6 files changed, 23 insertions, 22 deletions
diff --git a/src/sim/dum.cc b/src/sim/dum.cc
index f712fce..ab4eaa4 100644
--- a/src/sim/dum.cc
+++ b/src/sim/dum.cc
@@ -11,7 +11,6 @@ InstrDTO *DUM::advance(Response p)
 	InstrDTO *r = nullptr;
 
 	if (this->curr_instr && p == WAIT) {
-		this->curr_instr->set_time_of(this->id, this->clock_cycle);
 		r = new InstrDTO(*this->curr_instr);
 		delete this->curr_instr;
 		curr_instr = nullptr;
diff --git a/src/sim/id.cc b/src/sim/id.cc
index d4b56d2..3d5baef 100644
--- a/src/sim/id.cc
+++ b/src/sim/id.cc
@@ -38,7 +38,14 @@ Response ID::read_guard(signed int &v)
 
 void ID::write_guard(signed int &v)
 {
-	this->checked_out.push_back(v);
+	// zero register shouldn't be written.
+	if (v != 0) {
+		// keep track in the instrDTO for displaying to user and writeback
+		// keep track in checked_out so we can still access this information!
+		this->checked_out.push_back(v);
+		this->curr_instr->set_checked_out(v);
+		std::cout << "checked out: " << v << std::endl;
+	}
 	v = this->dereference_register(v);
 }
 
diff --git a/src/sim/if.cc b/src/sim/if.cc
index fb49749..1223149 100644
--- a/src/sim/if.cc
+++ b/src/sim/if.cc
@@ -14,7 +14,6 @@ InstrDTO *IF::advance(Response p)
 	if (this->curr_instr != nullptr && p == WAIT) {
 		// mutual consent
 		++this->pc;
-		this->curr_instr->set_time_of(this->id, this->clock_cycle);
 		r = new InstrDTO(*this->curr_instr);
 		delete curr_instr;
 		curr_instr = nullptr;
@@ -23,12 +22,12 @@ InstrDTO *IF::advance(Response p)
 	return r;
 }
 
-std::vector<int> IF::stage_info() { 
+std::vector<int> IF::stage_info() {
 	std::vector<int> info;
 	if(this->curr_instr){
 		info.push_back(this->curr_instr->get_pc());
 		info.push_back(this->curr_instr->get_instr_bits());
-	} 
+	}
 	return info;
 }
 
diff --git a/src/sim/instrDTO.cc b/src/sim/instrDTO.cc
index aa49b7e..a82ef28 100644
--- a/src/sim/instrDTO.cc
+++ b/src/sim/instrDTO.cc
@@ -4,6 +4,7 @@
 InstrDTO::InstrDTO()
 {
 	this->instr_bits = 0;
+	this->checked_out = -1;
 	this->s1 = 0;
 	this->s2 = 0;
 	this->s3 = 0;
@@ -12,10 +13,10 @@ InstrDTO::InstrDTO()
 	this->pc = 0;
 }
 
-int InstrDTO::get_time_of(Accessor a) { return this->hist[a]; }
-
 signed int InstrDTO::get_instr_bits() { return this->instr_bits; }
 
+signed int InstrDTO::get_checked_out() { return this->checked_out; }
+
 signed int InstrDTO::get_s1() { return this->s1; }
 
 signed int InstrDTO::get_s2() { return this->s2; }
@@ -28,10 +29,13 @@ Type InstrDTO::get_type() { return this->type; }
 
 unsigned int InstrDTO::get_pc() { return this->pc; }
 
-void InstrDTO::set_time_of(Accessor a, int i) { this->hist[a] = i; }
-
 void InstrDTO::set_instr_bits(signed int instr) { this->instr_bits = instr; }
 
+void InstrDTO::set_checked_out(signed int checked_out)
+{
+	this->checked_out = checked_out;
+}
+
 void InstrDTO::set_s1(signed int s) { this->s1 = s; }
 
 void InstrDTO::set_s2(signed int s) { this->s2 = s; }
diff --git a/src/sim/stage.cc b/src/sim/stage.cc
index b7926fd..7df1dba 100644
--- a/src/sim/stage.cc
+++ b/src/sim/stage.cc
@@ -38,7 +38,6 @@ InstrDTO *Stage::advance(Response p)
 	}
 	if (this->status == OK && p == WAIT && this->curr_instr) {
 		// mutual consent
-		this->curr_instr->set_time_of(this->id, this->clock_cycle);
 		r = new InstrDTO(*this->curr_instr);
 		delete curr_instr;
 		curr_instr = nullptr;
diff --git a/src/sim/wb.cc b/src/sim/wb.cc
index 01768e8..3fa7dd3 100644
--- a/src/sim/wb.cc
+++ b/src/sim/wb.cc
@@ -3,6 +3,8 @@
 #include "instrDTO.h"
 #include "response.h"
 #include "stage.h"
+#include <array>
+#include <algorithm>
 
 WB::WB(Stage *stage) : Stage(stage) { this->id = WRITE; }
 
@@ -10,7 +12,7 @@ void WB::advance_helper()
 {
 	if (this->curr_instr->get_mnemonic() != NOP &&
 		this->curr_instr->get_type() != INV) {
-		if (this->should_write())
+		if (this->curr_instr->get_checked_out() > 0)
 			this->write_handler();
 		else if (this->should_jump())
 			this->jump_handler();
@@ -26,8 +28,9 @@ void WB::write_handler()
 		throw std::runtime_error("instruction tried to pop a register out of "
 								 "an empty queue during writeback.");
 
-	reg = this->checked_out.front();
 	this->checked_out.pop_front();
+	reg = this->curr_instr->get_checked_out();
+	std::cout << "checked in: " << reg << std::endl;
 	this->store_register(reg, this->curr_instr->get_s1());
 }
 
@@ -49,13 +52,3 @@ bool WB::should_jump()
 	t = this->curr_instr->get_type();
 	return t == J;
 }
-
-bool WB::should_write()
-{
-	Mnemonic m;
-	Type t;
-
-	m = this->curr_instr->get_mnemonic();
-	t = this->curr_instr->get_type();
-	return (t == R || t == I) && (m != STORE && m != STOREV);
-}