-16 bit format:
-
-| PrCSR | (15..11) | 10 | 9 | 8 | (7..1) | 0 |
-| ----- | - | - | - | - | ------- | ------- |
-| 0 | predidx | zero0 | inv0 | i/f | regidx | ffirst0 |
-| 1 | predidx | zero1 | inv1 | i/f | regidx | ffirst1 |
-| 2 | predidx | zero2 | inv2 | i/f | regidx | ffirst2 |
-| 3 | predidx | zero3 | inv3 | i/f | regidx | ffirst3 |
-
-Note: predidx=x0, zero=1, inv=1 is a RESERVED encoding. Its use must
-generate an illegal instruction trap.
-
-8 bit format:
-
-| PrCSR | 7 | 6 | 5 | (4..0) |
-| ----- | - | - | - | ------- |
-| 0 | zero0 | inv0 | i/f | regnum |
-
-Mapping from 8 to 16 bit format, the table becomes:
-
-| PrCSR | (15..11) | 10 | 9 | 8 | (7..1) | 0 |
-| ----- | - | - | - | - | ------- | ------- |
-| 0 | x9 | zero0 | inv0 | i/f | regnum | ff=0 |
-| 1 | x10 | zero1 | inv1 | i/f | regnum | ff=0 |
-| 2 | x11 | zero2 | inv2 | i/f | regnum | ff=0 |
-| 3 | x12 | zero3 | inv3 | i/f | regnum | ff=0 |