!+
! Subroutine poscon (det, b1, b2, b3, b4, v, h) 
!
! Subroutine to convert button values to horizontal and vertical position.
!
! Input:
!   det -- Integer: detector index. If negative then do something special:
!            = -1 --> Set offset calibrations to 0.
!            = -2 --> Reset offset calibrations & reread calib file.
!            = -3 --> Turn off denominator summation normalization.
!            = -4 --> Turn back on denominator normalization.
!   b1, b2, b3, b4 -- Real: Button values.
!
! Output:
!   v   -- Real: Vertical position in meters.
!   h   -- Real: Horizontal position in meters.
!-

subroutine poscon(loc, f1, f2, f3, f4, v, h)

  use str_find_mod
  use cesr_utils_interface

  implicit none

  integer(4) loc, j, i, iu
  integer(4) three(120)

  real f1, f2, f3, f4, v, h, sum
  real pqv, pqh, hold, hhmm, factr, b1, b2, b3, b4
  real theta, c, c1, c2, c3, c4, s1, s2, s3, s4
  real, save :: ratio, eqsum(120), pdcm(2, 0:120)

  character(120) file_name, fname

  logical, save :: init_needed = .true., sumone = .false., iotit

  !! common /oftype/ iotit           Removed DCS 2009-01-05
  !! common /pdtcal/ pdcm            Removed DCS 2009-01-05
  !! common /ofaxis/ ratio, eqsum    Removed DCS 2009-01-05


! Init

  if (init_needed) then
    init_needed = .false.   ! once-only readin and convert mm to meters
    
    iu = open_cesr_constants_file('offset.bpm')
    do while(.true.)
      read(iu, *, end = 999) i, pdcm(1, i), pdcm(2, i)
    enddo
    999 close(unit = iu)
    pdcm = 0.001 * pdcm 

    three = 0
    call fullfilename('$CESR_ONLINE/machine_data/meas/orbit/three.inf', fname)
    open(unit = iu, file = fname, status='old',action='read')
    do while(.true.)
      read(iu, *, end = 888) i, three(i)
    enddo
    888 close(unit = iu)
  endif

! ------------------end-readin-det-calibration----------------------

  v = 0
  h = 0

  b1 = f1 ! protect in case three button modifies b1-b4
  b2 = f2
  b3 = f3
  b4 = f4

! -------------------convert-three-to-four-------------------------

  if (loc>0) then
    if (three(loc) /= 0) then
      if ((b1+b2+b3+b4)>10000.) then
        if (three(loc) == 1) then
          b1 = b4+(b3-b4)+(b2-b4)
        elseif (three(loc) == 2) then
          b2 = b3+(b4-b3)+(b1-b3)
        elseif (three(loc) == 3) then
          b3 = b2+(b4-b2)+(b1-b2)
        elseif (three(loc) == 4) then
          b4 = b1+(b3-b1)+(b2-b1)
        endif
      endif
    endif
  endif

! if something special needs to be done

  if (loc < -4 .or. loc > 120) then
    print *, 'ERROR IN POSCON: BAD DETECTOR LOC', loc
    return
  endif

  if (loc == -4) then
    sumone = .false.       ! for normal denominator
    return
  endif

  if (loc == -3) then
    sumone = .true.        ! for coupling meas
    return
  endif

  if (loc == -2) then
    init_needed = .true.        ! will cause re-cal (turn on zero offset)
    return
  endif

  if (loc == -1) then  ! turn off zero offset
    do j = 0, 100
      pdcm(1, j) = 0.
      pdcm(2, j) = 0.
    enddo
    return
  endif

! preceed as normal

  sum = b1+b2+b3+b4
  if (sumone) sum = 1
  if (sum == 0) return  

  pqv = pdcm(1, loc)
  pqh = pdcm(2, loc)

!--------------------------------------------------------------------
! usual case

