#! /usr/bin/env python3

# Read #define's and translate to Python code.
# Handle #include statements.
# Handle #define macros with one argument.
# Anything that isn't recognized or doesn't translate into valid
# Python is ignored.

# Without filename arguments, acts as a filter.
# If one or more filenames are given, output is written to corresponding
# filenames in the local directory, translated to all uppercase, with
# the extension replaced by ".py".

# By passing one or more options of the form "-i regular_expression"
# you can specify additional strings to be ignored. This is useful
# e.g. to ignore casts to u_long: simply specify "-i '(u_long)'".

# XXX To do:
# - turn trailing C comments into Python comments
# - turn C Boolean operators "&& || !" into Python "and or not"
# - what to do about #if(def)?
# - what to do about macros with multiple parameters?

import sys, re, getopt, os

p_define = re.compile(r'^[\t ]*#[\t ]*define[\t ]+([a-zA-Z0-9_]+)[\t ]+')

p_macro = re.compile(
 r'^[\t ]*#[\t ]*define[\t ]+'
 r'([a-zA-Z0-9_]+)\(([_a-zA-Z][_a-zA-Z0-9]*)\)[\t ]+')

p_include = re.compile(r'^[\t ]*#[\t ]*include[\t ]+<([^>\n]+)>')

p_comment = re.compile(r'/\*([^*]+|\*+[^/])*(\*+/)?')
p_cpp_comment = re.compile('//.*')

ignores = [p_comment, p_cpp_comment]

p_char = re.compile(r"'(\\.[^\\]*|[^\\])'")

p_hex = re.compile(r"0x([0-9a-fA-F]+)L?")

filedict = {}
importable = {}

try:
 searchdirs=os.environ['include'].split(';')
except KeyError:
 try:
 searchdirs=os.environ['INCLUDE'].split(';')
 except KeyError:
 searchdirs=['/usr/include']
 try:
 searchdirs.insert(0, os.path.join('/usr/include',
 os.environ['MULTIARCH']))
 except KeyError:
 pass

def main():
 global filedict
 opts, args = getopt.getopt(sys.argv[1:], 'i:')
 for o, a in opts:
 if o == '-i':
 ignores.append(re.compile(a))
 if not args:
 args = ['-']
 for filename in args:
 if filename == '-':
 sys.stdout.write('# Generated by h2py from stdin\n')
 process(sys.stdin, sys.stdout)
 else:
 fp = open(filename, 'r')
 outfile = os.path.basename(filename)
 i = outfile.rfind('.')
 if i > 0: outfile = outfile[:i]
 modname = outfile.upper()
 outfile = modname + '.py'
 outfp = open(outfile, 'w')
 outfp.write('# Generated by h2py from %s\n' % filename)
 filedict = {}
 for dir in searchdirs:
 if filename[:len(dir)] == dir:
 filedict[filename[len(dir)+1:]] = None # no '/' trailing
 importable[filename[len(dir)+1:]] = modname
 break
 process(fp, outfp)
 outfp.close()
 fp.close()

def pytify(body):
 # replace ignored patterns by spaces
 for p in ignores:
 body = p.sub(' ', body)
 # replace char literals by ord(...)
 body = p_char.sub("ord('\\1')", body)
 # Compute negative hexadecimal constants
 start = 0
 UMAX = 2*(sys.maxsize+1)
 while 1:
 m = p_hex.search(body, start)
 if not m: break
 s,e = m.span()
 val = int(body[slice(*m.span(1))], 16)
 if val > sys.maxsize:
 val -= UMAX
 body = body[:s] + "(" + str(val) + ")" + body[e:]
 start = s + 1
 return body

def process(fp, outfp, env = {}):
 lineno = 0
 while 1:
 line = fp.readline()
 if not line: break
 lineno = lineno + 1
 match = p_define.match(line)
 if match:
 # gobble up continuation lines
 while line[-2:] == '\\\n':
 nextline = fp.readline()
 if not nextline: break
 lineno = lineno + 1
 line = line + nextline
 name = match.group(1)
 body = line[match.end():]
 body = pytify(body)
 ok = 0
 stmt = '%s = %s\n' % (name, body.strip())
 try:
 exec(stmt, env)
 except:
 sys.stderr.write('Skipping: %s' % stmt)
 else:
 outfp.write(stmt)
 match = p_macro.match(line)
 if match:
 macro, arg = match.group(1, 2)
 body = line[match.end():]
 body = pytify(body)
 stmt = 'def %s(%s): return %s\n' % (macro, arg, body)
 try:
 exec(stmt, env)
 except:
 sys.stderr.write('Skipping: %s' % stmt)
 else:
 outfp.write(stmt)
 match = p_include.match(line)
 if match:
 regs = match.regs
 a, b = regs[1]
 filename = line[a:b]
 if filename in importable:
 outfp.write('from %s import *\n' % importable[filename])
 elif filename not in filedict:
 filedict[filename] = None
 inclfp = None
 for dir in searchdirs:
 try:
 inclfp = open(dir + '/' + filename)
 break
 except IOError:
 pass
 if inclfp:
 outfp.write(
 '\n# Included from %s\n' % filename)
 process(inclfp, outfp, env)
 else:
 sys.stderr.write('Warning - could not find file %s\n' %
 filename)

if __name__ == '__main__':
 main()