Eternity II puzzle backtracker.


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Just dropping by to say I've finished an FPGA-based solver for Eternity II style tile matching puzzles. (see




It runs on the Spartan 6 LX9 @ 200 MHz with a four-stage pipeline, allowing four 'threads' to share the logic resources and work on the same puzzle at any time.


Even better than that, I can fit four of these four stage pipelines in the LX9, giving 16 threads that each can place up to 50 M tiles per second. If I use distribututed RAM for some of the smaller RAM instances I can fit 12 threads @ but at a slower clock of 160MHz. Each thread is about 10% the speed of a highly optimised software solver running on a 3.5GHz i7 core, making the total LX9 about as fast as a single i7 core.


However, it is very, very unlikely that it will ever find a solution to the puzzle - even at > 100 million search nodes per second it takes a very long time to brute-force the the estimated 10^52 search nodes.







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TIme has expired. Working on Eternity 2 was what got me started looking at FPGAs, I always thought that it would be a dead end, but I now aim aiming 48 threads running at 200MHz on a LX9 - If it works it it will do as much work per second as an eigth i7 cores.

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