Commit 94597b61 authored by Richard Henderson's avatar Richard Henderson
Browse files

decodetree: Allow !function with no input bits 



Call this form a "parameter", returning a value extracted
from the DisasContext.

Reviewed-by: default avatarPhilippe Mathieu-Daude <philmd@redhat.com>
Signed-off-by: default avatarRichard Henderson <richard.henderson@linaro.org>
parent 3fbd3405

docs/devel/decodetree.rst

+7 −1
Original line number Diff line number Diff line
@@ -23,7 +23,7 @@ Fields 


Syntax::



  field_def     := '%' identifier ( unnamed_field )+ ( !function=identifier )?

  field_def     := '%' identifier ( unnamed_field )* ( !function=identifier )?

  unnamed_field := number ':' ( 's' ) number



For *unnamed_field*, the first number is the least-significant bit position
@@ -34,6 +34,12 @@ present, they are concatenated. In this way one can define disjoint fields. 
If ``!function`` is specified, the concatenated result is passed through the

named function, taking and returning an integral value.



One may use ``!function`` with zero ``unnamed_fields``.  This case is called

a *parameter*, and the named function is only passed the ``DisasContext``

and returns an integral value extracted from there.



A field with no ``unnamed_fields`` and no ``!function`` is in error.



FIXME: the fields of the structure into which this result will be stored

is restricted to ``int``.  Which means that we cannot expand 64-bit items.

scripts/decodetree.py

+38 −11
Original line number Diff line number Diff line
@@ -245,7 +245,7 @@ class ConstField: 




class FunctionField:

    """Class representing a field passed through an expander"""

    """Class representing a field passed through a function"""

    def __init__(self, func, base):

        self.mask = base.mask

        self.sign = base.sign
@@ -266,6 +266,27 @@ class FunctionField: 
# end FunctionField





class ParameterField:

    """Class representing a pseudo-field read from a function"""

    def __init__(self, func):

        self.mask = 0

        self.sign = 0

        self.func = func



    def __str__(self):

        return self.func



    def str_extract(self):

        return self.func + '(ctx)'



    def __eq__(self, other):

        return self.func == other.func



    def __ne__(self, other):

        return not self.__eq__(other)

# end ParameterField





class Arguments:

    """Class representing the extracted fields of a format"""

    def __init__(self, nm, flds, extern):
@@ -433,6 +454,12 @@ def parse_field(lineno, name, toks): 


    if width > insnwidth:

        error(lineno, 'field too large')

    if len(subs) == 0:

        if func:

            f = ParameterField(func)

        else:

            error(lineno, 'field with no value')

    else:

        if len(subs) == 1:

            f = subs[0]

        else:

tests/decode/err_field6.decode

0 → 100644
+5 −0
Original line number Diff line number Diff line 
# This work is licensed under the terms of the GNU LGPL, version 2 or later.

# See the COPYING.LIB file in the top-level directory.



# Diagnose no bits in field

%field

tests/decode/succ_function.decode

0 → 100644
+6 −0
Original line number Diff line number Diff line 
# This work is licensed under the terms of the GNU LGPL, version 2 or later.

# See the COPYING.LIB file in the top-level directory.



# "Field" as parameter pulled from DisasContext.

%foo  !function=foo

foo   00000000000000000000000000000000 %foo