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// Memory subsystem 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 "cache.h"
#include "definitions.h"
#include <cstdlib>
#include <iostream>
#include <iterator>
Cache::Cache(Storage *lower, unsigned int size, unsigned int ways, int delay) : Storage(delay)
{
int true_size;
true_size = 1 << size;
this->data->resize(true_size);
this->meta = std::vector<std::array<signed int, 3>>(true_size, {-1, -1, -1});
this->lower = lower;
this->size = size;
// store the number of bits which are moved into the tag field
this->ways = ways;
}
Cache::~Cache()
{
delete this->lower;
delete this->data;
}
unsigned int
Cache::get_size() { return this->size; }
int
Cache::write_word(void *id, signed int data, int address)
{
return process(id, address, [&](int index, int offset) {
this->data->at(index).at(offset) = data;
this->meta[index].at(1) = 1;
});
}
int
Cache::write_line(void *id, std::array<signed int, LINE_SIZE> data_line, int address)
{
return process(id, address, [&](int index, int offset) {
(void)offset;
this->data->at(index) = data_line;
this->meta[index].at(1) = 1;
});
}
int
Cache::read_line(void *id, int address, std::array<signed int, LINE_SIZE> &data_line)
{
return process(id, address, [&](int index, int offset) {
(void)offset;
data_line = this->data->at(index);
});
}
int
Cache::read_word(void *id, int address, signed int &data)
{
return process(
id, address, [&](int index, int offset) { data = this->data->at(index).at(offset); });
}
int
Cache::process(void *id, int address, std::function<void(int index, int offset)> request_handler)
{
address = WRAP_ADDRESS(address);
if (!preprocess(id) || priming_address(address) || !this->is_data_ready())
return 0;
int tag, index, offset;
GET_FIELDS(address, &tag, &index, &offset);
index = this->get_true_index(index);
request_handler(index, offset);
return 1;
}
int
Cache::priming_address(int address)
{
int tag, index, offset;
int r1, r2;
std::array<signed int, LINE_SIZE> *evict;
std::array<int, 3> *meta;
r1 = 0;
GET_FIELDS(address, &tag, &index, &offset);
index = this->get_true_index(index);
if (this->is_address_missing(index, tag)) {
r1 = 1;
index = this->get_replacement_index(index);
meta = &this->meta.at(index);
evict = &this->data->at(index);
// handle eviction of dirty cache lines
if (meta->at(1) >= 0) {
r2 = this->lower->write_line(
this, *evict, ((index << LINE_SPEC) + (meta->at(0) << (this->size + LINE_SPEC))));
if (r2)
meta->at(1) = -1;
} else {
r2 = this->lower->read_line(this, address, *evict);
if (r2) {
meta->at(0) = tag;
}
}
}
return r1;
}
int
Cache::is_address_missing(int index, int tag)
{
int i;
for (i = 0; i < (1 << this->ways); ++i)
if (this->meta.at(index + i).at(0) == tag)
return i;
return -1;
}
int
Cache::get_true_index(int index)
{
return index * (1 << this->ways);
}
int
Cache::get_replacement_index(int index)
{
return index + (rand() % (1 << this->ways));
}
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