diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..c9b1058
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+ldoc_output
diff --git a/.woodpecker/deploy.yml b/.woodpecker/deploy.yml
new file mode 100644
index 0000000..4fe75fd
--- /dev/null
+++ b/.woodpecker/deploy.yml
@@ -0,0 +1,23 @@
+steps:
+  ldoc-generate:
+    image: alpine
+    commands:
+      - apk update
+      - apk add git ldoc
+      - ldoc .
+      - git init ldoc_output
+  ldoc-push:
+    depends_on: ldoc-generate
+    image: appleboy/drone-git-push
+    settings:
+      ssh_key:
+        from_secret: ssh_key
+      remote: git@codeberg.org:y5nw/advtrains-doc-integration
+      branch: pages
+      path: ldoc_output
+      force: true
+      commit: true
+      commit_message: "[CI SKIP] LDoc for commit ${CI_COMMIT_SHA}"
+when:
+  - event: push
+    branch: master
diff --git a/.woodpecker.yml b/.woodpecker/test.yml
similarity index 100%
rename from .woodpecker.yml
rename to .woodpecker/test.yml
diff --git a/README.md b/README.md
index 2b2d81a..59f3c8a 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,7 @@
-This mod integrates Advtrains with the [doc][minetest-doc] mod.
+# Documentation System Integration for Advtrains
+
+This mod integrates Advtrains with the [doc][minetest-doc] mod, among
+other things.
 
 [minetest-doc]: https://content.minetest.net/packages/Wuzzy/doc/
 
diff --git a/config.ld b/config.ld
new file mode 100644
index 0000000..7e7ac05
--- /dev/null
+++ b/config.ld
@@ -0,0 +1,8 @@
+dir = "ldoc_output"
+file = {".", exclude = {"spec"}}
+format = "markdown"
+project = "Documentation System Integration for Advtrains"
+title = "Manual for advtrains_doc_integration"
+package = "advtrains_doc_integration"
+readme = "README.md"
+-- vim: syntax=lua
diff --git a/describe.lua b/describe.lua
new file mode 100644
index 0000000..ec8be95
--- /dev/null
+++ b/describe.lua
@@ -0,0 +1,83 @@
+--- Describing things.
+-- This module includes functions used for describing things.
+-- @module advtrains_doc_integration.describe
+-- @alias D
+local M = advtrains_doc_integration.mathutils
+local utils = advtrains_doc_integration.utils
+local D = {}
+
+--- Describe a conns object
+-- @tparam integer|table conns The conns object to describe.
+-- @treturn string|nil The description of the conns object.
+function D.conns(conns)
+	local connsdesc = {[0] = "N", "NNE", "NE", "ENE", "E", "ESE", "SE", "SSE", "S", "SSW", "SW", "WSW", "W", "WNW", "NW", "NNW"}
+	if type(conns) == "table" then
+		if conns.c then
+			if conns.y and conns.y ~= 0 then
+				return ("%s%+d%%"):format(D.conns(conns.c), conns.y*100)
+			else
+				return D.conns(conns.c)
+			end
+		else
+			local cst = utils.map(conns, D.conns)
+			local cstl = #cst
+			if cstl == 2 then
+				return ("%s - %s"):format(unpack(cst))
+			elseif cstl == 3 then
+				return ("[%s <-] %s -> %s"):format(cst[3], cst[1], cst[2])
+			elseif cstl == 4 then
+				return ("%s - %s; %s - %s"):format(unpack(cst))
+			elseif cstl == 5 then
+				return ("[%s,%s <-] %s -> %s"):format(cst[3], cst[4], cst[1], cst[2])
+			end
+		end
+	else
+		return connsdesc[tonumber(conns)]
+	end
+end
+
+--- Describe a (mixed) fraction
+-- @tparam integer int The integer part of the number.
+-- @tparam integer num The numerator.
+-- @tparam integer denom The denominator.
+-- @treturn string The description of the mixed fraction.
+function D.mixed_fraction(int, num, denom)
+	local str = tostring(int)
+	if num > 0 then
+		local fs = ("%d/%d"):format(num, denom)
+		if int ~= 0 then
+			str = ("%d %s"):format(int, fs)
+		else
+			str = fs
+		end
+	end
+	return str
+end
+
+--- Describe a short length (using mm and in).
+-- @tparam number x The length in meters.
+-- @treturn string The description of the length.
