separated base91 into a submodule

aprs/base91.py

@@ -0,0 +1,46 @@
+"""
+Provides facilities for covertion from/to base91
+"""
+from math import log
+from re import findall
+
+def to_decimal(text):
+    """
+    Takes a base91 char string and returns decimal
+    """
+
+    if not isinstance(text, str):
+        raise TypeError("expected str")
+
+    if findall(r"[\x00-\x20\x7c-\xff]", text):
+        raise ValueError("invalid character in sequence")
+
+    decimal = 0
+    length = len(text) - 1
+    for i, char in enumerate(text):
+        decimal += (ord(char) - 33) * (91 ** (length - i))
+
+    return decimal if text != '' else 0
+
+
+def from_decimal(n, padding=1):
+    """
+    Takes a decimal and returns base91 char string.
+    With optional padding to a specific length.
+    """
+    text = []
+
+    if not isinstance(n, (int, long)) is not int or n < 0:
+        raise ValueError("non-positive integer error")
+    elif not isinstance(n, (int, long)) or padding < 1:
+        raise ValueError("padding must be integer and >0")
+    elif n > 0:
+        for d in [91**e for e in reversed(range(int(log(n) / log(91)) + 1))]:
+            q = n / d
+            n = n % d
+            text.append(chr(33 + q))
+
+    # add padding if necessary
+    text = ['!'] * (padding-len(text)) + text
+
+    return "".join(text)

aprs/parse.py

@@ -8,6 +8,7 @@ import logging
 from datetime import datetime
 
 from .exceptions import (UnknownFormat, ParseError)
+import base91
 
 __all__ = ['parse']
 
@@ -37,19 +38,6 @@ MTYPE_TABLE_CUSTOM = {
     }
 
 
-def base91(text):
-    """
-    Takes a base91 char string and returns decimal
-    """
-
-    decimal = 0
-    length = len(text)
-    for i in range(length):
-        decimal += (ord(text[i]) - 33) * (91.0 ** (length-1-i))
-
-    return decimal if text != '' else ''
-
-
 def parse(raw_sentence):
     """
     Parses an APRS packet and returns a dict with decoded data
@@ -334,7 +322,7 @@ def parse(raw_sentence):
             if match:
                 body, altitude, extra = match[0]
 
-                altitude = base91(altitude) - 10000
+                altitude = base91.to_decimal(altitude) - 10000
                 parsed.update({'altitude': altitude})
 
                 body = body + extra
@@ -526,8 +514,8 @@ def parse(raw_sentence):
             symbol_table = packet[0]
             symbol = packet[9]
 
-            latitude = 90 - (base91(packet[1:5]) / 380926)
-            longitude = -180 + (base91(packet[5:9]) / 190463)
+            latitude = 90 - (base91.to_decimal(packet[1:5]) / 380926.0)
+            longitude = -180 + (base91.to_decimal(packet[5:9]) / 190463.0)
 
             # parse csT
 
@@ -659,18 +647,14 @@ def _parse_comment_telemetry(text):
     Looks for base91 telemetry found in comment field
     Returns [remaining_text, telemetry]
     """
-    match = re.findall(r"^(.*?)\|([!-{]{6,14})\|(.*)$", text)
+    match = re.findall(r"^(.*?)\|([!-{]{4,14})\|(.*)$", text)
     if match and len(match[0][1]) % 2 == 0:
         text, telemetry, post = match[0]
         text += post
 
-        temp = [''] * 7
+        temp = [0] * 7
         for i in range(7):
-            try:
-                temp[i] = base91(telemetry[i*2:i*2+2])
-                temp[i] = int(temp[i]) if temp[i].is_integer() else temp[i]
-            except:
-                continue
+            temp[i] = base91.to_decimal(telemetry[i*2:i*2+2])
 
         parsed = {
             'telemetry': {

aprs/version.py

@@ -1 +1 @@
-__version__ = '0.6.4'
+__version__ = '0.6.5'