Update README.md

Added information about demo

Author: pnoltof

README.md

@@ -1 +1,23 @@
 # automotive-fuzzing-example
+For the demo:
+- Initialize Project
+- Create Fuzz Test for a function
+- To compile it the "extern" functions need to be implemented for this use the scripts in fuzzing/auto-mock-fuzz:
+- ```python3 gen_template.py /path_to_project/automotive-fuzzing-example/modules/*/src/*.c /path_to_project/automotive-fuzzing-example/modules/*/src/*.h```
+- This will create two excel sheets. The Sheet called testgen_mocks.xlsx will contain information about the functions that are declared as extern
+- Fill in the excel sheet like this:
+
+| return: RETURN_INT(int)     | position_as_bytes: WRITE_BYTES(12) | hmac_as_bytes: WRITE_BYTES(64) |                        |                       |
+|-----------------------------|------------------------------------|--------------------------------|------------------------|-----------------------|
+| return: RETURN_INT(int)     | message: WRITE_BYTES(len)          | key: WRITE_BYTES(64)           | nonce: WRITE_BYTES(64) | hmac: WRITE_BYTES(64) |
+| return: RETURN_INT(uint8_t) |                                    |                                |                        |                       |
+| return: RETURN_INT(int)     |                                    |                                |                        |                       |
+
+- Run the second script to generate the mocking library from this: 
+- ```python3 gen_tests.py mocklib gen_template/testgen_mocks.xlsx ../mocks```
+- This creates mocklib.h and mocklib.cpp in fuzzing/mocks
+- Add the mocklib.cpp to the compiler options and also add the include path fuzzing/mocks
+- In the fuzztest you need to create a FuzzedDataProvider object and give a pointer to it to the mocking library. Add the following to the beginning of the FUZZ function:  
+```FuzzedDataProvider fuzz_data(Data, Size);```  
+```mocklib_set_data(&fuzz_data);```
+- You also need to include the FuzzedDataProvider.h and mocklib.h in the fuzztest