! 2W/E
! up to phase iii (10/10/2001) was:    dcs, jjw
!        v = .0287*(b3+b4-b1-b2)/sum - pqv   !fit to L0 Horz data spring 1999
!        h = .0287*(b2+b4-b3-b1)/sum - pqh   !q2 q48 45 degrees, elliptical pipe
! changed to standard BPM for phase iii


  select case (loc)

! 0W/E
! up to phase iii (10/10/2001) was:    dcs, jjw
!        v = .0204*(b3+b4-b1-b2)/sum - pqv   !fit Horz data spring 1999
!        h = .0204*(b2+b4-b3-b1)/sum - pqh   !0 det (formerly same as q1)
    
!  case (99, 100)
!!2002    if (loc == 100) theta  =  26.0   ! Det 0W
!!2002    if (loc ==  99) theta  =  37.5   ! Det 0E
!    if (loc == 100) theta  =  44.66   ! Det 0W    2003 JULY 11
!    if (loc ==  99) theta  =  44.56   ! Det 0E
!
!    c  =  0.0203 * sqrt(2.0)
!    c1  =  c * cosd(theta+180)
!    c2  =  c * cosd(theta-90)
!    c3  =  c * cosd(theta+90)
!    c4  =  c * cosd(theta)
!    s1  =  c * sind(theta+180)
!    s2  =  c * sind(theta-90)
!    s3  =  c * sind(theta+90)
!    s4  =  c * sind(theta)
!    h  =  (c1*b1 + c2*b2 + c3*b3 + c4*b4) / sum - pqh
!    v  =  (s1*b1 + s2*b2 + s3*b3 + s4*b4) / sum - pqv
!
! Changed to standard BPM for CesrTA. DCS 2008/11/18.

! 1W/E
! used .027 up through spring 1999; jwelch looked at h orbits, conclude
! was too small by 1.7 , det 0 and 2 too large, mult by .76, .68
! was 0.0463 up to phase iii (10/10/2001) dcs, jjw
!
!  case (1, 98)
!    v = .0542*(b3+b4-b1-b2)/sum - pqv
!    h = .0542*(b2+b4-b3-b1)/sum - pqh
!
! Changed to standard BPM for CesrTA. DCS 2008/11/18.

! 48W/E

  case (48, 51)
    v = .0287*(b3+b4-b1-b2)/sum - pqv   ! fit to L0 Horz data spring 1999
    h = .0287*(b2+b4-b3-b1)/sum - pqh   ! q2 q48 45 degrees, elliptical pipe

! 49W/E

  case (49, 50)
    v = .035*(b3+b4-b1-b2)/sum - pqv  ! q49  45 degree, 4" diam
    h = .035*(b2+b4-b3-b1)/sum - pqh  ! changed from .042 to .035, dec89 RML

! south arc       x5c to 9w
     
  case (1:7)
    v = .0104*(b3+b4-b1-b2)/sum - pqv  ! 
    h = .0102*(b2+b4-b3-b1)/sum - pqh  ! 

! south arc       x1a to x5b
    
  case (93:110)    
    v = .0104*(b3+b4-b1-b2)/sum - pqv  ! 
    h = .0102*(b2+b4-b3-b1)/sum - pqh  ! 
  
! normal arc detectors

  case default
    
    v = .0198*(b3+b4-b1-b2)/sum - pqv
    h = .0259*(b2+b4-b3-b1)/sum - pqh

!    if ((ratio /= 0).and.(eqsum(loc) /= 0)) then
!      if (sum*ratio/eqsum(loc)<.85) then
!        hold = 1000.*h
!        h = sign(.043-.0315*sum*ratio/eqsum(loc), h)-pqh
!        hhmm = 1000.*h
!        factr = sum*ratio/eqsum(loc)
        !if (iotit) then
        !  print '(a, f5.3, i3, 2f6.2)', ' but ratio ', factr, ' at', loc, &
        !             ' use offaxis:horz mm', hold, ' >>> ',  hhmm
        !endif
!      endif  !  sum*ratio/eqsum(loc)<85
!    endif  !  ratio /= 0

  end select

end subroutine poscon