xneg.c

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#include <grass/gis.h>
#include <grass/raster.h>
#include <grass/calc.h>
 
/**********************************************************************
neg(x) = -x
**********************************************************************/
 
int f_neg(int argc, const int *argt, void **args)
{
    int i;
 
    if (argc < 1)
        return E_ARG_LO;
    if (argc > 1)
        return E_ARG_HI;
 
    if (argt[0] != argt[1])
        return E_RES_TYPE;
 
    switch (argt[1]) {
    case CELL_TYPE: {
        CELL *res = args[0];
        CELL *arg1 = args[1];
 
        for (i = 0; i < columns; i++)
            if (IS_NULL_C(&arg1[i]))
                SET_NULL_C(&res[i]);
            else
                res[i] = -arg1[i];
        return 0;
    }
    case FCELL_TYPE: {
        FCELL *res = args[0];
        FCELL *arg1 = args[1];
 
        for (i = 0; i < columns; i++)
            if (IS_NULL_F(&arg1[i]))
                SET_NULL_F(&res[i]);
            else
                res[i] = -arg1[i];
        return 0;
    }
    case DCELL_TYPE: {
        DCELL *res = args[0];
        DCELL *arg1 = args[1];
 
        for (i = 0; i < columns; i++)
            if (IS_NULL_D(&arg1[i]))
                SET_NULL_D(&res[i]);
            else
                res[i] = -arg1[i];
        return 0;
    }
    default:
        return E_INV_TYPE;
    }
}