cdevtest_example.cpp

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 *   Copyright (C) 2015 Mark Charlebois. All rights reserved.
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/**
 * @file cdevtest_example.cpp
 * Example for Linux
 *
 * @author Mark Charlebois <charlebm@gmail.com>
 */

#include "cdevtest_example.h"

#include <px4_platform_common/tasks.h>
#include <px4_platform_common/time.h>
#include <drivers/drv_device.h>
#include <lib/cdev/CDev.hpp>
#include <unistd.h>
#include <stdio.h>

px4::AppState CDevExample::appState;

#define TESTDEV "/dev/cdevtest"

static bool g_exit = false;

static int writer_main(int argc, char *argv[])
{
    char buf[1];

    int fd = px4_open(TESTDEV, PX4_F_WRONLY);

    if (fd < 0) {
        PX4_INFO("Writer: Open failed %d", fd);
        return PX4_ERROR;
    }

    int ret = 0;
    int i = 0;

    while (!g_exit) {
        // Wait for 2 seconds
        PX4_INFO("Writer: Sleeping for 2 sec");
        ret = px4_sleep(2);

        if (ret < 0) {
            PX4_INFO("Writer: sleep failed %d %d", ret, errno);
            return ret;
        }

        buf[0] = 'A' + (char)(i % 26);
        PX4_INFO("Writer: writing char '%c'", buf[0]);
        ret = px4_write(fd, buf, 1);
        ++i;
    }

    px4_close(fd);
    PX4_INFO("Writer: stopped");
    return ret;
}

class PrivData
{
public:
    PrivData() : _read_offset(0) {}
    ~PrivData() = default;

    size_t _read_offset;
};

class CDevNode : public cdev::CDev
{
public:
    CDevNode() :
        CDev(TESTDEV),
        _is_open_for_write(false),
        _write_offset(0) {}

    ~CDevNode() override = default;

    int open(cdev::file_t *handlep) override;
    int close(cdev::file_t *handlep) override;
    ssize_t write(cdev::file_t *handlep, const char *buffer, size_t buflen) override;
    ssize_t read(cdev::file_t *handlep, char *buffer, size_t buflen) override;
private:
    bool _is_open_for_write;
    size_t _write_offset;
    char     _buf[1000];
};

int CDevNode::open(cdev::file_t *handlep)
{
    // Only allow one writer
    if (_is_open_for_write && (handlep->f_oflags & PX4_F_WRONLY)) {
        errno = EBUSY;
        return -1;
    }

    int ret = CDev::open(handlep);

    if (ret != 0) {
        return ret;
    }

    handlep->f_priv = new PrivData;

    if (_is_open_for_write && (handlep->f_oflags & PX4_F_WRONLY)) {
        _is_open_for_write = true;
    }

    return 0;
}

int CDevNode::close(cdev::file_t *handlep)
{
    delete (PrivData *)handlep->f_priv;
    handlep->f_priv = nullptr;
    CDev::close(handlep);

    // Enable a new writer of the device is re-opened for write
    if ((handlep->f_oflags & PX4_F_WRONLY) && _is_open_for_write) {
        _is_open_for_write = false;
    }

    return 0;
}

ssize_t CDevNode::write(cdev::file_t *handlep, const char *buffer, size_t buflen)
{
    for (size_t i = 0; i < buflen && _write_offset < 1000; i++) {
        _buf[_write_offset] = buffer[i];
        _write_offset++;
    }

