in each partition the sub-signal must start on a power-2 boundary,
and that "x" marks unused (padding) portions:
- |31| | | 16|15| | 8|7 0 |
- 32bit | x| x| x| x| x| x|10 .... 0 |
- 16bit | x| x|26 ... 16 | x| x|10 .... 0 |
- 8bit | x|28.24| 20.16| x|12 .. 8|x|4.. 0 |
+ |31| | | | 16|15| | 8|7 0 |
+ 32bit | x| x| x| | x| x| x|10 .... 0 |
+ 16bit | x| x|26 ... 16 | x| x|10 .... 0 |
+ 8bit | x|28 .. 24| 20.16| x|12 .. 8|x|4.. 0 |
thus, we deduce, we *actually* need breakpoints at these positions,
and that unused portions common to **all** cases can be deduced
and marked "x"
- |28|26|24| |20|16| |12|10|8| |4 0
- x x
+ | |28|26|24| |20|16| |12|10|8| |4 0 |
+ x x