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407 lines
12 KiB
407 lines
12 KiB
/*==========================================================================
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*
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* Copyright (C) 1996-2000 Microsoft Corporation. All Rights Reserved.
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*
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* File: CRC.cpp
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* Content: CRC Routines for COM port I/O
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*@@BEGIN_MSINTERNAL
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* History:
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* Date By Reason
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* ==== == ======
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* 12/18/98 johnkan Copied from DPlay 6.x and fixed up
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*@@END_MSINTERNAL
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***************************************************************************/
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#include "dnmdmi.h"
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//**********************************************************************
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// Constant definitions
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//**********************************************************************
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// uncomment the following to validate CRC table each time a CRC function is called
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//#define VALIDATE_CRC_TABLE
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// defines for 32-bit CRC
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///*
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// Name : "CRC-32"
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// Width : 32
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// Poly : 04C11DB7
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// Init : FFFFFFFF
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// RefIn : True
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// RefOut : True
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// XorOut : FFFFFFFF
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// Check : CBF43926
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//
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// This is supposedly what Ethernet uses
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//*/
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//
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//#define WIDTH 32
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//#define POLY 0x04C11DB7
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//#define INITVALUE 0xFFFFFFFF
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//#define REFIN TRUE
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//#define XOROUT 0xFFFFFFFF
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//#define CHECK 0xCBF43926
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//#define WIDMASK 0xFFFFFFFF // value is (2^WIDTH)-1
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/*
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Name : "CRC-16"
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Width : 16
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Poly : 8005
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Init : 0000
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RefIn : True
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RefOut : True
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XorOut : 0000
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Check : BB3D
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*/
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#define WIDTH 16
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#define POLY 0x8005
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#define INITVALUE 0
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#define REFIN TRUE
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#define XOROUT 0
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#define CHECK 0xBB3D
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#define WIDMASK 0x0000FFFF // value is (2^WIDTH)-1
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//**********************************************************************
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// Macro definitions
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//**********************************************************************
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#define BITMASK(X) (1L << (X))
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//**********************************************************************
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// Structure definitions
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//**********************************************************************
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//**********************************************************************
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// Variable definitions
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//**********************************************************************
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// precomputed CRC table values from GenerateCRC()
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static DWORD g_CRCTable[ 256 ] =
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{
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0x0, 0xc0c1, 0xc181, 0x140, 0xc301, 0x3c0, 0x280, 0xc241,
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0xc601, 0x6c0, 0x780, 0xc741, 0x500, 0xc5c1, 0xc481, 0x440,
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0xcc01, 0xcc0, 0xd80, 0xcd41, 0xf00, 0xcfc1, 0xce81, 0xe40,
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0xa00, 0xcac1, 0xcb81, 0xb40, 0xc901, 0x9c0, 0x880, 0xc841,
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0xd801, 0x18c0, 0x1980, 0xd941, 0x1b00, 0xdbc1, 0xda81, 0x1a40,
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0x1e00, 0xdec1, 0xdf81, 0x1f40, 0xdd01, 0x1dc0, 0x1c80, 0xdc41,
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0x1400, 0xd4c1, 0xd581, 0x1540, 0xd701, 0x17c0, 0x1680, 0xd641,
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0xd201, 0x12c0, 0x1380, 0xd341, 0x1100, 0xd1c1, 0xd081, 0x1040,
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0xf001, 0x30c0, 0x3180, 0xf141, 0x3300, 0xf3c1, 0xf281, 0x3240,
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0x3600, 0xf6c1, 0xf781, 0x3740, 0xf501, 0x35c0, 0x3480, 0xf441,
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0x3c00, 0xfcc1, 0xfd81, 0x3d40, 0xff01, 0x3fc0, 0x3e80, 0xfe41,
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0xfa01, 0x3ac0, 0x3b80, 0xfb41, 0x3900, 0xf9c1, 0xf881, 0x3840,
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0x2800, 0xe8c1, 0xe981, 0x2940, 0xeb01, 0x2bc0, 0x2a80, 0xea41,
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0xee01, 0x2ec0, 0x2f80, 0xef41, 0x2d00, 0xedc1, 0xec81, 0x2c40,
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0xe401, 0x24c0, 0x2580, 0xe541, 0x2700, 0xe7c1, 0xe681, 0x2640,
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0x2200, 0xe2c1, 0xe381, 0x2340, 0xe101, 0x21c0, 0x2080, 0xe041,
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0xa001, 0x60c0, 0x6180, 0xa141, 0x6300, 0xa3c1, 0xa281, 0x6240,
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0x6600, 0xa6c1, 0xa781, 0x6740, 0xa501, 0x65c0, 0x6480, 0xa441,
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0x6c00, 0xacc1, 0xad81, 0x6d40, 0xaf01, 0x6fc0, 0x6e80, 0xae41,
