diff --git a/tests/scripts/generate_code.py b/tests/scripts/generate_code.py
index 58020f1..6b37315 100644
--- a/tests/scripts/generate_code.py
+++ b/tests/scripts/generate_code.py
@@ -1,46 +1,44 @@
+# Test suites code generator.
+#
+# Copyright (C) 2006-2017, ARM Limited, All Rights Reserved
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# This file is part of mbed TLS (https://tls.mbed.org)
+
 """
-  Test suites code generator.
+Test Suite code generator.
 
-  Copyright (C) 2006-2017, ARM Limited, All Rights Reserved
-  SPDX-License-Identifier: Apache-2.0
+Generates a test source file using following input files:
 
-  Licensed under the Apache License, Version 2.0 (the "License"); you may
-  not use this file except in compliance with the License.
-  You may obtain a copy of the License at
-
-  http://www.apache.org/licenses/LICENSE-2.0
-
-  Unless required by applicable law or agreed to in writing, software
-  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-  See the License for the specific language governing permissions and
-  limitations under the License.
-
-  This file is part of mbed TLS (https://tls.mbed.org)
+test_suite_xyz.function - Read test functions from test suite functions file.
+test_suite_xyz.data - Read test functions and their dependencies to generate
+                      dispatch and dependency check code.
+main template - Substitute generated test function dispatch code, dependency
+                checking code.
+platform .function - Read host or target platform implementation for
+                     dispatching test cases from .data file.
+helper .function - Read common reusable functions.
 """
 
+
 import os
 import re
 import argparse
 import shutil
 
 
-"""
-Generates code in following structure.
-
-<output dir>/
- |-- mbedtls/
- |   |-- <test suite #1>/
- |   |    |-- main.c
- |   |    |-- *.data files
- |   ...
- |   |-- <test suite #n>/
- |   |    |-- main.c
- |   |    |-- *.data files
- |   |
-"""
-
-
 BEGIN_HEADER_REGEX = '/\*\s*BEGIN_HEADER\s*\*/'
 END_HEADER_REGEX = '/\*\s*END_HEADER\s*\*/'
 
@@ -67,7 +65,7 @@
         """
         Init file handle.
         
-        :param file_name: 
+        :param file_name: File path to open.
         """
         super(FileWrapper, self).__init__(file_name, 'r')
         self.line_no = 0
@@ -75,7 +73,7 @@
     def next(self):
         """
         Iterator return impl.
-        :return: 
+        :return: Line read from file.
         """
         line = super(FileWrapper, self).next()
         if line:
@@ -86,13 +84,19 @@
         """
         Wrap the base class readline.
         
-        :param limit: 
-        :return: 
+        :param limit: limit to match file.readline([limit])
+        :return: Line read from file.
         """
         return self.next()
 
 
 def split_dep(dep):
+    """
+    Split NOT character '!' from dependency. Used by gen_deps()
+
+    :param dep: Dependency list
+    :return: list of tuples where index 0 has '!' if there was a '!' before the dependency string
+    """
     return ('!', dep[1:]) if dep[0] == '!' else ('', dep)
 
 
@@ -100,8 +104,8 @@
     """
     Generates dependency i.e. if def and endif code
 
-    :param deps:
-    :return:
+    :param deps: List of dependencies.
+    :return: if defined and endif code with macro annotations for readability.
     """
     dep_start = ''.join(['#if %sdefined(%s)\n' % split_dep(x) for x in deps])
     dep_end = ''.join(['#endif /* %s */\n' % x for x in reversed(deps)])
@@ -113,8 +117,8 @@
     """
     Generates dependency checks in one line. Useful for writing code in #else case.
 
-    :param deps:
-    :return:
+    :param deps: List of dependencies.
+    :return: ifdef code
     """
     defines = ('#if ' if len(deps) else '') + ' && '.join(['%sdefined(%s)' % split_dep(x) for x in deps])
     return defines
@@ -122,12 +126,12 @@
 
 def gen_function_wrapper(name, locals, args_dispatch):
     """
-    Creates test function code
+    Creates test function wrapper code. A wrapper has the code to unpack parameters from parameters[] array.
 
