Merge branch 'master' into dan_stateless

1 files changed, 56 insertions, 0 deletions

diff --git a/src/console/zmq/utils/z85.py b/src/console/zmq/utils/z85.py
new file mode 100755
index 00000000..1bb1784e
--- /dev/null
+++ b/src/console/zmq/utils/z85.py
@@ -0,0 +1,56 @@
+"""Python implementation of Z85 85-bit encoding
+
+Z85 encoding is a plaintext encoding for a bytestring interpreted as 32bit integers.
+Since the chunks are 32bit, a bytestring must be a multiple of 4 bytes.
+See ZMQ RFC 32 for details.
+
+
+"""
+
+# Copyright (C) PyZMQ Developers
+# Distributed under the terms of the Modified BSD License.
+
+import sys
+import struct
+
+PY3 = sys.version_info[0] >= 3
+# Z85CHARS is the base 85 symbol table
+Z85CHARS = b"0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ.-:+=^!/*?&<>()[]{}@%$#"
+# Z85MAP maps integers in [0,84] to the appropriate character in Z85CHARS
+Z85MAP = dict([(c, idx) for idx, c in enumerate(Z85CHARS)])
+
+_85s = [ 85**i for i in range(5) ][::-1]
+
+def encode(rawbytes):
+    """encode raw bytes into Z85"""
+    # Accepts only byte arrays bounded to 4 bytes
+    if len(rawbytes) % 4:
+        raise ValueError("length must be multiple of 4, not %i" % len(rawbytes))
+    
+    nvalues = len(rawbytes) / 4
+    
+    values = struct.unpack('>%dI' % nvalues, rawbytes)
+    encoded = []
+    for v in values:
+        for offset in _85s:
+            encoded.append(Z85CHARS[(v // offset) % 85])
+    
+    # In Python 3, encoded is a list of integers (obviously?!)
+    if PY3:
+        return bytes(encoded)
+    else:
+        return b''.join(encoded)
+
+def decode(z85bytes):
+    """decode Z85 bytes to raw bytes"""
+    if len(z85bytes) % 5:
+        raise ValueError("Z85 length must be multiple of 5, not %i" % len(z85bytes))
+    
+    nvalues = len(z85bytes) / 5
+    values = []
+    for i in range(0, len(z85bytes), 5):
+        value = 0
+        for j, offset in enumerate(_85s):
+            value += Z85MAP[z85bytes[i+j]] * offset
+        values.append(value)
+    return struct.pack('>%dI' % nvalues, *values)