func pack7(in []uint32) uint32 {
	return 3<<28 |
		in[0] |
		in[1]<<4 |
		in[2]<<8 |
		in[3]<<12 |
		in[4]<<16 |
		in[5]<<20 |
		in[6]<<24
}
func pack7(in []uint32) uint32 {
	return 3<<28 |
		in[0] |
		in[1]<<4 |
		in[2]<<8 |
		in[3]<<12 |
		in[4]<<16 |
		in[5]<<20 |
		in[6]<<24
}
func pack7 ( in [ ] uint32 ) uint32 { return 3 << 28 | in [ 0 ] | in [ 1 ] << 4 | in [ 2 ] << 8 | in [ 3 ] << 12 | in [ 4 ] << 16 | in [ 5 ] << 20 | in [ 6 ] << 24 }
// pack7 packs 7 values from in using 4 bits each
pack7 packs 7 values from in using 4 bits each