-    :param name:
-    :param locals:
-    :param args_dispatch:
-    :return:
+    :param name: Test function name
+    :param locals: Local variables declaration code
+    :param args_dispatch: List of dispatch arguments. Ex: ['(char *)params[0]', '*((int *)params[1])']
+    :return: Test function wrapper.
     """
     # Then create the wrapper
     wrapper = '''
@@ -145,11 +149,11 @@
 
 def gen_dispatch(name, deps):
     """
-    Generates dispatch condition for the functions.
+    Generates dispatch code for the test function table.
 
-    :param name:
-    :param deps:
-    :return:
+    :param name: Test function name
+    :param deps: List of dependencies
+    :return: Dispatch code.
     """
     if len(deps):
         ifdef = gen_deps_one_line(deps)
@@ -172,8 +176,8 @@
     """
     Parses function headers.
     
-    :param funcs_f: 
-    :return: 
+    :param funcs_f: file object for .functions file
+    :return: Test suite headers code
     """
     headers = '#line %d "%s"\n' % (funcs_f.line_no + 1, funcs_f.name)
     for line in funcs_f:
@@ -188,10 +192,10 @@
 
 def parse_suite_deps(funcs_f):
     """
-    Parses function dependencies.
+    Parses test suite dependencies.
     
-    :param funcs_f: 
-    :return: 
+    :param funcs_f: file object for .functions file
+    :return: List of test suite dependencies.
     """
     deps = []
     for line in funcs_f:
@@ -208,9 +212,10 @@
 
 def parse_function_deps(line):
     """
+    Parses function dependencies.
     
-    :param line: 
-    :return: 
+    :param line: Line from .functions file that has dependencies.
+    :return: List of dependencies.
     """
     deps = []
     m = re.search(BEGIN_CASE_REGEX, line)
@@ -226,8 +231,8 @@
     """
     Parsing function signature
     
-    :param line: 
-    :return: 
+    :param line: Line from .functions file that has a function signature.
+    :return: function name, argument list, local variables for wrapper function and argument dispatch code.
     """
     args = []
     locals = ''
@@ -265,12 +270,12 @@
 
 def parse_function_code(funcs_f, deps, suite_deps):
     """
+    Parses out a function from function file object and generates function and dispatch code.
     
-    :param line_no: 
-    :param funcs_f: 
-    :param deps:
-    :param suite_deps:
-    :return: 
+    :param funcs_f: file object of the functions file.
+    :param deps: List of dependencies
+    :param suite_deps: List of test suite dependencies
+    :return: Function name, arguments, function code and dispatch code.
     """
     code = '#line %d "%s"\n' % (funcs_f.line_no + 1, funcs_f.name)
     for line in funcs_f:
@@ -315,8 +320,9 @@
     """
     Returns functions code pieces
     
-    :param funcs_f: 
-    :return:
+    :param funcs_f: file object of the functions file.
+    :return: List of test suite dependencies, test function dispatch code, function code and
+             a dict with function identifiers and arguments info.
     """
     suite_headers = ''
     suite_deps = []
@@ -354,9 +360,9 @@
     Since return value is used to write back to the intermediate data file. 
     Any escape characters in the input are retained in the output.
 
-    :param str:
-    :param ch:
-    :return:
+    :param str: String to split
+    :param ch: split character
+    :return: List of splits
     """
     if len(ch) > 1:
         raise ValueError('Expected split character. Found string!')
@@ -379,8 +385,8 @@
     """
     Parses .data file
     
-    :param data_f: 
-    :return: 
+    :param data_f: file object of the data file.
+    :return: Generator that yields test name, function name, dependency list and function argument list.
     """
     STATE_READ_NAME = 0
     STATE_READ_ARGS = 1
@@ -423,9 +429,9 @@
     """
     Generate code for the dependency.
     
