Instructions and Extensions
===========================

In order to analyze the complete ISA (Instruction Set Architecture) the tool parses the instr_dict.json provided by RISCV.

A default copy is provided with the install, however the user can override with a local copy:

.. code-block:: bash

    avl-riscv-coverage --ref <PATH TO instr_dict.json>

Once parsed all available instruction encodings are available in the :any:`_isa.ISA` dict.

This is indexed by the string mnemonic of the instruction encoding and in the :any:`_isa.Encoding` format. The :any:`_isa.Encoding` \
class provides the function to extract the exact instruction, including operands, from a given encoding value.

Initially all possible encodings are captured, for all extensions and bases. However, once the elf has been parsed this is reduced \
to the available set compiled for the given application.
This is to reduce the scope, allowing the user to generate coverage specific to the subset of extensions for their given implementation.