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https://issues.apache.org/jira/browse/DAFFODIL-2353?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Dave Thompson closed DAFFODIL-2353.
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Verified the specified commit (commit 098bb66fc44da51e7fabbc0eff178e1a7cafc8df)
is included in the latest pull from the daffodil repository.
Verified changes identified in commit comment were implemented.
Verified all affected daffodil sub-project sbt test suites execute
successfully, including the added tests.
Verified the nightly test schemas compile and save successfully.
Verified the nightly test suite executes successfully.
> long to double function - for preserving binary data floating point precision
> -----------------------------------------------------------------------------
>
> Key: DAFFODIL-2353
> URL: https://issues.apache.org/jira/browse/DAFFODIL-2353
> Project: Daffodil
> Issue Type: Bug
> Components: Back End
> Affects Versions: 2.6.0
> Reporter: Mike Beckerle
> Assignee: Min Phyo Aung
> Priority: Major
> Labels: beginner
> Fix For: 3.2.0
>
>
> Conversion to base 10 is required for XML, and that means floating point
> numbers converted from binary to base 10 are going to lose information
> sometimes vs. their binary IEEE 754 or other representation.
> But.... We or a user via UDF could provide a conversion function
> hexBinaryToDouble, then you could get something like this:
> <myValue>
> <ieeeHex>40FE208000000000</ieeeHex>
> <value>1.234e5</value>
> </myValue>
> The <value> element is there to exhibit the value in a human-understandable
> way, but the parsing would actually unparse from the raw ieeeHex element
> which is a hex dump of the actual value bits.
> On unparsing, if the base 10 value has been modified, and no longer matches
> the base-10 equivalent of the raw value, then the binary data could be
> recomputed from the new base 10 value.
> Due to big/little endian issues, we probably want to do this from 64-bit
> integers, not hexBinary. That way the conversion functions are byte order
> independent.
> Note about EXI (DAFFODIL-1959) - if we are converting data from binary to EXI
> representation or back for unparsing, it would be great if no conversion to
> base 10 text was required. This raises an issue however, of a different DFDL
> schema being appropriate when using EXI vs. when using XML text (or any other
> base-10 text representation).
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