/// <inheritdoc />
public override decimal Read(NpgsqlReadBuffer buf, int len, FieldDescription?fieldDescription = null)
{
var result = new DecimalRaw();
var groups = buf.ReadInt16();
var weight = buf.ReadInt16() - groups + 1;
var sign = buf.ReadUInt16();
if (sign == SignNan)
{
throw new InvalidCastException("Numeric NaN not supported by System.Decimal");
}
if (sign == SignNegative)
{
DecimalRaw.Negate(ref result);
}
var scale = buf.ReadInt16();
if (scale < 0 is var exponential && exponential)
{
scale = (short)(-scale);
}
/// <inheritdoc />
public override async ValueTask <decimal> Read(NpgsqlReadBuffer buf, int len, bool async, FieldDescription?fieldDescription = null)
{
await buf.Ensure(4 *sizeof(short), async);
var result = new DecimalRaw();
var groups = buf.ReadInt16();
var weight = buf.ReadInt16() - groups + 1;
var sign = buf.ReadUInt16();
if ((sign & SignSpecialMask) == SignSpecialMask)
{
throw sign switch
{
SignNan => new InvalidCastException("Numeric NaN not supported by System.Decimal"),
SignPinf => new InvalidCastException("Numeric Infinity not supported by System.Decimal"),
SignNinf => new InvalidCastException("Numeric -Infinity not supported by System.Decimal"),
_ => new InvalidCastException($"Numeric special value {sign} not supported by System.Decimal")
};
}
if (sign == SignNegative)
{
DecimalRaw.Negate(ref result);
}
var scale = buf.ReadInt16();
if (scale < 0 is var exponential && exponential)
{
scale = (short)(-scale);
}
else
{
result.Scale = scale;
}
if (scale > MaxDecimalScale)
{
throw new OverflowException("Numeric value does not fit in a System.Decimal");
}
var scaleDifference = exponential
? weight * MaxGroupScale
: weight * MaxGroupScale + scale;
if (groups > MaxGroupCount)
{
throw new OverflowException("Numeric value does not fit in a System.Decimal");
}
await buf.Ensure(groups *sizeof(ushort), async);
if (groups == MaxGroupCount)
{
while (groups-- > 1)
{
DecimalRaw.Multiply(ref result, MaxGroupSize);
DecimalRaw.Add(ref result, buf.ReadUInt16());
}
var group = buf.ReadUInt16();
var groupSize = DecimalRaw.Powers10[-scaleDifference];
if (group % groupSize != 0)
{
throw new OverflowException("Numeric value does not fit in a System.Decimal");
}
DecimalRaw.Multiply(ref result, MaxGroupSize / groupSize);
DecimalRaw.Add(ref result, group / groupSize);
}
else
{
while (groups-- > 0)
{
DecimalRaw.Multiply(ref result, MaxGroupSize);
DecimalRaw.Add(ref result, buf.ReadUInt16());
}
if (scaleDifference < 0)
{
DecimalRaw.Divide(ref result, DecimalRaw.Powers10[-scaleDifference]);
}
else
{
while (scaleDifference > 0)
{
var scaleChunk = Math.Min(DecimalRaw.MaxUInt32Scale, scaleDifference);
DecimalRaw.Multiply(ref result, DecimalRaw.Powers10[scaleChunk]);
scaleDifference -= scaleChunk;
}
}
}
return(result.Value);
}