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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 "instr.h"
#include "instrDTO.h"
#include "response.h"
#include "stage.h"
#include <algorithm>
#include <array>
void WB::advance_helper()
{
if (this->curr_instr->mnemonic != NOP) {
if (this->curr_instr->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->mnemonic == POP) {
// POP performs a second register write
reg = this->checked_out.front();
this->checked_out.pop_front();
this->store_register<signed int>(
reg, this->curr_instr->operands.integer.slot_three);
}
this->checked_out.pop_front();
reg = this->curr_instr->checked_out;
switch (this->curr_instr->type) {
case SI_INT:
this->store_register<signed int>(
reg, this->curr_instr->operands.integer.slot_one);
break;
case S_VECT:
case R_VECT:
this->store_register<std::array<signed int, V_R_LIMIT>>(
reg, this->copy_extra_vector_elements());
break;
}
}
void WB::jump_handler()
{
if (this->curr_instr->operands.integer.slot_one > 0) {
if (this->curr_instr->mnemonic == JAL)
this->gprs[1] = this->curr_instr->slot_B + 1;
this->pc = this->curr_instr->operands.integer.slot_one;
this->checked_out = {};
this->next->squash();
}
}
// TODO clean this up...
bool WB::should_jump()
{
vector<Mnemonic> Js = {JMP, JRL, JAL, BEQ, BGT, BUF, BOF, PUSH, POP, RET};
if (find(Js.begin(), Js.end(), this->curr_instr->mnemonic) != Js.end())
return true;
else
return false;
}
std::array<signed int, V_R_LIMIT> WB::copy_extra_vector_elements()
{
int i;
std::array<signed int, V_R_LIMIT> v;
if (this->curr_instr->type == R_VECT) {
if (this->curr_instr->slot_B == 0) {
v = {0};
return v;
}
}
v = this->curr_instr->operands.vector.slot_one;
for (i = V_R_LIMIT - 1; i >= this->curr_instr->slot_B; --i) {
v[i] = this->curr_instr->operands.vector.slot_three[i];
}
return v;
}
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