add sub_instruction

4 files changed, 32 insertions, 0 deletions

diff --git a/evaluator.cpp b/evaluator.cpp
index c182bcd..2741d84 100644
--- a/evaluator.cpp
+++ b/evaluator.cpp
@@ -129,3 +129,18 @@ abs_evaluator::evaluate(
 	}
 	return new float_value(fabsf(l->m_value));
 }
+
+sub_evaluator::sub_evaluator() :
+	evaluator("-")
+	{ }
+
+value *
+sub_evaluator::evaluate(
+	float_value * l,
+	float_value * r)
+{
+	if (!l || !r || !l->m_has_value || !r->m_has_value) {
+		return default_evaluate(l, r);
+	}
+	return new float_value(l->m_value - r->m_value);
+}
diff --git a/evaluator.h b/evaluator.h
index 02c7ff6..2b3f682 100644
--- a/evaluator.h
+++ b/evaluator.h
@@ -56,4 +56,12 @@ public:
 		float_value * l,
 		float_value * r);
 };
+
+class sub_evaluator : public evaluator {
+public:
+	sub_evaluator();
+	value * evaluate(
+		float_value * l,
+		float_value * r);
+};
 #endif //EVALUATOR_H_
diff --git a/instruction.cpp b/instruction.cpp
index 1f6f81d..779b397 100644
--- a/instruction.cpp
+++ b/instruction.cpp
@@ -119,3 +119,7 @@ mad_instruction::execute(emulator & emulator)
 abs_instruction::abs_instruction(std::vector<register_address> dst) :
 	instruction("ABS", new abs_evaluator(), dst, 1)
 	{ }
+
+sub_instruction::sub_instruction(std::vector<register_address> dst) :
+	instruction("SUB", new sub_evaluator(), dst, 2)
+	{ }
diff --git a/instruction.h b/instruction.h
index d178644..13bf4de 100644
--- a/instruction.h
+++ b/instruction.h
@@ -68,4 +68,9 @@ public:
 	abs_instruction(std::vector<register_address> dst);
 };
 
+class sub_instruction : public instruction {
+public:
+	sub_instruction(std::vector<register_address> dst);
+};
+
 #endif //INSTRUCTION_H_