Merge in (early) AC3 support #808
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This reverts commit 5f7da56.
This reverts commit 399e3ea.
Previously we had a version very close to v1.8.0. This adds an extra parameter to the __RS macro, so adjust the ld-process-efm use of it to match.
Only the decode directory needs to see ld-process-efm's includes, to pick up the ezpwd library.
Make the style of the CMakeLists.txt file match the other tools -- no need to list the include files.
ats's fixes for ac3
By default, reading from cin forces cout to be flushed first (in case you've printed a prompt to cout that needs to be visible). Since these programs both read a lot of data from cin one character at a time, they were spending significant amounts of time flushing cout.
This works the same way as the existing version, but it reworks the buffer code to avoid using % on the indexes in the loop. This means that GCC can use vector instructions, and schedule the unrolled outer loop a bit more effectively. I've also replaced 320 etc. with the derivations of the constants.
This means the comparison can be done with an XOR and popcount, which is quite a bit faster. Since ld-decode is currently C++17, we can't use std::popcount yet; use the GCC/Clang intrinsic if available, otherwise use a from-scratch implementation (based on the version GCC's optimiser recognises -- it's the HAKMEM-inspired algorithm from p69 of "Hacker's Delight").
Speed up AC3 demodulator
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With many, many thanks to Staffan Ulfberg, Leighton Smallshire, Ian Smallshire, we now have a nice AC3 decoder.
(kermit) yayyyyyy!