Add initial version of c-picker

Introduce the following features to c-picker:

* Picking of the elements from C source files:
  * Include directives
  * Functions
  * Variables
* Removing 'static' keyword from declarations
* Mapping coverage to the original source
* Documentation of the system

Signed-off-by: Imre Kis <imre.kis@arm.com>
Change-Id: Ia5cb90d3096b16b15aafb86363b8cabfe7d2ab72
diff --git a/c_picker/coverage.py b/c_picker/coverage.py
new file mode 100644
index 0000000..1c79db0
--- /dev/null
+++ b/c_picker/coverage.py
@@ -0,0 +1,189 @@
+#!/usr/bin/env python3
+# Copyright (c) 2020-2021, Arm Limited. All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+
+"""
+This module can map the coverage of c-picker generated files to the original source files.
+"""
+
+import argparse
+import json
+import os
+import re
+import sys
+
+class MappingDescriptor:
+    """ Storage class for file-line number data """
+
+    def __init__(self, file=None, line=None):
+        self.descriptor = {"file": file, "line": line}
+
+    def get_file(self):
+        """ Queries file name """
+        return self.descriptor["file"]
+
+    def get_line(self):
+        """ Queries line number """
+        return self.descriptor["line"]
+
+    @staticmethod
+    def serialize(mapping_descriptor):
+        """ Serializes the descriptor into a C comment containing JSON. """
+        return "/* C-PICKER-MAPPING " + json.dumps(mapping_descriptor.descriptor) + " */"
+
+    @staticmethod
+    def deserialize(line):
+        """
+        Deserializes the descriptor from a C comment containing JSON.
+        It returns None if the line is not matching the required pattern.
+        """
+        match = re.match(r"/\* C-PICKER-MAPPING ({.*}) \*/", line)
+        if not match:
+            return None
+
+        mapping_descriptor = MappingDescriptor()
+        mapping_descriptor.descriptor = json.loads(match.group(1))
+        return mapping_descriptor
+
+class CoverageMapper:
+    """ The class maps the coverage of the c-picker generated source files to the original ones. """
+
+    def __init__(self):
+        self.mapping_path = None
+        self.output = sys.stdout
+
+        self.test_name = None
+        self.mapping_enabled = False
+        self.mapping_descriptors = {}
+        self.mapped_source_file = None
+
+    def read_mapping_descriptors(self, filename):
+        """ Reads the mapping descriptors from the c-picker generated file. """
+        self.mapping_enabled = True
+
+        with open(filename, "r") as source_file:
+            source_lines = source_file.read().split("\n")
+            source_line_index = 1
+
+            for source_line in source_lines:
+                mapping_descriptor = MappingDescriptor.deserialize(source_line)
+
+                if mapping_descriptor:
+                    # +1: the elements start at the following line after the descriptor comment
+                    self.mapping_descriptors[source_line_index + 1] = mapping_descriptor
+                source_line_index += 1
+
+    def clear_mapping_descriptors(self):
+        """ Resets the mapping descriptor database. """
+        self.mapping_enabled = False
+        self.mapping_descriptors = {}
+        self.mapped_source_file = None
+
+    def find_mapping(self, line_number):
+        """ Find the mapping descriptor of a line number and also returns the mapped line. """
+        mapping_descriptor_index = 0
+        for i in self.mapping_descriptors:
+            if i > line_number:
+                break
+            mapping_descriptor_index = i
+
+        if not mapping_descriptor_index:
+            raise Exception("Invalid mapping for line %d" % line_number)
+
+        mapping_descriptor = self.mapping_descriptors[mapping_descriptor_index]
+        mapped_line = line_number - mapping_descriptor_index + mapping_descriptor.get_line()
+        return mapping_descriptor, mapped_line
+
+    def output_line(self, line):
+        """ Outputs a single line to the output """
+        self.output.write(line + "\n")
+
+    def process_line(self, trace_line):
+        """
+        The function processes a single line of the trace file and maintains the internal state of
+        the state matchine.
+        """
+        if not trace_line:
+            return
+
+        if trace_line == "end_of_record":
+            # End of record, exit mapping mode
+            self.clear_mapping_descriptors()
+            self.output_line(trace_line)
+            return
+
+        command, params = trace_line.split(":", 1)
+        if command == "TN":
+            # Test name TN:<test name>
+            self.test_name = params
+        elif command == "SF" and params.startswith(self.mapping_path):
+            # Source file SF:<absolute path to the source file>
+            # Matching source file, switch into mapping mode
+            self.read_mapping_descriptors(params)
+            return
+
+        if self.mapping_enabled and (command in ("FN", "BRDA", "DA")):
+            # Function        FN:<line number of function start>,<function name>
+            # Branch coverage BRDA:<line number>,<block number>,<branch number>,<taken>
+            # Line coverage   DA:<line number>,<execution count>[,<checksum>]
+            line_number, remaining_params = params.split(",", 1)
+            mapping_descriptor, mapped_line_number = self.find_mapping(int(line_number))
+
+            if mapping_descriptor.get_file() != self.mapped_source_file:
+                # Change in the name of the mapped source file, starting new record
+                if self.mapped_source_file is not None:
+                    # No need for this part if it was the first mapped file
+                    # because TN has been alread printed
+                    self.output_line("end_of_record")
+                    self.output_line("TN:%s" % self.test_name)
+                self.mapped_source_file = mapping_descriptor.get_file()
+                self.output_line("SF:%s" % self.mapped_source_file)
+
+            self.output_line("%s:%d,%s" % (command, mapped_line_number, remaining_params))
+            return
+
+        self.output_line(trace_line)
+
+    def main(self):
+        """ Runs coverage mapper configured by the command line arguments  """
+
+        try:
+            parser = argparse.ArgumentParser(prog="c-picker-coverage-mapper", description=__doc__)
+            parser.add_argument("--input", help="Input trace file", required=True)
+            parser.add_argument("--output", help="Input file")
+            parser.add_argument("--mapping-path", help="Directory of generated files",
+                                required=True)
+            args = parser.parse_args()
+
+            output_fp = open(args.output, "w") if args.output else None
+
+            self.output = output_fp if output_fp else sys.stdout
+            self.mapping_path = os.path.abspath(args.mapping_path)
+
+            with open(args.input, "r") as tracefile:
+                trace_lines = tracefile.read().split("\n")
+                for trace_line in trace_lines:
+                    self.process_line(trace_line)
+
+            if output_fp:
+                output_fp.close()
+
+            return 0
+        except FileNotFoundError as exception:
+            print("File not found: %s" % str(exception), file=sys.stderr)
+        except ValueError as exception:
+            print("Invalid format: %s" % str(exception), file=sys.stderr)
+        except Exception as exception: # pylint: disable=broad-except
+            print("Exception: %s" % exception, file=sys.stderr)
+
+        return 1
+
+def main():
+    """ Command line main function """
+    coverage_mapper = CoverageMapper()
+    result = coverage_mapper.main()
+    sys.exit(result)
+
+if __name__ == "__main__":
+    main()