https://github.com/7sageer/c2rars

The project is of narrow use unless you are mad in debugging RISC-V assembly code in RARS. It is a simple solution to convert C code to RISC-V assembly code that can run in RARS.
https://github.com/7sageer/c2rars

clang rars riscv32

Last synced: 21 days ago
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The project is of narrow use unless you are mad in debugging RISC-V assembly code in RARS. It is a simple solution to convert C code to RISC-V assembly code that can run in RARS.

• Host: GitHub
• URL: https://github.com/7sageer/c2rars
• Owner: 7Sageer
• Created: 2024-04-05T12:32:36.000Z (8 months ago)
• Default Branch: main
• Last Pushed: 2024-06-02T16:38:34.000Z (6 months ago)
• Last Synced: 2024-10-12T13:09:43.612Z (about 1 month ago)
• Topics: clang, rars, riscv32
• Language: C
• Homepage:
• Size: 6.84 KB
• Stars: 3
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: readme.md

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README

        
# C2RARS: A solution to solve the problem of C to RISC-V in RARS

**Warning** : The project is still in an early stage. But it is already possible to do the conversion of simple programs. Such like your lab assignments in OJ.

The project is of narrow use **unless** you are mad in debugging RISC-V assembly code in RARS. It is a simple solution to convert C code to RISC-V assembly code that can run in RARS.

## Usage

Firstly, you should install riscv64-unknown-elf-gcc. You can install it by the following command in Ubuntu:

``` bash

sudo apt-get install gcc-riscv64-unknown-elf

```

Or you prefer riscv32-unknown-elf-gcc, you can clone and compile it by the following command(although it could take 1-2 hours):

``` bash

git clone https://github.com/riscv/riscv-gnu-toolchain

cd riscv-gnu-toolchain

git submodule update --init --recursive

./configure --prefix=/opt/riscv --with-arch=rv32gc --with-abi=ilp32d

sudo make

```

Go to https://github.com/riscv-collab/riscv-gnu-toolchain to find more information.

If you are using Windows, you are highly recommended to use WSL.

Write your code in C, download and include `syscall.h` in your code. **Remember don't use std library in your code** such as `printf`, `scanf`, etc. Instead, you need to use the function in `syscall.h`. At the end of your C code, you should add `exit_program()` to make sure the program can exit correctly.

Up to now, you can use the following functions:

`read_int()`

`print_int(int value)`

`read_double()`

`print_double(double value)`

`read_str(char *buf, int len)`

`print_str(char* str)`

`exit_program()`

You can edit `syscall.h` to customize your own functions.

You can find a simple example in `fib.c`, which can calculate the Fibonacci number.

Then you can compile your code by the following command:

``` bash

riscv64-unknown-elf-gcc -S fib.c

```

or you are using riscv32-unknown-elf-gcc:

``` bash

riscv32-unknown-elf-gcc -S fib.c

```

Check the generated `fib.s` file, which contains the RISC-V assembly code that could directly run in RARS. Wow!

## How it works

The toolchain is based on the `riscv32-unknown-elf-gcc`. It will compile the C code into RISC-V assembly code. The generated assembly code couldn't run in RARS directly. So some modifications need to be done to make it run in RARS.

Since RARS is not supporting the std library, so I replace the function in the std library with the function in `syscall.h` by inline assembly of `ecall`.

RARS won't call the `main` function by default. So I add a `start` function to call the `main` function in the C code.