I've just tried compiling the strcmp example I pointed to, and the Arduino compiler doesn't like the brackets round the function name. This code compiles for me (but I don't have an Arduino to hand to try it out):
int strcmp(const char *s1, const char *s2)
{
unsigned char uc1, uc2;
/* Move s1 and s2 to the first differing characters
in each string, or the ends of the strings if they
are identical. */
while (*s1 != '\0' && *s1 == *s2) {
s1++;
s2++;
}
/* Compare the characters as unsigned char and
return the difference. */
uc1 = (*(unsigned char *) s1);
uc2 = (*(unsigned char *) s2);
if (uc1 != uc2)
return ((uc1 < uc2) ? -1 : (uc1 > uc2));
else
return 0;
}
If you stick that at the top of your sketch, then the "if (strcmp(code, "0415E9B02D") == 0) {" should work.
I think you're right with being able to put TextString into hardware/libraries, but I'm not an expert on where it looks for the libraries.