module U_blox
	def string2packet(s)
		s.split(/ /).collect{|item| item.hex}
	end
	
	def valid_header?(packet)
		return (packet[0] == 0xB5 and packet[1] == 0x62)
	end
	
	def valid_size?(packet)
		if packet.size < 6 then return false end
		size = packet[4] + (packet[5] << 8) + 8
		return false if size > packet.size
		if packet.size > size then
			packet.slice!(size...packet.size)
		end
		return true
	end
	
	def valid_parity?(packet)
		ck_a = 0
		ck_b = 0
		packet[2..-3].each{|item|
			ck_a += item
			ck_b += ck_a
		}
		ck_a %= (1 << 8)
		ck_b %= (1 << 8)
		
		return (packet[-2] == ck_a and packet[-1] == ck_b)
	end
	
	def fetch_ITOW(packet)
		return (packet[6 + 0] + (packet[6 + 1] << 8) + (packet[6 + 2] << 16) + (packet[6 + 3] << 24)) * 1E-3
	end
	
	def fetch_longlatheight(packet)
		if packet[2] != 0x01 or packet[3] != 0x02 then
			return nil
		end
		
		long = (packet[6 + 4] + (packet[6 + 5] << 8) + (packet[6 + 6] << 16) + (packet[6 + 7] << 24)) * 1E-7
		lat = (packet[6 + 8] + (packet[6 + 9] << 8) + (packet[6 + 10] << 16) + (packet[6 + 11] << 24)) * 1E-7
		height = (packet[6 + 12] + (packet[6 + 13] << 8) + (packet[6 + 14] << 16) + (packet[6 + 15] << 24)) * 1E-3
		return [long, lat, height]
	end
	
	def fetch_pos_acc(packet)
		if packet[2] != 0x01 or packet[3] != 0x02 then
			return nil
		end
		
		h_acc = (packet[6 + 20] + (packet[6 + 21] << 8) + (packet[6 + 22] << 16) + (packet[6 + 23] << 24)) * 1E-3
		v_acc = (packet[6 + 24] + (packet[6 + 25] << 8) + (packet[6 + 26] << 16) + (packet[6 + 27] << 24)) * 1E-3
		return [h_acc, v_acc]
	end
	
	def fetch_velned(packet)
		if packet[2] != 0x01 or packet[3] != 0x12 then
			return nil
		end
		
		vel_n = (packet[6 +  4] + (packet[6 +  5] << 8) + (packet[6 +  6] << 16) + ((packet[6 +  7] & 0b01111111) << 24))
		vel_n -= (1 << 31) if (packet[6 +  7] & 0b10000000) != 0
		vel_e = (packet[6 +  8] + (packet[6 +  9] << 8) + (packet[6 + 10] << 16) + ((packet[6 + 11] & 0b01111111) << 24))
		vel_e -= (1 << 31) if (packet[6 + 11] & 0b10000000) != 0
		vel_d = (packet[6 + 12] + (packet[6 + 13] << 8) + (packet[6 + 14] << 16) + ((packet[6 + 15] & 0b01111111) << 24))
		vel_d -= (1 << 31) if (packet[6 + 15] & 0b10000000) != 0
		return [vel_n * 1E-2, vel_e * 1E-2, vel_d * 1E-2]
	end
	
	def fetch_vel_acc(packet)
		if packet[2] != 0x01 or packet[3] != 0x12 then
			return nil
		end
		
		return [(packet[6 + 28] + (packet[6 + 29] << 8) + (packet[6 + 30] << 16) + (packet[6 + 31] << 24)) * 1E-2]
	end
		
	instance_methods.each{|method|
		eval("module_function :#{method}")
	}
end