Is it still ASCII? If so p is 01110000 and s is 01110011(?) but I don't know what \0 is, is it 00000000? Is there anything else know about the data? If the rest of the characters are all numbers, those all start with 0011 but that doesn't seem of much use. 4-9 have either the 5th or 6th bit set.

Only if AND with 00001100 yields zero the other 3 tests are needed.

Ofc I have no idea what opcodes the language provides.