Implemented a build system that generates offset header files for ARM assembly files, in Android.

The original CL was separated into two. Please refer to https://webrtc-codereview.appspot.com/860005 on how the build system and python script being used.
Review URL: https://webrtc-codereview.appspot.com/754005

git-svn-id: http://webrtc.googlecode.com/svn/trunk@3059 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/build/generate_asm_header.gypi

@@ -0,0 +1,64 @@
+# Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
+#
+# Use of this source code is governed by a BSD-style license
+# that can be found in the LICENSE file in the root of the source
+# tree. An additional intellectual property rights grant can be found
+# in the file PATENTS.  All contributing project authors may
+# be found in the AUTHORS file in the root of the source tree.
+
+# This file is meant to be included into a target to provide an action
+# to generate C header files. These headers include definitions
+# that can be used in ARM assembly files.
+#
+# To use this, create a gyp target with the following form:
+# {
+#   'target_name': 'my_asm_headers_lib',
+#   'type': 'static_library',
+#   'sources': [
+#     'foo.c',
+#     'bar.c',
+#   ],
+#   'includes': ['path/to/this/gypi/file'],
+# }
+#
+# The headers are guaranteed to be generated before any
+# source files, even within this target, are compiled.
+#
+# The 'asm_header_dir' variable specifies the path suffix that output
+# files are generated under.
+
+# TODO(kma): port this block from Android into other build systems.
+{
+  'variables': {
+    'gen_header': '<(DEPTH)/webrtc/build/generate_asm_header.py',
+    'out_dir': '<(SHARED_INTERMEDIATE_DIR)/<(asm_header_dir)',
+    'process_outputs_as_sources': 1,
+  },
+  'rules': [
+    {
+      'rule_name': 'generate_asm_header',
+      'extension': 'c',
+      'inputs': [
+        '<(gen_header)',
+      ],
+      'outputs': [
+        '<(out_dir)/<(RULE_INPUT_ROOT).h',
+      ],
+      'action': [
+        'python',
+        '<(gen_header)',
+        '--compiler=$(CC)',  # Specifiy the compiler.
+        '--options=-I.. -I<@(android_ndk_include) -S',  # Compiler options.
+        '--dir=<(out_dir)',
+        '<(RULE_INPUT_PATH)',
+      ],
+      'message': 'Generating assembly header files',
+      'process_outputs_as_sources': 1,
+    },
+  ],
+  'direct_dependent_settings': {
+    'include_dirs': ['<(out_dir)',],
+  },
+  # This target exports a hard dependency because it generates header files.
+  'hard_dependency': 1,
+}

webrtc/build/generate_asm_header.py

@@ -8,34 +8,53 @@
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
-"""This script generates a C header file of offsets from an ARM assembler file.
+"""This script is a tool to generate special header files from input
+C source files.
 
-It parses an ARM assembler generated .S file, finds declarations of variables
+It first assembles the input source files to generate intermediate assembly
+files (*.s). Then it parses the .s files and finds declarations of variables
 whose names start with the string specified as the third argument in the
-command-line, translates the variable names and values into constant defines and
-writes them into a header file.
+command-line, translates the variable names and values into constant defines
+and writes them into header files.
 """
 
+import os
 import sys
-
-def usage():
-  print("Usage: generate_asm_header.py " +
-     "<input filename> <output filename> <variable name pattern>")
-  sys.exit(1)
+import subprocess
+from optparse import OptionParser
 
 def main(argv):
-  if len(argv) != 3:
-    usage()
+  parser = OptionParser()
+  usage = 'Usage: %prog [options] input_file'
+  parser.set_usage(usage)
+  parser.add_option('--compiler', default = 'gcc', help = 'compiler name')
+  parser.add_option('--options', default = '-S', help = 'compiler options')
+  parser.add_option('--pattern', default = 'offset_', help = 'A match pattern'
+                    ' used for searching the relevant constants.')
+  parser.add_option('--dir', default = '.', help = 'output directory')
+  (options, args) = parser.parse_args()
 
-  infile = open(argv[0])
-  outfile = open(argv[1], 'w')
+  # Generate complete intermediate and header file names.
+  input_file_name = os.path.basename(args[0])
+  file_base_name = os.path.splitext(input_file_name)[0]
+  interim_file = options.dir + "/" + file_base_name + '.s'
+  out_file = interim_file.replace('.s', '.h')
 
+  # Set the shell command with the compiler and options inputs.
+  compiler_command = (options.compiler + " " + options.options + " " + args[0]
+      + " -o " + interim_file)
+  # Run the shell command and generate the intermediate file.
+  subprocess.check_call(compiler_command, shell=True)
+
+  infile = open(interim_file)  # The intermediate file.
+  outfile = open(out_file, 'w')  # The output header file.
+
+  # Generate the output header file.
   for line in infile:  # Iterate though all the lines in the input file.
-    if line.startswith(argv[2]):
+    if line.startswith(options.pattern):
       outfile.write('#define ')
       outfile.write(line.split(':')[0])  # Write the constant name.
       outfile.write(' ')
-
     if line.find('.word') >= 0:
       outfile.write(line.split('.word')[1])  # Write the constant value.