var scrollInt;
var scrTime, scrSt, scrDist, scrDur, scrInt;

function replaceAnchorLinks(){
    var anchors, i, targ, targarr;

    if( !document.getElementById ) return;

    /* get all anchors */
    anchors = document.getElementsByTagName("a");

    for( i=0; i<anchors.length; i++ ){
        /* check if href links to an anchor on this page */
        if( anchors[i].href.indexOf("#")!=-1 && anchors[i].href.indexOf(document.URL)!=-1 ){
            targ = anchors[i].href.substring( anchors[i].href.indexOf("#")+1 ); /* get name of target anchor */
            targarr = document.getElementsByName( targ );                       /* find target anchor */

            if( targarr.length ){
                anchors[i].className    = (targarr[0].offsetTop<anchors[i].offsetTop) ? "up" : "down";
                anchors[i].id           = "__" + targ;	/* save target as id with prefix (used in onclick function below) */
                anchors[i].onmousedown  = function(){
                    scrollToAnchor( this.id.substring(2) );
                    return false;
                };
                anchors[i].href         = "#";/* rewrite href */
            }
        }
    }
}


/** scroll functions */
function scrollPage(){
    scrTime += scrInt;
    if( scrTime<scrDur ){
        window.scrollTo( 0, easeInOut(scrTime,scrSt,scrDist,scrDur) );
    }else{
        window.scrollTo( 0, scrSt+scrDist );
        clearInterval(scrollInt);
    }
}

function scrollToAnchor( aname ){
    var anchors, i, ele;
    if( !document.getElementById )
        return;

    /* get anchor */
    anchors = document.getElementsByTagName("a");

    for( i=0; i<anchors.length; i++ )
        if( anchors[i].name==aname ){
            ele = anchors[i];
            i   = anchors.length;
        }

    /* set scroll target */
    if( window.scrollY )
        scrSt = window.scrollY;
    else if( document.documentElement.scrollTop )
        scrSt = document.documentElement.scrollTop;
    else
        scrSt = document.body.scrollTop;

    scrDist = ele.offsetTop-scrSt;
    scrDur  = 250;
    scrTime = 0;
    scrInt  = 10;
    /*
    scrDur  = 500;
    scrTime = 0;
    scrInt  = 10;
    */

    /* set interval */
    clearInterval(scrollInt);
    scrollInt = setInterval( scrollPage, scrInt );
}


/** easing functions */
function easeInOut( t,b,c,d ){
    return c/2 * (1 - Math.cos(Math.PI*t/d)) + b;
}