--[==[
Hi!
As you can see below, I'm trying to use strsub(string, i) in a little program that is an attempt at building a very simple vm on top of Lua 5.3:.
This is the output that I get:
j10 m20
false is not equal to 'true.'
m20 false
push30 m30 executed.
x35 print.lua
j40 m50
true is equal to 'true.'
lua53: main.lua:34: attempt to call a nil value (local 'strsub')
stack traceback:
main.lua:34: in main chunk
[C]: in ?
Does anyone see what I'm doing wrong?
Thanks,
Clint
Lua newbie
]==]--
memory = {}
-- write a simple program to memory
memory["j10"] = "m20" -- Line 10 and 11: If m20 is true, jump to x100
memory["m11"] = "x100"
memory["m20"] = "false"
memory["push30"] = "m30 executed."
memory["x35"] = "print.lua"
memory["j40"] = "m50"
memory["j41"] = "x100"
memory["m50"] = "true"
memory["m55"] = "Why wasn't this line skipped?"
memory["x100"] = "exit.lua"
-- Instruction pointer
ip = 0
-- Execution loop
while ip < 200 do
-- check for the existence of the next instruction in the dictionary. If more than one type of instruction
-- with the same number exists in the dictionary, don't worry about it. Test for that at the assembler level.
keyString = "j" .. ip
if memory[keyString] ~= nil then
print(keyString .. " " .. memory[keyString])
memoryToTest = memory[keyString]
if memory[memoryToTest] == "true" then
print(memory[memoryToTest] .. " is equal to 'true.'")
ip = ip + 1
keyString = "m" .. ip
substring1 = strsub(memory[keyString], 1)
-- print(strsub("Hi" , 1))
ip = tonumber(subString1)
print("ip = " .. ip)
-- get the number part of the memory indicator, and set ip to it.
else
print(memory[memoryToTest] .. " is not equal to 'true.'")
ip = ip + 2
end
end
keyString = "m" .. ip
if memory[keyString] ~= nil then
print(keyString .. " " .. memory[keyString])
end
keyString = "r" .. ip
if memory[keyString] ~= nil then
print(keyString .. " " .. memory[keyString])
end
keyString = "w" .. ip
if memory[keyString] ~= nil then
print(keyString .. " " .. memory[keyString])
end
keyString = "pop" .. ip
if memory[keyString] ~= nil then
print(keyString .. " " .. memory[keyString])
end
keyString = "push" .. ip
if memory[keyString] ~= nil then
print(keyString .. " " .. memory[keyString])
end
keyString = "x" .. ip
if memory[keyString] ~= nil then
print(keyString .. " " .. memory[keyString])
end
ip = ip + 1
end
