Use lengthCode to determine whether to read sequenceLength again #101
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| // dHeader for inner object not written again because the object size is already specified in the emHeader and the lengthCode of 5 allows it to not be written again | ||
| writer.emHeader(true, 1, 1, 5); // pointer emHeader |
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is the reader supposed to be able to handle this both ways (length code ≥5 or <5)? If so, should we have another test which uses a length code <5?
(same applies to below test as well)
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Yeah that's correct. I'll add some more tests to account for this.
| // Special case can happen where the emHeader is not divisible by the typeLength and there is a remainder of 4 bytes. | ||
| // 4 bytes of 0's are printed after the header length | ||
| // This can happen for 8 byte typeLength types. |
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was this just wrong? or where is the sequence length getting read now?
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Yeah this was just wrong because I didn't know about the lengthCode caveat. Previously I was always using emHeader size instead of sequenceLength. This case would've arisen for when the lengthCode was <5 and the object size was less than the size of the type. So there was an emHeader object size of 4 and a sequence length. Now that I'm accounting for length code, I will read the sequenceLength earlier in the array handling because the emHeaderSize isn't being used.
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Does this end up also fixing FG-5301? |
I found an instance when the emHeader length was being used as sequenceLength when I thought that it should always print the sequenceLength in the other PR. So I looked at emheader again in the spec and found the passage above |
**User-Facing Changes** <!-- will be used as a changelog entry --> - Fix omgidl array and string reading **Description** Applies fixes in omgidl-serialization found here: foxglove/omgidl#101 Fixes: FG-5300 Fixes: FG-5301 <!-- link relevant GitHub issues --> <!-- add `docs` label if this PR requires documentation updates --> <!-- add relevant metric tracking for experimental / new features -->
Depends on: foxglove/cdr#20
In PL_CDR2 lengthCode value is used to determine whether the size specified by the emHeader can also be used as the array/string/struct length. This enables that capability.
