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#include "bid_trans.h"

BID_F80_CONST_DEF( c_half,    3ffe000000000000, 0000000000000000); // 0.5

BID_TYPE0_FUNCTION_ARGTYPE1(BID_UINT64, bid64_atanh, BID_UINT64, x)

  BID_UINT64 sign_x, coefficient_x, xn, tmp, y;
  BID_UINT64 valid_x, res, one, one_m_x;
  BID_F80_TYPE xq, rq;
  int exponent_x;

  valid_x = unpack_BID64 (&sign_x, &exponent_x, &coefficient_x, x);

  if (!valid_x) {
    // test if x is NaN
if ((x & 0x7c00000000000000ull) == 0x7c00000000000000ull) {
#ifdef BID_SET_STATUS_FLAGS
  if ((x & 0x7e00000000000000ull) == 0x7e00000000000000ull)	// sNaN
    __set_status_flags (pfpsf, BID_INVALID_EXCEPTION);
#endif
	res = (coefficient_x) & QUIET_MASK64;
	BID_RETURN (res);
}
    // x is Infinity?
if ((x & 0x7800000000000000ull) == 0x7800000000000000ull) {
#ifdef BID_SET_STATUS_FLAGS
    __set_status_flags (pfpsf, BID_INVALID_EXCEPTION);
#endif
	  res = 0x7c00000000000000ull;
      BID_RETURN (res);
  }
    // x is 0
	 res = sign_x | coefficient_x;
     BID_RETURN (res);
}

	
    if(exponent_x <= DECIMAL_EXPONENT_BIAS - 24)
	{
		res = x;
		BID_RETURN (res);
	}

	// |x| 
	xn = x & 0x7fffffffffffffffull;

	// 1.0
	one = 0x31c0000000000001ull;    

	// 1 - |x|
	BIDECIMAL_CALL2 (bid64_sub, one_m_x, one, xn);

	if(one_m_x & 0x8000000000000000ull)
	{
		// |x|>1
#ifdef BID_SET_STATUS_FLAGS
    __set_status_flags (pfpsf, BID_INVALID_EXCEPTION);
#endif
	  res = 0x7c00000000000000ull;
      BID_RETURN (res);
  }

  if(!(one_m_x<<(64-53)) && ((one_m_x & SPECIAL_ENCODING_MASK64)!=SPECIAL_ENCODING_MASK64))
  {
	  // |x|==1
#ifdef BID_SET_STATUS_FLAGS
    __set_status_flags (pfpsf, BID_ZERO_DIVIDE_EXCEPTION);
#endif
	  res = sign_x | 0x7800000000000000ull;
      BID_RETURN (res);
  }

	// (2*|x|)/(1-|x|)
	BIDECIMAL_CALL2 (bid64_div, tmp, xn, one_m_x);
	BIDECIMAL_CALL2 (bid64_add, y, tmp, tmp);

	BIDECIMAL_CALL1 (bid64_to_binary80, xq, y);
	__bid_f80_log1p(rq, xq);
	__bid_f80_mul( rq,rq, c_half.v );
	BIDECIMAL_CALL1 (binary80_to_bid64, res, rq);

	res ^= sign_x;

	BID_RETURN (res);
}


