read_interface_map Subroutine

      subroutine read_interface_map(files, control, bc, dims)
        !< Read mapping file in the system/mesh/layout/mapping.txt
        implicit none
        type(filetype), intent(in) :: files
        !< Files' name and handler
        type(controltype), intent(in) :: control
        !< Control parameters
        type(extent), intent(in) :: dims
        !< Extent of the domain:imx,jmx,kmx
        type(boundarytype), intent(inout) :: bc
        !< boundary conditions and fixed values
        integer :: ios
        integer :: max_call

        integer :: i
        integer :: b1,b2,f1,f2
        integer :: s11,s12,s21,s22
        integer :: e11,e12,e21,e22
        integer :: switch
        integer :: class
        !--- initialize indicies --!
        max_call = control%total_process*6
        ilo(1) = 1  ; ihi(1) = 1
        ilo(2) = dims%imx; ihi(2) = dims%imx
        ilo(3) = 1  ; ihi(3) = dims%imx
        ilo(4) = 1  ; ihi(4) = dims%imx
        ilo(5) = 1  ; ihi(5) = dims%imx
        ilo(6) = 1  ; ihi(6) = dims%imx

        jlo(1) = 1  ; jhi(1) = dims%jmx
        jlo(2) = 1  ; jhi(2) = dims%jmx
        jlo(3) = 1  ; jhi(3) = 1
        jlo(4) = dims%jmx; jhi(4) = dims%jmx
        jlo(5) = 1  ; jhi(5) = dims%jmx
        jlo(6) = 1  ; jhi(6) = dims%jmx

        klo(1) = 1  ; khi(1) = dims%kmx
        klo(2) = 1  ; khi(2) = dims%kmx
        klo(3) = 1  ; khi(3) = dims%kmx
        klo(4) = 1  ; khi(4) = dims%kmx
        klo(5) = 1  ; khi(5) = 1
        klo(6) = dims%kmx; khi(6) = dims%kmx

        bc%otherface(1)=2
        bc%otherface(2)=1
        bc%otherface(3)=4
        bc%otherface(4)=3
        bc%otherface(5)=6
        bc%otherface(6)=5
        bc%dir_switch = 0
        !--- end of variable intializaiton --!

        !--- reading map file  ---!

        open(files%MAP_FILE_UNIT, file=files%mapfile, status='old', action='read')
        read(files%MAP_FILE_UNIT,*) ! ignore header
        do i=1,max_call
          read(files%MAP_FILE_UNIT,*, iostat=ios) b1,f1,s11,e11,s12,e12,&
                                            b2,f2,s21,e21,s22,e22,switch,class
          if(is_iostat_end(ios)) EXIT
          if(b1==control%process_id)then
            if(f1==1) then
              bc%otherface(1)=f2
              jlo(1)=s21
              jhi(1)=e21
              klo(1)=s22
              khi(1)=e22
              bc%dir_switch(1)=switch
              mpi_class(1)=class
            elseif(f1==2) then
              bc%otherface(2)=f2
              jlo(2)=s21
              jhi(2)=e21
              klo(2)=s22
              khi(2)=e22
              bc%dir_switch(2)=switch
              mpi_class(2)=class
            elseif(f1==3) then
              bc%otherface(3)=f2
              ilo(3)=s21
              ihi(3)=e21
              klo(3)=s22
              khi(3)=e22
              bc%dir_switch(3)=switch
              mpi_class(3)=class
            elseif(f1==4) then
              bc%otherface(4)=f2
              ilo(4)=s21
              ihi(4)=e21
              klo(4)=s22
              khi(4)=e22
              bc%dir_switch(4)=switch
              mpi_class(4)=class
            elseif(f1==5) then
              bc%otherface(5)=f2
              ilo(5)=s21
              ihi(5)=e21
              jlo(5)=s22
              jhi(5)=e22
              bc%dir_switch(5)=switch
              mpi_class(5)=class
            elseif(f1==6) then
              bc%otherface(6)=f2
              ilo(6)=s21
              ihi(6)=e21
              jlo(6)=s22
              jhi(6)=e22
              bc%dir_switch(6)=switch
              mpi_class(6)=class
            end if
          else 
            continue
          end if
        end do

        close(files%MAP_FILE_UNIT)
        call change_map_to_particular_range()

        call read_periodic_bc_file(files, control, bc)
      end subroutine read_interface_map