* Use memchr to find '\r'
* Lock stdin/stdout
* Refactor to use a wrapper type around Read instances, which replaces
'\r' with '\n'
* Refactor to use std lib LineWriter to automatically flush on newline
* Use std::io::copy to fully copy from stdin to stdout
* Add some sm...
* Avoid heap allocations when possible
* Refactor out a function to calculate the u64 hash value from a nonce
* When a value is returned, cancel the other threads, so they don't each
continue to try to find a solution
I used the blur renderscript intrinsic, which is very fast (see [here](http://android-developers.blogspot.com/2013/08/renderscript-intrinsics.html)). It does use a Gaussian blur though, which reacts differently with alpha than your implementation.