-    :param dep_id: 
-    :param dep: 
-    :return: 
+    :param dep_id: Dependency identifier
+    :param dep: Dependency macro
+    :return: Dependency check code
     """
     assert dep_id > -1, "Dependency Id should be a positive integer."
     noT, dep = ('!', dep[1:]) if dep[0] == '!' else ('', dep)
@@ -447,9 +453,9 @@
     """
     Generates code for expression check
     
-    :param exp_id: 
-    :param exp: 
-    :return: 
+    :param exp_id: Expression Identifier
+    :param exp: Expression/Macro
+    :return: Expression check code
     """
     assert exp_id > -1, "Expression Id should be a positive integer."
     assert len(exp) > 0, "Expression should not be an empty string."
@@ -467,10 +473,10 @@
     Write dependencies to intermediate test data file.
     It also returns dependency check code.
       
-    :param out_data_f:
-    :param dep: 
-    :param unique_deps: 
-    :return: 
+    :param out_data_f: Output intermediate data file
+    :param test_deps: Dependencies
+    :param unique_deps: Mutable list to track unique dependencies that are global to this re-entrant function.
+    :return: returns dependency check code.
     """
     dep_check_code = ''
     if len(test_deps):
@@ -492,11 +498,11 @@
     Writes test parameters to the intermediate data file.
     Also generates expression code.
      
-    :param out_data_f: 
-    :param test_args: 
-    :param func_args:
-    :param unique_expressions: 
-    :return: 
+    :param out_data_f: Output intermediate data file
+    :param test_args: Test parameters
+    :param func_args: Function arguments
+    :param unique_expressions: Mutable list to track unique expressions that are global to this re-entrant function.
+    :return: Returns expression check code.
     """
     expression_code = ''
     for i in xrange(len(test_args)):
@@ -524,10 +530,10 @@
     """
     Adds preprocessor checks for test suite dependencies.
     
-    :param suite_deps: 
-    :param dep_check_code: 
-    :param expression_code: 
-    :return: 
+    :param suite_deps: Test suite dependencies read from the .functions file.
+    :param dep_check_code: Dependency check code
+    :param expression_code: Expression check code
+    :return: Dependency and expression code guarded by test suite dependencies.
     """
     if len(suite_deps):
         ifdef = gen_deps_one_line(suite_deps)
@@ -548,11 +554,11 @@
     """
     Generates dependency checks, expression code and intermediate data file from test data file.
     
-    :param data_f: 
-    :param out_data_f:
-    :param func_info: 
-    :param suite_deps:
-    :return: 
+    :param data_f: Data file object
+    :param out_data_f:Output intermediate data file
+    :param func_info: Dict keyed by function and with function id and arguments info
+    :param suite_deps: Test suite deps
+    :return: Returns dependency and expression check code
     """
     unique_deps = []
     unique_expressions = []
@@ -586,14 +592,14 @@
     """
     Generate mbed-os test code.
 
-    :param funcs_file:
-    :param dat  a_file:
-    :param template_file:
-    :param platform_file:
-    :param help_file:
-    :param suites_dir:
-    :param c_file:
-    :param out_data_file:
+    :param funcs_file: Functions file object
+    :param data_file: Data file object
+    :param template_file: Template file object
+    :param platform_file: Platform file object
+    :param help_file: Helper functions file object
+    :param suites_dir: Test suites dir
+    :param c_file: Output C file object
+    :param out_data_file: Output intermediate data file object
     :return:
     """
     for name, path in [('Functions file', funcs_file),
diff --git a/tests/scripts/generate_code_ut.py b/tests/scripts/generate_code_ut.py
index 4baeeaf..bc9f6b6 100644
--- a/tests/scripts/generate_code_ut.py
+++ b/tests/scripts/generate_code_ut.py
@@ -1,19 +1,22 @@
-"""
-mbed TLS
-Copyright (c) 2017 ARM Limited
+# Unit test for generate_code.py
+#
+# Copyright (C) 2006-2017, ARM Limited, All Rights Reserved
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# This file is part of mbed TLS (https://tls.mbed.org)
 