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0xaa01, 0x6ac0, 0x6b80, 0xab41, 0x6900, 0xa9c1, 0xa881, 0x6840,
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0x7800, 0xb8c1, 0xb981, 0x7940, 0xbb01, 0x7bc0, 0x7a80, 0xba41,
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0xbe01, 0x7ec0, 0x7f80, 0xbf41, 0x7d00, 0xbdc1, 0xbc81, 0x7c40,
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0xb401, 0x74c0, 0x7580, 0xb541, 0x7700, 0xb7c1, 0xb681, 0x7640,
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0x7200, 0xb2c1, 0xb381, 0x7340, 0xb101, 0x71c0, 0x7080, 0xb041,
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0x5000, 0x90c1, 0x9181, 0x5140, 0x9301, 0x53c0, 0x5280, 0x9241,
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0x9601, 0x56c0, 0x5780, 0x9741, 0x5500, 0x95c1, 0x9481, 0x5440,
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0x9c01, 0x5cc0, 0x5d80, 0x9d41, 0x5f00, 0x9fc1, 0x9e81, 0x5e40,
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0x5a00, 0x9ac1, 0x9b81, 0x5b40, 0x9901, 0x59c0, 0x5880, 0x9841,
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0x8801, 0x48c0, 0x4980, 0x8941, 0x4b00, 0x8bc1, 0x8a81, 0x4a40,
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0x4e00, 0x8ec1, 0x8f81, 0x4f40, 0x8d01, 0x4dc0, 0x4c80, 0x8c41,
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0x4400, 0x84c1, 0x8581, 0x4540, 0x8701, 0x47c0, 0x4680, 0x8641,
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0x8201, 0x42c0, 0x4380, 0x8341, 0x4100, 0x81c1, 0x8081, 0x4040
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};
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// since the talbe is static, no reason for this variable
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//static BOOL g_fTableCreated = FALSE;
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//**********************************************************************
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// Function prototypes
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//**********************************************************************
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static DWORD crc_reflected( LPBYTE blk_adr, DWORD blk_len, const DWORD *crctable );
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#ifdef DBG
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static DWORD reflect( DWORD v, int b );
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static DWORD cm_tab( int index );
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#endif // DBG
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//**********************************************************************
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// Function definitions
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//**********************************************************************
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////**********************************************************************
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//// ------------------------------
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//// crc_normal - generate a normal CRC
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////
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//// Entry: Pointer to input data block
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//// Size of data block
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//// Pointer to CRC table
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////
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//// Exit: 32-bit CRC
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//// ------------------------------
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//static DWORD crc_normal( LPBYTE blk_adr, DWORD blk_len, DWORD crctable[] )
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//{
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// DWORD crc = INITVALUE;
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//
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// while (blk_len--)
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// crc = crctable[((crc>>24) ^ *blk_adr++) & 0xFFL] ^ (crc << 8);
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//
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// return (crc ^ XOROUT);
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//}
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////**********************************************************************
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//**********************************************************************
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// ------------------------------
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// crc_reflected - generate a reflected CRC
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//
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// Entry: Pointer to input data block
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// Size of data block
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// Pointer to CRC table
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//
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// Exit: 32-bit CRC
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// ------------------------------
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static DWORD crc_reflected( BYTE *blk_adr, DWORD blk_len, const DWORD *crctable )
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{
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DWORD crc = INITVALUE;
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DEBUG_ONLY( DWORD dwOffset = 0 );
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// DPFX(DPFPREP, 9, "Enter crc_reflected" );
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while (blk_len--)
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{
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crc = crctable[(crc ^ *blk_adr) & 0xFFL] ^ (crc >> 8);
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// DPFX(DPFPREP, 8, "TempCRC: 0x%x\tOffset: %d\tChar 0x%x", crc, dwOffset, *blk_adr );
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blk_adr++;
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DEBUG_ONLY( dwOffset++ );
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}
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crc ^= XOROUT;
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// DPFX(DPFPREP, 8, "Computed CRC: 0x%x", crc );
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// DPFX(DPFPREP, 9, "Leave crc_reflected" );
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return crc;
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}
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//**********************************************************************
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////**********************************************************************
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//// ------------------------------
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//// GenerateCRCTable - create CRC table
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////
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//// Entry: Nothing
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////
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//// Exit: Nothing
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//// ------------------------------
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//void GenerateCRCTable( void )
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//{
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// DWORD i;
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//
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//
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// // had the table been built?
