tbase_encode/base_decode: performance improvement - electrum - Electrum Bitcoin wallet
HTML git clone https://git.parazyd.org/electrum
DIR Log
DIR Files
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DIR Submodules
---
DIR commit 01f94fcf5817be9ff9182bfcda957a8e0e31bf8e
DIR parent 369d972aed376a59bb21952afa16b43105724a32
HTML Author: SomberNight <somber.night@protonmail.com>
Date: Sun, 8 Dec 2019 06:07:01 +0100
base_encode/base_decode: performance improvement
For example, for 50 KB of random data, and base 43,
previously,
- base_encode took ~38 seconds
- base_decode took ~270 seconds
now,
- base_encode takes ~7.5 seconds
- base_decode takes ~6 seconds
Diffstat:
M electrum/bitcoin.py | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
---
DIR diff --git a/electrum/bitcoin.py b/electrum/bitcoin.py
t@@ -455,8 +455,11 @@ def base_encode(v: bytes, base: int) -> str:
if base == 43:
chars = __b43chars
long_value = 0
- for (i, c) in enumerate(v[::-1]):
- long_value += (256**i) * c
+ power_of_base = 1
+ for c in v[::-1]:
+ # naive but slow variant: long_value += (256**i) * c
+ long_value += power_of_base * c
+ power_of_base <<= 8
result = bytearray()
while long_value >= base:
div, mod = divmod(long_value, base)
t@@ -486,11 +489,14 @@ def base_decode(v: Union[bytes, str], length: Optional[int], base: int) -> Optio
if base == 43:
chars = __b43chars
long_value = 0
- for (i, c) in enumerate(v[::-1]):
+ power_of_base = 1
+ for c in v[::-1]:
digit = chars.find(bytes([c]))
if digit == -1:
raise ValueError('Forbidden character {} for base {}'.format(c, base))
- long_value += digit * (base**i)
+ # naive but slow variant: long_value += digit * (base**i)
+ long_value += digit * power_of_base
+ power_of_base *= base
result = bytearray()
while long_value >= 256:
div, mod = divmod(long_value, 256)