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BitArray performance enhancements via introduction of UnsafeArray and UnsafeBitArray #3265

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BitArray performance enhancements via introduction of UnsafeArray and UnsafeBitArray #3265

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33 changes: 33 additions & 0 deletions base/array.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,39 @@ strides{T}(a::Array{T,3}) = (1, size(a,1), size(a,1)*size(a,2))

isassigned(a::Array, i::Int...) = isdefined(a, i...)

## UnsafeArrays ##

# This type is unsafe in 3 ways:
# 1) it can only be used on bitstype Arrays
# (i.e. Array{T} such that isbits(T)=true),
# but no check is performed
# 2) no boundary checking
# 3) calling functions must keep a reference to the
# original Array to avoid garbage collection
# (e.g. A=UnsafeArray(A) is dangerous)
# It must be used with care!
immutable UnsafeArray{T} <: AbstractVector{T}
p::Ptr{T}
l::Int
function UnsafeArray(A::Array{T})
new(pointer(A), length(A))
end
end

UnsafeArray{T}(A::Array{T}) = UnsafeArray{T}(A)

getindex(uA::UnsafeArray, i::Int) = unsafe_load(uA.p, i)
setindex!{T}(uA::UnsafeArray{T}, x, i::Int) = unsafe_store!(uA.p, x, i)
setindex!{T}(uA::UnsafeArray{T}, x, r::Range1) = for i in r unsafe_store!(uA.p, x, i); end
length(uA::UnsafeArray) = uA.l
endof(uA::UnsafeArray) = uA.l

start(uA::UnsafeArray) = 1
next(uA::UnsafeArray, ind::Int) = (uA[ind], ind+1)
done(uA::UnsafeArray, ind::Int) = ind > length(uA)

unsafe{T}(A::Array{T}) = UnsafeArray(A)

## copy ##

function unsafe_copy!{T}(dest::Ptr{T}, src::Ptr{T}, N)
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