Upstreaming utilities to chisel3

[ducky64]

This has been talked about on and off for quite a while now, but some of the utilities in rocket-chip, like the async FIFOs, are quite general and would be good candidates for inclusion in a chisel standard library, which is being discussed in freechipsproject/chisel3#818

I'd just like to get thoughts from the rocket people about including these in a chisel standard library, which other parts could be useful to include, and how it could be done.

[hcook]

In approximate order from you-really-ought-to down through might-be-nice-to-have:

Better muxing logic for literal constants: https://github.com/freechipsproject/rocket-chip/blob/master/src/main/scala/util/MuxLiteral.scala

Collections where every element is the same type but differently parameterized: https://github.com/freechipsproject/rocket-chip/blob/master/src/main/scala/util/HeterogeneousBag.scala

All these implicit classes should have their methods added to the original Chisel class (IMO): https://github.com/freechipsproject/rocket-chip/blob/master/src/main/scala/util/package.scala

Async reset registers (but perhaps reimplemented to use parameterized black boxes): https://github.com/freechipsproject/rocket-chip/blob/master/src/main/scala/util/AsyncResetReg.scala

PRNG generation in HW (@seldridge mentioned his own version in the chisel issue): https://github.com/freechipsproject/rocket-chip/blob/master/src/main/scala/util/LCG.scala https://github.com/freechipsproject/rocket-chip/blob/master/src/main/scala/util/Frequency.scala https://github.com/freechipsproject/rocket-chip/blob/master/src/main/scala/util/Misc.scala

Various other helper objects from this miscellaneous file: https://github.com/freechipsproject/rocket-chip/blob/master/src/main/scala/util/Misc.scala

[codelec]

an optimized 2-entry fluid queue https://github.com/masc-ucsc/fluid/blob/master/src/main/scala/elastic-reg.scala

update: just figured out ShiftQueue(rocket-chip) is faster than ElasticReg using qflow(gscl45nm)

[edcote]

I vote for Diplomacy.

[sequencer]

diplomacy is ongoing! splitting rocket utils to chisel3 standard lib is certainly on its way. we need a concrete plan on doing this.