#10: Edited instruction struct and introduce decoder (#32)

Basic decoder
Closes #10
Decoder something like skeleton.
I added opcodes from basic commands: RV32I and RV64I acording to pages
130-131 (148-149) of [RISCV ISA
specification](https://github.com/riscv/riscv-isa-manual/releases/download/Ratified-IMAFDQC/riscv-spec-20191213.pdf)

.gitignore

@@ -11,3 +11,5 @@ cmake-build-debug
 
 # autogen files
 include/besm-666/autogen/*
+!include/besm-666/autogen/opcodes-to-format.hpp
+!include/besm-666/autogen/operations-matrix.hpp

include/besm-666/autogen/opcodes-to-format.hpp

@@ -0,0 +1,29 @@
+#pragma once
+
+#include "operations-matrix.hpp"
+#include <cstdint>
+
+namespace besm::dec {
+
+// @todo #10:90m Generate this file with matrix instead of copypaste from the
+// current raw generator.
+
+constexpr static uint8_t OPCODE2FORMAT[128] = {
+    ILLEGAL, ILLEGAL, ILLEGAL, I,       ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL,
+    ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, I,
+    ILLEGAL, ILLEGAL, ILLEGAL, I,       ILLEGAL, ILLEGAL, ILLEGAL, U,
+    ILLEGAL, ILLEGAL, ILLEGAL, I,       ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL,
+    ILLEGAL, ILLEGAL, ILLEGAL, S,       ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL,
+    ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL,
+    ILLEGAL, ILLEGAL, ILLEGAL, R,       ILLEGAL, ILLEGAL, ILLEGAL, U,
+    ILLEGAL, ILLEGAL, ILLEGAL, R,       ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL,
+    ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL,
+    ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL,
+    ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL,
+    ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL,
+    ILLEGAL, ILLEGAL, ILLEGAL, B,       ILLEGAL, ILLEGAL, ILLEGAL, I,
+    ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, J,
+    ILLEGAL, ILLEGAL, ILLEGAL, I,       ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL,
+    ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL, ILLEGAL};
+
+} // namespace besm::dec