source: trunk/WRF.COMMON/WRFV2/external/RSL_LITE/task_for_point.c @ 3094

#include <stdio.h>
#include "rsl_lite.h"

/* updated 20051021, new algorithm distributes the remainder, if any, at either ends of the dimension
   rather than the first remainder number of processors in the dimension. Idea is that the processes
   on the ends have less work because they're boundary processes.  New alg works like this:
                     a                         b
         + + + + + + o o o o o o o o o o o o o + + + + + +

   + represents a process with an extra point (npoints is n/p+1), o processors that don't (n/p)
   a and b are the starting process indices in the dimension of the new section of o or x.
   JM
*/

TASK_FOR_POINT ( i_p , j_p , ids_p, ide_p , jds_p, jde_p , npx_p , npy_p , Px_p, Py_p )
  int_p i_p , j_p , Px_p , Py_p , ids_p, ide_p , jds_p, jde_p , npx_p , npy_p ;
{
  int i , j , ids, ide, jds, jde, npx, npy ;  /* inputs */
  int Px, Py ;                                /* output */
  int idim, jdim ;
  int rem, a, b ;
  i = *i_p - 1 ;
  j = *j_p - 1 ;
  npx = *npx_p ;
  npy = *npy_p ;
  ids = *ids_p - 1 ; ide = *ide_p - 1 ;
  jds = *jds_p - 1 ; jde = *jde_p - 1 ;
  idim = ide - ids + 1 ;
  jdim = jde - jds + 1 ;

  i = i >= ids ? i : ids ; i = i <= ide ? i : ide ;
  rem = idim % npx ;
  a = ( rem / 2 ) * ( (idim / npx) + 1 ) ;
  b = a + ( npx - rem ) * ( idim / npx ) ;
  if ( i-ids < a ) {
    Px = (i-ids) / ( (idim / npx) + 1 ) ;
  }
  else if ( i-ids < b ) {
    Px = ( a / ( (idim / npx) + 1 ) ) + (i-a-ids) / ( ( b - a ) / ( npx - rem ) )     ;
  }
  else {
    Px = ( a / ( (idim / npx) + 1 ) ) + (b-a-ids) / ( ( b - a ) / ( npx - rem ) ) +
                                        (i-b-ids) / ( ( idim / npx ) + 1 )  ;
  }

  j = j >= jds ? j : jds ; j = j <= jde ? j : jde ;
  rem = jdim % npy ;
  a = ( rem / 2 ) * ( (jdim / npy) + 1 ) ;
  b = a + ( npy - rem ) * ( jdim / npy ) ;
  if ( j-jds < a ) {
    Py = (j-jds) / ( (jdim / npy) + 1 ) ;
  }
  else if ( j-jds < b ) {
    Py = ( a / ( (jdim / npy) + 1 ) ) + (j-a-jds) / ( ( b - a ) / ( npy - rem ) )     ;
  }
  else {
    Py = ( a / ( (jdim / npy) + 1 ) ) + (b-a-jds) / ( ( b - a ) / ( npy - rem ) ) +
                                        (j-b-jds) / ( ( jdim / npy ) + 1 )  ;
  }

  *Px_p = Px ;
  *Py_p = Py ;
}

#if 0
main()
{
  int ips[100], ipe[100] ;
  int jps[100], jpe[100] ;
  int shw, i , j , ids, ide, jds, jde, npx, npy ;  /* inputs */
  int Px, Py, P ;                             /* output */
  printf("i, j, ids, ide, jds, jde, npx, npy\n") ;
  scanf("%d %d %d %d %d %d %d %d",&i, &j, &ids,&ide,&jds,&jde,&npx,&npy ) ;
  shw =0 ;
  for ( i = 0 ; i < 100 ; i++ ) { ips[i] = 9999999 ; ipe[i] = -99999999 ; }
  for ( i = 0 ; i < 100 ; i++ ) { jps[i] = 9999999 ; jpe[i] = -99999999 ; }
#if 1
  for ( j = jds-shw ; j <= jde+shw ; j++ )
  {
  for ( i = ids-shw ; i <= ide+shw ; i++ )
  {
#endif
  TASK_FOR_POINT ( &i , &j ,
                   &ids, &ide, &jds, &jde , &npx , &npy ,
                   &Px, &Py ) ;
/*  printf("%3d",P) ; */
#if 1
  }
/*  printf("\n") ; */
  }
for ( i = 0 ; i < npx*npy ; i++ ) {
  fprintf(stderr,"%3d. ips %d ipe %d (%d) jps %d jpe %d (%d)\n", i, ips[i], ipe[i], ipe[i]-ips[i]+1, jps[i], jpe[i], jpe[i]-jps[i]+1 ) ;
}
#endif
}
#endif