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Mailing lists / fpc-devel / 2015-04

avr port: rtl, unit system

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Georg Hieber

Hello,

I started to implement parts of the rtl system unit for avr in assembler. First results are encouraging: fpc_move takes 29 opcodes compared to 104 of the Pascal version already optimized for the platform, and 23:150 for fpc_mul_word.

Of course, I want to be as efficient as possible in this task, and first convert routines that are either

- called often, to reduce execution time, or
- linked into most binaries, to reduce code size.

I made my own priority list, starting with the essential string routines and arithmetic helpers, but due to lack of experience I certainly overlooked things or overestimated others. So, question to everybody:

Which are according to your experience / opinion the library routines that profit most from being implemented in assembler, considering an embedded environment? (so, nothing about file I/O, system call wrappers, etc.)

Thanks for a lot of answers....

Georg

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Florian Klämpfl
to Georg Hieber
Georg Hieber wrote 20 lines
Hello, I started to implement parts of the rtl system unit for avr in assembler. First results are encouraging: fpc_move takes 29 opcodes compared to 104 of the Pascal version already optimized for the platform, and 23:150 for fpc_mul_word. Of course, I want to be as efficient as possible in this task, and first convert routines that are either - called often, to reduce execution time, or - linked into most binaries, to reduce code size. I made my own priority list, starting with the essential string routines and arithmetic helpers, but due to lack of experience I certainly overlooked things or overestimated others. So, question to everybody: Which are according to your experience / opinion the library routines that profit most from being implemented in assembler, considering an embedded environment? (so, nothing about file I/O, system call wrappers, etc.)

As you said, arithmetics and string helpers, further, "bit fiddling routines" (bsr, bsf, rol, ror, sar), fillchar and maybe the set helpers.

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