reader: add unsigned integer types

gds/reader.py

@@ -1,7 +1,7 @@
 from datetime import datetime
 from .record import *
 import abc
-
+import ctypes
 
 class ProgressGetter(object, metaclass=abc.ABCMeta):
     @abc.abstractproperty
@@ -40,20 +40,36 @@ class Reader(ProgressGetter):
     def skip(self, n):
         self.stream.read(n)
 
-    def read_int(self):
+    def read_uint(self):
         temp = self.stream.read(4)
         if len(temp) != 4:
             return None
 
         return int(temp[3]) | int(temp[2]) << 8 | int(temp[1]) << 16 | int(temp[0]) << 24
 
-    def read_short(self):
+    def read_ushort(self):
         temp = self.stream.read(2)
         if len(temp) != 2:
             return None
 
         return int(temp[1]) | int(temp[0]) << 8
 
+    def read_short(self):
+        temp = self.read_ushort()
+
+        if temp == None:
+            return None
+        
+        return ctypes.c_short(temp).value
+        
+    def read_int(self):
+        temp = self.read_uint()
+
+        if temp == None:
+            return None
+
+        return ctypes.c_int(temp).value
+        
     def read_double(self):
         temp = self.stream.read(8)
         if len(temp) != 8:
@@ -64,10 +80,8 @@ class Reader(ProgressGetter):
         for i in temp:
             if int(i) != 0: 
                 # read double
-                result = 1
-
                 for j in range(1,8):
-                    result += float(temp[8-j])/(2**(j*8))
+                    result += float(temp[j])/(2.0**(j*8))
 
                 exp = int(temp[0]) & 0x7F
                 exp -= 64
@@ -78,6 +92,7 @@ class Reader(ProgressGetter):
 
                 return result
                 
+        
         # double is Zero
         return 0
 
@@ -87,8 +102,8 @@ class Reader(ProgressGetter):
     def read_record(self):
         result = Record()
         try:
-            result.len = self.read_short() 
-            result.ident = Records(self.read_short())
+            result.len = self.read_ushort() 
+            result.ident = Records(self.read_ushort())
         except ValueError:
             return None
 
@@ -98,14 +113,14 @@ class Reader(ProgressGetter):
 
     def read_date(self):
         # date
-        year  = self.read_short()
-        month = self.read_short()
-        day   = self.read_short()
+        year  = self.read_ushort()
+        month = self.read_ushort()
+        day   = self.read_ushort()
 
         # time
-        hour   = self.read_short()
-        minute = self.read_short()
-        second = self.read_short()
+        hour   = self.read_ushort()
+        minute = self.read_ushort()
+        second = self.read_ushort()
 
         return datetime(year=year, month=month, day=day, hour=hour, minute=minute, second=second)