140 lines
6.9 KiB
C
140 lines
6.9 KiB
C
/*
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* File......: ONTICK.C
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* Author....: Ted Means
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* CIS ID....: 73067,3332
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*
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* This function is an original work by Ted Means and is placed in the
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* public domain.
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*
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* Modification history:
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* ---------------------
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*
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* Rev 1.0 01 Jan 1995 03:01:00 TED
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* Initial release
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*/
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/* $DOC$
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* $FUNCNAME$
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* FT_OnTick()
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* $CATEGORY$
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* Event
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* $ONELINER$
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* Evaluate a designated code block at a designated interval.
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* $SYNTAX$
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* FT_OnTick( bCode, nInterval )
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* $ARGUMENTS$
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* <bCode> is the code block to evaluate.
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* <nInterval> is the number of clock ticks to wait between
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* evaluations of the code block.
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* $RETURNS$
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* NIL
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* $DESCRIPTION$
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* This function effectively allows you to run tasks in the background
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* by transparently and periodically calling a designated routine.
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*
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* To halt the execution of the background function, call FT_OnTick()
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* with no arguments.
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*
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* This function makes heavy use of several undocumented internal
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* routines. If this fact makes you uncomfortable then don't use
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* this function, you quivering sack of cowardly slime.
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* $EXAMPLES$
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*
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* // Set up a self-updating on-screen clock
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*
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* FT_OnTick( "CLOCK", 9 )
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*
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* procedure Clock
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*
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* local nRow := Row()
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* local nCol := Col()
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*
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* @ 0, 0 say Time()
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*
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* SetPos( nRow, nCol )
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*
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* return
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*
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* $SEEALSO$
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* $END$
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*/
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#include <extend.api>
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#include <item.api>
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#include <cpmi.h>
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typedef union
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{
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long far * Address;
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struct
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{
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unsigned int Offset;
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unsigned int Segment;
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} Pointer;
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} LONGPTR;
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void cdecl _evLow( unsigned int, void *, unsigned int );
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void cdecl _bcopy( void *, void *, unsigned int );
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static long far Ticks = 0;
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static long far Interval = 1;
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static ITEM far codeBlock;
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static char inProgress = 0;
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static void cdecl TickTock( void )
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{
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auto unsigned int ProtMode = cpmiIsProtected();
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auto LONGPTR Timer;
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auto EVALINFO eval;
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if ( inProgress ) return;
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inProgress = 1;
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if ( ProtMode )
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{
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Timer.Pointer.Segment = cpmiProtectedPtr( ( long * ) ( 0x0000046C ), sizeof( long ) );
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Timer.Pointer.Offset = 0;
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if ( Timer.Pointer.Segment == 0 ) goto Exit;
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}
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else
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Timer.Address = ( long * ) ( 0x0000046C );
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if ( *Timer.Address >= ( Ticks + Interval ) ||
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( *Timer.Address < Ticks ) )
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{
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Ticks = *Timer.Address;
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_evalNew( &eval, codeBlock );
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_itemRelease( _evalLaunch( &eval ) );
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}
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if ( ProtMode ) cpmiFreeSelector( Timer.Pointer.Segment );
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Exit: inProgress = 0;
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return;
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}
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CLIPPER FT_OnTick( void )
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{
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if ( _itemType( codeBlock ) == BLOCK ) _itemRelease( codeBlock );
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codeBlock = _itemParam( 1 );
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if ( _itemType( codeBlock ) == BLOCK )
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{
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Interval = _parnl( 2 );
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_evLow( 5, TickTock, TRUE );
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}
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else
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_evLow( 5, TickTock, FALSE );
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return;
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}
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