ParallelIO

////

/// @file pio_rearrange.c

/// @author Jim Edwards

/// @date 2014

/// @brief Code to map IO to model decomposition

///

/// 

/// 

/// 

/// @see  http://code.google.com/p/parallelio/

////

#include <pio.h>

#include <pio_internal.h>

​

/** internal variable used for debugging */

int tmpioproc=-1;  

​

​

/** @internal

 ** Convert an index into a list of dimensions. E.g., for index 4 into a

 ** array defined as a[3][2], will return 1 1.

 ** @endinternal

*/

void idx_to_dim_list(const int ndims, const int gdims[], const PIO_Offset idx,

                     PIO_Offset dim_list[])

{

  int i, curr_idx, next_idx;

  curr_idx = idx;

  // Easiest to start from the right and move left.

  for (i = ndims-1; i >= 0; --i) {

    // This way of doing div/mod is slightly faster than using "/" and "%".

    next_idx = curr_idx / gdims[i];

    dim_list[i] = curr_idx - (next_idx*gdims[i]);

    curr_idx = next_idx;

  }

}

/**

 ** @internal

 ** Expand a region along dimension dim, by incrementing count[i] as much as

 ** possible, consistent with the map.

 **

 ** Once max_size is reached, the map is exhausted, or the next entries fail

 ** to match, expand_region updates the count and calls itself with the next

 ** outermost dimension, until the region has been expanded as much as

 ** possible along all dimensions.

 ** @endinternal

 */

void expand_region(const int dim, const int gdims[], const int maplen,

                   const PIO_Offset map[], const int region_size,

                   const int region_stride, const int max_size[],

                   PIO_Offset count[])