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46 lines
1.2 KiB
46 lines
1.2 KiB
// $Header: G:/SwDev/WDM/Video/bt848/rcs/Compreg.cpp 1.3 1998/04/29 22:43:31 tomz Exp $
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#include "compreg.h"
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/* Method: CompositeReg::operator DWORD()
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* Purpose: Performs the read from a composite register
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*/
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CompositeReg::operator DWORD()
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{
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// if write-only return the shadow
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if ( GetRegisterType() == WO )
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return GetShadow();
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// obtain the low and high values
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DWORD dwLowBits = (DWORD)LSBPart_;
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DWORD dwHighBits = (DWORD)MSBPart_;
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// put high part to the proper place
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dwHighBits <<= LowPartWidth_;
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// done !
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return dwHighBits | dwLowBits;
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}
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/* Method: CompositeReg::operator=
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* Purpose: performs the assignment to a composite register
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*/
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DWORD CompositeReg::operator=( DWORD dwValue )
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{
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// if a register is read-only nothing is done. This is an error
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if ( GetRegisterType() == RO )
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return ReturnAllFs();
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// keep a shadow around
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SetShadow( dwValue );
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// compute the mask to apply to the passed value, so it can be...
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DWORD dwMask = ::MakeAMask( LowPartWidth_ );
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// ... assigned to the low portion register
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LSBPart_ = dwValue & dwMask;
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// shift is enough to get the high part
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MSBPart_ = ( dwValue >> LowPartWidth_ );
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return dwValue;
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}
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