@hackage bits-extras0.1.2

This package contains efficient implementations of high-level bit operations missing from Data.Bits. The implementation is based on GCC builtins, which translate to specialized instructions where available.

All operations in this package can also be (less efficiently) implemented in terms of Data.Bits operations.

Issues: A GCC-provided library, libgcc_s, is dynamically linked to provide software fallbacks on architectures without instructions corresponding to specific operations. This is currently only expected to work on Linux systems, and even there can lead to issues with GHCi's custom linker. A workaround for GHCi on a linux system: ln -s /lib/libgcc_s.so.1 /lib/libgcc_s.so.

The current plan for broader support is to replace the libgcc dependency with built-in fallbacks in C or Haskell code. This needs to closely follow GCC's fall-back behaviour for each architecture. Alternative ideas would be appreciated.

Relevant Hackage tickets:

• http://hackage.haskell.org/trac/ghc/ticket/3563

• http://hackage.haskell.org/trac/ghc/ticket/4102