Advent of Code 2019 - Lua
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function get_arg(mem, pos, arg)
local param_mode = mem[pos] // (10 ^ (arg + 1)) % 10
if #mem < pos + arg then
print(string.format("Error: Opcode too short at end of memory: %d", pos))
os.exit(false)
end
local arg = mem[pos + arg]
if param_mode == 0 then
arg = arg + 1
if #mem < arg then
print(string.format("Error: Memory offset out of bounds: %d", arg))
os.exit(false)
end
end
return arg
end
function get_param(mem, pos, arg)
local param_mode = mem[pos] // (10 ^ (arg + 1)) % 10
local arg = get_arg(mem, pos, arg)
if param_mode == 0 then
return mem[arg]
end
return arg
end
function interpret(mem)
local pos = 1
while true do
if #mem < pos then
print(string.format("Instruction pointer ran off of memory"))
os.exit(false)
end
local opcode = mem[pos] % 100
if opcode == 1 then
mem[get_arg(mem, pos, 3)] = get_param(mem, pos, 1) + get_param(mem, pos, 2)
pos = pos + 4
elseif opcode == 2 then
mem[get_arg(mem, pos, 3)] = get_param(mem, pos, 1) * get_param(mem, pos, 2)
pos = pos + 4
elseif opcode == 3 then
io.stdout:write("> ")
mem[get_arg(mem, pos, 1)] = io.stdin:read("n")
pos = pos + 2
elseif opcode == 4 then
io.stdout:write(get_param(mem, pos, 1))
io.stdout:write("\n")
pos = pos + 2
elseif opcode == 5 then
if get_param(mem, pos, 1) ~= 0 then
pos = get_param(mem, pos, 2) + 1
else
pos = pos + 3
end
elseif opcode == 6 then
if get_param(mem, pos, 1) == 0 then
pos = get_param(mem, pos, 2) + 1
else
pos = pos + 3
end
elseif opcode == 7 then
mem[get_arg(mem, pos, 3)] = get_param(mem, pos, 1) < get_param(mem, pos, 2) and 1 or 0
pos = pos + 4
elseif opcode == 8 then
mem[get_arg(mem, pos, 3)] = get_param(mem, pos, 1) == get_param(mem, pos, 2) and 1 or 0
pos = pos + 4
elseif opcode == 99 then
return
else
print(string.format("Error: Invalid opcode %d at %d", opcode, pos - 1))
os.exit(false)
end
end
end
file = io.open(arg[1])
memory = {}
for num in string.gmatch(file:read(), "(-?%d+),?") do
table.insert(memory, tonumber(num))
end
file:close()
interpret(memory)