75 lines
1.4 KiB
C
75 lines
1.4 KiB
C
/*
|
|
* Copyright (c) 2011-2020, Shanghai Real-Thread Electronic Technology Co.,Ltd
|
|
*
|
|
* Change Logs:
|
|
* Date Author Notes
|
|
* 2020-12-03 quanzhao the first version
|
|
*/
|
|
|
|
#include <time.h>
|
|
#include <string.h>
|
|
#include <rtthread.h>
|
|
|
|
static struct rt_device null_dev;
|
|
|
|
static rt_ssize_t null_read (rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static rt_ssize_t null_write (rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
|
|
{
|
|
return size;
|
|
}
|
|
|
|
static rt_err_t null_control (rt_device_t dev, int cmd, void *args)
|
|
{
|
|
return RT_EOK;
|
|
}
|
|
|
|
#ifdef RT_USING_DEVICE_OPS
|
|
const static struct rt_device_ops null_ops =
|
|
{
|
|
RT_NULL,
|
|
RT_NULL,
|
|
RT_NULL,
|
|
null_read,
|
|
null_write,
|
|
null_control
|
|
};
|
|
#endif
|
|
|
|
int null_device_init(void)
|
|
{
|
|
static rt_bool_t init_ok = RT_FALSE;
|
|
|
|
if (init_ok)
|
|
{
|
|
return 0;
|
|
}
|
|
RT_ASSERT(!rt_device_find("null"));
|
|
null_dev.type = RT_Device_Class_Miscellaneous;
|
|
|
|
#ifdef RT_USING_DEVICE_OPS
|
|
null_dev.ops = &null_ops;
|
|
#else
|
|
null_dev.init = RT_NULL;
|
|
null_dev.open = RT_NULL;
|
|
null_dev.close = RT_NULL;
|
|
null_dev.read = null_read;
|
|
null_dev.write = null_write;
|
|
null_dev.control = null_control;
|
|
#endif
|
|
|
|
/* no private */
|
|
null_dev.user_data = RT_NULL;
|
|
|
|
rt_device_register(&null_dev, "null", RT_DEVICE_FLAG_RDWR);
|
|
|
|
init_ok = RT_TRUE;
|
|
|
|
return 0;
|
|
}
|
|
INIT_DEVICE_EXPORT(null_device_init);
|
|
|