Websocket.mask: def of bend-kit-websocket@0.4.0.0
Import: import bend-kit-websocket@0.4.0.0/websocket.bend as Websocket
Lines 296-300 of bend-kit-websocket@0.4.0.0/websocket.bend: https://jend.leeeet.dev/read.txt?path=bend-kit-websocket@0.4.0.0/websocket.bend&start_line=296&end_line=300

import Base
import bend-kit-bytes@0.3.3.0/bytes.bend as Bytes

# The payload XOR the mask key (§5.3), a word at a time. key's byte k (low first) is mask octet k.
# Masking twice gives the payload back.
def mask(+key: U32, b: Bytes.Bytes) -> Bytes.Bytes:
  Bytes.Bytes{+len, buf} = b
  Bytes.Bytes{len, mask.trim(len, mask.go(U32.to_nat(Bytes.words(len)), Array.get(U32, buf, 0), 0, key))}

Uses (7):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Array.get
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.to_nat
  https://jend.leeeet.dev/definition.txt?path=bend-kit-bytes@0.3.3.0/bytes.bend&name=Bytes
  https://jend.leeeet.dev/definition.txt?path=bend-kit-bytes@0.3.3.0/bytes.bend&name=words
  https://jend.leeeet.dev/definition.txt?path=bend-kit-websocket@0.4.0.0/websocket.bend&name=mask.go
  https://jend.leeeet.dev/definition.txt?path=bend-kit-websocket@0.4.0.0/websocket.bend&name=mask.trim