SysPwm.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/linux/SysPwm.hpp>
#include <duds/general/Errors.hpp>
#include <boost/exception/errinfo_file_name.hpp>
#include <sstream>

// !@?!#?!#?
#undef linux

namespace duds { namespace hardware { namespace interface { namespace linux {

static const char *prefix = "/sys/class/pwm/pwmchip"; // 0/pwm0
// files:
// duty_cycle  enable  period  polarity
SysPwm::SysPwm(int chip, int channel) {
    std::ostringstream fname;
    fname << prefix << chip << "/pwm" << channel << "/enable";
    en.open(fname.str());
    if (!en.is_open()) {
        DUDS_THROW_EXCEPTION(PwmError() << SysPwmChip(chip) <<
            SysPwmChannel(channel) << boost::errinfo_file_name(fname.str())
        );
    }
    unsigned int val;
    en >> val;
    if (en.fail() || (val > 1)) {
        DUDS_THROW_EXCEPTION(PwmError() << SysPwmChip(chip) <<
            SysPwmChannel(channel) << boost::errinfo_file_name(fname.str())
        );
    }
    running = val == 1;
    // unwrite "enable"
    fname.seekp(-6, std::ios_base::cur);
    fname << "period";
    per.open(fname.str());
    if (!per.is_open()) {
        DUDS_THROW_EXCEPTION(PwmError() << SysPwmChip(chip) <<
            SysPwmChannel(channel) << boost::errinfo_file_name(fname.str())
        );
    }
    per >> val;
    if (per.fail()) {
        DUDS_THROW_EXCEPTION(PwmError() << SysPwmChip(chip) <<
            SysPwmChannel(channel) << boost::errinfo_file_name(fname.str())
        );
    }
    periodNs = std::chrono::nanoseconds(val);
    // unwrite "period"
    fname.seekp(-6, std::ios_base::cur);
    fname << "duty_cycle";
    dc.open(fname.str());
    if (!dc.is_open()) {
        DUDS_THROW_EXCEPTION(PwmError() << SysPwmChip(chip) <<
            SysPwmChannel(channel) << boost::errinfo_file_name(fname.str())
        );
    }
    dc >> val;
    if (dc.fail()) {
        DUDS_THROW_EXCEPTION(PwmError() << SysPwmChip(chip) <<
            SysPwmChannel(channel) << boost::errinfo_file_name(fname.str())
        );
    }
    dutyNs = std::chrono::nanoseconds(val);
};

SysPwm::~SysPwm() {
    disable();
}

void SysPwm::enable(bool state) {
    if (state != running) {
        en.seekg(0);
        char v = '0';
        if (state) {
            ++v;
        }
        en << v << std::endl;
        if (en.fail()) {
            DUDS_THROW_EXCEPTION(PwmError());
        }
        running = state;
    }
}

void SysPwm::dutyPeriod(const std::chrono::nanoseconds &ns) {
    if (dutyNs != ns) {
        dc.seekg(0);
        dc << ns.count() << std::endl;
        if (dc.fail()) {
            DUDS_THROW_EXCEPTION(PwmError() << SysPwmDutyNs(ns.count()));
        }
        dutyNs = ns;
    }
}

double SysPwm::dutyCycle() const {
    return (double)dutyNs.count() / (double)periodNs.count();
}

void SysPwm::period(const std::chrono::nanoseconds &ns) {
    if (periodNs != ns) {
        per.seekg(0);
        per << ns.count() << std::endl;
        if (per.fail()) {
            DUDS_THROW_EXCEPTION(PwmError() << SysPwmPeriodNs(ns.count()));
        }
        periodNs = ns;
    }
}

void SysPwm::dutyCycle(double ratio) {
    std::chrono::nanoseconds t((std::chrono::nanoseconds::rep)(
        (double)(periodNs.count()) * ratio)
    );
    dutyPeriod(t);
}

void SysPwm::frequency(unsigned int hz) {
    period(
        std::chrono::nanoseconds((std::chrono::nanoseconds::rep)(
            (1.0 / (double)hz) * (double)(std::nano::den))
        )
    );
}

unsigned int SysPwm::frequency() const {
    return 1.0 / (double)periodNs.count();
}

} } } }