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#include <fcntl.h>
#include <inttypes.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <unistd.h>
#if __LP64__
#define strtoptr strtoull
#else
#define strtoptr strtoul
#endif
static int usage()
{
fprintf(stderr,"r [-b|-s] <address> [<value>]\n");
return -1;
}
int main(int argc, char *argv[])
{
if(argc < 2) return usage();
int width = 4;
if(!strcmp(argv[1], "-b")) {
width = 1;
argc--;
argv++;
} else if(!strcmp(argv[1], "-s")) {
width = 2;
argc--;
argv++;
}
if(argc < 2) return usage();
uintptr_t addr = strtoptr(argv[1], 0, 16);
uintptr_t endaddr = 0;
char* end = strchr(argv[1], '-');
if (end)
endaddr = strtoptr(end + 1, 0, 16);
if (!endaddr)
endaddr = addr + width - 1;
if (endaddr <= addr) {
fprintf(stderr, "end address <= start address\n");
return -1;
}
bool set = false;
uint32_t value = 0;
if(argc > 2) {
set = true;
value = strtoul(argv[2], 0, 16);
}
int fd = open("/dev/mem", O_RDWR | O_SYNC);
if(fd < 0) {
fprintf(stderr,"cannot open /dev/mem\n");
return -1;
}
off64_t mmap_start = addr & ~(PAGE_SIZE - 1);
size_t mmap_size = endaddr - mmap_start + 1;
mmap_size = (mmap_size + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1);
void* page = mmap64(0, mmap_size, PROT_READ | PROT_WRITE,
MAP_SHARED, fd, mmap_start);
if(page == MAP_FAILED){
fprintf(stderr,"cannot mmap region\n");
return -1;
}
while (addr <= endaddr) {
switch(width){
case 4: {
uint32_t* x = (uint32_t*) (((uintptr_t) page) + (addr & 4095));
if(set) *x = value;
fprintf(stderr,"%08"PRIxPTR": %08x\n", addr, *x);
break;
}
case 2: {
uint16_t* x = (uint16_t*) (((uintptr_t) page) + (addr & 4095));
if(set) *x = value;
fprintf(stderr,"%08"PRIxPTR": %04x\n", addr, *x);
break;
}
case 1: {
uint8_t* x = (uint8_t*) (((uintptr_t) page) + (addr & 4095));
if(set) *x = value;
fprintf(stderr,"%08"PRIxPTR": %02x\n", addr, *x);
break;
}
}
addr += width;
}
return 0;
}
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