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'''
This module contains helper classes for structure fields and length expressions.
'''
class Field(object):
'''
Represents a field of a structure.
type is the datatype object for the field.
field_type is the name of the type (string tuple)
field_name is the name of the structure field.
visible is true iff the field should be in the request API.
wire is true iff the field should be in the request structure.
auto is true iff the field is on the wire but not in the request API (e.g. opcode)
enum is the enum name this field refers to, if any.
'''
def __init__(self, type, field_type, field_name, visible, wire, auto, enum=None, isfd=False):
self.type = type
self.field_type = field_type
self.field_name = field_name
self.enum = enum
self.visible = visible
self.wire = wire
self.auto = auto
self.isfd = isfd
self.parent = None
def __str__(self):
field_string = "Field"
if self.field_name is None:
if self.field_type is not None:
field_string += " with type " + str(self.type)
else:
field_string += " \"" + self.field_name + "\""
if self.parent is not None:
field_string += " in " + str(self.parent)
return field_string
class Expression(object):
'''
Represents a mathematical expression for a list length or exprfield.
Public fields:
op is the operation (text +,*,/,<<,~) or None.
lhs and rhs are the sub-Expressions if op is set.
lenfield_name is the name of the length field, or None for request lists.
lenfield is the Field object for the length field, or None.
bitfield is True if the length field is a bitmask instead of a number.
nmemb is the fixed size (value)of the expression, or None
'''
def __init__(self, elt, parent):
self.parent = parent
self.nmemb = None
self.lenfield_name = None
self.lenfield_type = None
self.lenfield_parent = None
self.lenfield = None
self.lenwire = False
self.bitfield = False
self.op = None
self.lhs = None
self.rhs = None
self.contains_listelement_ref = False
if elt.tag == 'list':
# List going into a request, which has no length field (inferred by server)
self.lenfield_name = elt.get('name') + '_len'
self.lenfield_type = 'CARD32'
elif elt.tag == 'fieldref':
# Standard list with a fieldref
self.lenfield_name = elt.text
elif elt.tag == 'paramref':
self.lenfield_name = elt.text
self.lenfield_type = elt.get('type')
elif elt.tag == 'op':
# Op field. Need to recurse.
self.op = elt.get('op')
self.lhs = Expression(list(elt)[0], parent)
self.rhs = Expression(list(elt)[1], parent)
# Hopefully we don't have two separate length fields...
self.lenfield_name = self.lhs.lenfield_name
if self.lenfield_name == None:
self.lenfield_name = self.rhs.lenfield_name
elif elt.tag == 'unop':
# Op field. Need to recurse.
self.op = elt.get('op')
self.rhs = Expression(list(elt)[0], parent)
self.lenfield_name = self.rhs.lenfield_name
elif elt.tag == 'value':
# Constant expression
self.nmemb = int(elt.text, 0)
elif elt.tag == 'popcount':
self.op = 'popcount'
self.rhs = Expression(list(elt)[0], parent)
self.lenfield_name = self.rhs.lenfield_name
# xcb_popcount returns 'int' - handle the type in the language-specific part
elif elt.tag == 'enumref':
self.op = 'enumref'
self.lenfield_name = (elt.get('ref'), elt.text)
elif elt.tag == 'sumof':
self.op = 'sumof'
self.lenfield_name = elt.get('ref')
subexpressions = list(elt)
if len(subexpressions) > 0:
# sumof with a nested expression which is to be evaluated
# for each list-element in the context of that list-element.
# sumof then returns the sum of the results of these evaluations
self.rhs = Expression(subexpressions[0], parent)
elif elt.tag == 'listelement-ref':
# current list element inside iterating expressions such as sumof
self.op = 'listelement-ref'
self.contains_listelement_ref = True
else:
# Notreached
raise Exception("undefined tag '%s'" % elt.tag)
def fixed_size(self):
return self.nmemb != None
def get_value(self):
return self.nmemb
# if the value of the expression is a guaranteed multiple of a number
# return this number, else return 1 (which is trivially guaranteed for integers)
def get_multiple(self):
multiple = 1
if self.op == '*':
if self.lhs.fixed_size():
multiple *= self.lhs.get_value()
if self.rhs.fixed_size():
multiple *= self.rhs.get_value()
return multiple
def recursive_resolve_tasks(self, module, parents):
for subexpr in (self.lhs, self.rhs):
if subexpr != None:
subexpr.recursive_resolve_tasks(module, parents)
self.contains_listelement_ref |= subexpr.contains_listelement_ref
def resolve(self, module, parents):
if self.op == 'enumref':
self.lenfield_type = module.get_type(self.lenfield_name[0])
self.lenfield_name = self.lenfield_name[1]
elif self.op == 'sumof':
# need to find the field with lenfield_name
for p in reversed(parents):
fields = dict([(f.field_name, f) for f in p.fields])
if self.lenfield_name in fields.keys():
if p.is_case_or_bitcase:
# switch is the anchestor
self.lenfield_parent = p.parents[-1]
else:
self.lenfield_parent = p
self.lenfield_type = fields[self.lenfield_name].field_type
self.lenfield = fields[self.lenfield_name]
break
self.recursive_resolve_tasks(module, parents)
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