RADEON_CRTC_H_TOTAL
if( h_total > H_TOTAL_2PIX( RADEON_CRTC_H_TOTAL ) ) {
h_total = H_TOTAL_2PIX( RADEON_CRTC_H_TOTAL );
((mode->timing.h_total / 8 - 1) & RADEON_CRTC_H_TOTAL)
a = (r & RADEON_CRTC_H_TOTAL);