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write multiple bytes of Char at once #27267 #27380

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write multiple bytes of Char at once #27267 #27380

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e854888
write multiple bytes of Char at once
yeonsookimdev Jun 2, 2018
ec305dd
add GC.@preserve to avoid broken Ref
yeonsookimdev Jun 4, 2018
e6adf65
use trailing_zeros instead of if-else
yeonsookimdev Jun 5, 2018
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12 changes: 6 additions & 6 deletions base/io.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -565,12 +565,12 @@ function write(s::IO, a::SubArray{T,N,<:Array}) where {T,N}
end

function write(io::IO, c::Char)
u = bswap(reinterpret(UInt32, c))
n = 1
while true
write(io, u % UInt8)
(u >>= 8) == 0 && return n
n += 1
v = reinterpret(UInt32, c)
u = Ref{UInt32}(hton(v)) # BIG-endian
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@StefanKarpinski StefanKarpinski Jun 4, 2018

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This should be an unconditional bswap since UTF-8 is independent of the endianess of the system.

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@yeonsookimdev yeonsookimdev Jun 5, 2018

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UTF-8 is independent of the endianess of the system.

Yes, it is true, but UInt32 isn't.

GC.@preserve u begin
p = unsafe_convert(Ptr{Cvoid}, u)
n = max(1, 4 - (trailing_zeros(v) >>> 3))
unsafe_write(io, p, n)
end
end
# write(io, ::AbstractChar) is not defined: implementations
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