Fixed and cleaned up signed integer reading and encoding. Implemented some value...

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

diff --git a/ebml/core.py b/ebml/core.py
index 24d849f..e076c8b 100644 (file)
--- a/ebml/core.py
+++ b/ebml/core.py
@@ -138,13 +138,13 @@ def read_signed_integer(stream, size):
        
        value = 0
        if size > 0:
-               byte = ord(stream.read(1))
-               if (byte & 0b10000000) == 0b10000000:
-                       value = -1 << 8
-               value |= byte
+               first_byte = ord(stream.read(1))
+               value = first_byte
                for i in xrange(1, size):
                        byte = ord(stream.read(1))
-                       value = (value << 1) | byte
+                       value = (value << 8) | byte
+               if (first_byte & 0b10000000) == 0b10000000:
+                       value = -(2**(size*8) - value)
        return value
 
 
@@ -391,9 +391,7 @@ def encode_signed_integer(sint, length=None):
                if sint >= 0:
                        uint = sint
                else:
-                       uint = 0b10000000 << (length - 1)
-                       uint += sint
-                       uint |= 0b10000000 << (length - 1)
+                       uint = 2**(length*8) - abs(sint)
        
        data = bytearray(length)
        for index in reversed(xrange(length)):