    // ignore what was written, but let pollers know something was written
    poll_notify(POLLIN);

    return buflen;
}

ssize_t CDevNode::read(cdev::file_t *handlep, char *buffer, size_t buflen)
{
    PrivData *p = (PrivData *)handlep->f_priv;
    ssize_t chars_read = 0;
    PX4_INFO("read %zu write %zu", p->_read_offset, _write_offset);

    for (size_t i = 0; i < buflen && (p->_read_offset < _write_offset); i++) {
        buffer[i] = _buf[p->_read_offset];
        p->_read_offset++;
        chars_read++;
    }

    return chars_read;
}

CDevExample::~CDevExample()
{
    if (_node) {
        delete _node;
        _node = nullptr;
    }
}

int CDevExample::do_poll(int fd, int timeout, int iterations, int delayms_after_poll)
{
    int pollret, readret;
    int loop_count = 0;
    char readbuf[10];
    px4_pollfd_struct_t fds[1];

    fds[0].fd = fd;
    fds[0].events = POLLIN;
    fds[0].revents = 0;

    bool mustblock = (timeout < 0);

    // Test indefinte blocking poll
    while ((!appState.exitRequested()) && (loop_count < iterations)) {
        pollret = px4_poll(fds, 1, timeout);

        if (pollret < 0) {
            PX4_ERR("Reader: px4_poll failed %d FAIL", pollret);
            goto fail;
        }

        PX4_INFO("Reader: px4_poll returned %d", pollret);

        if (pollret) {
            readret = px4_read(fd, readbuf, 10);

            if (readret != 1) {
                if (mustblock) {
                    PX4_ERR("Reader:     read failed %d FAIL", readret);
                    goto fail;

                } else {
                    PX4_INFO("Reader:     read failed %d FAIL", readret);
                }

            } else {
                readbuf[readret] = '\0';
                PX4_INFO("Reader: px4_poll     returned %d, read '%s' PASS", pollret, readbuf);
            }
        }

        if (delayms_after_poll) {
            px4_usleep(delayms_after_poll * 1000);
        }

        loop_count++;
    }

    return 0;
fail:
    return 1;
}
int CDevExample::main()
{
    appState.setRunning(true);

    _node = new CDevNode();

    if (_node == nullptr) {
        PX4_INFO("Failed to allocate CDevNode");
        return -ENOMEM;
    }

    if (_node->init() != PX4_OK) {
        PX4_INFO("Failed to init CDevNode");
        return 1;
    }

    int fd = px4_open(TESTDEV, PX4_F_RDONLY);

    if (fd < 0) {
        PX4_INFO("Open failed %d", fd);
        return PX4_ERROR;
    }

    // Start a task that will write something in 4 seconds
    (void)px4_task_spawn_cmd("writer",
                 SCHED_DEFAULT,
                 SCHED_PRIORITY_MAX - 6,
                 2000,
                 writer_main,
                 (char *const *)nullptr);

    int ret = 0;

    PX4_INFO("TEST: BLOCKING POLL ---------------");

    if (do_poll(fd, -1, 3, 0)) {
        ret = 1;
        goto fail2;
    }

    PX4_INFO("TEST: ZERO TIMEOUT POLL -----------");

    if (do_poll(fd, 0, 3, 0)) {
        ret = 1;
        goto fail2;
        goto fail2;
    }

    PX4_INFO("TEST: ZERO TIMEOUT POLL -----------");

    if (do_poll(fd, 0, 3, 0)) {
        ret = 1;
        goto fail2;
        goto fail2;
    }

    PX4_INFO("TEST: ZERO TIMEOUT POLL -----------");

    if (do_poll(fd, 0, 3, 0)) {
        ret = 1;
        goto fail2;
    }

    PX4_INFO("TEST: 100ms TIMEOUT POLL -----------");

    if (do_poll(fd, 0, 30, 100)) {
        ret = 1;
        goto fail2;
    }

    PX4_INFO("TEST: 1 SEC TIMOUT POLL ------------");

    if (do_poll(fd, 1000, 3, 0)) {
        ret = 1;
        goto fail2;
    }

    PX4_INFO("TEST: waiting for writer to stop");
fail2:
    g_exit = true;
    px4_close(fd);
    PX4_INFO("TEST: waiting for writer to stop");
    px4_sleep(3);
    return ret;
}