Comprehensive F extension support with SoftFloat integration

[visitorckw]

This PR aimed at achieving full F extension support within rv32emu. It incorporates the SoftFloat open-source library into the rv32emu project to provide comprehensive support for the F extension.

The key changes in this PR include:

1. Integrated the SoftFloat library into rv32emu, completing the F extension support within the project.
2. Introduced F extension testing in the CI pipeline, ensuring thorough validation of the implemented functionality.
3. Updated the README to correct the description of F extension support from incomplete to full support.

Close: #78

[jserv]

Is it possible to use git submodule instead of copying SoftFloat files in this repository?

[jserv]

The key changes in this PR include:

1. Integrated the SoftFloat library into rv32emu, completing the F extension support within the project.

I would like to revoke my opinion on the implementation of the RISC-V F extension. Integrating SoftFloat would achieve full compatibility and reduce maintenance efforts. There is no need to retain the original RV32F-specific code. That means the conditional build between the original and SoftFloat-specific code can be removed, and let's focus on SoftFloat.

[visitorckw]

Is it possible to use git submodule instead of copying SoftFloat files in this repository?

Currently, I've copied all files as I added additional files in the SoftFloat folder to comply with the risc-v F extension standard. Perhaps we can explore alternatives, such as copying these files into the SoftFloat directory during compilation.

[visitorckw]

I would like to revoke my opinion on the implementation of the RISC-V F extension. Integrating SoftFloat would achieve full compatibility and reduce maintenance efforts. There is no need to retain the original RV32F-specific code. That means the conditional build between the original and SoftFloat-specific code can be removed, and let's focus on SoftFloat.

Sounds like a good idea, I'll make the change later.

[jserv]

Currently, I've copied all files as I added additional files in the SoftFloat folder to comply with the risc-v F extension standard. Perhaps we can explore alternatives, such as copying these files into the SoftFloat directory during compilation.

To incorporate external source code, please refer to the Makefile and examine the sections related to mini-gdbstub. These sections contain information on how to utilize git submodule and their associated build rules.

[jserv]

Can you review src/softfloat.h and determine whether we should retain it (partially) or not?

[visitorckw]

Can you review src/softfloat.h and determine whether we should retain it (partially) or not?

We can remove the is_snan function as the softfloat library already provides the same functionality with isSignalingNaN. However, the rest of the content needs to be retained. Additionally, I'm considering whether renaming src/softfloat.h could prevent confusion.

[visitorckw]

I'm uncertain why the current code is failing the Codacy Security Scan test.

[jserv]

I'm uncertain why the current code is failing the Codacy Security Scan test.

It seems that something is wrong with Docker Hub.

[github-advanced-security]

This pull request sets up GitHub code scanning for this repository. Once the scans have completed and the checks have passed, the analysis results for this pull request branch will appear on this overview. Once you merge this pull request, the 'Security' tab will show more code scanning analysis results (for example, for the default branch). Depending on your configuration and choice of analysis tool, future pull requests will be annotated with code scanning analysis results. For more information about GitHub code scanning, check out the documentation.

[jserv]

When rv32emu is built without F extension, i.e., make ENABLE_EXT_F=0, I got the following error messages:

src/riscv.h:9:10: fatal error: softfloat/softfloat.h: No such file or directory
    9 | #include "softfloat/softfloat.h"
      |          ^~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.

[jserv]

Fix build without F extension support.

[visitorckw]

Apologies for the error. I've corrected it. It should be resolved now.

[jserv]

Thank @visitorckw for contributing!