commands are read line by line

[<labelname>:] [<commandname> [<arg1>[,<arg2[…]]]] [; <comment>]

arguments can be either variables, labels or immediates,
labels are replaced with immediates which have the line numbers of the labels as their values
true/false: boolean (immediate)
12.6: number (immediate)
$hello nwae: string (immediate)
nodolla: either a label is called so (immediate) or it's a variable

Types:

e   anything
v   any variable
ve  any set variable
s   string
vs  string variable
n   number
vn  number variable
ui  unsigned integer number
b   bool
vn  bool variable


Instructions:

mov          <v to>, <e from>              Copies from into to.
getvar       <vs varname>[, <ve exists>]   Sets varname to the current variable called <varname> if it's set. If exists is passed, it's set to a bool indicating whether the variable was set.
add          <vn to>, <n from>             to += from
add          <vb to>, <b from>             to = to and from
add          <vs to>, <s from>             to = to .. from
mul          <vn to>, <n from>             to *= from
mul          <vb to>, <b from>             to = to or from
mul          <vs str>, <n cnt>             str = str:rep(from)
neg          <vn num>                      num = -num
neg          <vb var>                      var = not var
neg          <vs str>                      str = str:rev()
inv          <vn num>                      num = 1 / num
mod          <vn num>, <n dv>              num = num % dv
jmp          <ui p>[, <e c>]               If c is not false, the instruction pointer is set to p. To disallow infinite loops, the program is interrupted after changing the ip, the mod should then consider restarting it.
call         <ui p>                        push the ip, then jmp p; used to execute subroutines
ret                                        pop something, then jmp there; used to exit subroutines
push         <e a>[, <e b>[, <e c>[…]]]  put values onto the stack; from left to right
pop          <v a>[, <v b>[, <v c>[…]]]  takes values from the stack and sets the passed variables to them; from left to right
equal        <v a>, <e b>                  a = a == b
less         <vn a>, <n b>                 a = a < b; after executing, a is a bool
less         <vs a>, <s b>                 a = a < b; less also works for strings
usleep       <n t>                         aborts the program for at least floor(max(0, t)) ms
sleep        <n t>                         executes usleep with t * 1000000 as argument
get_us_time  <v to>                        stores minetest.get_us_time() into to; can be used to measure time differences
tostring     <ve var>                      var = tostring(var)
print        <e a>[, <e b>[, <e c>[…]]]  adds variables to the log, seperated by \t, \n is added at the end
flush                                      Output the log, this should vary for every mod.

How mods can use this mod:

local mylog = print

local parsed_code = pdisc.parse(code_text)

local function mystart(parsed_code)
	local thread = pdisc.create_thread(function(thread)
		thread.flush = function(self)
			mylog(self.log)
			self.log = ""
			return true
		end
	end, parsed_code)
	thread:suscitate()
	mykeepalive(thread)
end

mystart(parsed_code)

local function mykeepalive(thread)
	if not thread.stopped then
		return
	end
	thread:try_rebirth()
	minetest.after(0.1, function()
		mykeepalive()
	end)
end