Reorganize some builtin functions in preparation for async env

builtin/game/misc_s.lua

@@ -0,0 +1,93 @@
+-- Minetest: builtin/misc_s.lua
+-- The distinction of what goes here is a bit tricky, basically it's everything
+-- that does not (directly or indirectly) need access to ServerEnvironment,
+-- Server or writable access to IGameDef on the engine side.
+-- (The '_s' stands for standalone.)
+
+--
+-- Misc. API functions
+--
+
+function core.hash_node_position(pos)
+	return (pos.z + 32768) * 65536 * 65536
+		 + (pos.y + 32768) * 65536
+		 +  pos.x + 32768
+end
+
+
+function core.get_position_from_hash(hash)
+	local x = (hash % 65536) - 32768
+	hash  = math.floor(hash / 65536)
+	local y = (hash % 65536) - 32768
+	hash  = math.floor(hash / 65536)
+	local z = (hash % 65536) - 32768
+	return vector.new(x, y, z)
+end
+
+
+function core.get_item_group(name, group)
+	if not core.registered_items[name] or not
+			core.registered_items[name].groups[group] then
+		return 0
+	end
+	return core.registered_items[name].groups[group]
+end
+
+
+function core.get_node_group(name, group)
+	core.log("deprecated", "Deprecated usage of get_node_group, use get_item_group instead")
+	return core.get_item_group(name, group)
+end
+
+
+function core.setting_get_pos(name)
+	local value = core.settings:get(name)
+	if not value then
+		return nil
+	end
+	return core.string_to_pos(value)
+end
+
+
+-- See l_env.cpp for the other functions
+function core.get_artificial_light(param1)
+	return math.floor(param1 / 16)
+end
+
+-- PNG encoder safety wrapper
+
+local o_encode_png = core.encode_png
+function core.encode_png(width, height, data, compression)
+	if type(width) ~= "number" then
+		error("Incorrect type for 'width', expected number, got " .. type(width))
+	end
+	if type(height) ~= "number" then
+		error("Incorrect type for 'height', expected number, got " .. type(height))
+	end
+
+	local expected_byte_count = width * height * 4
+
+	if type(data) ~= "table" and type(data) ~= "string" then
+		error("Incorrect type for 'data', expected table or string, got " .. type(data))
+	end
+
+	local data_length = type(data) == "table" and #data * 4 or string.len(data)
+
+	if data_length ~= expected_byte_count then
+		error(string.format(
+			"Incorrect length of 'data', width and height imply %d bytes but %d were provided",
+			expected_byte_count,
+			data_length
+		))
+	end
+
+	if type(data) == "table" then
+		local dataBuf = {}
+		for i = 1, #data do
+			dataBuf[i] = core.colorspec_to_bytes(data[i])
+		end
+		data = table.concat(dataBuf)
+	end
+
+	return o_encode_png(width, height, data, compression or 6)
+end