double hypotl(long double x, long double y) {
  return hypot(x, y);
}
#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
#if LDBL_MANT_DIG == 64
#define SPLIT (0x1p32L + 1)
#elif LDBL_MANT_DIG == 113
#define SPLIT (0x1p57L + 1)
#endif

static void sq(long double* hi, long double* lo, long double x) {
  long double xh, xl, xc;
  xc = x * SPLIT;
  xh = x - xc + xc;
  xl = x - xh;
  *hi = x * x;
  *lo = xh * xh - *hi + 2 * xh * xl + xl * xl;
}

long double hypotl(long double x, long double y) {
  union ldshape ux = {x}, uy = {y};
  int ex, ey;
  long double hx, lx, hy, ly, z;

  ux.i.se &= 0x7fff;
  uy.i.se &= 0x7fff;
  if (ux.i.se < uy.i.se) {
    ex = uy.i.se;
    ey = ux.i.se;
    x = uy.f;
    y = ux.f;
  } else {
    ex = ux.i.se;
    ey = uy.i.se;
    x = ux.f;
    y = uy.f;
  }

  if (ex == 0x7fff && isinf(y))
    return y;
  if (ex == 0x7fff || y == 0)
    return x;
  if (ex - ey > LDBL_MANT_DIG)
    return x + y;

  z = 1;
  if (ex > 0x3fff + 8000) {
    z = 0x1p10000L;
    x *= 0x1p-10000L;
    y *= 0x1p-10000L;
  } else if (ey < 0x3fff - 8000) {
    z = 0x1p-10000L;
    x *= 0x1p10000L;
    y *= 0x1p10000L;
  }
  sq(&hx, &lx, x);
  sq(&hy, &ly, y);
  return z * sqrtl(ly + lx + hy + hx);
}
#endif