feat(furvm): introduce global variables

Closes: #59

furvm/include/furvm/instruction.hpp

@@ -21,6 +21,7 @@ struct instruction_argument {
         Constant,
         Type,
         Variable,
+        GlobalVariable,
         Function,
         Offset,
 
@@ -78,6 +79,8 @@ struct instruction {
         Lengthof,
         Load,
         Store,
+        LoadGlobal,
+        StoreGlobal,
         Call,
         Jump,
         JumpNotZero,

furvm/include/furvm/module.hpp

@@ -6,10 +6,14 @@
 #include "furvm/function.hpp"
 #include "furvm/fwd.hpp"
 #include "furvm/handle.hpp"
+#include "furvm/thing.hpp"
 
 #include <functional>
 #include <istream>
+#include <limits>
+#include <optional>
 #include <ostream>
+#include <stdexcept>
 #include <string>
 #include <type_traits>
 #include <unordered_map>
@@ -348,6 +352,33 @@ public:
     }
 
     const handle_container<mod_type_h>& types() const { return m_types; }
+public:
+    void set_global_variable_count(std::uint16_t count) {
+        m_globalVariables.resize(count);
+        m_globalVariables.shrink_to_fit();
+    }
+
+    std::uint16_t get_global_variable_count() const { return static_cast<std::uint16_t>(m_globalVariables.size()); }
+
+    void store_global_variable(std::uint16_t var, thing<>&& thing) {
+        if (var >= m_globalVariables.size()) throw std::runtime_error("invalid slot");
+        m_globalVariables.emplace(m_globalVariables.cbegin() + var, std::move(thing));
+    }
+
+    void store_global_variable(std::uint16_t var, const thing<>& thing) {
+        if (var >= m_globalVariables.size()) throw std::runtime_error("invalid slot");
+        m_globalVariables.emplace(m_globalVariables.cbegin() + var, thing);
+    }
+
+    thing<>& load_global_variable(std::uint16_t var) {
+        if (var >= m_globalVariables.size()) throw std::runtime_error("invalid slot");
+        return m_globalVariables[var];
+    }
+
+    const thing<>& load_global_variable(std::uint16_t var) const {
+        if (var >= m_globalVariables.size()) throw std::runtime_error("invalid slot");
+        return m_globalVariables[var];
+    }
 public:
     /**
      * @brief Prints the module in a bytecode form to an output stream.
@@ -376,6 +407,8 @@ private:
 
     handle_container<mod_type_h> m_types;
 
+    std::vector<thing<>> m_globalVariables;
+
     std::unordered_map<std::string, native_function> m_nativeFunctions;
 };
 

furvm/src/executor.cpp

@@ -326,6 +326,12 @@ void executor::step() {
     case instruction_t::Store: {
         store_thing(instr.arg.u16, std::move(pop_thing()));
     } break;
+    case instruction_t::LoadGlobal: {
+        push_thing(make_reference(frame.mod->load_global_variable(instr.arg.u16)));
+    } break;
+    case instruction_t::StoreGlobal: {
+        frame.mod->store_global_variable(instr.arg.u16, std::move(pop_thing()));
+    } break;
     case instruction_t::Call: {
         push_frame(frame.mod, *frame.mod->function_at(instr.arg.u16));
     } break;

furvm/src/instruction.cpp

@@ -27,6 +27,8 @@ const std::size_t instruction_argument::s_sizes[instruction_argument::Count] = {
     4,
     // Variable:
     2,
+    // GlobalVariable:
+    2,
     // Function:
     4,
     // Offset:
@@ -54,6 +56,8 @@ const bool instruction_argument::s_signedness[instruction_argument::Count] = {
     false,
     // Variable:
     false,
+    // GlobalVariable:
+    false,
     // Function:
     false,
     // Offset:
@@ -125,6 +129,10 @@ const instruction_argument_t instruction::s_arguments[instruction::Count] = {
     instruction_argument::Variable,
     // Store:
     instruction_argument::Variable,
+    // LoadGlobal:
+    instruction_argument::GlobalVariable,
+    // StoreGlobal:
+    instruction_argument::GlobalVariable,
     // Call:
     instruction_argument::Function,
     // Jump:

furvm/src/module.cpp

@@ -88,6 +88,8 @@ std::ostream& mod::serialize(std::ostream& os) const {
         }
     }
 
+    detail::serialize(os, static_cast<std::uint16_t>(m_globalVariables.size()));
+
     detail::serialize(os, std::uint64_t(m_bytecode.size()));
     return os.write(reinterpret_cast<const char*>(m_bytecode.data()), static_cast<std::streamsize>(m_bytecode.size()));
 }
@@ -197,6 +199,10 @@ mod mod::load(std::istream& is) {
         }
     }
 
+    std::uint16_t globalVariables = 0;
+    detail::load(is, globalVariables);
+    mod.set_global_variable_count(globalVariables);
+
     std::uint64_t bytecodeLength = 0;
     detail::load(is, bytecodeLength);
     mod.bytecode().resize(bytecodeLength);