subroutine get_gain(gain)

use cesrv_struct
use cesr_basic_mod
use cesr_read_data_mod

implicit none

type (but_value_struct) gain(0:120)
integer i, ios
integer iu
integer ix
character(130) gain_file
character(130) line_in, correction_file
character(20) :: r_name = 'get_gain'

namelist / button_gains / gain

!

do i = lbound(gain, 1), ubound(gain, 1)
  gain(i)%value = [1, 1, 1, 1]
enddo

if (.not. logic%gain_correction) return

call fullfilename (logic%btns_gain_correction_file, correction_file)
call set_bpm_button_correction_file (gain_file = correction_file)

iu=lunget()
open (iu, file = correction_file, status = 'old', iostat = ios)
if (ios /= 0) then
  call out_io (s_fatal$, r_name, 'CANNOT OPEN BPM GAIN FILE: ' // correction_file)
  call err_exit
endif

read (iu, nml = button_gains)
close (iu)

end subroutine