Merge pull request #46 from bdunahu/bdunahu

 Ensure all stages only do work if they are not 'OK' 

1 files changed, 52 insertions, 30 deletions

diff --git a/src/sim/wb.cc b/src/sim/wb.cc
index ac47f25..01768e8 100644
--- a/src/sim/wb.cc
+++ b/src/sim/wb.cc
@@ -6,34 +6,56 @@
 
 WB::WB(Stage *stage) : Stage(stage) { this->id = WRITE; }
 
-void WB::advance_helper() {
-    if(this -> curr_instr) {
-        if(this->curr_instr->get_type() == R || this->curr_instr->get_type() == I){ 
-            if(this->checked_out.size() > 0) {
-                signed int reg = this->checked_out.front();
-                this->checked_out.pop_front();
-                if(reg >= GPR_NUM){
-                    // TODO: handle vector instructions
-                } else {
-                    if(this->curr_instr->get_mnemonic() != STORE && this->curr_instr->get_mnemonic() != STOREV){
-                        this->gprs[reg] = this->curr_instr->get_s1();
-                    }
-                }
-            }
-        } else if (this->curr_instr->get_type() == J) {
-            // TODO:handle push pop
-            // branch taken
-            if(this->pc != this->curr_instr->get_s1()) {
-                if(this->curr_instr->get_mnemonic() == JAL){
-                    // set link register to next instruction
-                    this->gprs[1] = this->pc + 1;
-                }
-                this->pc = this->curr_instr->get_s1();  
-                //clear pending registers and squash pipeline
-                this->checked_out = {};
-                this->next->squash();
-            }
-        }
-    }
-    this->status = OK;
+void WB::advance_helper()
+{
+	if (this->curr_instr->get_mnemonic() != NOP &&
+		this->curr_instr->get_type() != INV) {
+		if (this->should_write())
+			this->write_handler();
+		else if (this->should_jump())
+			this->jump_handler();
+	}
+	this->status = OK;
+}
+
+void WB::write_handler()
+{
+	signed int reg;
+
+	if (this->checked_out.size() < 1)
+		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();
+	this->store_register(reg, this->curr_instr->get_s1());
+}
+
+void WB::jump_handler()
+{
+	if (this->curr_instr->get_s1() > 0) {
+		if (this->curr_instr->get_mnemonic() == JAL)
+			this->gprs[1] = this->pc + 1;
+		this->pc = this->curr_instr->get_s1();
+		this->checked_out = {};
+		this->next->squash();
+	}
+}
+
+bool WB::should_jump()
+{
+	Type t;
+
+	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);
 }