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Copy pathRandom.lua
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162 lines (152 loc) · 4.91 KB
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-- Compiled from https://github.com/dotnet/corefx/blob/master/src/Common/src/CoreLib/System/Random.cs
-- Generated by CSharp.lua Compiler
-- Licensed to the .NET Foundation under one or more agreements.
-- The .NET Foundation licenses this file to you under the MIT license.
-- See the LICENSE file in the project root for more information.
local System = System
local ArrayInt32 = System.Array(System.Int32)
System.define("System.Random", (function ()
local Sample, InternalSample, GenerateSeed, Next, GetSampleForLargeRange, NextDouble,
NextBytes, internal, __ctor__, rnd
internal = function (this)
this._seedArray = ArrayInt32:new(56)
end
__ctor__ = function (this, Seed)
if not Seed then Seed = GenerateSeed() end
internal(this)
local ii = 0
local mj, mk
--Initialize our Seed array.
local subtraction = (Seed == -2147483648 --[[Int32.MinValue]]) and 2147483647 --[[Int32.MaxValue]] or math.Abs(Seed)
mj = 161803398 --[[Random.MSEED]] - subtraction
this._seedArray:set(55, mj)
mk = 1
for i = 1, 54 do
--Apparently the range [1..55] is special (Knuth) and so we're wasting the 0'th position.
ii = ii + 21
if ii >= 55 then
ii = ii - 55
end
this._seedArray:set(ii, mk)
mk = mj - mk
if mk < 0 then
mk = mk + 2147483647 --[[Random.MBIG]]
end
mj = this._seedArray:get(ii)
end
for k = 1, 4 do
for i = 1, 55 do
local n = i + 30
if n >= 55 then
n = n - 55
end
this._seedArray:set(i, this._seedArray:get(i) - this._seedArray:get(1 + n))
if this._seedArray:get(i) < 0 then
this._seedArray:set(i, this._seedArray:get(i) + 2147483647 --[[Random.MBIG]])
end
end
end
this._inext = 0
this._inextp = 21
Seed = 1
end
Sample = function (this)
--Including this division at the end gives us significantly improved
--random number distribution.
return (InternalSample(this) * (4.6566128752458E-10 --[[1.0 / MBIG]]))
end
InternalSample = function (this)
local retVal
local locINext = this._inext
local locINextp = this._inextp
locINext = locINext + 1
if locINext >= 56 then
locINext = 1
end
locINextp = locINextp + 1
if locINextp >= 56 then
locINextp = 1
end
retVal = this._seedArray:get(locINext) - this._seedArray:get(locINextp)
if retVal == 2147483647 --[[Random.MBIG]] then
retVal = retVal - 1
end
if retVal < 0 then
retVal = retVal + 2147483647 --[[Random.MBIG]]
end
this._seedArray:set(locINext, retVal)
this._inext = locINext
this._inextp = locINextp
return retVal
end
GenerateSeed = function ()
if not rnd then
math.randomseed(os.time())
rnd = math.random
end
return rnd(0, 2147483647)
end
Next = function (this, minValue, maxValue)
if not minValue then
return InternalSample(this)
end
if not maxValue then
maxValue = minValue
if maxValue < 0 then
System.throw(System.ArgumentOutOfRangeException("maxValue" --[[nameof(maxValue)]], "'maxValue' must be greater than zero."))
end
return System.ToInt32((Sample(this) * maxValue))
end
if minValue > maxValue then
System.throw(System.ArgumentOutOfRangeException("minValue" --[[nameof(minValue)]], "'minValue' cannot be greater than maxValue."))
end
local range = maxValue - minValue
if range <= 2147483647 --[[Int32.MaxValue]] then
return (System.ToInt32((Sample(this) * range)) + minValue)
else
return System.toInt32((System.ToInt64((GetSampleForLargeRange(this) * range)) + minValue))
end
end
GetSampleForLargeRange = function (this)
-- The distribution of double value returned by Sample
-- is not distributed well enough for a large range.
-- If we use Sample for a range [int.MinValue..int.MaxValue)
-- We will end up getting even numbers only.
local result = InternalSample(this)
-- Note we can't use addition here. The distribution will be bad if we do that.
local negative = (InternalSample(this) % 2 == 0) and true or false
-- decide the sign based on second sample
if negative then
result = - result
end
local d = result
d = d + (2147483646 --[[int.MaxValue - 1]])
-- get a number in range [0 .. 2 * Int32MaxValue - 1)
d = d / (4294967293 --[[2 * (uint)int.MaxValue - 1]])
return d
end
NextDouble = function (this)
return Sample(this)
end
NextBytes = function (this, buffer)
if buffer == nil then
System.throw(System.ArgumentNullException("buffer" --[[nameof(buffer)]]))
end
do
local i = 0
while i < #buffer do
buffer:set(i, System.toByte(InternalSample(this)))
i = i + 1
end
end
end
return {
_inext = 0,
_inextp = 0,
Sample = Sample,
Next = Next,
NextDouble = NextDouble,
NextBytes = NextBytes,
__ctor__ = __ctor__
}
end)())