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// Simulator for the RISC-V[ECTOR] mini-ISA
// Copyright (C) 2025 Siddarth Suresh
// Copyright (C) 2025 bdunahu
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
#include "wb.h"
#include "accessor.h"
#include "instrDTO.h"
#include "response.h"
#include "stage.h"
#include <array>
#include <algorithm>
WB::WB(Stage *stage) : Stage(stage) { this->id = WRITE; }
void WB::advance_helper()
{
if (this->curr_instr->get_mnemonic() != NOP &&
this->curr_instr->get_type() != INV) {
if (this->curr_instr->get_checked_out() > 0)
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.");
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());
}
this->checked_out.pop_front();
reg = this->curr_instr->get_checked_out();
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->curr_instr->get_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;
}
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