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|
--nodedb.lua
--database of all nodes that have 'save_in_nodedb' field set to true in node definition
--serialization format:
--(6byte poshash) (2byte contentid)
--contentid := (14bit nodeid, 2bit param2)
local function hash_to_bytes(x)
local aH = math.floor(x / 1099511627776) % 256;
local aL = math.floor(x / 4294967296) % 256;
local bH = math.floor(x / 16777216) % 256;
local bL = math.floor(x / 65536) % 256;
local cH = math.floor(x / 256) % 256;
local cL = math.floor(x ) % 256;
return(string.char(aH, aL, bH, bL, cH, cL));
end
local function cid_to_bytes(x)
local cH = math.floor(x / 256) % 256;
local cL = math.floor(x ) % 256;
return(string.char(cH, cL));
end
local function bytes_to_hash(bytes)
local t={string.byte(bytes,1,-1)}
local n =
t[1] * 1099511627776 +
t[2] * 4294967296 +
t[3] * 16777216 +
t[4] * 65536 +
t[5] * 256 +
t[6]
return n
end
local function bytes_to_cid(bytes)
local t={string.byte(bytes,1,-1)}
local n =
t[1] * 256 +
t[2]
return n
end
local function l2b(x)
return x%4
end
local function u14b(x)
return math.floor(x/4)
end
local ndb={}
--local variables for performance
local ndb_nodeids={}
local ndb_nodes={}
--load
--nodeids get loaded by advtrains init.lua and passed here
function ndb.load_data(data)
ndb_nodeids = data and data.nodeids or {}
end
local path=minetest.get_worldpath().."/advtrains_ndb"
local file, err = io.open(path, "r")
if not file then
atprint("load ndb failed: ", err or "Unknown Error")
else
local cnt=0
local hst=file:read(6)
local cid=file:read(2)
while hst and #hst==6 and cid and #cid==2 do
ndb_nodes[bytes_to_hash(hst)]=bytes_to_cid(cid)
cnt=cnt+1
hst=file:read(6)
cid=file:read(2)
end
atprint("nodedb: read", cnt, "nodes.")
file:close()
end
--save
function ndb.save_data()
local file, err = io.open(path, "w")
if not file then
atprint("load ndb failed: ", err or "Unknown Error")
else
for hash, cid in pairs(ndb_nodes) do
file:write(hash_to_bytes(hash))
file:write(cid_to_bytes(cid))
end
file:close()
end
return {nodeids = ndb_nodeids}
end
--function to get node. track database is not helpful here.
function ndb.get_node_or_nil(pos)
local node=minetest.get_node_or_nil(pos)
if node then
return node
else
--maybe we have the node in the database...
local cid=ndb_nodes[minetest.hash_node_position(pos)]
if cid then
local nodeid = ndb_nodeids[u14b(cid)]
if nodeid then
--atprint("ndb.get_node_or_nil",pos,"found node",nodeid,"cid",cid,"par2",l2b(cid))
return {name=nodeid, param2 = l2b(cid)}
end
end
end
atprint("ndb.get_node_or_nil",pos,"not found")
end
function ndb.get_node(pos)
local n=ndb.get_node_or_nil(pos)
if not n then
return {name="ignore", param2=0}
end
return n
end
function ndb.swap_node(pos, node)
minetest.swap_node(pos, node)
|
