updatePEAKC.ca

/*
    
Copyright (c) 2013 Centre for Water Systems,
                   University of Exeter

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

*/

// Zeroed Water Depth that is less than tolerance. 
// WARNING compute the absolute value.

CA_FUNCTION updatePEAKC(CA_GRID grid, CA_CELLBUFF_REAL_IO PEAK, CA_CELLBUFF_REAL_I SRC, CA_CELLBUFF_STATE_I MASK)
{
  // Initialise the grid
  CA_GRID_INIT(grid);

  // Read Mask.
  CA_STATE mask  = caReadCellBuffState(grid,MASK,0);

  // Read bit 0  (false the main cell has nodata)
  CA_STATE bit0  = caReadBitsState(mask,0,1);

  // Read bit 31 (true if the main cell is nodata in at least one
  // neighbour has data)
  CA_STATE bit31  = caReadBitsState(mask,31,32);

  // If the main cell has no data and none of the neighbour has data,
  // then do nothing.
  if(bit0 == 0 && bit31 == 0)
    return;
  
  // Retrive the source value.
  CA_REAL  src  = caReadCellBuffReal(grid,SRC,0);

  // Retrive the absolute value of the PEAK buffer.
  CA_REAL  peak = caReadCellBuffReal(grid,PEAK,0);
  
  // Get the maximum.
  CA_REAL  max = caMaxReal(caAbsReal(src),peak);

  // Update the maximum value.
  caWriteCellBuffReal(grid,PEAK,max);  
}