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# frozen_string_literal: true
module MessagePack
module Bigint
# We split the bigint in 32bits chunks so that individual part fits into
# a MRI immediate Integer.
CHUNK_BITLENGTH = 32
FORMAT = 'CL>*'
if Integer.instance_method(:[]).arity != 1 # Ruby 2.7 and newer
# Starting from Ruby 2.7 we can address arbitrary bitranges inside an Integer with Integer#[]
# This allows to not allocate any Integer.
def self.to_msgpack_ext(bigint)
members = []
if bigint < 0
bigint = -bigint
members << 1
else
members << 0
end
offset = 0
length = bigint.bit_length
while offset < length
members << bigint[offset, CHUNK_BITLENGTH]
offset += CHUNK_BITLENGTH
end
members.pack(FORMAT)
end
else
# On 2.6 and older since we can't address arbitrary bitranges, so we fallback to shifting the bigint.
# This means that after each shift, we may allocate another Integer instance.
BASE = (2**CHUNK_BITLENGTH) - 1
def self.to_msgpack_ext(bigint)
members = []
if bigint < 0
bigint = -bigint
members << 1
else
members << 0
end
while bigint > 0
members << (bigint & BASE)
bigint = bigint >> CHUNK_BITLENGTH
end
members.pack(FORMAT)
end
end
def self.from_msgpack_ext(data)
parts = data.unpack(FORMAT)
sign = parts.shift
sum = parts.pop.to_i
parts.reverse_each do |part|
sum = sum << CHUNK_BITLENGTH
sum += part
end
sign == 0 ? sum : -sum
end
end
end
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