mmap.c

来自「该代码适用于嵌入式开发」· C语言 代码 · 共 32 行

//#define _POSIX_MAPPED_FILES 1
#include <sys/mman.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>

int main(){
	int nLength;
	int fd,mapped_mem;
	unsigned char *pz;
	int ret;
	ret=getpagesize();
	printf("page size=%d\n",ret);
	fd=open("1.txt",O_RDWR);
	//fd=open("1.txt",O_RDONLY);
	printf("fd=%d\n",fd);
	if(fd<=0){
		printf("open file 1.txt error\n");
		return 0;
	}
	nLength=lseek(fd,0,SEEK_END);
	printf("file size %d sizes\n",nLength);
	lseek(fd,0,SEEK_SET);
	mapped_mem=(char *)mmap(0,nLength,PROT_WRITE | PROT_READ,MAP_SHARED,fd,0);
	pz=mapped_mem;
	printf("mapped=%x\n",mapped_mem);
	//printf("pz=%s\n",pz);
	return 0;
}