39 lines
844 B
C
39 lines
844 B
C
#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <string.h>
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int main(int argc, char **argv)
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{
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int fd;
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char* filename=NULL;
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int val;
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filename = argv[1];
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fd = open(filename, O_RDWR);//打开dev/设备文件
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if (fd < 0)//小于0说明没有成功
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{
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printf("error, can't open %s\n", filename);
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return 0;
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}
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if(argc !=3)
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{
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printf(argv[1]);//打印用法
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}
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if(!strcmp(argv[2], "on")) //如果输入等于on，则LED亮
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val = 0;
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else if(!strcmp(argv[2], "off")) //如果输入等于off，则LED灭
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val = 1;
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else
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goto error;
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write(fd, &val, 4);//操作LED
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close(fd);
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return 0;
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error:
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printf("usage: ./led_dev.exe [device] [on/off]\n");
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close(fd);
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return -1;
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}
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