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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>
29 lines
600 B
C
29 lines
600 B
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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#include "common.h"
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#include "crc8.h"
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inline uint8_t crc8(const uint8_t *data, int len)
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{
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return crc8_arg(data, len, 0);
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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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{
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unsigned crc = previous_crc << 8;
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int i, j;
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for (j = len; j; j--, data++) {
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crc ^= (*data << 8);
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for (i = 8; i; i--) {
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if (crc & 0x8000)
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crc ^= (0x1070 << 3);
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crc <<= 1;
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}
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}
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return (uint8_t)(crc >> 8);
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}
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