hexdump

void print_hexdump(unsigned char *data, int data_len, int off)
{
    int line, offset, m;
    const int digits = ceil(log(data_len / 16.0) / log(16)) + 1;

    for (line = 0; line < data_len; line += 16) {
        printf("        %0*X   ", digits, line + off);
        for (m = 0; m <= 1; m++) {
            for (offset = 0; offset < 16; offset++) {
                if (line + offset < data_len)
                    switch (m) {
                        case 0:
                            printf("%02x ", data[line + offset]);
                            break;

                        case 1:
                            if (data[line + offset] >= 0x20 && data[line + offset] <= 0x7E)
                                printf("%c", data[line + offset]);
                            else
                                printf(".");
                            break;
                    }
                else
                    printf("   ");

                if (offset % 8 == 7)
                    printf(" ");
            }
            printf("  ");
        }
        printf("\n");
    }
}