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Author Topic: IDA xrefs after loading a2l  (Read 2848 times)
HexTrain
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« on: August 20, 2019, 03:18:11 AM »

I got some ori files with a2l, I wrote a script to load them on IDA, and it looks like everything makes sense - the data offsets look like they are resolved correctly.

One thing that I can't understand is why there are no x-refs from the data offsets defined by the a2l from the code section.

For example, from IDA:
Code:
ROM:001C0678 05          NetMng_ctGEMOOffDec_C:.byte    5
ROM:001C0679 03          NetMng_ctGEMOOffInc_C:.byte    3
ROM:001C067A 80          NetMng_ctGEMOOffMax_C:.byte 0x80
ROM:001C067B 05          NetMng_ctGEOffDec_C:.byte    5
ROM:001C067C 03          NetMng_ctGEOffInc_C:.byte    3
ROM:001C067D 80          NetMng_ctGEOffMax_C:.byte 0x80
ROM:001C067E 05          NetMng_ctMOGEOffDec_C:.byte    5
ROM:001C067F 03          NetMng_ctMOGEOffInc_C:.byte    3

There are a lot of CHARACTERISTICs, but no x-refs at all from the code.

Does anyone know the explanation for that? how does this data reference from the code?
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daniel2345
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« Reply #1 on: August 20, 2019, 07:30:20 AM »

It does indirect addressing via custom bosch library functions.

They also differ from software project to software project.

It can be summarized like: Large function groups have an own base address which is a memory location or a register.
Access to calibration area is then done with an indirect load/move which loads base of function group and map offset. Specific functions of that function group can use 8 Bit addresses then which saves memory and calculation time.

So no easy cherry picking here Smiley
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