How are decimal (number with decimal point) values expressed in a binary file?

["Costello, Roger L." <co...@mitre.org>]

Hello DFDL community,

Scenario: The book cost is: 19.95

The book data is in binary.

How is 19.95 expressed in binary?

How would the cost be expressed in a DFDL schema? Simply this:

<xs:element name="cost" type="decimal" />

/Roger

Re: How are decimal (number with decimal point) values expressed in a binary file?

[Steve Lawrence <sl...@apache.org>]

If the type were xs:float or xs:double, then the dfdl:binaryFloatRep
property defines how binary is converted to a number. Daffodil currently
only supports "ieee", which is IEEE 754-1985 floating point
representation. And byte lengths must be 4 for xs:float or 8 for xs:double.

Things are a bit different for xs:decimal. In that case, we parse the
number of bits as an integer (based on the dfdl:binaryNumberRep
property), and then move the decimal point of that integer base on the
value of dfdl:binaryDecimalVirtualPoint.

So in your example, let's say your field length was 2 bytes and
dfdl:binaryNumberRep="binary" (i.e. two's complement). In order to get a
value of 19.95, your data would contain the bytes 0x07CB (1995 in two's
complement binary) and you'd have dfdl:binaryDecimalVirtualPoint="2" to
move the decimal point two places to the left.


On 9/30/19 7:19 AM, Costello, Roger L. wrote:
> Hello DFDL community,
> 
> Scenario: The book cost is: 19.95
> 
> The book data is in binary.
> 
> How is 19.95 expressed in binary?
> 
> How would the cost be expressed in a DFDL schema? Simply this:
> 
> <xs:element name="cost" type="decimal" />
> 
> /Roger
>