comparison.lua

local based = require 'based.32.crockford'
local basexx = require 'basexx'

local function bench(name, fn, vector)
	local before = os.clock()
	for _, input in ipairs(vector) do
		fn(input)
	end
	local after = os.clock()
	print(string.format("%-10s %1.6f seconds", name..":", after-before))
end

local function benchAll(subjects, vector)
	for name, fn in pairs(subjects) do
		bench(name, fn, vector)
	end
end

local function compare(subjects, vector)
	benchAll(subjects, vector)

	for i = 1, 10 do
		local item = vector[i]
		local ref = next(subjects)
		local result = subjects[ref](item)
		for name in next, subjects, ref do
			local new = subjects[name](item)
			if new ~= result then
				print("Mismatch: "..result.." vs. "..new)
			end
		end
	end
end

-----

print(_VERSION)

---

local strings = {}
for i = 1, 1e3 do
	if not strings[i] then
		strings[i] = string.rep("x", 20):gsub(".", function() return string.char(math.random(("a"):byte(), ("z"):byte())) end)
	end
end

print("Encoding:")

compare({
	Based = based.encode,
	BaseXX = basexx.to_crockford,
}, strings)

print "-----"

local encoded = {}
for i = 1, 1e3 do
	if not encoded[i] then
		encoded[i] = based.encode(strings[i])
	end
end

print("Decoding: ")

compare({
	Based = based.decode,
	BaseXX = basexx.from_crockford,
}, encoded)

evaluation.md

Why?

I recently started my own Lua project combining encoders and decoders for different Base-N encodings and only after pushing it to luarocks.org found out that such a project already exists, so I decided to benchmark them both to see if my new code is at least faster. Lo and behold, yes.

---

Results

Encoding

Lua	Based	BaseXX	ratio
Lua	0.010629	0.078772	x0.13
JIT (on)	0.002530	0.024218	x0.1
JIT (off)	0.005205	0.034397	x0.15

Decoding

Lua	Based	BaseXX	ratio
Lua	0.009658	0.080785	x0.12
JIT (on)	0.002203	0.037336	x0.06
JIT (off)	0.004537	0.037538	x0.12

---

Note: Tests for incorrect decoding have been removed, but the corresponding code has been kept, as it has no real effect on the output.

output.txt

$ lua -v
Lua 5.4.3  Copyright (C) 1994-2021 Lua.org, PUC-Rio
$ lua comparison.lua
Lua 5.4
Encoding:
Based:     0.010629 seconds
BaseXX:    0.078772 seconds
-----
Decoding: 
Based:     0.009658 seconds
BaseXX:    0.080785 seconds
$ luajit -v
LuaJIT 2.1.0-beta3 -- Copyright (C) 2005-2017 Mike Pall. http://luajit.org/
$ luajit comparison.lua
Lua 5.1
Encoding:
BaseXX:    0.024218 seconds
Based:     0.002530 seconds
-----
Decoding: 
BaseXX:    0.037336 seconds
Based:     0.002203 seconds
$ luajit -joff comparison.lua
Lua 5.1
Encoding:
BaseXX:    0.034397 seconds
Based:     0.005205 seconds
-----
Decoding: 
BaseXX:    0.037538 seconds
Based:     0.004537 seconds