zeroedVA.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
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

*/

// Zeroed Velocity and Angle  when water depth is less than tolerance. 

CA_FUNCTION zeroedVA(CA_GRID grid, CA_CELLBUFF_REAL_IO V, CA_CELLBUFF_REAL_IO A,
		     CA_CELLBUFF_REAL_I WD, CA_CELLBUFF_STATE_I MASK, CA_GLOB_REAL_I tol)
{
  // Initialise the grid
  CA_GRID_INIT(grid);

  // Read Mask of the main cell.
  CA_STATE mask  = caReadCellBuffState(grid,MASK,0);

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

  // If the main cell has no data 
  // then do nothing.
  if(bit0 == 0)
    return;
  
  // Retrieve the water depth of the main cell.
  CA_REAL  wdmain = caReadCellBuffReal(grid,WD,0);

  // Set the multiplier to zero if water depth is less then tolerance.
  CA_REAL  mul = caStepReal(wdmain,tol);

  // Retrieve the V and A of the main cell and use the multiplier.
  CA_REAL  v = mul*caReadCellBuffReal(grid,V,0);
  CA_REAL  a = mul*caReadCellBuffReal(grid,A,0);

  // Update the V and A.
  caWriteCellBuffReal(grid,V,v);  
  caWriteCellBuffReal(grid,A,a);  
}