From: Richard Henderson <richard.henderson@linaro.org>
To: qemu-devel@nongnu.org
Cc: peter.maydell@linaro.org
Subject: [Qemu-devel] [PATCH v2 1/3] decodetree: Allow !function with no input bits
Date: Sun, 18 Aug 2019 07:39:57 +0100 [thread overview]
Message-ID: <20190818063959.14533-2-richard.henderson@linaro.org> (raw)
In-Reply-To: <20190818063959.14533-1-richard.henderson@linaro.org>
Call this form a "parameter", returning a value extracted
from the DisasContext.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
docs/devel/decodetree.rst | 8 ++++-
scripts/decodetree.py | 49 ++++++++++++++++++++++++-------
tests/decode/err_field6.decode | 5 ++++
tests/decode/succ_function.decode | 6 ++++
4 files changed, 56 insertions(+), 12 deletions(-)
create mode 100644 tests/decode/err_field6.decode
create mode 100644 tests/decode/succ_function.decode
diff --git a/docs/devel/decodetree.rst b/docs/devel/decodetree.rst
index 44ac621ea8..ce7f52308f 100644
--- a/docs/devel/decodetree.rst
+++ b/docs/devel/decodetree.rst
@@ -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.
diff --git a/scripts/decodetree.py b/scripts/decodetree.py
index d7a59d63ac..31e2f04ecb 100755
--- a/scripts/decodetree.py
+++ b/scripts/decodetree.py
@@ -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 FunctionField
+
+
class Arguments:
"""Class representing the extracted fields of a format"""
def __init__(self, nm, flds, extern):
@@ -433,17 +454,23 @@ def parse_field(lineno, name, toks):
if width > insnwidth:
error(lineno, 'field too large')
- if len(subs) == 1:
- f = subs[0]
+ if len(subs) == 0:
+ if func:
+ f = ParameterField(func)
+ else:
+ error(lineno, 'field with no value')
else:
- mask = 0
- for s in subs:
- if mask & s.mask:
- error(lineno, 'field components overlap')
- mask |= s.mask
- f = MultiField(subs, mask)
- if func:
- f = FunctionField(func, f)
+ if len(subs) == 1:
+ f = subs[0]
+ else:
+ mask = 0
+ for s in subs:
+ if mask & s.mask:
+ error(lineno, 'field components overlap')
+ mask |= s.mask
+ f = MultiField(subs, mask)
+ if func:
+ f = FunctionField(func, f)
if name in fields:
error(lineno, 'duplicate field', name)
diff --git a/tests/decode/err_field6.decode b/tests/decode/err_field6.decode
new file mode 100644
index 0000000000..a719884572
--- /dev/null
+++ b/tests/decode/err_field6.decode
@@ -0,0 +1,5 @@
+# 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
diff --git a/tests/decode/succ_function.decode b/tests/decode/succ_function.decode
new file mode 100644
index 0000000000..7751b1784e
--- /dev/null
+++ b/tests/decode/succ_function.decode
@@ -0,0 +1,6 @@
+# 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
--
2.17.1
next prev parent reply other threads:[~2019-08-18 6:41 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-18 6:39 [Qemu-devel] [PATCH v2 0/3] decodetree improvements Richard Henderson
2019-08-18 6:39 ` Richard Henderson [this message]
2019-08-18 21:49 ` [Qemu-devel] [PATCH v2 1/3] decodetree: Allow !function with no input bits Philippe Mathieu-Daudé
2019-08-18 6:39 ` [Qemu-devel] [PATCH v2 2/3] decodetree: Suppress redundant declaration warnings Richard Henderson
2019-08-18 6:39 ` [Qemu-devel] [PATCH v2 3/3] target/riscv: Remove redundant declaration pragmas Richard Henderson
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