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194 lines
9.1 KiB
C
194 lines
9.1 KiB
C
/*****************************************************************************
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* FullFAT - High Performance, Thread-Safe Embedded FAT File-System *
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* Copyright (C) 2009 James Walmsley (james@worm.me.uk) *
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* *
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* This program is free software: you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation, either version 3 of the License, or *
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* (at your option) any later version. *
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* *
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* This program is distributed in the hope that it will be useful, *
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* but WITHOUT ANY WARRANTY; without even the implied warranty of *
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
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* GNU General Public License for more details. *
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* *
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* You should have received a copy of the GNU General Public License *
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* along with this program. If not, see <http://www.gnu.org/licenses/>. *
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* *
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* IMPORTANT NOTICE: *
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* ================= *
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* Alternative Licensing is available directly from the Copyright holder, *
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* (James Walmsley). For more information consult LICENSING.TXT to obtain *
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* a Commercial license. *
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* *
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* See RESTRICTIONS.TXT for extra restrictions on the use of FullFAT. *
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* *
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* Removing the above notice is illegal and will invalidate this license. *
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*****************************************************************************
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* See http://worm.me.uk/fullfat for more information. *
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* Or http://fullfat.googlecode.com/ for latest releases and the wiki. *
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*****************************************************************************/
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/**
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* @file ff_crc.c
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* @author James Walmsley
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* @ingroup CRC
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*
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* @defgroup CRC CRC Checksums for Strings
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* @brief Provides fast hashing functions.
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*
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**/
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#include "ff_crc.h"
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static const FF_T_UINT8 CRC16_Low[256] =
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{
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0x000, 0x0c1, 0x081, 0x040, 0x001, 0x0c0, 0x080, 0x041,
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0x001, 0x0c0, 0x080, 0x041, 0x000, 0x0c1, 0x081, 0x040,
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0x001, 0x0c0, 0x080, 0x041, 0x000, 0x0c1, 0x081, 0x040,
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0x000, 0x0c1, 0x081, 0x040, 0x001, 0x0c0, 0x080, 0x041,
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0x001, 0x0c0, 0x080, 0x041, 0x000, 0x0c1, 0x081, 0x040,
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0x000, 0x0c1, 0x081, 0x040, 0x001, 0x0c0, 0x080, 0x041,
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0x000, 0x0c1, 0x081, 0x040, 0x001, 0x0c0, 0x080, 0x041,
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0x001, 0x0c0, 0x080, 0x041, 0x000, 0x0c1, 0x081, 0x040,
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0x001, 0x0c0, 0x080, 0x041, 0x000, 0x0c1, 0x081, 0x040,
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0x000, 0x0c1, 0x081, 0x040, 0x001, 0x0c0, 0x080, 0x041,
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0x000, 0x0c1, 0x081, 0x040, 0x001, 0x0c0, 0x080, 0x041,
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0x001, 0x0c0, 0x080, 0x041, 0x000, 0x0c1, 0x081, 0x040,
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0x000, 0x0c1, 0x081, 0x040, 0x001, 0x0c0, 0x080, 0x041,
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0x001, 0x0c0, 0x080, 0x041, 0x000, 0x0c1, 0x081, 0x040,
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0x001, 0x0c0, 0x080, 0x041, 0x000, 0x0c1, 0x081, 0x040,
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0x000, 0x0c1, 0x081, 0x040, 0x001, 0x0c0, 0x080, 0x041,
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0x001, 0x0c0, 0x080, 0x041, 0x000, 0x0c1, 0x081, 0x040,
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0x000, 0x0c1, 0x081, 0x040, 0x001, 0x0c0, 0x080, 0x041,
