LNMBackendBitAccessor.h

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// SPDX-FileCopyrightText: Deutsches Elektronen-Synchrotron DESY, MSK, ChimeraTK Project <chimeratk-support@desy.de>
// SPDX-License-Identifier: LGPL-3.0-or-later
#pragma once
 
#include "LogicalNameMappingBackend.h"
#include "NDRegisterAccessor.h"
#include "NDRegisterAccessorDecorator.h"
 
#include <ChimeraTK/cppext/finally.hpp>
 
namespace ChimeraTK {
 
  /********************************************************************************************************************/
 
  template<typename UserType>
  class LNMBackendBitAccessor : public NDRegisterAccessor<UserType> {
   public:
    LNMBackendBitAccessor(const boost::shared_ptr<DeviceBackend>& dev, const RegisterPath& registerPathName,
        size_t numberOfWords, size_t wordOffsetInRegister, AccessModeFlags flags)
    : NDRegisterAccessor<UserType>(registerPathName, flags), _registerPathName(registerPathName) {
      // check for unknown flags
      flags.checkForUnknownFlags({AccessMode::raw});
      // check for illegal parameter combinations
      if(flags.has(AccessMode::raw)) {
        throw ChimeraTK::logic_error("LNMBackendBitAccessor: raw access not supported: " + registerPathName);
      }
      _dev = boost::dynamic_pointer_cast<LogicalNameMappingBackend>(dev);
      // copy the register info and create the internal accessors, if needed
      auto info = _dev->_catalogue_mutable.getBackendRegister(_registerPathName);
 
      // check for incorrect usage of this accessor
      if(info.targetType != LNMBackendRegisterInfo::TargetType::BIT) {
        throw ChimeraTK::logic_error("LNMBackendBitAccessor used for wrong register type."); // LCOV_EXCL_LINE
                                                                                             // (impossible to test...)
      }
      if(wordOffsetInRegister != 0) {
        throw ChimeraTK::logic_error("LNMBackendBitAccessors cannot have a word offset: " + registerPathName);
      }
      if(numberOfWords > 1) {
        throw ChimeraTK::logic_error("LNMBackendBitAccessors must have size 1, but " + registerPathName + " has size " +
            std::to_string(numberOfWords) + ".");
        // The case that the target size actually is 1 if numberOfWords == 0 cannot be checked here.
        // 0 is allowed. It is tested after the target has created the accessor with 0 as length parameter.
      }
 
      // get target device and accessor
      std::string devName = info.deviceName;
      boost::shared_ptr<DeviceBackend> targetDevice;
      if(devName != "this") {
        targetDevice = _dev->_devices[devName];
      }
      else {
        targetDevice = dev;
      }
      {
        std::unique_lock<std::mutex> l{_dev->sharedAccessorMap_mutex};
        auto& map = boost::fusion::at_key<uint64_t>(_dev->sharedAccessorMap.table);
        // we need an identifier of the device in the key, in case the logical name mapping accesses more than one
        // device with same set of register names
        RegisterPath path{info.registerName};
        path.setAltSeparator(".");
        LogicalNameMappingBackend::AccessorKey key(targetDevice.get(), path);
        auto it = map.find(key);
        // Obtain accessor if not found in the map or if weak pointer has expired
        // Note: we must not use boost::weak_ptr::expired() here, because we have to check the status and obtain the
        // accessor in one atomic step.
        if(it == map.end() || (_accessor = map[key].accessor.lock()) == nullptr) {
          _accessor = targetDevice->getRegisterAccessor<uint64_t>(key.second, numberOfWords, wordOffsetInRegister, {});
          if(_accessor->getNumberOfSamples() != 1) {
            throw ChimeraTK::logic_error(
                "LNMBackendBitAccessors only work with target registers of size 1: " + registerPathName);
          }
          map[key].accessor = _accessor;
        }
        lock = std::unique_lock<std::recursive_mutex>(map[key].mutex, std::defer_lock);
      }
      // allocate and initialise the buffer
      NDRegisterAccessor<UserType>::buffer_2D.resize(1);
      NDRegisterAccessor<UserType>::buffer_2D[0].resize(1);
      NDRegisterAccessor<UserType>::buffer_2D[0][0] = numericToUserType<UserType>(false);
      // set the bit mask
      _bitMask = size_t(1) << info.bit;
    }
 
    void doReadTransferSynchronously() override {
      assert(lock.owns_lock());
      _accessor->readTransfer();
    }
 
    bool doWriteTransfer(ChimeraTK::VersionNumber) override {
      assert(lock.owns_lock());
      return _accessor->writeTransfer(_versionNumberTemp);
    }
 
