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Home Our Services Programming Tools Business Unit Other Tools and Utilities Development of object file converter

Development of object file converter

• Requirements
• To develop a utility that will convert IEEE695 format object file to ELF\DWARF2 object file.
• Support for customer specific IEEE695 Extensions.
• The converted object file should be compatible with GNU tools chain for the customer platform.


• Challenges
• The conversion was not straight forward. Information had to extracted from multiple places and using this the target information had to be formed. For example: Symbol size of a symbol was not a readily available information in IEEE695 format.
• Conversion of customer specific relocation to standard GNU relocation types. IEEE695 format uses expressions to represent relocation. This had to be decoded and equalent GNU relocation type had to be identified.
• Cater for loss of information in the source object file. For example : Static variable information is not available in IEEE695 format.
• Support for conversion of object files without debug information.


• Solution
• Environment

OS	Windows Linux
Language/Platform	MSVC 6.0 GCC 3.2
Development model	Waterfall model

• Features
• Support for both absolute and relocatable files.
• Support for object files with or without debug information.
• Customer specific relocation types introduced in GNU linker.
• Converted output file is compatible with GNU tool chain for the customer platform.
• Support for MIPS 32 and MIPS 16 instructions. Instruction decoding had to be done to identify the relocation types.
• Description

ELF format had more information on ths symbols and sections that the IEEE695 format. So the conversion was not really staright forward. Information had to be extracted from multiple sections and the target information had to be constructed.

In IEEE695, The relocation information was expressed in terms of expression. This expression had to be parsed and evaluated to idetify the equalent relocation type in GNU liker. For few cases we had to introduce custom relocation types in GNU tools chain to support the conversion. The converted output was tested in GDB ported for target platform.

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