--turns a screen-space fill pattern, into an object-space fill pattern by wrapping the patterns row and column by the given x and y amount.
function get_local_fill_pattern(x,y,fill_pattern)
    local add_bits=band(fill_pattern,0x0000.FFFF)
    fill_pattern=band(fill_pattern,0xFFFF)
    y=flr(y)%4
    if(y~=0)then
        local r_masks={0xFFF0,0xFF00,0xF000}
        local l_masks={0x000F,0x00FF,0x0FFF}
        fill_pattern=bxor(lshr(band(fill_pattern,r_masks[y]),y*4),shl(band(fill_pattern,l_masks[y]),(4-y)*4))
    end

    x=flr(x)%4
    if(x~=0)then
        local r_masks={0xEEEE,0xCCCC,0x8888}
        local l_masks={0x1111,0x3333,0x7777}
        fill_pattern=bxor(lshr(band(fill_pattern,r_masks[x]),x),shl(band(fill_pattern,l_masks[x]),4-x))
    end

    return bxor(fill_pattern,add_bits)
end

_fillp_xmask_lo={[0]=0xffff,0x7777,0x3333,0x1111}
_fillp_xmask_hi={[0]=0x0000,0x8888,0xcccc,0xeeee}
_fillp_original=fillp

function fillp(p,x,y)
    if y then
        x=band(x,3)
        local p16=flr(p)
        local p32=rotr(p16+lshr(p16,16),band(y,3)*4+x)
        p+=flr(band(p32,_fillp_xmask_lo[x])+band(rotl(p32,4),_fillp_xmask_hi[x]))-p16
    end
    return _fillp_original(p)
end