xor2.c

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#include <grass/gis.h>
#include <grass/raster.h>
#include <grass/calc.h>

/****************************************************************
or2(a,b,c,...) = a || b || c || ...

Differs from or() in that the boolean axioms:

        true || x == true
        x || true == true

hold even when x is null.
****************************************************************/

int f_or2(int argc, const int *argt, void **args)
{
    CELL *res = args[0];
    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] != argt[0])
            return E_ARG_TYPE;

    for (i = 0; i < columns; i++) {
        res[i] = 0;
        for (j = 1; j <= argc; j++) {
            CELL *arg = args[j];
            if (!IS_NULL_C(&arg[i]) && arg[i]) {
                res[i] = 1;
                break;
            }
            if (IS_NULL_C(&arg[i]))
                SET_NULL_C(&res[i]);
        }
    }

    return 0;
}