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0x000, 0x0c1, 0x081, 0x040, 0x001, 0x0c0, 0x080, 0x041,
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0x001, 0x0c0, 0x080, 0x041, 0x000, 0x0c1, 0x081, 0x040,
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0x000, 0x0c1, 0x081, 0x040, 0x001, 0x0c0, 0x080, 0x041,
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0x001, 0x0c0, 0x080, 0x041, 0x000, 0x0c1, 0x081, 0x040,
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0x001, 0x0c0, 0x080, 0x041, 0x000, 0x0c1, 0x081, 0x040,
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0x000, 0x0c1, 0x081, 0x040, 0x001, 0x0c0, 0x080, 0x041,
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0x000, 0x0c1, 0x081, 0x040, 0x001, 0x0c0, 0x080, 0x041,
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0x001, 0x0c0, 0x080, 0x041, 0x000, 0x0c1, 0x081, 0x040,
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0x001, 0x0c0, 0x080, 0x041, 0x000, 0x0c1, 0x081, 0x040,
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0x000, 0x0c1, 0x081, 0x040, 0x001, 0x0c0, 0x080, 0x041,
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0x001, 0x0c0, 0x080, 0x041, 0x000, 0x0c1, 0x081, 0x040,
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0x000, 0x0c1, 0x081, 0x040, 0x001, 0x0c0, 0x080, 0x041,
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0x000, 0x0c1, 0x081, 0x040, 0x001, 0x0c0, 0x080, 0x041,
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0x001, 0x0c0, 0x080, 0x041, 0x000, 0x0c1, 0x081, 0x040,
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};
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static const FF_T_UINT8 CRC16_High[256] =
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{
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0x000, 0x0c0, 0x0c1, 0x001, 0x0c3, 0x003, 0x002, 0x0c2,
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0x0c6, 0x006, 0x007, 0x0c7, 0x005, 0x0c5, 0x0c4, 0x004,
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0x0cc, 0x00c, 0x00d, 0x0cd, 0x00f, 0x0cf, 0x0ce, 0x00e,
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0x00a, 0x0ca, 0x0cb, 0x00b, 0x0c9, 0x009, 0x008, 0x0c8,
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0x0d8, 0x018, 0x019, 0x0d9, 0x01b, 0x0db, 0x0da, 0x01a,
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0x01e, 0x0de, 0x0df, 0x01f, 0x0dd, 0x01d, 0x01c, 0x0dc,
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0x014, 0x0d4, 0x0d5, 0x015, 0x0d7, 0x017, 0x016, 0x0d6,
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0x0d2, 0x012, 0x013, 0x0d3, 0x011, 0x0d1, 0x0d0, 0x010,
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0x0f0, 0x030, 0x031, 0x0f1, 0x033, 0x0f3, 0x0f2, 0x032,
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0x036, 0x0f6, 0x0f7, 0x037, 0x0f5, 0x035, 0x034, 0x0f4,
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0x03c, 0x0fc, 0x0fd, 0x03d, 0x0ff, 0x03f, 0x03e, 0x0fe,
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0x0fa, 0x03a, 0x03b, 0x0fb, 0x039, 0x0f9, 0x0f8, 0x038,
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0x028, 0x0e8, 0x0e9, 0x029, 0x0eb, 0x02b, 0x02a, 0x0ea,
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0x0ee, 0x02e, 0x02f, 0x0ef, 0x02d, 0x0ed, 0x0ec, 0x02c,
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0x0e4, 0x024, 0x025, 0x0e5, 0x027, 0x0e7, 0x0e6, 0x026,
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0x022, 0x0e2, 0x0e3, 0x023, 0x0e1, 0x021, 0x020, 0x0e0,
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0x0a0, 0x060, 0x061, 0x0a1, 0x063, 0x0a3, 0x0a2, 0x062,
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0x066, 0x0a6, 0x0a7, 0x067, 0x0a5, 0x065, 0x064, 0x0a4,
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0x06c, 0x0ac, 0x0ad, 0x06d, 0x0af, 0x06f, 0x06e, 0x0ae,
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0x0aa, 0x06a, 0x06b, 0x0ab, 0x069, 0x0a9, 0x0a8, 0x068,
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0x078, 0x0b8, 0x0b9, 0x079, 0x0bb, 0x07b, 0x07a, 0x0ba,
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0x0be, 0x07e, 0x07f, 0x0bf, 0x07d, 0x0bd, 0x0bc, 0x07c,
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0x0b4, 0x074, 0x075, 0x0b5, 0x077, 0x0b7, 0x0b6, 0x076,
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0x072, 0x0b2, 0x0b3, 0x073, 0x0b1, 0x071, 0x070, 0x0b0,
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0x050, 0x090, 0x091, 0x051, 0x093, 0x053, 0x052, 0x092,
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0x096, 0x056, 0x057, 0x097, 0x055, 0x095, 0x094, 0x054,
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0x09c, 0x05c, 0x05d, 0x09d, 0x05f, 0x09f, 0x09e, 0x05e,
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0x05a, 0x09a, 0x09b, 0x05b, 0x099, 0x059, 0x058, 0x098,
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0x088, 0x048, 0x049, 0x089, 0x04b, 0x08b, 0x08a, 0x04a,
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0x04e, 0x08e, 0x08f, 0x04f, 0x08d, 0x04d, 0x04c, 0x08c,
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0x044, 0x084, 0x085, 0x045, 0x087, 0x047, 0x046, 0x086,
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0x082, 0x042, 0x043, 0x083, 0x041, 0x081, 0x080, 0x040,
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};
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/*****************************************************************************
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* Description: Function to 16 bit CRC check a block of memory
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*
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* Parameters: pbyData - Pointer to the source data
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* stLength - The length to CRC
