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[tests] add function comments to bignum

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This commit is contained in:
John Newbery
2019-10-30 10:22:36 -04:00
parent f31fc0e92e
commit 1dc68aee66
1 changed files with 5 additions and 1 deletions
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6
test/functional/test_framework/bignum.py
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@@ -12,12 +12,14 @@ This file is copied from python-bitcoinlib.
import struct import struct
def bn_bytes(v, have_ext=False): def bn_bytes(v, have_ext=False):
"""Return number of bytes in integer representation of v."""
ext = 0 ext = 0
if have_ext: if have_ext:
ext = 1 ext = 1
return (v.bit_length() + 7) // 8 + ext return (v.bit_length() + 7) // 8 + ext
def bn2bin(v): def bn2bin(v):
"""Convert a number to a byte array."""
s = bytearray() s = bytearray()
i = bn_bytes(v) i = bn_bytes(v)
while i > 0: while i > 0:
@@ -26,6 +28,7 @@ def bn2bin(v):
return s return s
def bn2mpi(v): def bn2mpi(v):
"""Convert number to MPI format."""
have_ext = False have_ext = False
if v.bit_length() > 0: if v.bit_length() > 0:
have_ext = (v.bit_length() & 0x07) == 0 have_ext = (v.bit_length() & 0x07) == 0
@@ -47,11 +50,12 @@ def bn2mpi(v):
v_bin[0] |= 0x80 v_bin[0] |= 0x80
return s + ext + v_bin return s + ext + v_bin
# bitcoin-specific little endian format, with implicit size
def mpi2vch(s): def mpi2vch(s):
"""Convert MPI format to bitcoin-specific little endian format, with implicit size."""
r = s[4:] # strip size r = s[4:] # strip size
r = r[::-1] # reverse string, converting BE->LE r = r[::-1] # reverse string, converting BE->LE
return r return r
def bn2vch(v): def bn2vch(v):
"""Convert number to bitcoin-specific little endian format."""
return bytes(mpi2vch(bn2mpi(v))) return bytes(mpi2vch(bn2mpi(v)))