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bech32: another around 10% speedup for bech32_decode

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turns out stdlib ord() is somewhat slow;
also, only lookup data chars once

benchmarked with:
```
import time
import electrum
from electrum.segwit_addr import bech32_decode

electrum.constants.set_testnet()

inv = "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"

def f():
  for _ in range(10000):
    addr = bech32_decode(inv, ignore_long_length=True)

t0 = time.time()
f()
t1 = time.time()
print(f"{t1-t0:.4f}")
```
This commit is contained in:
SomberNight
2021-02-28 18:13:06 +01:00
parent b83f7159a9
commit e0cfb2179d
1 changed files with 10 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
electrum/segwit_addr.py
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@@ -61,19 +61,23 @@ def bech32_encode(hrp, data):
return hrp + '1' + ''.join([CHARSET[d] for d in combined])
def bech32_decode(bech, ignore_long_length=False):
def bech32_decode(bech: str, ignore_long_length=False):
"""Validate a Bech32 string, and determine HRP and data."""
if ((any(ord(x) < 33 or ord(x) > 126 for x in bech)) or
(bech.lower() != bech and bech.upper() != bech)):
bech_lower = bech.lower()
if bech_lower != bech and bech.upper() != bech:
return (None, None)
bech = bech.lower()
pos = bech.rfind('1')
if pos < 1 or pos + 7 > len(bech) or (not ignore_long_length and len(bech) > 90):
return (None, None)
if not all(x in CHARSET for x in bech[pos+1:]):
# check that HRP only consists of sane ASCII chars
if any(ord(x) < 33 or ord(x) > 126 for x in bech[:pos+1]):
return (None, None)
bech = bech_lower
hrp = bech[:pos]
data = [_CHARSET_INVERSE[x] for x in bech[pos+1:]]
try:
data = [_CHARSET_INVERSE[x] for x in bech[pos+1:]]
except KeyError:
return (None, None)
if not bech32_verify_checksum(hrp, data):
return (None, None)
return (hrp, data[:-6])