OpenOS SHA-256 speedtest

--[[
  Simple program to find out the speed of making sha256 hashes in OpenOS (OpenComputers Minecraft mod's OS)
  using Tier 3 Data card and IgorTimofeev's SHA-256 library (https://raw.githubusercontent.com/IgorTimofeev/MineOS/master/Libraries/SHA-256.lua)
  My results are 0.47 and 3.9 for Data Card and Lib, respectively
  P.S. Sorry for bad lua code, I'm new to this
--]]

s = require('SHA-256')
component = require('component')

function AddZeroes(x, n)
    local p = tostring(x)
    while string.len(p) < n do
        p = "0" .. p
    end
    return p
end

function GetLastI(n)
    local p = ""
    for i = 1, n do
        p = p .. "9"
    end
    local x = tonumber(p)
    return x
end

function string.tohex(str)
    return (str:gsub('.', function (c)
        return string.format('%02X', string.byte(c))
    end))
end

data = component.data

local x = os.clock()
for a=1, 3 do
    for b=0, GetLastI(a) do
        p = AddZeroes(b,a)
        d = p .. ":" .. string.lower(string.tohex(data.sha256(p)))
        os.sleep(0)
    end
end
print("Using datacard: " .. os.clock() - x)

local x = os.clock()
for a=1, 3 do
  for b=0, GetLastI(a) do
    p = AddZeroes(b,a)
    d = p .. ":" .. s.hash(p)
    os.sleep(0)
  end
end
print("Using library: " .. os.clock() - x)