The following code will give you a hex dump of arbitrary memory from within your code.
#include <stdio.h>
// Usage:
// hexDump(desc, addr, len, perLine);
// desc: if non-NULL, printed as a description before hex dump.
// addr: the address to start dumping from.
// len: the number of bytes to dump.
// perLine: number of bytes on each output line.
void hexDump (
const char * desc,
const void * addr,
const int len,
int perLine
) {
// Silently ignore silly per-line values.
if (perLine < 4 || perLine > 64) perLine = 16;
int i;
unsigned char buff[perLine+1];
const unsigned char * pc = (const unsigned char *)addr;
// Output description if given.
if (desc != NULL) printf ("%s:\n", desc);
// Length checks.
if (len == 0) {
printf(" ZERO LENGTH\n");
return;
}
if (len < 0) {
printf(" NEGATIVE LENGTH: %d\n", len);
return;
}
// Process every byte in the data.
for (i = 0; i < len; i++) {
// Multiple of perLine means new or first line (with line offset).
if ((i % perLine) == 0) {
// Only print previous-line ASCII buffer for lines beyond first.
if (i != 0) printf (" %s\n", buff);
// Output the offset of current line.
printf (" %04x ", i);
}
// Now the hex code for the specific character.
printf (" %02x", pc[i]);
// And buffer a printable ASCII character for later.
if ((pc[i] < 0x20) || (pc[i] > 0x7e)) // isprint() may be better.
buff[i % perLine] = '.';
else
buff[i % perLine] = pc[i];
buff[(i % perLine) + 1] = '\0';
}
// Pad out last line if not exactly perLine characters.
while ((i % perLine) != 0) {
printf (" ");
i++;
}
// And print the final ASCII buffer.
printf (" %s\n", buff);
}
// Very simple test harness.
int main (int argc, char *argv[]) {
char my_str[] = "a char string greater than 16 chars";
hexDump ("my_str", &my_str, sizeof (my_str), 16);
return 0;
}
You pass into hexDump
a description, memory address, length, and how many bytes you want on each line.
It will output a hex dump (including character data) for examination. When you run it with the included main
, the output is:
my_str:
0000 61 20 63 68 61 72 20 73 74 72 69 6e 67 20 67 72 a char string gr
0010 65 61 74 65 72 20 74 68 61 6e 20 31 36 20 63 68 eater than 16 ch
0020 61 72 73 00 ars.