mirror of
https://github.com/electronicarts/CnC_Remastered_Collection
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03416d24e1
Initial commit of original Tiberian Dawn and Red Alert source code converted to build as DLLs, and compatible with the release version of Command & Conquer Remastered.
134 lines
7.4 KiB
C++
134 lines
7.4 KiB
C++
//
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// Copyright 2020 Electronic Arts Inc.
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//
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// TiberianDawn.DLL and RedAlert.dll and corresponding source code is free
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// software: you can redistribute it and/or modify it under the terms of
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// the GNU General Public License as published by the Free Software Foundation,
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// either version 3 of the License, or (at your option) any later version.
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// TiberianDawn.DLL and RedAlert.dll and corresponding source code is distributed
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// in the hope that it will be useful, but with permitted additional restrictions
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// under Section 7 of the GPL. See the GNU General Public License in LICENSE.TXT
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// distributed with this program. You should have received a copy of the
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// GNU General Public License along with permitted additional restrictions
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// with this program. If not, see https://github.com/electronicarts/CnC_Remastered_Collection
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/* $Header: /CounterStrike/CRC.CPP 1 3/03/97 10:24a Joe_bostic $ */
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/***********************************************************************************************
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*** C O N F I D E N T I A L --- W E S T W O O D S T U D I O S ***
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***********************************************************************************************
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* *
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* Project Name : Command & Conquer *
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* *
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* File Name : CRC.CPP *
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* *
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* Programmer : Joe L. Bostic *
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* *
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* Start Date : 03/02/96 *
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* *
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* Last Update : March 2, 1996 [JLB] *
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* *
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*---------------------------------------------------------------------------------------------*
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* Functions: *
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* CRCEngine::operator() -- Submits one byte of data to the CRC engine. *
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* CRCEngine::operator() -- Submits an arbitrary data block to the CRC engine. *
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* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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#include "crc.h"
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/***********************************************************************************************
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* CRCEngine::operator() -- Submits one byte of data to the CRC engine. *
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* *
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* This routine will take the specified byte of data and submit it to the CRC engine *
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* for processing. This routine is designed to be as fast as possible since the typical *
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* use of this routine is to feed one of presumably many byte sized chunks of data to the *
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* CRC engine. *
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* *
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* INPUT: datum -- One byte of data to submit to the CRC engine. *
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* *
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* OUTPUT: none *
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* *
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* WARNINGS: If possible, use the buffer/size operator to submit data rather than repeated *
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* calls to this routine. *
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* *
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* HISTORY: *
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* 03/02/1996 JLB : Created. *
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*=============================================================================================*/
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void CRCEngine::operator() (char datum)
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{
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StagingBuffer.Buffer[Index++] = datum;
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if (Index == sizeof(long)) {
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CRC = Value();
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StagingBuffer.Composite = 0;
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Index = 0;
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}
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}
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/***********************************************************************************************
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* CRCEngine::operator() -- Submits an arbitrary data block to the CRC engine. *
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* *
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* This routine will submit the specified block to the CRC engine. The block can be of *
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* arbitrary length. *
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* *
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* INPUT: buffer -- Pointer to the buffer that contains the data. The buffer will not *
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* be modified. *
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* *
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* length -- The length of the buffer (in bytes). *
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* *
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* OUTPUT: Returns with the current CRC value accumulated so far. *
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* *
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* WARNINGS: none *
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* *
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* HISTORY: *
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* 03/02/1996 JLB : Created. *
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*=============================================================================================*/
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long CRCEngine::operator() (void const * buffer, int length)
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{
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if (buffer != NULL && length > 0) {
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char const * dataptr = (char const *)buffer;
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int bytes_left = length;
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/*
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** If there are any leader bytes (needed to fill the staging buffer)
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** then process those by first using them to fill up the staging
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** buffer. The bulk of the data block will be processed by the high
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** speed longword processing loop.
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*/
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while (bytes_left && Buffer_Needs_Data()) {
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operator()(*dataptr);
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dataptr++;
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bytes_left--;
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}
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/*
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** Perform the fast 'bulk' processing by reading long word sized
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** data blocks.
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*/
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long const * longptr = (long const *)dataptr;
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int longcount = bytes_left / sizeof(long); // Whole 'long' elements remaining.
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while (longcount--) {
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CRC = _lrotl(CRC, 1) + *longptr++;
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bytes_left -= sizeof(long);
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}
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/*
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** If there are remainder bytes, then process these by adding them
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** to the staging buffer.
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*/
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dataptr = (char const *)longptr;
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while (bytes_left) {
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operator()(*dataptr);
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dataptr++;
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bytes_left--;
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}
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}
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/*
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** Return the current CRC value.
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*/
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return(Value());
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}
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