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// if ( g_fTableCreated == FALSE )
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// {
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// for (i = 0; i < 256; i++)
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// {
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// g_CRCTable[i] = cm_tab(i);
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// }
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//
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// // note that the table has been built
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// g_fTableCreated = TRUE;
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// }
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//
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// // code to pregenerate CRC table
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// DPFX(DPFPREP, 0, "\nHexDump:\n" );
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// for( i = 0; i < 256; i+=8 )
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// {
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// DPFX(DPFPREP, 3, "0x%x, 0x%x, 0x%x, 0x%x, 0x%x, 0x%x, 0x%x, 0x%x,", g_CRCTable[ i ],
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// g_CRCTable[ i + 1 ],
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// g_CRCTable[ i + 2 ],
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// g_CRCTable[ i + 3 ],
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// g_CRCTable[ i + 4 ],
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// g_CRCTable[ i + 5 ],
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// g_CRCTable[ i + 6 ],
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// g_CRCTable[ i + 7 ] );
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//
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// }
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//}
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////**********************************************************************
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//**********************************************************************
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// ------------------------------
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// GenerateCRC - generate a CRC
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//
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// Entry: Pointer to data
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// Size of data
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//
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// Exit: CRC
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// ------------------------------
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DWORD GenerateCRC( const BYTE *const pBuffer, const DWORD dwBufferSize )
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{
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// DNASSERT( g_fTableCreated != FALSE );
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#ifdef VALIDATE_CRC_TABLE
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ValidateCRCTable();
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#endif // VALIDATE_CRC_TABLE
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return ( crc_reflected( const_cast<BYTE*>( pBuffer ), dwBufferSize, g_CRCTable ) );
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}
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//**********************************************************************
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//**********************************************************************
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// ------------------------------
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// GenerateMultiBufferCRC - generate a CRC from multiple buffers
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//
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// Entry: Pointer to buffer descriptions
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// Count of buffers
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//
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// Exit: CRC
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// ------------------------------
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#undef DPF_MODNAME
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#define DPF_MODNAME "GenerateMultiBufferCRC"
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DWORD GenerateMultiBufferCRC( const BUFFERDESC *const pBuffer, const DWORD dwBufferCount )
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{
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DWORD TempCRC;
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// DWORD crc = INITVALUE;
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DWORD Count;
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// DNASSERT( g_fTableCreated != FALSE );
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// DPFX(DPFPREP, 9, "Entering GenerateMultiBufferCRC" );
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// initialize
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TempCRC = INITVALUE;
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// generate CRC
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for ( Count = 0; Count < dwBufferCount; Count++ )
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{
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LPBYTE pWorkingByte;
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DWORD dwBufferSize;
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// initialize
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dwBufferSize = pBuffer[ Count ].dwBufferSize;
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pWorkingByte = static_cast<BYTE*>( pBuffer[ Count ].pBufferData );
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// CRC this block
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while ( dwBufferSize > 0 )
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{
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TempCRC = g_CRCTable[ ( TempCRC ^ (*pWorkingByte) ) & 0xFFL ] ^ ( TempCRC >> 8 );
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// DPFX(DPFPREP, 8, "TempCRC: 0x%x\tOffset: %d\tChar: 0x%x",
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// TempCRC,
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// ( pWorkingByte - static_cast<BYTE*>( pBuffer[ Count ].lpBufferData ) ),
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// *pWorkingByte
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// );
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pWorkingByte++;
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dwBufferSize--;
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}
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}
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TempCRC ^= XOROUT;
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// DPFX(DPFPREP, 8, "Computed CRC: 0x%x", TempCRC );
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// DPFX(DPFPREP, 9, "Leaving GenerateMultiBufferCRC" );
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return TempCRC;
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}
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//**********************************************************************
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#ifdef DBG
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//**********************************************************************
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// ------------------------------
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// reflect - reflect the bottom N bits of a DWORD
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//
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// Entry: Input DWORD
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// Number of bits to reflect
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//
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// Exit: Reflected value
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//
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// Returns the value v with the bottom b [0,32] bits reflected.
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// Example: reflect(0x3e23L,3) == 0x3e26
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// -----------------------------
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static DWORD reflect( DWORD v, int b )
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{
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int i;
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DWORD t = v;
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for (i = 0; i < b; i++)
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{
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if (t & 1L)
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v |= BITMASK((b-1)-i);
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else
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v &= ~BITMASK((b-1)-i);
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t >>= 1;
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}
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return v;
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}
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//**********************************************************************
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//**********************************************************************
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// ------------------------------
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// cm_tab - do something
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//
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// Entry: Index
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//
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// Exit: DWORD
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// ------------------------------
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static DWORD cm_tab( int index )
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{
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int i;
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DWORD r;
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DWORD topbit = (DWORD) BITMASK(WIDTH-1);
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DWORD inbyte = (DWORD) index;
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if (REFIN)
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inbyte = reflect(inbyte, 8);
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r = inbyte << (WIDTH-8);
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for (i = 0; i < 8; i++)
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{
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if (r & topbit)
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r = (r << 1) ^ POLY;
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else
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r <<= 1;
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}
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if (REFIN)
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r = reflect(r, WIDTH);
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return (r & WIDMASK);
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}
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//**********************************************************************
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//**********************************************************************
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// ------------------------------
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// ValidateCRCTable - validate that the CRC table is correct
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//
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// Entry: Nothing
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// Nothing
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//
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// Exit: Nothing
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// ------------------------------
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#undef DPF_MODNAME
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#define DPF_MODNAME "ValidateCRCTable"
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void ValidateCRCTable( void )
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{
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DWORD i;
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for (i = 0; i < LENGTHOF( g_CRCTable ); i++)
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{
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DNASSERT( g_CRCTable[ i ] == cm_tab(i) );
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}
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}
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//**********************************************************************
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#endif // DBG
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