Imperas

Created by: eroom1966

@ross144 Hi Ross, I have refactored the code, and added a local copy of rvvi-trace, we can remove this when you have a copy of the full software.

I have created 2 do scripts to run with/without ImperasDV - but still populate the rvvi interface correctly You should be able to run an example by executing (for example)

    # Without IDV
    IMPERAS_TOOLS=$(pwd)/imperas.ic \
        OTHERFLAGS="+TRACE2LOG_ENABLE=1 VERBOSE=1" \
        TESTDIR=../../tests/riscof_lee/work/riscv-arch-test/rv64i_m/F/src/fadd_b1-01.S  \
        vsim -c -do "do wally-pipelined-imperas-no-idv.do rv64gc"

We have found some issues regarding the CSR values upon exception, we will describe these in separate issues.