xbitxor.c

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#include <grass/gis.h>
#include <grass/raster.h>
#include <grass/calc.h>
 
/****************************************************************
bitxor(a,b,c,...) = a ^ b ^ c ^ ...
****************************************************************/
 
int f_bitxor(int argc, const int *argt, void **args)
{
    CELL *res = args[0];
    CELL **argz = (CELL **)args;
    int i, j;
 
    if (argc < 1)
        return E_ARG_LO;
 
    if (argt[0] != CELL_TYPE)
        return E_RES_TYPE;
 
    for (i = 1; i <= argc; i++)
        if (argt[i] != CELL_TYPE)
            return E_ARG_TYPE;
 
    for (i = 0; i < columns; i++) {
        res[i] = 0;
        for (j = 1; j <= argc; j++) {
            if (IS_NULL_C(&argz[j][i])) {
                SET_NULL_C(&res[i]);
                break;
            }
            res[i] ^= argz[j][i];
        }
    }
 
    return 0;
}