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⚡️ Speed up function is_witness by 13% #28

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⚡️ Speed up function is_witness by 13% #28

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12 changes: 8 additions & 4 deletions electrum/plugins/ledger/ledger.py
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Original file line number Diff line number Diff line change
Expand Up @@ -151,14 +151,18 @@ def is_witness(script: bytes) -> Tuple[bool, int, bytes]:
an int representing the witness version,
and the bytes of the witness program.
"""
if len(script) < 4 or len(script) > 42:
script_len = len(script)
# Check script length bounds early for short-circuit
if script_len < 4 or script_len > 42:
return (False, 0, b"")

if script[0] != 0 and (script[0] < 81 or script[0] > 96):
first = script[0]
if first != 0 and (first < 81 or first > 96):
return (False, 0, b"")

if script[1] + 2 == len(script):
return (True, script[0] - 0x50 if script[0] else 0, script[2:])
# Avoid repeated len(script)
if script_len == script[1] + 2:
return (True, first - 0x50 if first else 0, script[2:])

return (False, 0, b"")

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