Add STDIN interrupt and error handling for all interrupts

bin/test.wasm

@@ -90,7 +90,10 @@ int $3;
 
 # Jump over the interrupt
 call noop_function;
-int $3;
+
+# Echo a character
+int $4;
+int $0;
 exit;
 
 noop_function:

include/execute/error.hpp

@@ -33,6 +33,12 @@ namespace Execute
 		MissingLabel(std::string const & label);
 	};
 
+	class InterruptIndexOutOfRange : public RuntimeError
+	{
+	public:
+		InterruptIndexOutOfRange(int const index);
+	};
+
 	namespace Internal
 	{
 		class BadValueType : public RuntimeError

src/execute/error.cpp

@@ -34,6 +34,13 @@ namespace Execute
 		message += '"';
 	}
 
+	InterruptIndexOutOfRange::InterruptIndexOutOfRange(int const index)
+	{
+		message = "Interrupt index ";
+		message += std::to_string(index);
+		message += " is out of range";
+	}
+
 	namespace Internal
 	{
 		BadValueType::BadValueType()

src/execute/interrupts.cpp

@@ -7,6 +7,7 @@ namespace Execute
 	{
 		return std::vector<InterruptFn>
 		{
+			/* STDOUT INTERRUPTS */
 			// 0 print char
 			[](Execute::Registers & registers, std::vector<std::uint8_t> & memory) { std::putc(registers.A, stdout); },
 			// 1 print decimal integer
@@ -21,6 +22,13 @@ namespace Execute
 				{
 					std::putc(memory[i], stdout);
 				}
+			},
+
+			/* STDIN INTERRUPTS */
+			// 10 get char from STDIN
+			[](Execute::Registers & registers, std::vector<std::uint8_t> & memory)
+			{
+				registers.A = std::getchar();
 			}
 		};
 	}

src/interpret/statement.cpp

@@ -89,7 +89,13 @@ namespace Interpret
 
 	void InterruptStatement::Execute(Execute::Flags & flags, Execute::State & state, Execute::Registers & registers)
 	{
-		state.interrupts[firstArgument.GetValue(state, registers)](registers, state.memory);
+		auto const interruptIndex = firstArgument.GetValue(state, registers);
+		if (interruptIndex < 0 || static_cast<unsigned>(interruptIndex) > state.interrupts.size())
+		{
+			throw Execute::InterruptIndexOutOfRange(interruptIndex);
+		}
+
+		state.interrupts[interruptIndex](registers, state.memory);
 	}
 
 	void PopStatement::Execute(Execute::Flags & flags, Execute::State & state, Execute::Registers & registers)