LNMBackendChannelAccessor.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 "Device.h"
#include "LogicalNameMappingBackend.h"
#include "NDRegisterAccessor.h"
#include "TwoDRegisterAccessor.h"
 
#include <algorithm>
 
namespace ChimeraTK {
 
  /********************************************************************************************************************/
 
  template<typename UserType>
  class LNMBackendChannelAccessor : public NDRegisterAccessor<UserType> {
   public:
    LNMBackendChannelAccessor(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::wait_for_new_data});
 
      // FIXME: use right type in constructor argument...
      _dev = boost::dynamic_pointer_cast<LogicalNameMappingBackend>(dev);
 
      // copy the register info and create the internal accessors, if needed
      _info = _dev->_catalogue_mutable.getBackendRegister(_registerPathName);
 
      // propagate the (plugin-updated) engineering unit and description from the register info into the accessor
      this->_unit = _info.engineeringUnit;
      this->_description = _info.description;
 
      // check for incorrect usage of this accessor
      assert(_info.targetType == LNMBackendRegisterInfo::TargetType::CHANNEL);
 
      // 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;
      }
      _accessor = targetDevice->getRegisterAccessor<UserType>(
          RegisterPath(_info.registerName), numberOfWords, wordOffsetInRegister, flags);
 
      // verify channel number
      if(_info.channel >= _accessor->getNumberOfChannels()) {
        throw ChimeraTK::logic_error("LNMBackendChannelAccessor: Requested channel number " +
            std::to_string(_info.channel) +
            " exceeds number of channels of target register,"
            " in accesor for register '" +
            registerPathName + "'.");
      }
 
      // allocate the buffer
      NDRegisterAccessor<UserType>::buffer_2D.resize(1);
      NDRegisterAccessor<UserType>::buffer_2D[0].resize(_accessor->getNumberOfSamples());
 
      // set readQueue
      TransferElement::_readQueue = _accessor->getReadQueue();
    }
 
    void doReadTransferSynchronously() override { _accessor->readTransfer(); }
 
    bool doWriteTransfer(ChimeraTK::VersionNumber /*versionNumber*/) override {
      assert(false); // writing not allowed
      return true;
    }
 
    void doPreWrite(TransferType type, VersionNumber) override {
      std::ignore = type;
      throw ChimeraTK::logic_error("Writing to channel-type registers of logical "
                                   "name mapping devices is not supported.");
    }
 
    void doPreRead(TransferType type) override { _accessor->preRead(type); }
 
    void doPostRead(TransferType type, bool hasNewData) override {
      _accessor->postRead(type, hasNewData);
      if(!hasNewData) return;
      _accessor->accessChannel(_info.channel).swap(NDRegisterAccessor<UserType>::buffer_2D[0]);
      this->_versionNumber = _accessor->getVersionNumber();
      this->_dataValidity = _accessor->dataValidity();
    }
 
    [[nodiscard]] bool mayReplaceOther(const boost::shared_ptr<TransferElement const>& other) const override {
      auto rhsCasted = boost::dynamic_pointer_cast<const LNMBackendChannelAccessor<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 { return true; }
 
    [[nodiscard]] bool isReadable() const override { return true; }
 
    [[nodiscard]] bool isWriteable() const override { return false; }
 
    void setExceptionBackend(boost::shared_ptr<DeviceBackend> exceptionBackend) override {
      this->_exceptionBackend = exceptionBackend;
      _accessor->setExceptionBackend(exceptionBackend);
    }
 
    void interrupt() override { _accessor->interrupt(); }
 
   protected:
    boost::shared_ptr<NDRegisterAccessor<UserType>> _accessor;
 
    RegisterPath _registerPathName;
 
    boost::shared_ptr<LogicalNameMappingBackend> _dev;
 
    LNMBackendRegisterInfo _info;
 
    std::vector<boost::shared_ptr<TransferElement>> getHardwareAccessingElements() override {
      return _accessor->getHardwareAccessingElements();
    }
 
    std::list<boost::shared_ptr<TransferElement>> getInternalElements() override {
      auto result = _accessor->getInternalElements();
      result.push_front(_accessor);
      return result;
    }
 
    void replaceTransferElement(boost::shared_ptr<TransferElement> newElement) override {
      auto casted = boost::dynamic_pointer_cast<NDRegisterAccessor<UserType>>(newElement);
      if(casted && _accessor->mayReplaceOther(newElement)) {
        _accessor = casted;
      }
      else {
        _accessor->replaceTransferElement(newElement);
      }
      _accessor->setExceptionBackend(this->_exceptionBackend);
    }
  };
 
  DECLARE_TEMPLATE_FOR_CHIMERATK_USER_TYPES(LNMBackendChannelAccessor);
 
} // namespace ChimeraTK