first comit

venv/lib/python3.10/site-packages/zmq/utils/z85.py

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+"""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 struct
+
+# Z85CHARS is the base 85 symbol table
+Z85CHARS = b"0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ.-:+=^!/*?&<>()[]{}@%$#"
+# Z85MAP maps integers in [0,84] to the appropriate character in Z85CHARS
+Z85MAP = {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])
+
+    return bytes(encoded)
+
+
+def decode(z85bytes):
+    """decode Z85 bytes to raw bytes, accepts ASCII string"""
+    if isinstance(z85bytes, str):
+        try:
+            z85bytes = z85bytes.encode('ascii')
+        except UnicodeEncodeError:
+            raise ValueError('string argument should contain only ASCII characters')
+
+    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)