    void doPreRead(TransferType type) override {
      lock.lock();
      _accessor->preRead(type);
    }
 
    void doPostRead(TransferType type, bool hasNewData) override {
      auto unlock = cppext::finally([this] { this->lock.unlock(); });
      _accessor->postRead(type, hasNewData);
      if(!hasNewData) return;
      if(_accessor->accessData(0) & _bitMask) {
        NDRegisterAccessor<UserType>::buffer_2D[0][0] = numericToUserType<UserType>(true);
      }
      else {
        NDRegisterAccessor<UserType>::buffer_2D[0][0] = numericToUserType<UserType>(false);
      }
      this->_versionNumber = {}; // VersionNumber needs to be decoupled from target accessor
      this->_dataValidity = _accessor->dataValidity();
    }
 
    void doPreWrite(TransferType type, VersionNumber) override {
      lock.lock();
 
      if(!userTypeToNumeric<ChimeraTK::Boolean>(NDRegisterAccessor<UserType>::buffer_2D[0][0])) {
        _accessor->accessData(0) &= ~(_bitMask);
      }
      else {
        _accessor->accessData(0) |= _bitMask;
      }
 
      _versionNumberTemp = {};
      _accessor->setDataValidity(this->_dataValidity);
      _accessor->preWrite(type, _versionNumberTemp);
    }
 
    void doPostWrite(TransferType type, VersionNumber) override {
      auto unlock = cppext::finally([this] { this->lock.unlock(); });
      _accessor->postWrite(type, _versionNumberTemp);
    }
 
    [[nodiscard]] bool mayReplaceOther(const boost::shared_ptr<TransferElement const>& other) const override {
      auto rhsCasted = boost::dynamic_pointer_cast<const LNMBackendBitAccessor<UserType>>(other);
      if(rhsCasted.get() == this) {
        return false;
      }
      if(!rhsCasted) return false;
      if(_registerPathName != rhsCasted->_registerPathName) return false;
      if(_dev != rhsCasted->_dev) return false;
      return true;
    }
 
    [[nodiscard]] bool isReadOnly() const override {
      std::lock_guard<std::recursive_mutex> guard(*lock.mutex());
      return _accessor->isReadOnly();
    }
 
    [[nodiscard]] bool isReadable() const override {
      std::lock_guard<std::recursive_mutex> guard(*lock.mutex());
      return _accessor->isReadable();
    }
 
    [[nodiscard]] bool isWriteable() const override {
      std::lock_guard<std::recursive_mutex> guard(*lock.mutex());
      return _accessor->isWriteable();
    }
 
    void setExceptionBackend(boost::shared_ptr<DeviceBackend> exceptionBackend) override {
      std::lock_guard<std::recursive_mutex> guard(*lock.mutex());
      this->_exceptionBackend = exceptionBackend;
      _accessor->setExceptionBackend(exceptionBackend);
    }
 
   protected:
    boost::shared_ptr<NDRegisterAccessor<uint64_t>> _accessor;
 
    std::unique_lock<std::recursive_mutex> lock;
 
    RegisterPath _registerPathName;
 
    VersionNumber _versionNumberTemp{nullptr};
 
    boost::shared_ptr<LogicalNameMappingBackend> _dev;
 
    size_t _bitMask;
 
    std::vector<boost::shared_ptr<TransferElement>> getHardwareAccessingElements() override {
      std::lock_guard<std::recursive_mutex> guard(*lock.mutex());
      return _accessor->getHardwareAccessingElements();
    }
 
    std::list<boost::shared_ptr<TransferElement>> getInternalElements() override {
      std::lock_guard<std::recursive_mutex> guard(*lock.mutex());
      auto result = _accessor->getInternalElements();
      result.push_front(_accessor);
      return result;
    }
 
    void replaceTransferElement(boost::shared_ptr<TransferElement> newElement) override {
      std::lock_guard<std::recursive_mutex> guard(*lock.mutex());
      auto casted = boost::dynamic_pointer_cast<NDRegisterAccessor<uint64_t>>(newElement);
      if(casted && _accessor->mayReplaceOther(newElement)) {
        _accessor = detail::createCopyDecorator<uint64_t>(casted);
      }
      else {
        _accessor->replaceTransferElement(newElement);
      }
      _accessor->setExceptionBackend(this->_exceptionBackend);
    }
  };
 
  DECLARE_TEMPLATE_FOR_CHIMERATK_USER_TYPES(LNMBackendBitAccessor);
 
} // namespace ChimeraTK