# BinarySearch.py
# DEMO to extract binary data...
# Written in such a way as to be easily understood.
# NOTE:- There are more Pythonic ways to do this...

import os
import sys

# The _variable_ used to test with...
block_one=b"?"
block_two=b"?"
subscript_begin=0

# Set to a _temporary_ directory. NOTE:- 4 different platforms shown...
# Change to suit your platform and path
if sys.platform=="linux2": os.chdir("/tmp/")
if sys.platform=="darwin": os.chdir("/Users/barrywalker/")
if sys.platform=="win32": os.chdir("C:\\Windows\\Temp\\")
if sys.platform=="amiga": os.chdir("T:")

# A basic "bin_extract()" function to extract binary data from a binary file...
def bin_extract(subscript_start=0, subscript_end=0, filename="?", char_start=b"\x00\xFF", char_end=b"\xFF\x00"):
	bin_var=b""
	toggle=0
	binfile=open(filename, "rb")
	for position in range(subscript_start, subscript_end, 1):
		binfile.seek(position)
		if binfile.read(2)==char_start:
			bin_var=bin_var+char_start[1:2]
			toggle=1
		if toggle>=1: bin_var=bin_var+binfile.read(1)
		if binfile.read(2)==char_end:
			bin_var=bin_var+char_end[0:1]
			toggle=0
			break
	binfile.close()
	return(bin_var, position)

# Test...
# ******** Do the first iteration and find the first block... *******
block_one, subscript_begin=bin_extract(0, 816, "BinaryFile", b"\xFF\x32", b"\xFF\x34")
print(block_one)
print(subscript_begin)
# When successful..........
# Just extract the required data from the _variable_ "new_binary" using standard simple Python methods
# and when finished with set new values to the function for the next block run using "subscript_begin"
# + or - 2 as the next "subscript_start" in the function, something like below...
block_two, subscript_begin=bin_extract((subscript_begin+2), 816, "BinaryFile", b"\xFF\x32", b"\xFF\x34")
print(block_two)
print(subscript_begin)
# DEMO end...