dwrite.c

请在解压时看说明文档 内有详细说明

/************************************************************/
/***** dwrite.c, this is a test program for upperdrv.c *****/
/************************************************************/

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <asm/io.h>

/************************************************************/
/***** define some constants used in upperdrv.c  *****/
/************************************************************/
#ifndef _UPPER_DEVICE_H
#define _UPPER_DEVICE_H
#include <linux/ioctl.h>
#define UPPER_MAJOR 117
#define UPPER_LOW2UPPER 1 // change the input string from low to upper characters
#define UPPER_UNCHAN 0     //copy the input string to the output
#define UPPER_MAGIC UPPER_MAJOR
#define UPPER_RESET _IO(UPPER_MAGIC,0)   // reset the data
#define UPPER_QUERY_NEW_MSG _IO(UPPER_MAGIC,1) // check for new message
#define UPPER_QUERY_MSG_LENGTH _IO(UPPER_MAGIC,2) // get message length
#define IOC_NEW_MSG 1
#endif

char buf[1512];

int main(int argc,char **argv) {
	int fd,len=0,quit=0;
	int dbg;
	if(argc<3){
		printf("usage: dwrite+device name+[string]\n");
		exit(0);}
	fd=open("/dev/upper",O_WRONLY);
	if(fd<=0) {
		printf("Error opening device for writing!\n");
		return 0;
	}
	while(!quit){
		sscanf(argv[2],"%s",buf);
		printf("buf=\"%s\" ",buf);
		if(!strcmp(buf,"exit"))
		quit=1;
		while(ioctl(fd,UPPER_QUERY_NEW_MSG)){
			usleep(1000);
//			printf("usleep\n");
			}
		printf("strlen(buf) = %d\n",strlen(buf));
		len=write(fd,buf,strlen(buf));
		printf("  After write,return len=%d\n",len);
		if(len<0) {
			printf("Error writing to device!\n");
			printf("len=%d",len);
			close(fd);
			return 0;
		}
		else
			quit=1;
		printf("%d bytes written to device!\n",len);
	}
	close(fd);
}