I'll PM you a link to my C code for logic reduction in a few mins. You can compile C right? And know how to code? It should be quite a bit faster than Mathmatica or Maple.
It uses de Morgan's rules and some basic reduction rules to optimize the circuit.
It uses de Morgan's rules and some basic reduction rules to optimize the circuit.
This is excellent by the way
I will start integrating with my code. Right now my stuff is all C#, so I will have to compile your code into a lib and do marshaling - though at first glance of your API I don't think marshaling will have too bad of a perf impact. I'll try with c=a+b to test the runtime and validate the results match yours. Do you know how your de Morgan approach compares to this Quine McCluskey one I keep reading about? http://en.wikipedia.org/wiki/Quine%E2%80%93McCluskey_algorithm
Quine-McCluskey is the analytical twin of Karnaugh Maps (http://en.wikipedia.org/wiki/Karnaugh_map)
Basically, QMC/KMap takes I/O and creates formulas. My lib lets you build the formulas directly and simplify them. You *could* create the formulas based on I/Os I guess. But since we know the SHA-256 formulas you could skip that step.
In fact you really want to, otherwise you will never have the correct formula unless you iterate all possible inputs for the SHA256 compression function (2^256 + 2^(W-array inputs) ).
Even 2^32 addition is going to be massive. The nth (0..31) output bit of 32bit-add will be 2^(n+1) terms long. You're only hope is multiple 32bit-adds start simplifying.
Download logred_v3.zip - there was a bug in performing (A+BCD+EFG+...)(HI+!JK+...)(...)... operations.
Cheers
Edit:
Playing a bit here, turns out the A=A+AB and A+B=A+!AB reductions have no effect in 32bit add. Guess that's what makes it a nice 32bit bijection.
Download logred_v4.zip which will be faster for your application.
You can disable those reduction algorithms by commenting out logred_set_reduce_2_A_AB() and logred_set_reduce_4_A_nAB_n() inside logred_set_reduce()