75 lines
1.4 KiB
C
75 lines
1.4 KiB
C
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/*
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* Copyright (c) 2011-2023, Shanghai Real-Thread Electronic Technology Co.,Ltd
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*
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* Change Logs:
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* Date Author Notes
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* 2020-12-03 quanzhao the first version
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*/
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#include <time.h>
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#include <string.h>
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#include <rtthread.h>
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static struct rt_device null_dev;
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static rt_ssize_t null_read (rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
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{
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return 0;
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}
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static rt_ssize_t null_write (rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
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{
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return size;
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}
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static rt_err_t null_control (rt_device_t dev, int cmd, void *args)
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{
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return RT_EOK;
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}
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#ifdef RT_USING_DEVICE_OPS
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const static struct rt_device_ops null_ops =
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{
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RT_NULL,
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RT_NULL,
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RT_NULL,
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null_read,
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null_write,
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null_control
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};
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#endif
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int null_device_init(void)
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{
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static rt_bool_t init_ok = RT_FALSE;
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if (init_ok)
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{
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return 0;
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}
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RT_ASSERT(!rt_device_find("null"));
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null_dev.type = RT_Device_Class_Miscellaneous;
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#ifdef RT_USING_DEVICE_OPS
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null_dev.ops = &null_ops;
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#else
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null_dev.init = RT_NULL;
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null_dev.open = RT_NULL;
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null_dev.close = RT_NULL;
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null_dev.read = null_read;
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null_dev.write = null_write;
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null_dev.control = null_control;
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#endif
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/* no private */
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null_dev.user_data = RT_NULL;
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rt_device_register(&null_dev, "null", RT_DEVICE_FLAG_RDWR);
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init_ok = RT_TRUE;
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return 0;
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}
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INIT_DEVICE_EXPORT(null_device_init);
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