+function D.length(x)
+	local inch, inchfrac = math.modf(x/0.0254)
+	local ft = math.floor(inch/12)
+	inch, inchfrac = inch%12, math.floor(inchfrac*32)
+	local imst = {}
+	if ft > 0 then
+		table.insert(imst, ft .. "'")
+	end
+	if inch > 0 or inchfrac > 0 or ft == 0 then
+		table.insert(imst, D.mixed_fraction(inch, M.reduce_fraction(inchfrac, 32)) .. '"')
+	end
+	return ("%d mm (%s)"):format(1000*x, table.concat(imst, " "))
+end
+
+--- Describe a speed value (using m/s, km/h and mph).
+-- @tparam number x The speed in m/s.
+-- @treturn string The description of the speed.
+function D.speed(x)
+	local kmph = x*3.6
+	local mph = kmph/1.609344
+	return string.format("%.1f m/s (%.1f km/h; %.1f mph)", x, kmph, mph)
+end
+
+return D
diff --git a/init.lua b/init.lua
index b1ba21d..7acd4d4 100644
--- a/init.lua
+++ b/init.lua
@@ -1,8 +1,16 @@
+--- Entry point.
+-- @module advtrains_doc_integration
+local worldpath = minetest.get_worldpath() .. "/"
+local modpath = minetest.get_modpath("advtrains_doc_integration")
 local S = minetest.get_translator("advtrains_doc_integration")
 local fsescape = minetest.formspec_escape
-local worldpath = minetest.get_worldpath() .. DIR_DELIM
 advtrains_doc_integration = {}
 
+for _, m in ipairs{"mathutils", "describe", "utils"} do
+	advtrains_doc_integration[m] = dofile(("%s/%s.lua"):format(modpath, m))
+end
+local D = advtrains_doc_integration.describe
+
 local function S2(a, b)
 	return S(a, S(b))
 end
@@ -102,68 +110,6 @@ local function htsound(action, soundspec)
 	return sounddesc
 end
 
-local function describe_conns(conns)
-	local connsdesc = {[0] = "N", "NNE", "NE", "ENE", "E", "ESE", "SE", "SSE", "S", "SSW", "SW", "WSW", "W", "WNW", "NW", "NNW"}
-	if type(conns) == "table" then
-		if conns.c then
-			if conns.y and conns.y ~= 0 then
-				return ("%s%+d%%"):format(describe_conns(conns.c), conns.y*100)
-			else
-				return describe_conns(conns.c)
-			end
-		else
-			local cst = map(conns, describe_conns)
-			local cstl = #cst
-			if cstl == 2 then
-				return ("%s - %s"):format(unpack(cst))
-			elseif cstl == 3 then
-				return ("[%s <-] %s -> %s"):format(cst[3], cst[1], cst[2])
-			elseif cstl == 4 then
-				return ("%s - %s; %s - %s"):format(unpack(cst))
-			elseif cstl == 5 then
-				return ("[%s,%s <-] %s -> %s"):format(cst[3], cst[4], cst[1], cst[2])
-			end
-		end
-	else
-		return connsdesc[tonumber(conns)]
-	end
-end
-advtrains_doc_integration.describe_conns = describe_conns
-
-local function describe_length(x)
-	local inch = x/0.0254
-	local infdenom = 32
-	local infnum = math.floor(inch*infdenom)%infdenom
-	local ft = math.floor(inch/12)
-	inch = math.floor(inch)%12
-	local st = {}
-	if ft > 0 then
-		table.insert(st, ft .. "'")
-	end
-	local infstr = ""
-	if infnum > 0 then
-		while infnum%2 == 0 do
-			infnum, infdenom = infnum/2, infdenom/2
-		end
-		infstr = string.format(" %d/%d", infnum, infdenom)
-	end
-	if inch > 0 then
-		table.insert(st, string.format(' %s%s"', inch, infstr))
-	elseif infnum > 0 then
-		table.insert(st, infstr .. '"')
-	end
-	if not next(st) then
-		st = '0"'
-	end
-	return string.format("%d mm (%s)", 1000*x, table.concat(st))
-end
-
-local function describe_speed(x)
-	local kmph = x*3.6
-	local mph = kmph/1.609344
-	return string.format("%.1f m/s (%.1f km/h; %.1f mph)", x, kmph, mph)
-end
-
 local function addlist(lst, tbl, title, fallback1, fallback2, mapf)
 	if not tbl then
 		if fallback2 then
@@ -437,8 +383,8 @@ local function doc_render_wagon_information(prototype, pname)
