linuxrw

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <signal.h>
#include <fcntl.h>
#include <ctype.h>
#include <termios.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <string.h>
#define AUTHOR "smile"
#define MAP_SIZE 4096UL
#define MAP_MASK (MAP_SIZE - 1)

int main(int argc, char **argv)
{
	int fd;
	void *map_base, *virt_addr;
	unsigned int value;
	unsigned int reg;
	switch (argc) {
	case 3:
		if (strcmp(argv[1], "-r")) {
			printf("usage:\nlinuxrw -r        0x10000000\nlinuxrw -w 
			0x10000000 0x20000000\n");
			exit(-1);
		}
		break;

	case 4:
		if (strcmp(argv[1], "-w")) {
			printf("usage:\nlinuxrw -r 0x10000000\nlinuxrw -w 0x10000000 0x20000000\n");
			exit(-1);
		}
		break;

	default :
		printf("usage:\nlinuxrw -r 0x10000000\nlinuxrw -w 0x10000000 0x20000000\n");
		exit (-1);
	}

	reg = strtol(argv[2], NULL, 16);

	if ((fd = open("/dev/mem", O_RDWR | O_SYNC)) <0) {
		perror("open");
		return -1;
	}

	map_base = mmap(0, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, reg & ~MAP_MASK);

	virt_addr = map_base + (reg & MAP_MASK);
	if (argc == 3) {
		value = *(unsigned int *) virt_addr;
		printf("reg :0x%x \nvalue:0x%x \n", reg, value);
	} else if (argc ==4 ) {
		value = strtol(argv[3], NULL, 16);
		*(unsigned int *) virt_addr = value;
		printf("reg :0x%x \nvalue: 0x%x \n", reg, *(unsigned int*)virt_addr);
	}
	munmap(map_base,MAP_SIZE);
	close(fd);
	return 0;
}
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