vortex/sim/simx/shared_mem.cpp

// Copyright © 2019-2023
// 
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "shared_mem.h"
#include "core.h"
#include <bitmanip.h>
#include <vector>
#include "types.h"

using namespace vortex;

class SharedMem::Impl {
protected:
    SharedMem* simobject_;
    Config    config_;
    RAM       ram_;
    uint32_t  bank_sel_addr_start_;
    uint32_t  bank_sel_addr_end_;
    PerfStats perf_stats_;

    uint64_t to_local_addr(uint64_t addr) {
        uint32_t total_lines = config_.capacity / config_.line_size;        
        uint32_t line_bits = log2ceil(total_lines);
        uint32_t offset = bit_getw(addr, 0, line_bits-1);
        return offset;
    }

public:
    Impl(SharedMem* simobject, const Config& config) 
        : simobject_(simobject)
        , config_(config)
        , ram_(config.capacity, config.capacity)
        , bank_sel_addr_start_(0)
        , bank_sel_addr_end_(0 + log2ceil(config.num_banks)-1)
    {}    
    
    virtual ~Impl() {}

    void reset() {
        perf_stats_ = PerfStats();
    }

    void read(void* data, uint64_t addr, uint32_t size) {
        auto s_addr = to_local_addr(addr);        
        DPH(3, "Shared Mem addr=0x" << std::hex << s_addr << std::endl);
        ram_.read(data, s_addr, size);
    }

    void write(const void* data, uint64_t addr, uint32_t size) {
        auto s_addr = to_local_addr(addr);        
        DPH(3, "Shared Mem addr=0x" << std::hex << s_addr << std::endl);
        ram_.write(data, s_addr, size);
    }

    void tick() {
        std::vector<bool> in_used_banks(config_.num_banks);
        for (uint32_t req_id = 0; req_id < config_.num_reqs; ++req_id) {
            auto& core_req_port = simobject_->Inputs.at(req_id);            
            if (core_req_port.empty())
                continue;

            auto& core_req = core_req_port.front();

            uint32_t bank_id = 0;
            if (bank_sel_addr_start_ <= bank_sel_addr_end_) {
                bank_id = (uint32_t)bit_getw(core_req.addr, bank_sel_addr_start_, bank_sel_addr_end_);
            }

            // bank conflict check
            if (in_used_banks.at(bank_id)) {
                ++perf_stats_.bank_stalls;
                continue;
            }

            in_used_banks.at(bank_id) = true;

            if (!core_req.write || config_.write_reponse) {
                // send response
                MemRsp core_rsp{core_req.tag, core_req.cid};
                simobject_->Outputs.at(req_id).send(core_rsp, 1);
            }

            // update perf counters
            perf_stats_.reads += !core_req.write;            
            perf_stats_.writes += core_req.write;

            // remove input
            core_req_port.pop();
        }
    }

    const PerfStats& perf_stats() const { 
        return perf_stats_; 
    }
};

///////////////////////////////////////////////////////////////////////////////

SharedMem::SharedMem(const SimContext& ctx, const char* name, const Config& config) 
    : SimObject<SharedMem>(ctx, name)   
    , Inputs(config.num_reqs, this)
    , Outputs(config.num_reqs, this)
    , impl_(new Impl(this, config))
{}

SharedMem::~SharedMem() {
    delete impl_;
}

void SharedMem::reset() {
    impl_->reset();
}

void SharedMem::read(void* data, uint64_t addr, uint32_t size) {
    impl_->read(data, addr, size);
}

void SharedMem::write(const void* data, uint64_t addr, uint32_t size) {
    impl_->write(data, addr, size);
}

void SharedMem::tick() {
    impl_->tick();
}

const SharedMem::PerfStats& SharedMem::perf_stats() const {
    return impl_->perf_stats();
}