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*
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* Return value: The 16 bit CRC value
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*
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*****************************************************************************/
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FF_T_UINT16 FF_GetCRC16(FF_T_UINT8 *pbyData, FF_T_UINT32 stLength) {
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FF_T_UINT8 bTableValue;
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FF_T_UINT16 wCRC = 0;
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while (stLength--) {
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bTableValue = (FF_T_UINT8)((wCRC & 0x00FF) ^ *pbyData++);
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wCRC = (FF_T_UINT16)(((CRC16_High[bTableValue]) << 8)
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+ (CRC16_Low[bTableValue] ^ ((wCRC >> 8) & 0x00FF)));
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}
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return wCRC;
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}
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static const FF_T_UINT8 byCRCLookUpTable[256] =
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{
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0, 94, 188, 226, 97, 63, 221, 131,
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194, 156, 126, 32, 163, 253, 31, 65,
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157, 195, 33, 127, 252, 162, 64, 30,
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95, 1, 227, 189, 62, 96, 130, 220,
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35, 125, 159, 193, 66, 28, 254, 160,
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225, 191, 93, 3, 128, 222, 60, 98,
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190, 224, 2, 92, 223, 129, 99, 61,
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124, 34, 192, 158, 29, 67, 161, 255,
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70, 24, 250, 164, 39, 121, 155, 197,
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132, 218, 56, 102, 229, 187, 89, 7,
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219, 133, 103, 57, 186, 228, 6, 88,
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25, 71, 165, 251, 120, 38, 196, 154,
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101, 59, 217, 135, 4, 90, 184, 230,
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167, 249, 27, 69, 198, 152, 122, 36,
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248, 166, 68, 26, 153, 199, 37, 123,
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58, 100, 134, 216, 91, 5, 231, 185,
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140, 210, 48, 110, 237, 179, 81, 15,
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78, 16, 242, 172, 47, 113, 147, 205,
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17, 79, 173, 243, 112, 46, 204, 146,
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211, 141, 111, 49, 178, 236, 14, 80,
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175, 241, 19, 77, 206, 144, 114, 44,
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109, 51, 209, 143, 12, 82, 176, 238,
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50, 108, 142, 208, 83, 13, 239, 177,
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240, 174, 76, 18, 145, 207, 45, 115,
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202, 148, 118, 40, 171, 245, 23, 73,
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8, 86, 180, 234, 105, 55, 213, 139,
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87, 9, 235, 181, 54, 104, 138, 212,
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149, 203, 41, 119, 244, 170, 72, 22,
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233, 183, 85, 11, 136, 214, 52, 106,
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43, 117, 151, 201, 74, 20, 246, 168,
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116, 42, 200, 150, 21, 75, 169, 247,
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182, 232, 10, 84, 215, 137, 107, 53
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};
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/*****************************************************************************
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* Description: Function to CRC check a block of memory
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*
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* Parameters: pbyData - Pointer to the source data
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* stLength - The length to CRC
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*
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* Return value: The 8 bit CRC value
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*
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*****************************************************************************/
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FF_T_UINT8 FF_GetCRC8(FF_T_UINT8 *pbyData, FF_T_UINT32 stLength) {
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FF_T_UINT8 byCRC = 0, byData;
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while (stLength--) {
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byData = *pbyData++;
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byCRC = byCRCLookUpTable[(byCRC ^ byData)];
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}
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return byCRC;
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}
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