105 lines
2.5 KiB
C++
105 lines
2.5 KiB
C++
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/*
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** Command & Conquer Red Alert(tm)
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** Copyright 2025 Electronic Arts Inc.
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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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/****************************************************************************
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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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*
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* FILE
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* testvb.c
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*
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* DESCRIPTION
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* Video mode setting. (32-Bit protected mode)
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*
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* PROGRAMMER
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* Denzil E. Long, Jr.
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*
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* DATE
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* Febuary 3, 1995
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*
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*----------------------------------------------------------------------------
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*
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* PUBLIC
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* TestVBIBit - Test the polarity of the vertical blank bit.
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*
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****************************************************************************/
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#include <sys\timeb.h>
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#ifdef __BORLANDC__
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#include "portio.h"
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#else
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#include <conio.h>
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#endif
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/****************************************************************************
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*
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* NAME
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* TestVBIBit - Test the polarity of the vertical blank bit.
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*
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* SYNOPSIS
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* Polarity = TestVBIBit()
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*
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* long TestVBIBit(void);
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*
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* FUNCTION
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*
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* INPUTS
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* NONE
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*
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* RESULT
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* Polarity - Polarity of the vertical blank bit.
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*
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****************************************************************************/
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long TestVBIBit(void)
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{
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static struct timeb mytime;
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long curtime;
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long endtime;
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unsigned long high = 0;
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unsigned long low = 0;
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/* Set the check time for .25 (1/4) of a second. */
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ftime(&mytime);
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curtime = ((mytime.time * 1000) + mytime.millitm);
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endtime = (curtime + (1000 / 4));
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/* Sample the vertical blank bit for the specified period of time.
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* The state in which it is in the least is the vertical blank state,
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* the state in which it is in the most is the active scan state.
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*/
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while (endtime >= curtime) {
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ftime(&mytime);
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curtime = ((mytime.time * 1000) + mytime.millitm);
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if (inp(0x3DA) & 0x08) {
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high++;
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} else {
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low++;
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}
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}
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return (high > low);
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}
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