util.cpp

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#include "usb_cam/util.h"
 
using namespace usb_cam;
 
time_t util::get_epoch_time_shift_us()
{
    struct timeval epoch_time;
    struct timespec monotonic_time;
 
    gettimeofday(&epoch_time, NULL);
    clock_gettime(CLOCK_MONOTONIC, &monotonic_time);
 
    const int64_t uptime_ms =
            monotonic_time.tv_sec * 1000 + static_cast<int64_t>(
                std::round(monotonic_time.tv_nsec / 1000000.0));
    const int64_t epoch_ms =
            epoch_time.tv_sec * 1000 + static_cast<int64_t>(
                std::round(epoch_time.tv_usec / 1000.0));
 
    return static_cast<time_t>((epoch_ms - uptime_ms) * 1000);
}
 
timespec util::calc_img_timestamp(const timeval & buffer_time, const time_t & epoch_time_shift_us)
{
  timespec img_timestamp;
 
  int64_t buffer_time_us = (buffer_time.tv_sec * 1000000) + buffer_time.tv_usec;
  buffer_time_us += epoch_time_shift_us;
 
  img_timestamp.tv_sec = (buffer_time_us / 1000000);
  img_timestamp.tv_nsec = (buffer_time_us % 1000000) * 1000;
 
  return img_timestamp;
}
 
int util::xioctl(int fd, int request, void * arg)
{
    int r;
    do
    {
        r = ioctl(fd, request, arg);
        continue;
    } while (-1 == r && EINTR == errno);
 
    return r;
}
 
unsigned char util::CLIPVALUE(const int & val)
{
    // Old method (if)
    /*   val = val < 0 ? 0 : val; */
    /*   return val > 255 ? 255 : val; */
 
    try {
        // New method array
        return usb_cam::constants::uchar_clipping_table.at(
                    val + usb_cam::constants::clipping_table_offset);
    } catch (std::out_of_range const &) {
        // fall back to old method
        unsigned char clipped_val = val < 0 ? 0 : static_cast<unsigned char>(val);
        return val > 255 ? 255 : clipped_val;
    }
}