Bug

[scholtz]

There is a bug in

openfastdotnet/OpenFast/DecimalValue.cs

    public override Decimal ToBigDecimal()
    {
        return (decimal) (Mantissa/Math.Pow(10, - Exponent));
    }

It should be :
public override Decimal ToBigDecimal()
{
return (decimal) (Mantissa/Math.Pow(10, Exponent));
}

[scholtz]

After further investigating, the issue was not in function ToBigDecimal, but in initializing value from decimal value..

Test case:

[TestMethod]
        public void FromDecimalToDecimalTest()
        {
            decimal[] testValues = new decimal[] { 100.1M, 0M, -20.3M, 123456789.123456M };
            foreach (var value in testValues) {

                var val = new OpenFAST.DecimalValue(value);
                var test = val.ToBigDecimal();
                Assert.AreEqual(value, test);
            }
        }
        [TestMethod]
        public void FromDecimalToDoubleTest()
        {
            decimal[] testValues = new decimal[] { 100.1M, 0M, -20.3M, 123456789.123456M };
            foreach (var value in testValues) {

                var val = new OpenFAST.DecimalValue(value);
                var test = (decimal) Math.Round(val.ToDouble(),6);
                Assert.AreEqual(value, test);
            }
        }
        [TestMethod]
        public void FromDoubleToDecimalTest()
        {
            double[] testValues = new double[] { 100.1, 0.0, -20.3, 123456789.123456 };
            foreach (var value in testValues) {

                var val = new OpenFAST.DecimalValue(value);
                var test = Math.Round((double) val.ToBigDecimal(),6);
                Assert.AreEqual(value, test);
            }
        }
        [TestMethod]
        public void FromDoubleToDoubleTest()
        {
            double[] testValues = new double[] { 100.1, 0.0, -20.3, 123456789.123456 };
            foreach (var value in testValues) {

                var val = new OpenFAST.DecimalValue(value);
                var test = Math.Round(val.ToDouble(),6);
                Assert.AreEqual(value, test);
            }
        }

I am suggesting bugfix at line 65:

        public DecimalValue(Decimal bigDecimal)
        {
            Mantissa = Util.BigDecimalUnScaledValue(bigDecimal);
            Exponent = -1 * Util.BigDecimalScale(bigDecimal);
        }