27 lines
1.8 KiB
Markdown
27 lines
1.8 KiB
Markdown
# libasm
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## Why I did this project
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I wanted to do this project for a while because I am interested in low level programming
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and assembly seemed very interesting.
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I had a lot of fun doing it, learning about function calling conventions, x86_64 architecture
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and other things.
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## How to compile it
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To compile the project, you'll need `nasm` and `make`. Optionally, if you want to compile the tests,
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you will need `clang`.
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Once you have these requirements, simply run the command `make` and the project should compile.
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The result is a library that you can add to your project with `-L<folder> -lasm`, folder being the folder where the file `libasm.a` is located
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## test the project
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for every function asked for by the subject, there is a testing function in the file test.c
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To compile the tests run the command `make tests`. Then run the resulting executable with `./test`
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## Useful documentation
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While doing this project, since I had never programmed in x86_64 assembly before, I had to find some basic documentation.
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I mostly had trouble with remembering the order of the functions parameters in the registers, I kept going back to
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[this stackoverflow thread](https://stackoverflow.com/questions/13901261/calling-assembly-function-from-c)
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provided the order I needed. And in this thread I found information about the System V calling convention.
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During this project, I also needed to make system calls. To their parameters and numbers, I used [this page](https://blog.rchapman.org/posts/Linux_System_Call_Table_for_x86_64/) which has a table of all the system calls.
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Finally I also used [this website](https://www.felixcloutier.com/x86/) to find more info about some instructions I didn't understand. It was also a useful resource for finding the appropriate jump instructions based on my needs.
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