Decoding doesn't work when compiled with mingw64

[xzn]

As titled, decoding is broken when compiled with g++ from mingw64, always complaining about invalid encoded data.

Maybe a compiler bug? Not sure what in the myriad of templates triggers it (or something else entirely..)

(clang++ or g++ with ucrt doesn't work either..)

[vbaderks]

Thanks for the report. I Will try to reproduce it. On which version of Charls and mingw64 do you see the problem?

[xzn]

g++

$ g++ --version
g++.exe (Rev5, Built by MSYS2 project) 13.1.0
Copyright (C) 2023 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE

clang

$ clang++ --version
clang version 16.0.2
Target: x86_64-w64-windows-gnu
Thread model: posix
InstalledDir: D:/Compilers/msys64/clang64/bin

To compile I used cmake -G "Unix Makefiles" in mingw64 prompt
or CC=clang CXX=clang++ cmake -G "Unix Makefiles" in clang64 prompt
Then make charlstest
Then make test
Which fails

My own attempts at using the decoding interface don't work either.

(Also just tried WinLibs MinGW-w64 distribution which has the same problem so it's likely not a problem with my mingw64 installation)

Forgot to mention the charls version:
I tried both the current main branch and the 2.x branch, both exhibit the same problem.

[xzn]

I've bisected the problem to commit 0b3ac70

Hope it helps.

[xzn]

eh why does g++ generate 32-bit bsr and mask??

This is so weird.

Edit:
nvm I just remembered that on windows long is 32-bit even on 64-bit platform, need __builtin_clzll i guess.

[xzn]

I guess this workaround will do for now ...

template<class T>
auto countl_zero(T value) noexcept -> std::enable_if_t<is_uint_v<64, T>, int>
{
    return countl_zero(static_cast<uint32_t>(value >> 32));
}

Maybe change the name of the function to countl32_zero if going with this.

Edit: this works:

diff --git a/src/util.h b/src/util.h
index ffae177..215ebd4 100644
--- a/src/util.h
+++ b/src/util.h
@@ -445,7 +445,11 @@ auto countl_zero(T value) noexcept -> std::enable_if_t<is_uint_v<64, T>, int>
     if (value == 0)
         return 64;

+#ifdef _WIN32
+    return __builtin_clzll(value);
+#else
     return __builtin_clzl(value);
+#endif
 }

 /// <summary>

[vbaderks]

commit 36807a0 resolves this problem in the main branch.
Note: using __builtin_clzll is always possible and is preferable then an extra #ifdef/#else/#endif construction.

Intend is to apply this fix to the v2.4.x branch and research if it is possible to add msys2 to the CI pipeline.

[vbaderks]

A fix for this defect has been applied to the release/2.x branch and release v2.4.2 is available.

[vbaderks]

The CI pipeline has been extended with MSYS2 to ensure that future releases are automatically verified.
Again, thanks for the report and the fix.