amun-code/sources/compression.F90

!!******************************************************************************
!!
!!  This file is part of the AMUN source code, a program to perform
!!  Newtonian or relativistic magnetohydrodynamical simulations on uniform or
!!  adaptive mesh.
!!
!!  Copyright (C) 2020 Grzegorz Kowal <grzegorz@amuncode.org>
!!
!!  This program is free software: you can redistribute it and/or modify
!!  it under the terms of the GNU General Public License as published by
!!  the Free Software Foundation, either version 3 of the License, or
!!  (at your option) any later version.
!!
!!  This program is distributed in the hope that it will be useful,
!!  but WITHOUT ANY WARRANTY; without even the implied warranty of
!!  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
!!  GNU General Public License for more details.
!!
!!  You should have received a copy of the GNU General Public License
!!  along with this program.  If not, see <http://www.gnu.org/licenses/>.
!!
!!******************************************************************************
!!
!! module: COMPRESSION
!!
!!  This module provides compression for the XML-binary format.
!!
!!******************************************************************************
!
module compression

! module variables are not implicit by default
!
  implicit none

! compression parameters
!
  integer, save :: compression_format = 0
  integer, save :: compression_level  = 0

! supported compression formats
!
  integer, parameter :: compression_none = 0

! by default everything is private
!
  private

! declare public subroutines
!
  public :: set_compression, get_compression, compress

!- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
!
  contains
!
!===============================================================================
!!
!!***  PUBLIC SUBROUTINES  ****************************************************
!!
!===============================================================================
!
!===============================================================================
!
! subroutine SET_COMPRESSION:
! --------------------------
!
!   Subroutine sets the compression format and level.
!
!   Arguments:
!
!     cformat - the compression format string;
!     clevel  - the compression level;
!     suffix  - the compressed file suffix;
!     success - returns the compression format set;
!
!===============================================================================
!
  subroutine set_compression(cformat, clevel, suffix, success)

    implicit none

! subroutine arguments
!
    character(len=*) , intent(in)  :: cformat
    integer          , intent(in)  :: clevel
    character(len=8) , intent(out) :: suffix
    logical          , intent(out) :: success

!-------------------------------------------------------------------------------
!
    success = .false.
    select case(trim(adjustl(cformat)))
    case default
      compression_format = compression_none
      compression_level  = 0
      suffix             = ""
      success            = .true.
    end select

!-------------------------------------------------------------------------------
!
  end subroutine set_compression
!
!===============================================================================
!
! function GET_COMPRESSION:
! ------------------------
!
!   Function returns the compression format index.
!
!
!===============================================================================
!
  integer function get_compression()

    implicit none

!-------------------------------------------------------------------------------
!
    get_compression = compression_format
    return

!-------------------------------------------------------------------------------
!
  end function get_compression
!
!===============================================================================
!
! subroutine COMPRESS:
! -------------------
!
!   Subroutine compressed input buffer using ZSTD compression.
!
!   Arguments:
!
!     input - the input sequence of bytes;
!
!===============================================================================
!
  subroutine compress(input, output, csize)

    implicit none

! subroutine arguments
!
    integer(kind=1), dimension(:), target, intent(in)  :: input
    integer(kind=1), dimension(:), target, intent(out) :: output
    integer(kind=8)                      , intent(out) :: csize

! local variables
!
    integer(kind=8) :: bsize

!-------------------------------------------------------------------------------
!
    bsize = min(size(input), size(output))
    select case(compression_format)
    case default
      output(1:bsize) = input(1:bsize)
    end select

!-------------------------------------------------------------------------------
!
  end subroutine compress

!===============================================================================
!
end module compression