!Copyright (c) 2013 by https://git.em3d.cn/ under guide of Xiu Li(lixiu@chd.edu.cn)
!written by Huaifeng Sun(sunhuaifeng@email.sdu.edu.cn) and Xushan Lu(luxushan@gmail.com)
!Code distribution @ https://git.em3d.cn/

! This is a finite difference time domain (FDTD) code for the simulation of transient electromagnetic (TEM);
! This code is designed to  be used in semi_airborne TEM with a loop source;
! This code is written by Huaifeng Sun (sunhuaifeng@email.sdu.edu.cn) and Xushan Lu (luxushan@gmail.com), The conformal mesh part is written by Xinyu Li (202335098@mail.sdu.edu.cn) and Qi Zhao(zhaoqi_326326@163.com);
! OpenACC API is used in this code for the acceleration with GPU device; therefore, you are recommended to compile this code with --
! --PGI Accelerator Fortran Workstation compiler. A Nvidia GPU card with CUDA capability is required if you want to run this code in parallel mode.
! Nobody is allowed to copy or distribute this code to people outside of https://git.em3d.cn/ group without the permission from Prof. Xiu Li (lixiu@chd.edu.cn)--
! --or you will be 
! Contact the author for more detailed information.

!------------------------------------------------Instruction part--------------------------------------------------!
! This module is used to declare most of the parameters which are used in the entire code.
!-----------------------------------------------------------------------------------------------------------------------! 
!==========================The main program begins==============================
PROGRAM MAIN
  USE OMP_LIB
  USE CONSTANTPARAMETERS
  USE ELECTROMAGNETIC_VARIABLES
  USE RES_MODEL_PARAMETER
  USE TIME_PARAMETER
  IMPLICIT none
  CHARACTER*20, XSTRING
  CHARACTER*20, SYS_TIME 
  OPEN(10005,FILE='logfile.log',STATUS='UNKNOWN')
  !CALL GET_SYS_TIMEDATA(SYS_TIME)
  WRITE(10005,*)'----------------------',SYS_TIME,'----------------------'
  CALL GETDATA                  !This subroutine is used to input all the needed parameter of each calculation from 'input.dat' file.
  CALL CHECKPARAMETERS          !This subroutine is used to chech the correctness of input
  WRITE (XSTRING,'(I3)') NX
  XSTRING = '('//TRIM(ADJUSTL(XSTRING))//'E28.16E3)' 
  XSTRING = TRIM(ADJUSTL(XSTRING)) 
  CALL MEMORY_USE_ESTIMATION  !This subroutine is used to estimate the total memory usage according to the input,
  CALL ALLOCATEMEMORY         !This subroutine is used to allocate the memory in Host.
  WRITE(*,*)'Preparing the grid.. .. .. ..'
  IF(Logic_PML==1)THEN
     WRITE(*,*)'Boundary condition: CPML absorbing boundary -> uniform grid meshing'
     CALL GET_UNIFORM_GRID    !CPML 吸收边界：采用均匀网格剖分（与参考实现 tem3dfdtd_第二版 的组合一致）
  ELSE
     WRITE(*,*)'Boundary condition: Dirichlet (zero-field) boundary -> non-uniform grid meshing'
     CALL GET_NON_UNIFORMGRID !Dirichlet 边界：采用非均匀网格剖分（原版方式）
  ENDIF
  WRITE(*,*)'Initializing the parameters.. .. ..'
  CALL ZERO                     !This subroutine is used to initialize the value of array.
  WRITE(*,*)'Creating resistivity model.. .. ..'
  CALL GET_COORDINATES
  CALL Get_Receiver_Gridlabel 	!This subroutine is used to calculate the global coordinates and grid dispersion at the receiving point
  CALL RES_CONFIGURE            !This subroutine is used to distribute the resistivity (or conductivity) of the geology model to each grid
  WRITE(*,*)'Creating computing time series.. .. ..'
  CALL TIME_SERIOUS             !This subroutine is used to creat the time series of the entire computation
  WRITE(*,*)'Preparing array receiver points.. .. ..'
  WRITE(*,*)'Starting computing.. .. ..'
  !CALL GET_SYS_TIMEDATA(SYS_TIME)
  WRITE(10005,*)'----------------------',SYS_TIME,'----------------------'
  call Get_eps_r                !This subroutine is used to get the fictitious dielectric constant
  IF(Logic_PML==1)THEN
     call Get_pml_parameters    !This subroutine is used to get the CPML sigma/alpha/kappa profiles and the den_* scaling arrays
  ENDIF
  call Get_mstop                !This subroutine is used to cut the entire computation process into computation fractions
  call GetSourcePosition        !This subroutine is used to get the source position in the model.
  IF(Logic_PML==1)THEN
     WRITE(*,*)'Starting CPML iteration (Iteration_cpml) .. .. .. ..'
     call Iteration_cpml        !CPML 吸收边界迭代子程序
  ELSE
     WRITE(*,*)'Starting Dirichlet iteration (Iteration) .. .. .. ..'
     call Iteration             !Dirichlet 边界迭代子程序（原版）
  ENDIF
  CALL FREE_MEMORY         !This subroutine is used to deallocate all the memory allocated before iteration
  !CALL GET_SYS_TIMEDATA(SYS_TIME)
  WRITE(10005,*)'----------------------',SYS_TIME,'----------------------'
  WRITE(10005,*)'Computation finished！'
  CLOSE(10005)
END PROGRAM MAIN