ChipMultiplexerSelectManager.cpp

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/*
 * This file is part of the DUDS project. It is subject to the BSD-style
 * license terms in the LICENSE file found in the top-level directory of this
 * distribution and at https://github.com/jjackowski/duds/blob/master/LICENSE.
 * No part of DUDS, including this file, may be copied, modified, propagated,
 * or distributed except according to the terms contained in the LICENSE file.
 *
 * Copyright (C) 2017  Jeff Jackowski
 */
#include <duds/hardware/interface/ChipMultiplexerSelectManager.hpp>

namespace duds { namespace hardware { namespace interface {

ChipMultiplexerSelectManager::ChipMultiplexerSelectManager(
    std::unique_ptr<DigitalPinSetAccess> &&acc
) {
    setAccess(std::move(acc));
}

bool ChipMultiplexerSelectManager::validChip(int chipId) const noexcept {
    if (outacc) {
        return (chipId > 0) && (chipId < (1 << outacc->size()));
    }
    return false;
}

void ChipMultiplexerSelectManager::setAccess(
    std::unique_ptr<DigitalPinSetAccess> &&acc
) {
    if (!acc || !acc->havePins()) {
        DUDS_THROW_EXCEPTION(PinDoesNotExist());
    }
    // require exclusive access
    std::unique_lock<std::mutex> lock(block);
    // is a chip in use?
    if (inUse()) {
        assert(outacc);
        // fail; provide the pin and chip IDs for what is currently in use
        DUDS_THROW_EXCEPTION(ChipSelectInUse() <<
            ChipSelectIdError(cid)
        );
    }
    // get the capabilities for inspection
    std::vector<DigitalPinCap> caps = acc->capabilities();
    // prepare to configure each pin
    std::vector<DigitalPinConfig> conf;
    conf.reserve(caps.size());
    // iteratate over all the pins
    std::vector<DigitalPinCap>::const_iterator iter = caps.cbegin();
    unsigned int pos = 0;
    for (; iter != caps.cend(); ++pos, ++iter) {
        // check for no output ability
        if (!iter->canOutput()) {
            DUDS_THROW_EXCEPTION(DigitalPinCannotOutputError() <<
                PinErrorId(acc->globalId(pos))
            );
        }
        // work out the actual output config
        conf.push_back(DigitalPinConfig(iter->firstOutputDriveConfigFlags()));
    }
    // assure a deselected state prior to requesting output
    acc->output(false);
    // make all pins outputs
    acc->modifyConfig(conf);
    // store this access object; seems good if it got this far without
    // an exception
    outacc = std::move(acc);
}

std::unique_ptr<DigitalPinSetAccess>
ChipMultiplexerSelectManager::releaseAccess() {
    // get exclusive access to manager data
    std::unique_lock<std::mutex> lock(block);
    // is a chip in use?
    if (inUse()) {
        // fail; provide the chip ID for what is currently in use
        DUDS_THROW_EXCEPTION(ChipSelectInUse() << ChipSelectIdError(cid));
    }
    return std::move(outacc);
}

void ChipMultiplexerSelectManager::select() {
    outacc->write(cid);
}

void ChipMultiplexerSelectManager::deselect() {
    outacc->write((std::int32_t)0);
}

} } }