MPACT-RiscV is an implementation of an instruction set simulator for the RiscV instruction set architecture created using the MPACT-Sim simulator tools and framework, for which there are tutorials at Google for Developers.
The instruction set is described in a set of .isa files, and the instruction
encoding in a corresponding set of .bin_fmt files. The instruction semantics
are implemented in a set of of functions distributed over a large set of C++
files *_instructions.{cc,h}.
The top level simulator control is implemented in riscv_top.{cc,h}, and the
simulators are instantiated from main in rv{32,64}g_sim.cc.
MPACT-Sim utilizes the Bazel build system. The easiest
way to install bazel is to use
Bazelisk, a wrapper for Bazel that
automates selecting and downloading the right version of bazel. Use brew install bazelisk on macOS, choco install bazelisk on Windows, and on linux,
download the Bazelisk binary, add it to your PATH, then alias bazel to the
bazelisk binary.
MPACT-Sim depends on Java, so a reasonable JRE has to be installed. For macOS,
run brew install java, on linux sudo apt install default-jre, and on Windows
follow the appropriate instructions at java.com.
To build the mpact-sim libraries for x86 based processors, use the command
bazel build ...:all from the top level directory. To run the tests, use the
command bazel test ...:all.
For Apple computers with Arm64 M series chips, use bazel build --cpu=darwin_arm64 ...:all and bazel test --cpu=darwin_arm64 ...:all.
The build targets rv32g_sim and rv64g_sim provide RiscV simulators for the
32 bit and 64 bit variants of RiscV scalar architectures respectively. Decoding
and execution support for vector instructions is included, but has not been
built into these targets, though adding them to these simulators is not
particularly daunting.