function bit_to_byte,x

N=n_elements(x)

if N eq 0 then begin
message,'You should define argument.'
	return,0b
endif

mask=2b^(7b-bindgen(8))

i=lindgen(N)
y=bytarr(N*8)

	for j=0,7 do y(i*8+j)=(x and mask(j)) ne 0

i=0

y=ishft(temporary(y),7)

return, y

	end