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https://github.com/projectacrn/acrn-hypervisor.git
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ba02583f2d
This patch ports the ACPI parsing module from BITS (BIOS Implementation Test Suite) in order to ease the access to ACPI tables during board XML generation. This library allows accessing ACPI table fields as Python class members, getting rid of hard coding or calculating offsets within tables. Compared to the original library, this port makes the following changes. * Extract only the scripts and functions that contribute to ACPI parsing. * Separate the parser of each ACPI table into different files. * Read raw ACPI tables from Linux sysfs. * Adapt to Python 3. Tracked-On: #5649 Signed-off-by: Junjie Mao <junjie.mao@intel.com>
70 lines
3.1 KiB
Python
70 lines
3.1 KiB
Python
# Copyright (c) 2015, Intel Corporation
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are met:
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#
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# * Redistributions of source code must retain the above copyright notice,
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# this list of conditions and the following disclaimer.
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# * Redistributions in binary form must reproduce the above copyright notice,
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# this list of conditions and the following disclaimer in the documentation
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# and/or other materials provided with the distribution.
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# * Neither the name of Intel Corporation nor the names of its contributors
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# may be used to endorse or promote products derived from this software
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# without specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
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# ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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# ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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"""Helper functions to work with bitfields.
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Documentation frequently writes bitfields as the inclusive range [msb:lsb];
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this module provides functions to work with bitfields using msb and lsb rather
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than manually computing shifts and masks from those."""
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def bitfield_max(msb, lsb=None):
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"""Return the largest value that fits in the bitfield [msb:lsb] (or [msb] if lsb is None)"""
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if lsb is None:
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lsb = msb
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return (1 << (msb - lsb + 1)) - 1
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def bitmask(msb, lsb=None):
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"""Creates a mask with bits [msb:lsb] (or [msb] if lsb is None) set."""
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if lsb is None:
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lsb = msb
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return bitfield_max(msb, lsb) << lsb
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def bitfield(value, msb, lsb=None):
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"""Shift value to fit in the bitfield [msb:lsb] (or [msb] if lsb is None).
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Raise OverflowError if value does not fit in that bitfield."""
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if lsb is None:
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lsb = msb
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if value > bitfield_max(msb, lsb):
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if msb == lsb:
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field = "[{0}]".format(msb)
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else:
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field = "[{0}:{1}]".format(msb, lsb)
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raise OverflowError("Value {value:#x} too big for bitfield {field}".format(**locals()))
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return value << lsb
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def getbits(value, msb, lsb=None):
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"""From the specified value, extract the bitfield [msb:lsb] (or [msb] if lsb is None)"""
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if lsb is None:
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lsb = msb
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return (value >> lsb) & bitfield_max(msb, lsb)
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def setbits(value, fieldvalue, msb, lsb=None):
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"""In the specified value, set the bitfield [msb:lsb] (or [msb] if lsb is None) to fieldvalue"""
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value &= ~bitmask(msb, lsb)
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value |= bitfield(fieldvalue, msb, lsb)
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return value
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