LoadStoreQueue.cpp

#include "LoadStoreQueue.h"

void LoadStoreQueue::capture(int tag, int val) {
  for (auto &entry : rs) {
    if (!entry.busy)
      continue;
    if (entry.Qj == tag) {
      entry.Vj = val;
      entry.Qj = -1;
    }
    if (entry.Qk == tag) {
      entry.Vk = val;
      entry.Qk = -1;
    }
  }
}

void LoadStoreQueue::initialise() {
  result = -1;
  has_result = false;
  has_exception = false;
  address = -1;
  dest = -1;
}

void LoadStoreQueue::executeCycle(std::vector<int> &Memory,
                                  std::deque<ROBEntry> &ROB, int rob_head,
                                  int rob_tail, int rob_count) {

  initialise();

  if (rs.empty())
    return;

  for (auto &entry : rs) {
    if (!((entry.Qj == -1) && (entry.Qk == -1))) {
      break;
    } else if (!entry.executing && entry.busy) {
      entry.executing = true;
      entry.remaining_cycles = latency;
      break;
    }
  }

  int completed_idx = -1;
  for (int i = 0; i < static_cast<int>(rs.size()); i++) {
    auto &entry = rs[i];

    if (!entry.busy || !entry.executing)
      continue;

    entry.remaining_cycles--;

    if (entry.remaining_cycles == 0) {
      address = entry.Vj + entry.imm;
      dest = entry.dest;

      if (address < 0 || address >= (int)Memory.size()) {
        has_exception = true;
      } else {
        if (entry.op == OpCode::LW) {
          result = Memory[address];
          for (int index = 0; index < rob_count; index++) {
            int rob_idx = (rob_head + index) % ROB.size();
            if (rob_idx == dest)
              break;

            ROBEntry &rob_entry = ROB[rob_idx];
            if (rob_entry.valid && rob_entry.op == OpCode::SW &&
                rob_entry.destRegWritten && rob_entry.storeAddr == address) {
              result = ROB[rob_idx].storeData;
            }
          }
        } else if (entry.op == OpCode::SW) {
          result = entry.Vk;
        }
        has_result = true;
      }
      entry.busy = false;
      if (completed_idx == -1) {
        completed_idx = i;
      }
    }
  }

  if (completed_idx != -1) {
    rs.erase(rs.begin() + completed_idx);
  }
}