 	addlist(desctext, prototype.drives_on, S("Drives on:"), nil, nil, htmono)
 	addlist(desctext, prototype.coupler_types_front, S("Compatible front couplers:"), S2("Front coupler: @1", "Absent"), S2("Front coupler: @1", "Universal"), ht_coupler_name)
 	addlist(desctext, prototype.coupler_types_back, S("Compatible rear couplers:"), S2("Rear coupler: @1", "Absent"), S2("Rear coupler: @1", "Universal"), ht_coupler_name)
-	table.insert(desctext, S("Wagon span: @1", prototype.wagon_span and describe_length(2*prototype.wagon_span) or S("Undefined")))
-	table.insert(desctext, S("Maximum speed: @1", prototype.max_speed and describe_speed(prototype.max_speed) or S("Undefined")))
+	table.insert(desctext, S("Wagon span: @1", prototype.wagon_span and D.length(2*prototype.wagon_span) or S("Undefined")))
+	table.insert(desctext, S("Maximum speed: @1", prototype.max_speed and D.speed(prototype.max_speed) or S("Undefined")))
 	table.insert(desctext, S2("Motive power: @1", prototype.is_locomotive and "Present" or "Absent"))
 	table.insert(desctext, S("Horn sound: @1", htsound("playhorn", prototype.horn_sound)))
 	if prototype.doors.open.sound or prototype.doors.close.sound then
@@ -636,7 +582,7 @@ if doc then
 				end
 			end
 			if ndef.at_conns then
-				return S("This track has the following conns table by default: @1", describe_conns(ndef.at_conns) or "?")
+				return S("This track has the following conns table by default: @1", D.conns(ndef.at_conns) or "?")
 			end
 			return ""
 		end)
diff --git a/mathutils.lua b/mathutils.lua
new file mode 100644
index 0000000..c7377ff
--- /dev/null
+++ b/mathutils.lua
@@ -0,0 +1,43 @@
+--- Math utilities.
+-- @module advtrains_doc_integration.mathutils
+-- @alias M
+local M = {}
+
+local function gcdmain(x, y, ...)
+	if y == nil then
+		return x or 1
+	end
+	y = y%x
+	if y == 0 then
+		return gcdmain(x, ...)
+	end
+	return gcdmain(y, x, ...)
+end
+
+--- Compute the greatest common divider.
+-- @tparam integer ... The numbers used for the computation.
+-- @treturn integer The GCD of the given numbers.
+function M.gcd(...)
+	local args = {...}
+	for k, v in pairs(args) do
+		if v == 0 then
+			return 0
+		elseif v ~= v then
+			return v
+		elseif v < 0 then
+			args[k] = -v
+		end
+	end
+	return gcdmain(unpack(args))
+end
+
+--- Reduce a fraction.
+-- @tparam integer num The numerator.
+-- @tparam integer denom The denominator.
+-- @treturn int,int The reduced fraction.
+function M.reduce_fraction(num, denom)
+	local gcd = M.gcd(num, denom)
+	return num/gcd, denom/gcd
+end
+
+return M
diff --git a/spec/mathutils_spec.lua b/spec/mathutils_spec.lua
new file mode 100644
index 0000000..8c2befc
--- /dev/null
+++ b/spec/mathutils_spec.lua
@@ -0,0 +1,7 @@
+local M = require "mathutils"
+describe("GCD", function()
+	it("should calculate values correctly", function()
+		assert.equals(1, M.gcd(5, 7, 9))
+		assert.equals(4, M.gcd(8, 24, 20))
+	end)
+end)
diff --git a/utils.lua b/utils.lua
new file mode 100644
index 0000000..077148d
--- /dev/null
+++ b/utils.lua
@@ -0,0 +1,18 @@
+--- Utility functions.
+-- @module advtrains_doc_integration.utils
+-- @alias M
+local M = {}
+
+--- Create a table by applying a function to each element.
+-- @tparam table tbl The table to map from.
+-- @tparam function func The function to apply.
+-- @treturn table The resulting table.
+function M.map(tbl, func)
+	local t = {}
+	for k, v in pairs(tbl or {}) do
+		t[k] = func(v)
+	end
+	return t
+end
+
+return M