5 files changed, 55 insertions, 8 deletions

diff --git a/src/sim/controller.cc b/src/sim/controller.cc
index 65e5676..9256151 100644
--- a/src/sim/controller.cc
+++ b/src/sim/controller.cc
@@ -11,6 +11,7 @@ Controller::Controller(Stage *stage, Storage *storage, bool is_pipelined)
 	this->pc = 0x0;
 	this->checked_out = {};
 	this->gprs = {0};
+	this->gprs.at(2) = MEM_WORDS; // set the stack pointer
 	// grant side-door access
 	this->id = SIDE;
 }
diff --git a/src/sim/ex.cc b/src/sim/ex.cc
index d20d15f..c676781 100644
--- a/src/sim/ex.cc
+++ b/src/sim/ex.cc
@@ -340,20 +340,20 @@ EX::EX(Stage *stage) : Stage(stage)
 		INIT_INSTRUCTION(
 			PUSH,
 			{
+				std::cout << "adding " << s1 << " and " << s3;
+				s1 = s1 + s3;
+				std::cout << " for " << s1 << std::endl;
 				(void)pc;
-				(void)s3;
 				(void)s2;
-				(void)s1;
 				(void)this;
 			}),
 
 		INIT_INSTRUCTION(
 			POP,
 			{
+				s1 = s1 + s3;
 				(void)pc;
-				(void)s3;
 				(void)s2;
-				(void)s1;
 				(void)this;
 			}),
 
diff --git a/src/sim/id.cc b/src/sim/id.cc
index 37c6773..de412d4 100644
--- a/src/sim/id.cc
+++ b/src/sim/id.cc
@@ -86,7 +86,7 @@ void ID::get_instr_fields(
 		break;
 	case 0b10:
 		t = J;
-		this->decode_J_type(s1, s2, s3);
+		this->decode_J_type(s1, s2, s3, m);
 		break;
 	case 0b11:
 		t = INV;
@@ -159,8 +159,10 @@ void ID::decode_I_type(
 	this->status = r1;
 }
 
-void ID::decode_J_type(signed int &s1, signed int &s2, signed int &s3)
+void ID::decode_J_type(
+	signed int &s1, signed int &s2, signed int &s3, Mnemonic &m)
 {
+	Response r1, r2;
 	unsigned int s0b, s1b;
 
 	s0b = REG_SIZE;
@@ -169,7 +171,35 @@ void ID::decode_J_type(signed int &s1, signed int &s2, signed int &s3)
 	s2 = GET_BITS_SIGN_EXTEND(s1, s0b, s1b);
 	s1 = GET_LS_BITS(s1, s0b);
 
-	this->status = this->read_guard(*&s1);
+	switch (m) {
+	case PUSH:
+		s2 = s1; // source
+		s3 = 2;  // stack pointer
+		s1 = -1; // increment amount
+		r1 = this->read_guard(s2);
+		r2 = (this->is_checked_out(s3)) ? STALLED : OK; // we read the stack pointer
+		if (r1 == OK && r2 == OK) {
+			this->write_guard(s3); // we write the stack pointer
+		}
+		this->status = (r1 == OK && r2 == OK) ? OK : STALLED;
+		break;
+	case POP:
+		s2 = s1; // destination
+		s3 = 2;  // stack pointer
+		s1 = 1;  // increment amount
+		r1 = (this->is_checked_out(s3)) ? STALLED : OK; // we read the stack pointer
+		if (r1 == OK) {
+			this->write_guard(s2);
+			this->write_guard(s3); // we write the stack pointer
+		}
+		this->status = r1;
+		break;
+	default:
+		this->status = this->read_guard(*&s1);
+	}
+
+	std::cout << m << ":" << this->status << std::endl;
+
 }
 
 std::vector<int> ID::stage_info()
diff --git a/src/sim/mm.cc b/src/sim/mm.cc
index a9a60c2..a02ca83 100644
--- a/src/sim/mm.cc
+++ b/src/sim/mm.cc
@@ -21,8 +21,8 @@ void MM::advance_helper()
 			this->status = STALLED;
 		break;
 
+	case PUSH:
 	case STORE:
-		// TODO signed issues, we aren't wrapping addresses
 		i = this->storage->write_word(
 			this, this->curr_instr->get_s2(), this->curr_instr->get_s1());
 		this->status = i ? OK : STALLED;
@@ -31,6 +31,15 @@ void MM::advance_helper()
 		}
 		break;
 
+	case POP:
+		i = this->storage->read_word(this, this->curr_instr->get_s3(), data);
+		this->status = i ? OK : STALLED;
+		if (this->status == OK) {
+			this->curr_instr->set_s3(data);
+		} else
+			this->status = STALLED;
+		break;
+
 	default:
 		this->status = OK;
 	}
diff --git a/src/sim/wb.cc b/src/sim/wb.cc
index 4e6b2b0..08e5ed3 100644
--- a/src/sim/wb.cc
+++ b/src/sim/wb.cc
@@ -31,6 +31,13 @@ void WB::write_handler()
 	this->checked_out.pop_front();
 	reg = this->curr_instr->get_checked_out();
 	this->store_register(reg, this->curr_instr->get_s1());
+
+	if (this->curr_instr->get_mnemonic() == POP) {
+		// POP performs a second register write
+		reg = this->checked_out.front();
+		this->checked_out.pop_front();
+		this->store_register(reg, this->curr_instr->get_s3());
+	}
 }
 
 void WB::jump_handler()