makerng.lua

--[[------------------------------------
RandomLua v0.3.1
Pure Lua Pseudo-Random Numbers Generator
Under the MIT license.
copyright(c) 2017 linux-man
--]]------------------------------------

-- Multiply-with-carry
local multiply_with_carry = {}
multiply_with_carry.__index = multiply_with_carry

function multiply_with_carry:random(a, b)
    local m = self.m
    local t = self.a * self.x + self.c
    local y = t % m
    self.x = y
    self.c = math.floor(t / m)
    if not a then return y / m
    elseif not b then
        if a == 0 then return y
        else return 1 + (y % a) end
    else
        return a + (y % (b - a + 1))
    end
end

function multiply_with_carry:randomseed(s)
    self.c = self.ic
    self.x = (s or os.time()) % 0x80000000
end

local function mwc(s, r)
    local temp = {}
    setmetatable(temp, multiply_with_carry)
    temp.a, temp.c, temp.m = 1103515245, 12345, 0x10000000  --from Ansi C
    if r then
        if r == 'nr' then temp.a, temp.c, temp.m = 1664525, 1013904223, 0x10000000 --from Numerical Recipes.
        elseif r == 'mvc' then temp.a, temp.c, temp.m = 214013, 2531011, 0x10000000 end--from MVC
    end
    temp.ic = temp.c
    temp:randomseed(s)
    return temp
end

return mwc