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#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <string.h>
static int usage()
{
fprintf(stderr,"r [-b|-s] <address> [<value>]\n");
return -1;
}
int r_main(int argc, char *argv[])
{
int width = 4, set = 0, fd;
unsigned addr, value;
void *page;
if(argc < 2) return usage();
if(!strcmp(argv[1], "-b")) {
width = 1;
argc--;
argv++;
} else if(!strcmp(argv[1], "-s")) {
width = 2;
argc--;
argv++;
}
if(argc < 2) return usage();
addr = strtoul(argv[1], 0, 16);
if(argc > 2) {
set = 1;
value = strtoul(argv[2], 0, 16);
}
fd = open("/dev/mem", O_RDWR | O_SYNC);
if(fd < 0) {
fprintf(stderr,"cannot open /dev/mem\n");
return -1;
}
page = mmap(0, 8192, PROT_READ | PROT_WRITE,
MAP_SHARED, fd, addr & (~4095));
if(page == MAP_FAILED){
fprintf(stderr,"cannot mmap region\n");
return -1;
}
switch(width){
case 4: {
unsigned *x = (unsigned*) (((unsigned) page) + (addr & 4095));
if(set) *x = value;
fprintf(stderr,"%08x: %08x\n", addr, *x);
break;
}
case 2: {
unsigned short *x = (unsigned short*) (((unsigned) page) + (addr & 4095));
if(set) *x = value;
fprintf(stderr,"%08x: %04x\n", addr, *x);
break;
}
case 1: {
unsigned char *x = (unsigned char*) (((unsigned) page) + (addr & 4095));
if(set) *x = value;
fprintf(stderr,"%08x: %02x\n", addr, *x);
break;
}
}
return 0;
}
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