C++ (Cpp) mraa_gpio_context::mmap_read Examples

Example #1

File: gpio.c Project: chenyiran/mraa

int
mraa_gpio_read(mraa_gpio_context dev)
{
    if (dev == NULL)
        return -1;

    if (dev->mmap_read != NULL)
        return dev->mmap_read(dev);

    if (dev->value_fp == -1) {
        if (mraa_gpio_get_valfp(dev) != MRAA_SUCCESS) {
            syslog(LOG_ERR, "gpio: Failed to get value file pointer");
            return -1;
        }
    }
    else {
        // if value_fp is new this is pointless
        lseek(dev->value_fp, 0, SEEK_SET);
    }
    char bu[2];
    if (read(dev->value_fp, bu, 2*sizeof(char)) != 2) {
        syslog(LOG_ERR, "gpio: Failed to read a sensible value from sysfs");
        return -1;
    }
    lseek(dev->value_fp, 0, SEEK_SET);

    return (int) strtol(bu, NULL, 10);
}

Example #2

File: gpio.c Project: fboudra/mraa

int
mraa_gpio_read(mraa_gpio_context dev)
{
    if (dev == NULL) {
        syslog(LOG_ERR, "gpio: read: context is invalid");
        return -1;
    }

    if (IS_FUNC_DEFINED(dev, gpio_read_replace))
        return dev->advance_func->gpio_read_replace(dev);

    if (dev->mmap_read != NULL)
        return dev->mmap_read(dev);

    if (dev->value_fp == -1) {
        if (mraa_gpio_get_valfp(dev) != MRAA_SUCCESS) {
            return -1;
        }
    } else {
        // if value_fp is new this is pointless
        lseek(dev->value_fp, 0, SEEK_SET);
    }
    char bu[2];
    if (read(dev->value_fp, bu, 2 * sizeof(char)) != 2) {
        syslog(LOG_ERR, "gpio%i: read: Failed to read a sensible value from sysfs: %s", dev->pin, strerror(errno));
        return -1;
    }
    lseek(dev->value_fp, 0, SEEK_SET);

    return (int) strtol(bu, NULL, 10);
}