public static BID_UINT64 get_BID64_UF()

in csharp/EPAM.Deltix.DFP/DotNetReImpl.cs [996:1098]

• 77 lines of code
• 30 McCabe index (conditional complexity)

		public static BID_UINT64 get_BID64_UF(BID_UINT64 sgn, int expon, BID_UINT64 coeff, BID_UINT64 R, int rmode, ref uint fpsc)
		{
			BID_UINT128 C128, Q_low, Stemp;
			BID_UINT64 _C64, remainder_h, QH, carry, CY;
			int extra_digits, amount, amount2;
			uint status;

			// underflow
			if (expon + MAX_FORMAT_DIGITS < 0)
			{
				__set_status_flags(ref fpsc, BID_UNDERFLOW_EXCEPTION | BID_INEXACT_EXCEPTION);
				if (rmode == BID_ROUNDING_DOWN && sgn != 0)
					return 0x8000000000000001UL;
				if (rmode == BID_ROUNDING_UP && sgn == 0)
					return 1UL;
				// result is 0
				return sgn;
			}
			// 10*coeff
			coeff = (coeff << 3) + (coeff << 1);
			if (sgn != 0 && (uint)(rmode - 1) < 2)
				rmode = 3 - rmode;
			if (R != 0)
				coeff |= 1;
			// get digits to be shifted out
			extra_digits = 1 - expon;
			C128.w0 = coeff + bid_round_const_table[rmode, extra_digits];

			// get coeff*(2^M[extra_digits])/10^extra_digits
			__mul_64x128_full(out QH, out Q_low, C128.w0, bid_reciprocals10_128[extra_digits]);

			// now get P/10^extra_digits: shift Q_high right by M[extra_digits]-128
			amount = bid_recip_scale[extra_digits];

			_C64 = QH >> amount;
			//__shr_128(C128, Q_high, amount);

			if (rmode == 0) //BID_ROUNDING_TO_NEAREST
				if ((_C64 & 1) != 0)
				{
					// check whether fractional part of initial_P/10^extra_digits is exactly .5

					// get remainder
					amount2 = 64 - amount;
					remainder_h = 0;
					remainder_h--;
					remainder_h >>= amount2;
					remainder_h = remainder_h & QH;

					if (remainder_h == 0
					&& (Q_low.w1 < bid_reciprocals10_128[extra_digits].w1
						|| (Q_low.w1 == bid_reciprocals10_128[extra_digits].w1
						&& Q_low.w0 < bid_reciprocals10_128[extra_digits].w0)))
					{
						_C64--;
					}
				}


			if (is_inexact(fpsc))
				__set_status_flags(ref fpsc, BID_UNDERFLOW_EXCEPTION);
			else
			{
				status = BID_INEXACT_EXCEPTION;
				// get remainder
				remainder_h = QH << (64 - amount);

				switch (rmode)
				{
					case BID_ROUNDING_TO_NEAREST:
					case BID_ROUNDING_TIES_AWAY:
						// test whether fractional part is 0
						if (remainder_h == 0x8000000000000000UL
						&& (Q_low.w1 < bid_reciprocals10_128[extra_digits].w1
							|| (Q_low.w1 == bid_reciprocals10_128[extra_digits].w1
							&& Q_low.w0 < bid_reciprocals10_128[extra_digits].w0)))
							status = BID_EXACT_STATUS;
						break;
					case BID_ROUNDING_DOWN:
					case BID_ROUNDING_TO_ZERO:
						if (remainder_h == 0
						&& (Q_low.w1 < bid_reciprocals10_128[extra_digits].w1
							|| (Q_low.w1 == bid_reciprocals10_128[extra_digits].w1
							&& Q_low.w0 < bid_reciprocals10_128[extra_digits].w0)))
							status = BID_EXACT_STATUS;
						break;
					default:
						// round up
						__add_carry_out(out Stemp.w0, out CY, Q_low.w0, bid_reciprocals10_128[extra_digits].w0);
						__add_carry_in_out(out Stemp.w1, out carry, Q_low.w1, bid_reciprocals10_128[extra_digits].w1, CY);
						if ((remainder_h >> (64 - amount)) + carry >= (((BID_UINT64)1) << amount))
							status = BID_EXACT_STATUS;
						break;
				}

				if (status != BID_EXACT_STATUS)
					__set_status_flags(ref fpsc, BID_UNDERFLOW_EXCEPTION | status);
			}


			return sgn | _C64;

		}