1 files changed, 58 insertions, 0 deletions
diff --git a/test/functional/test_framework/bignum.py b/test/functional/test_framework/bignum.py
new file mode 100644
index 0000000000..db5ccd62c2
--- /dev/null
+++ b/test/functional/test_framework/bignum.py
@@ -0,0 +1,58 @@
+#!/usr/bin/env python3
+#
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+"""Big number routines.
+
+This file is copied from python-bitcoinlib.
+"""
+
+import struct
+
+
+# generic big endian MPI format
+
+def bn_bytes(v, have_ext=False):
+    ext = 0
+    if have_ext:
+        ext = 1
+    return ((v.bit_length()+7)//8) + ext
+
+def bn2bin(v):
+    s = bytearray()
+    i = bn_bytes(v)
+    while i > 0:
+        s.append((v >> ((i-1) * 8)) & 0xff)
+        i -= 1
+    return s
+
+def bn2mpi(v):
+    have_ext = False
+    if v.bit_length() > 0:
+        have_ext = (v.bit_length() & 0x07) == 0
+
+    neg = False
+    if v < 0:
+        neg = True
+        v = -v
+
+    s = struct.pack(b">I", bn_bytes(v, have_ext))
+    ext = bytearray()
+    if have_ext:
+        ext.append(0)
+    v_bin = bn2bin(v)
+    if neg:
+        if have_ext:
+            ext[0] |= 0x80
+        else:
+            v_bin[0] |= 0x80
+    return s + ext + v_bin
+
+# bitcoin-specific little endian format, with implicit size
+def mpi2vch(s):
+    r = s[4:]           # strip size
+    r = r[::-1]         # reverse string, converting BE->LE
+    return r
+
+def bn2vch(v):
+    return bytes(mpi2vch(bn2mpi(v)))