moved util.bases into util.math

[p2pool.git] / p2pool / util / math.py

diff --git a/p2pool/util/math.py b/p2pool/util/math.py
index 06c9244..5db5616 100644 (file)
--- a/p2pool/util/math.py
+++ b/p2pool/util/math.py
@@ -183,6 +183,32 @@ def weighted_choice(choices):
         target -= weight
     raise AssertionError()
 
+def natural_to_string(n, alphabet=None):
+    if n < 0:
+        raise TypeError('n must be a natural')
+    if alphabet is None:
+        s = '%x' % (n,)
+        if len(s) % 2:
+            s = '0' + s
+        return s.decode('hex')
+    else:
+        assert len(set(alphabet)) == len(alphabet)
+        res = []
+        while n:
+            n, x = divmod(n, len(alphabet))
+            res.append(alphabet[x])
+        res.reverse()
+        return ''.join(res)
+
+def string_to_natural(s, alphabet=None):
+    if alphabet is None:
+        assert not s.startswith('\x00')
+        return int(s.encode('hex'), 16) if s else 0
+    else:
+        assert len(set(alphabet)) == len(alphabet)
+        assert not s.startswith(alphabet[0])
+        return sum(alphabet.index(char) * len(alphabet)**i for i, char in enumerate(reversed(s)))
+
 if __name__ == '__main__':
     import random
     a = 1