内存查看工具源码

/*

• devmem2.c: Simple program to read/write from/to any location in memory.
• Copyright © 2000, Jan-Derk Bakker (J.D.Bakker@its.tudelft.nl)
• This software has been developed for the LART computing board
• (http://www.lart.tudelft.nl/). The development has been sponsored by
• the Mobile MultiMedia Communications (http://www.mmc.tudelft.nl/)
• and Ubiquitous Communications (http://www.ubicom.tudelft.nl/)
• projects.
• The author can be reached at:
• Jan-Derk Bakker
• Information and Communication Theory Group
• Faculty of Information Technology and Systems
• Delft University of Technology
• P.O. Box 5031
• 2600 GA Delft
• The Netherlands
• This program is free software; you can redistribute it and/or modify
• it under the terms of the GNU General Public License as published by
• the Free Software Foundation; either version 2 of the License, or
• (at your option) any later version.
• This program is distributed in the hope that it will be useful,
• but WITHOUT ANY WARRANTY; without even the implied warranty of
• MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
• GNU General Public License for more details.
• You should have received a copy of the GNU General Public License
• along with this program; if not, write to the Free Software
• Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

*/

#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>

#define FATAL do { fprintf(stderr, “Error at line %d, file %s (%d) [%s]\n”,
LINE, FILE, errno, strerror(errno)); exit(1); } while(0)

#define MAP_SIZE 4096UL
#define MAP_MASK (MAP_SIZE - 1)

int main(int argc, char **argv) {
int fd;
void *map_base, *virt_addr;
unsigned long read_result, writeval;
off_t target;
int access_type = ‘w’;

if(argc < 2) {
	fprintf(stderr, "\nUsage:\t%s { address } [ type [ data ] ]\n"
		"\taddress : memory address to act upon\n"
		"\ttype    : access operation type : [b]yte, [h]alfword, [w]ord\n"
		"\tdata    : data to be written\n\n",
		argv[0]);
	exit(1);
}
target = strtoul(argv[1], 0, 0);

if(argc > 2)
	access_type = tolower(argv[2][0]);


if((fd = open("/dev/mem", O_RDWR | O_SYNC)) == -1) FATAL;
printf("/dev/mem opened.\n"); 
fflush(stdout);

/* Map one page */
map_base = mmap(0, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, target & ~MAP_MASK);
if(map_base == (void *) -1) FATAL;
printf("Memory mapped at address %p.\n", map_base); 
fflush(stdout);

virt_addr = map_base + (target & MAP_MASK);
switch(access_type) {
	case 'b':
		read_result = *((unsigned char *) virt_addr);
		break;
	case 'h':
		read_result = *((unsigned short *) virt_addr);
		break;
	case 'w':
		read_result = *((unsigned long *) virt_addr);
		break;
	default:
		fprintf(stderr, "Illegal data type '%c'.\n", access_type);
		exit(2);
}
printf("Value at address 0x%X (%p): 0x%X\n", target, virt_addr, read_result); 
fflush(stdout);

if(argc > 3) {
	writeval = strtoul(argv[3], 0, 0);
	switch(access_type) {
		case 'b':
			*((unsigned char *) virt_addr) = writeval;
			read_result = *((unsigned char *) virt_addr);
			break;
		case 'h':
			*((unsigned short *) virt_addr) = writeval;
			read_result = *((unsigned short *) virt_addr);
			break;
		case 'w':
			*((unsigned long *) virt_addr) = writeval;
			read_result = *((unsigned long *) virt_addr);
			break;
	}
	printf("Written 0x%X; readback 0x%X\n", writeval, read_result); 
	fflush(stdout);
}

if(munmap(map_base, MAP_SIZE) == -1) FATAL;
close(fd);
return 0;

}