-Licensed under the Apache License, Version 2.0 (the "License");
-you may not use this file except in compliance with the License.
-You may obtain a copy of the License at
-
-    http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing, software
-distributed under the License is distributed on an "AS IS" BASIS,
-WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-See the License for the specific language governing permissions and
-limitations under the License.
-"""
 from StringIO import StringIO
 from unittest import TestCase, main as unittest_main
 from mock import patch
@@ -425,7 +428,7 @@
 
     def test_int_and_char_params(self):
         """
-        
+        Test int and char parameters parsing
         :return: 
         """
         line = 'void entropy_threshold( char * a, int b, int result )'
@@ -437,7 +440,7 @@
 
     def test_hex_params(self):
         """
-        
+        Test hex parameters parsing
         :return: 
         """
         line = 'void entropy_threshold( char * a, HexParam_t * h, int result )'
@@ -449,7 +452,7 @@
 
     def test_non_void_function(self):
         """
-        
+        Test invalid signature (non void).
         :return: 
         """
         line = 'int entropy_threshold( char * a, HexParam_t * h, int result )'
@@ -457,7 +460,7 @@
 
     def test_unsupported_arg(self):
         """
-        
+        Test unsupported arguments (not among int, char * and HexParam_t)
         :return: 
         """
         line = 'int entropy_threshold( char * a, HexParam_t * h, int * result )'
@@ -465,7 +468,7 @@
 
     def test_no_params(self):
         """
-        
+        Test no parameters.
         :return: 
         """
         line = 'void entropy_threshold()'
@@ -483,7 +486,7 @@
 
     def test_no_function(self):
         """
-        
+        Test no test function found.
         :return: 
         """
         data = '''
@@ -496,7 +499,7 @@
 
     def test_no_end_case_comment(self):
         """
-        
+        Test missing end case.
         :return: 
         """
         data = '''
@@ -510,7 +513,7 @@
     @patch("generate_code.parse_function_signature")
     def test_parse_function_signature_called(self, parse_function_signature_mock):
         """
-        
+        Test parse_function_code()
         :return: 
         """
         parse_function_signature_mock.return_value = ('test_func', [], '', [])
@@ -533,7 +536,7 @@
                                              gen_deps_mock,
                                              gen_dispatch_mock):
         """
-        
+        Test generated code.
         :return: 
         """
         parse_function_signature_mock.return_value = ('func', [], '', [])
@@ -578,7 +581,7 @@
                            gen_deps_mock,
                            gen_dispatch_mock):
         """
-        
+        Test when exit label is present.
         :return: 
         """
         parse_function_signature_mock.return_value = ('func', [], '', [])
diff --git a/tests/scripts/mbedtls_test.py b/tests/scripts/mbedtls_test.py
index b8f8a37..7dba1b2 100644
--- a/tests/scripts/mbedtls_test.py
+++ b/tests/scripts/mbedtls_test.py
@@ -1,24 +1,33 @@
+# Greentea host test script for on-target tests.
+#
+# Copyright (C) 2006-2017, ARM Limited, All Rights Reserved
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# This file is part of mbed TLS (https://tls.mbed.org)
+
+
 """
-  Greentea host test script for on-target tests.
+Greentea host test script for on-target tests.
 
-  Copyright (C) 2006-2017, ARM Limited, All Rights Reserved
-  SPDX-License-Identifier: Apache-2.0
-
-  Licensed under the Apache License, Version 2.0 (the "License"); you may
-  not use this file except in compliance with the License.
-  You may obtain a copy of the License at
-
-  http://www.apache.org/licenses/LICENSE-2.0
-
-  Unless required by applicable law or agreed to in writing, software
-  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-  See the License for the specific language governing permissions and
-  limitations under the License.
-
-  This file is part of mbed TLS (https://tls.mbed.org)
+Host test script for testing mbed TLS test suites on target. Implements
+BaseHostTest to handle key,value pairs (events) coming from mbed TLS
+tests. Reads data file corresponding to the executing binary and dispatches
+test cases.
 """
 
+
 import re
 import os
 import binascii
@@ -38,7 +47,9 @@
 
     def parse(self, data_file):
         """
+        Data file parser.
 
