Philippe 17/01/2020: move quicksort to tools + add kpos optional dummy argument

src/MNH/rain_ice_red.f90

-!MNH_LIC Copyright 1995-2019 CNRS, Meteo-France and Universite Paul Sabatier
+!MNH_LIC Copyright 1995-2020 CNRS, Meteo-France and Universite Paul Sabatier
 !MNH_LIC This is part of the Meso-NH software governed by the CeCILL-C licence
 !MNH_LIC version 1. See LICENSE, CeCILL-C_V1-en.txt and CeCILL-C_V1-fr.txt
 !MNH_LIC for details. version 1.
@@ -242,6 +242,7 @@ END MODULE MODI_RAIN_ICE_RED
 !  P. Wautelet 10/04/2019: replace ABORT and STOP calls by Print_msg
 !  P. Wautelet 28/05/2019: move COUNTJV function to tools.f90
 !  P. Wautelet 29/05/2019: remove PACK/UNPACK intrinsics (to get more performance and better OpenACC support)
+!  P. Wautelet 17/01/2020: move Quicksort to tools.f90
 !
 !*       0.    DECLARATIONS
 !              ------------
@@ -1729,30 +1730,5 @@ CONTAINS
   !
   !
   END SUBROUTINE CORRECT_NEGATIVITIES
-!
-  recursive subroutine quicksort(a, first, last)
-  implicit none
-  integer  a(*), x, t
-  integer first, last
-  integer i, j
-
-  x = a( (first+last) / 2 )
-  i = first
-  j = last
-  do
-     do while (a(i) < x)
-        i=i+1
-     end do
-     do while (x < a(j))
-        j=j-1
-     end do
-     if (i >= j) exit
-     t = a(i);  a(i) = a(j);  a(j) = t
-     i=i+1
-     j=j-1
-  end do
-  if (first < i-1) call quicksort(a, first, i-1)
-  if (j+1 < last)  call quicksort(a, j+1, last)
-  end subroutine quicksort
 
 END SUBROUTINE RAIN_ICE_RED

src/MNH/tools.f90

-!MNH_LIC Copyright 2019-2019 CNRS, Meteo-France and Universite Paul Sabatier
+!MNH_LIC Copyright 2019-2020 CNRS, Meteo-France and Universite Paul Sabatier
 !MNH_LIC This is part of the Meso-NH software governed by the CeCILL-C licence
 !MNH_LIC version 1. See LICENSE, CeCILL-C_V1-en.txt and CeCILL-C_V1-fr.txt
 !MNH_LIC for details. version 1.
@@ -19,12 +19,14 @@ module mode_tools
 !
 ! Modifications:
 !  P. Wautelet 28/05/2019: move COUNTJV function to tools.f90
+!  P. Wautelet 17/01/2020: move Quicksort to tools.f90
 
 implicit none
 
 private
 
 public :: Countjv
+public :: Quicksort
 public :: Upcase
 
 interface Countjv
@@ -79,6 +81,44 @@ function Countjv3d(ltab,i1,i2,i3) result(ic)
 end function Countjv3d
 
 
+recursive subroutine Quicksort( ka, kbeg, kend, kpos )
+  integer, dimension(:),           intent(inout) :: ka
+  integer,                         intent(in)    :: kbeg, kend
+  integer, dimension(:), optional, intent(inout) :: kpos
+
+  integer :: ji, jj
+  integer :: itmp, itmp2, ival
+
+  ival = ka( ( kbeg + kend ) / 2 )
+  ji = kbeg
+  jj = kend
+  do
+     do while ( ka(ji) < ival )
+        ji = ji + 1
+     end do
+     do while ( ival < ka(jj) )
+        jj = jj - 1
+     end do
+     if ( ji >= jj ) exit
+
+     itmp = ka(ji)
+     ka(ji) = ka(jj)
+     ka(jj) = itmp
+
+     if ( present( kpos ) ) then
+      itmp2 = kpos(ji)
+      kpos(ji) = kpos(jj)
+      kpos(jj) = itmp2
+     end if
+
+     ji=ji+1
+     jj=jj-1
+  end do
+  if ( kbeg   < ji - 1 ) call Quicksort( ka, kbeg,   ji - 1, kpos )
+  if ( jj + 1 < kend   ) call Quicksort( ka, jj + 1, kend,   kpos )
+end subroutine Quicksort
+
+
 function Upcase(hstring)
   character(len=*), intent(in) :: hstring
   character(len=len(hstring))  :: upcase