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Re: Help with Decode Re: Decimals
jason braswell / Chopper Trading <>
15 Feb 2010 11:30AM ET OK, I understand now. I was thinking there was a difference between a value being null and it being empty. In particular, I was assuming it could only be null if a null value was actually sent on the wire.
Got it. Thanks.
> Hi Jason,
>
> From your post:
>
> My problem is that for the very last field, tag 451, there is no initial
> value in the template for the exponent. Also, if I'm reading it
> correctly, the pmap bit is turned off for this field (because all pmaps
> end with an infinite string of zeros).
> >> This is correct.
>
> This means the exponent can't be null, which means I'm supposed to read
> the mantissa.
> >> This is incorrect. In your template exponent is Optional Default
> >> filed which means it can be null. (Please review the Table 3.2 on
> >> this page http://jettekfix.com/node/47)
> In your case exponent is null (as does not present in the stream and
> does not have initial value). (http://jettekfix.com/node/76) So if
> exponent is null we does not decode mandatory field at all. The null
> decoded value of Exponent means null of complex decimal value. (Please
> read the notes after the image 3.20 on this page
> http://jettekfix.com/node/58)
>
> In such case your table should look like:
>
> 11110011 Pmap 10110000 MandatoryDefault EntryType(269) Y 10000001
> OptionalDefault PriceExp(270) Y 01111110 11100010 MandatoryDelta
> PriceMant(270) N/A 10001011 OptionalDelta EntrySize(271) N/A 10000000
> OptionalDefault QuoteCond(276) Y OptionalConstant TradeCond(277) N
> OptionalCopy PriceLevel(1023) N 10000010 OptionalCopy NumOrders(346) Y
> 10000000 OptionalDefault TradingSessID(277) Y OptionalDelta
> TradeVol(1020) N OptionalDefault Tick Direction(274) N OptionalDefault
> NetChangeExp(451) N MandatoryDelta NetChangeMantissa(451) N/A 10000000
> (Should be next Pmap)
>
> 11110101 (the first field in the fields group)
> ____________________
> Best regards, Roman
>
> > I've read the other threads dealing with decimals and pmaps, but I'm
> > still stumped with a recent decode problem. Below is a snippet of
> > production data that I tried to parse the other day; it's the first
> > element of a sequence. The bits are on the left, and my reading of the
> > pmap status is on the far right.
> >
> > My problem is that for the very last field, tag 451, there is no
> > initial value in the template for the exponent. Also, if I'm reading
> > it correctly, the pmap bit is turned off for this field (because all
> > pmaps end with an infinite string of zeros). This means the exponent
> > can't be null, which means I'm supposed to read the mantissa. However,
> > as you can see, it appears that the mantissa field is lined up with
> > what looks like a null value on the wire. Even if it's not a null
> > value, just a zero value, what can I do with a decimal that has no
> > exponent? I'm thinking I *must* be reading that first pmap
> > incorrectly.
> >
> > Help would be greatly appreciated. Thanks.
> >
> > 11110011 Pmap 10110000 MandatoryDefault EntryType(269) Y 10000001
> > OptionalDefault PriceExp(270) Y 01111110 11100010 MandatoryDelta
> > PriceMant(270) N/A 10001011 OptionalDelta EntrySize(271) N/A 10000000
> > OptionalDefault QuoteCond(276) Y OptionalConstant TradeCond(277) N
> > OptionalCopy PriceLevel(1023) N 10000010 OptionalCopy NumOrders(346) Y
> > 10000000 OptionalDefault TradingSessID(277) Y OptionalDelta
> > TradeVol(1020) N OptionalDefault Tick Direction(274) N OptionalDefault
> > NetChangeExp(451) N 10000000 MandatoryDelta NetChangeMantissa(451) N/A
> > 11110101 (Should be next Pmap)
Re: Help with Decode Re: Decimals
jason braswell / Chopper Trading 15 Feb 2010 11:30AM ET
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