+        :param data_file: Data file path
         """
         with open(data_file, 'r') as f:
             self.__parse(f)
@@ -46,6 +57,11 @@
     @staticmethod
     def __escaped_split(str, ch):
         """
+        Splits str on ch except when escaped.
+
+        :param str: String to split
+        :param ch: Split character
+        :return: List of splits
         """
         if len(ch) > 1:
             raise ValueError('Expected split character. Found string!')
@@ -65,6 +81,10 @@
 
     def __parse(self, file):
         """
+        Parses data file using supplied file object.
+
+        :param file: Data file object
+        :return:
         """
         for line in file:
             line = line.strip()
@@ -93,6 +113,7 @@
 
     def get_test_data(self):
         """
+        Returns test data.
         """
         return self.tests
 
@@ -115,6 +136,7 @@
 
     def __init__(self):
         """
+        Constructor initialises test index to 0.
         """
         super(MbedTlsTest, self).__init__()
         self.tests = []
@@ -130,6 +152,7 @@
 
     def setup(self):
         """
+        Setup hook implementation. Reads test suite data file and parses out tests.
         """
         binary_path = self.get_config_item('image_path')
         script_dir = os.path.split(os.path.abspath(__file__))[0]
@@ -148,6 +171,7 @@
 
     def print_test_info(self):
         """
+        Prints test summary read by Greentea to detect test cases.
         """
         self.log('{{__testcase_count;%d}}' % len(self.tests))
         for name, _, _, _ in self.tests:
@@ -156,7 +180,7 @@
     @staticmethod
     def align_32bit(b):
         """
-        4 byte aligns byte array.
+        4 byte aligns input byte array.
 
         :return:
         """
@@ -167,8 +191,8 @@
         """
         Converts Hex string representation to byte array
 
-        :param hex_str:
-        :return:
+        :param hex_str: Hex in string format.
+        :return: Output Byte array
         """
         assert hex_str[0] == '"' and hex_str[len(hex_str) - 1] == '"', \
             "HEX test parameter missing '\"': %s" % hex_str
@@ -183,8 +207,8 @@
         """
         Coverts i to bytearray in big endian format.
 
-        :param i:
-        :return:
+        :param i: Input integer
+        :return: Output bytes array in big endian or network order
         """
         b = bytearray([((i >> x) & 0xff) for x in [24, 16, 8, 0]])
         return b
@@ -193,10 +217,10 @@
         """
         Converts test vector into a byte array that can be sent to the target.
 
-        :param function_id:
-        :param deps:
-        :param parameters:
-        :return:
+        :param function_id: Test Function Identifier
+        :param deps: Dependency list
+        :param parameters: Test function input parameters
+        :return: Byte array and its length
         """
         b = bytearray([len(deps)])
         if len(deps):
@@ -243,10 +267,10 @@
         """
         Runs the test.
 
-        :param name:
-        :param function_id:
-        :param deps:
-        :param args:
+        :param name: Test name
+        :param function_id: function identifier
+        :param deps: Dependencies list
+        :param args: test parameters
         :return:
         """
         self.log("Running: %s" % name)
@@ -256,6 +280,11 @@
 
     @staticmethod
     def get_result(value):
+        """
+        Converts result from string type to integer
+        :param value: Result code in string
+        :return: Integer result code
+        """
         try:
             return int(value)
         except ValueError:
@@ -264,13 +293,25 @@
 
     @event_callback('GO')
     def on_go(self, key, value, timestamp):
+        """
+        Called on key "GO". Kicks off test execution.
+
+        :param key: Event key
+        :param value: Value. ignored
+        :param timestamp: Timestamp ignored.
+        :return:
+        """
         self.run_next_test()
 
     @event_callback("R")
     def on_result(self, key, value, timestamp):
         """
-        Handle result.
+        Handle result. Prints test start, finish prints required by Greentea to detect test execution.
 
+        :param key: Event key
+        :param value: Value. ignored
+        :param timestamp: Timestamp ignored.
+        :return:
         """
         int_val = self.get_result(value)
         name, function, deps, args = self.tests[self.test_index]
@@ -282,11 +323,12 @@
     @event_callback("F")
     def on_failure(self, key, value, timestamp):
         """
-        Handles test execution failure. Hence marking test as skipped.
+        Handles test execution failure. That means dependency not supported or
+        Test function not supported. Hence marking test as skipped.
 
-        :param key:
-        :param value:
-        :param timestamp:
+        :param key: Event key
+        :param value: Value. ignored
+        :param timestamp: Timestamp ignored.
         :return:
         """
         int_val = self.get_result(value)