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952b2a54e1
Building a single buffer for crc calculation is often inefficient, so add a new function that calculates crc8 from an existing crc8. BUG=chromium:576911 BRANCH=None TEST=Manual on sentry with subsequent commit. Verify that smbus communication with battery is functional. Change-Id: I05ffedb81ffcf0c126acda5f6212b3147b1580a1 Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/333786 Commit-Ready: Shawn N <shawnn@chromium.org> Tested-by: Shawn N <shawnn@chromium.org> Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
34 lines
1.1 KiB
C
34 lines
1.1 KiB
C
/* Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*
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* Very simple 8-bit CRC function.
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*/
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#ifndef __CROS_EC_CRC8_H
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#define __CROS_EC_CRC8_H
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/**
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* crc8
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* Return CRC-8 of the data, using x^8 + x^2 + x + 1 polynomial. A table-based
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* algorithm would be faster, but for only a few bytes it isn't worth the code
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* size.
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* @param data uint8_t *, input, a pointer to input data
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* @param len int, input, size of input data in bytes
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* @return the crc-8 of the input data.
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*/
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uint8_t crc8(const uint8_t *data, int len);
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/**
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* crc8_arg
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* Return CRC-8 of the data, based upon pre-calculated partial CRC of previous
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* data.
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* @param data uint8_t *, input, a pointer to input data
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* @param len int, input, size of input data in bytes
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* @param previous_crc uint8_t, input, pre-calculated CRC of previous data.
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* Seed with zero for a new calculation (or use the result of crc8()).
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* @return the crc-8 of the input data.
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*/
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uint8_t crc8_arg(const uint8_t *data, int len, uint8_t previous_crc);
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#endif /* __CROS_EC_CRC8_H */
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