astc-encoder: init at 2.5

[dasisdormax]

This builds the astc-encoder for the x86_64 architecture and sets
an astcenc symlink for the most compatible sse2 version.

Motivation for this change

I use the ASTC format for texture compression in a mobile game I develop with LibGDX, as it can encode alpha values and is supported by hardware on modern iOS and Android devices. This is a command line utility for converting regular images (optionally created by a texture packer) into the ASTC or KTX format.

Usage example:

• Encoding: astcenc -cl input.png compressed.astc 6x6 -medium
• Decoding: astcenc -dl compressed.astc decompressed.png

Original source on Github: https://github.com/ARM-software/astc-encoder

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

[dasisdormax]

@SuperSandro2000 Thanks for your suggestions. I added the compile settings for ARM and other platforms.

I tested the changes by cross-compiling with nix-build --arg crossSystem '(import <nixpkgs/lib>).systems.examples.aarch64-multiplatform' -A astc-encoder. This worked, but I cannot test if the binary works as intended.

[SuperSandro2000]

LGTM with this change

[risicle]

Fails to build for me, macos 10.14.

builder for '/nix/store/6a88aqmhd2gr1c4j2nqk9j85n991cb37-astc-encoder-2.5.drv' failed with exit code 2; last 10 log lines:
  [ 61%] Building CXX object Source/CMakeFiles/astcenc-sse2-static.dir/astcenc_platform_isa_detection.cpp.o
  [ 64%] Building CXX object Source/CMakeFiles/astcenc-sse2-static.dir/astcenc_quantization.cpp.o
  [ 67%] Building CXX object Source/CMakeFiles/astcenc-sse2-static.dir/astcenc_symbolic_physical.cpp.o
  [ 70%] Building CXX object Source/CMakeFiles/astcenc-sse2-static.dir/astcenc_weight_align.cpp.o
  [ 73%] Building CXX object Source/CMakeFiles/astcenc-sse2-static.dir/astcenc_weight_quant_xfer_tables.cpp.o
  [ 76%] Linking CXX static library libastcenc-sse2-static.a
  Error running link command: No such file or directory
  make[2]: *** [Source/CMakeFiles/astcenc-sse2-static.dir/build.make:464: Source/libastcenc-sse2-static.a] Error 2
  make[1]: *** [CMakeFiles/Makefile2:115: Source/CMakeFiles/astcenc-sse2-static.dir/all] Error 2
  make: *** [Makefile:171: all] Error 2

edit: I think it's trying to find ranlib.

[dasisdormax]

Thanks for noticing the build error on Mac. After installing nix and trying the build myself, I got the same problem.

I'm not sure if this is easy to fix. If not, I'll mark the package as linux-only in the meantime.

[dasisdormax]

@risicle I got the macOS build fixed by switching from stdenv to gccStdenv

[risicle]

Ah well done - I'm sure it's possible to get it working using clang but it's a bit beyond my darwin-fu.