Implemented basic EBMLFile class for parsing files.

[~jspiros/python-ebml.git] / ebml / core.py

diff --git a/ebml/core.py b/ebml/core.py
index 2e0702c..6e8d338 100644 (file)
--- a/ebml/core.py
+++ b/ebml/core.py
@@ -1,4 +1,5 @@
-import warnings
+import struct
+import datetime
 from .exceptions import *
 
 
@@ -124,4 +125,68 @@ def read_element_id(stream, max_width=EBMLMaxIDLength):
        elif min_bytes == vint_len:
                raise ReservedElementIDError('All value bits set to 0')
        
-       return value, vint_len
\ No newline at end of file
+       return value, vint_len
+
+
+def read_int(stream, size):
+       value = 0
+       if size > 0:
+               byte = ord(stream.read(1))
+               if (byte & 0b10000000) == 0b10000000:
+                       value = -1 << 8
+               value |= byte
+               for i in range(1, size):
+                       byte = ord(stream.read(1))
+                       value = (value << 1) | byte
+       return value
+
+
+def read_uint(stream, size):
+       value = 0
+       for i in range(0, size):
+               byte = ord(stream.read(1))
+               value = (value << 8) | byte
+       return value
+
+
+def read_float(stream, size):
+       if size not in (0, 4, 8):
+               # http://www.matroska.org/technical/specs/rfc/index.html allows for 10-byte floats.
+               # http://www.matroska.org/technical/specs/index.html specifies 4-byte and 8-byte only.
+               # I'm following the latter due to it being more up-to-date than the former, and because it's easier to implement.
+               raise ValueError('floats must be 0, 4, or 8 bytes long')
+       value = 0.0
+       if size in (4, 8):
+               data = stream.read(size)
+               value = struct.unpack({
+                       4: '>f',
+                       8: '>d'
+               }[size], data)[0]
+       return value
+
+
+def read_string(stream, size):
+       value = ''
+       if size > 0:
+               value = stream.read(size)
+       return value
+
+
+def read_unicode(stream, size):
+       value = u''
+       if size > 0:
+               data = stream.read(size)
+               value = unicode(data, 'utf_8')
+       return value
+
+
+def read_date(stream):
+       size = 8 # date is always an 8-byte signed integer
+       data = stream.read(size)
+       nanoseconds = struct.unpack('>q', data)[0]
+       delta = datetime.timedelta(microseconds=(nanoseconds // 1000))
+       return datetime.datetime(2001, 1, 1) + delta
+
+
+def read_binary(stream, size):
+       return stream.read(size)
\ No newline at end of file