Implement support for named fields, i.e. where one field is defined
in terms of another, rather than directly in terms of bits extracted
from the instruction.
The new method referenced_fields() on all the Field classes returns a
list of fields that this field references. This just passes through,
except for the new NamedField class.
We can then use referenced_fields() to:
* construct a list of 'dangling references' for a format or
pattern, which is the fields that the format/pattern uses but
doesn't define itself
* do a topological sort, so that we output "field = value"
assignments in an order that means that we assign a field before
we reference it in a subsequent assignment
* check when we output the code for a pattern whether we need to
fill in the format fields before or after the pattern fields, and
do other error checking
Signed-off-by: Peter Maydell<peter.maydell@linaro.org>
---
scripts/decodetree.py | 145 ++++++++++++++++++++++++++++++++++++++++--
1 file changed, 139 insertions(+), 6 deletions(-)