rand32.jl

import Base.Random.rand
immutable RandIntGen2{T<:Integer, U<:Unsigned}
    a::T   # first element of the range
    k::U   # range length
    u::U   # maximum multiple of k within the domain of U

    RandIntGen2(a::T, k::U) = new(a, k, div(typemax(U),k)*k)
    RandIntGen2(a::Uint64, k::Uint64) = new(a, k, div(( k >> 32 != 0)*0xFFFFFFFF00000000 + 0x00000000FFFFFFFF ,k)*k )
    RandIntGen2(a::Int64, k::Int64) = new(a, k, div(( k >> 32 != 0)*0xFFFFFFFF00000000 + 0x00000000FFFFFFFF ,k)*k )

end
immutable RandIntGen1{T<:Integer, U<:Unsigned}
    a::T   # first element of the range
    k::U   # range length
    u::U   # maximum multiple of k within the domain of U

    RandIntGen1(a::T, k::U) = new(a, k, div(typemax(U),k)*k)
  
end


function rand{T<:Integer,U<:Unsigned}(g::RandIntGen1{T,U})
    x = rand(U)
    while x >= g.u
        x = rand(U)
    end
    convert(T, g.a + rem(x, g.k))
end


function rand{T}(g::RandIntGen2{T,Uint64})
    local x::Uint64
    if g.k >> 32 == 0
	    x = convert(Uint64,rand(Uint32))
	    while x >= g.u
		    x = convert(Uint64,rand(Uint32))
	    end
	else
        x = rand(Uint64)
        while x >= g.u
            x = rand(Uint64)
        end
    end
    return convert(T, g.a + rem(x, g.k))
end

# print elapsed time, return expression value
macro timen(N, ex)
    quote
        local b0 = Base.gc_bytes()
        local t0 = time_ns()
        for i in 1:$N
             $(esc(ex))
        end
        local t1 = time_ns()
        local b1 = Base.gc_bytes()
        println("elapsed time: ", (t1-t0)/1e9, " seconds (", b1-b0, " bytes allocated)")
    end
end
rand(RandIntGen1{Uint, Uint}(0x0000000000000000,0x0000010000000000))
rand(RandIntGen2{Uint, Uint}(0x0000000000000000,0x0000010000000000))

@timen 10^8  rand(RandIntGen1{Uint, Uint}(0x0000000000000000,0x0000010000000000))
@timen 10^8  rand(RandIntGen2{Uint, Uint}(0x0000000000000000,0x0000010000000000))
@timen 10^8  rand(RandIntGen1{Uint, Uint}(0x0000000000000000,0x0000000010001000))
@timen 10^8  rand(RandIntGen2{Uint, Uint}(0x0000000000000000,0x0000000010001000))

srand(123); println(rand(RandIntGen2{Uint32, Uint32}(0x00000000,0x10001000)))
srand(123); println(rand(RandIntGen2{Uint64, Uint64}(0x0000000000000000,0x0000000010001000)))