subscr.c

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*                            Open Watcom Project
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//
// SUBSCR       : compile-time subscripting
//

#include "ftnstd.h"
#include "symdefs.h"


bool    DoSubscript( act_dim_list *dims, intstar4 *subscrs, intstar4 *res ) {
//===========================================================================

// Do subscript operation for EQUIVALENCE or DATA statements and
// NAMELIST-directed i/o at run-time.

    int         dims_no;
    intstar4    offset;
    intstar4    multiplier;
    intstar4    ss;
    intstar4    lo;
    intstar4    hi;
    intstar4    *bounds;

    *res = 0;
    dims_no = _DimCount( dims->dim_flags );
    bounds = &dims->subs_1_lo;
    multiplier = 1;
    offset = 0;
    for(;;) {
        ss = *subscrs;
        subscrs++;
        lo = *bounds;
        bounds++;
        hi = *bounds;
        bounds++;
        if( ss < lo ) return( FALSE );
        if( ss > hi ) return( FALSE );
        offset += ( ss - lo ) * multiplier;
        if( offset < 0 ) return( FALSE );
        if( offset > dims->num_elts ) return( FALSE );
        dims_no--;
        if( dims_no == 0 ) break;
        multiplier *= ( hi - lo + 1 );
    }
    *res = offset;
    return( TRUE );
}