swtxuart.c

Real Time Operating System for Hi-Tech C compiler.

/************************************************************ 
Copyright (C) 1995-2002 Pumpkin, Inc. and its
Licensor(s). Freely distributable.

$Source: C:\\RCS\\D\\salvo\\demo\\d5\\swtxuart.c,v $
$Author: aek $
$Revision: 1.9 $
$Date: 2001-10-25 19:56:53-07 $

Support file.

************************************************************/

#ifndef SWTXUART_C_INCLUDES
#define SWTXUART_C_INCLUDES

#include "d5.h"
#include "main.h"
#include "salvo.h"

#if TRANSMITTERS >= 1
_OSLabel(TaskTxa);
_OSLabel(TaskTxb);
_OSLabel(TaskTxc);
_OSLabel(TaskTxd);
#endif

/************************************************************
****                                                     ****
**                                                         **
TaskTx()

This is bit-banging transmit task that handles up to four
transmitters at once. 

It explicitly takes its data from txNBuff[] and places it in
txNData. It context-switches whenever it has nothing to do.

There's little point in having independent transmitter tasks,
since having the transmitters run synchronously results in a
maximum of one character delay. By placing all four 
transmitters in the same task, a considerable RAM and ROM
savings is realized. 

**                                                         **
****                                                     ****
************************************************************/
#if TRANSMITTERS >= 1
void TaskTx( void )
{
    /* Start with all Tx outputs inactive (i.e. idling).*/
    TX1 = 1;
    
    #if TRANSMITTERS >= 2
    TX2 = 1;
    #endif
    
    #if TRANSMITTERS >= 3
    TX3 = 1;
    #endif
    
    #if TRANSMITTERS >= 4
    TX4 = 1;
    #endif
    
    /* initialize transmitters.                         */
    InitBcb(TX1BCBP, TX1_BUFF_SIZE);

    #if TRANSMITTERS >= 2
    InitBcb(TX2BCBP, TX2_BUFF_SIZE);
    #endif
    
     #if TRANSMITTERS >= 3
    InitBcb(TX3BCBP, TX3_BUFF_SIZE);
    #endif
    
     #if TRANSMITTERS >= 4
    InitBcb(TX4BCBP, TX4_BUFF_SIZE);
    #endif
    
    txState = 0;
        
    for (;;) {
    
        /* nothing happens until the semaphore is       */
        /*  signaled.                                   */
        OS_WaitBinSem(BINSEM_TXBUFF_P, OSNO_TIMEOUT, TaskTxa);
        
        /* get local copy of data to be sent. Activate  */
        /*  transmitter if there's data to send. O/wise */
        /*   deactivate transmitter.                    */
        if ( GetTx1Buff(&tx1Data) )
            txStatus.tx1Active = 1;
        else
            txStatus.tx1Active = 0;
            
        #if TRANSMITTERS >= 2
        if ( GetTx2Buff(&tx2Data) )
            txStatus.tx2Active = 1;
        else
            txStatus.tx2Active = 0;
        #endif
            
        #if TRANSMITTERS >= 3
        if ( GetTx3Buff(&tx3Data) )
            txStatus.tx3Active = 1;
        else
            txStatus.tx3Active = 0;
        #endif
            
        #if TRANSMITTERS >= 4
        if ( GetTx4Buff(&tx4Data) )
            txStatus.tx4Active = 1;
        else
            txStatus.tx4Active = 0;
        #endif
                
        /* tell ISR data is ready to be shifted out.    */        
        OSProtect();    
        OSSignalBinSem(BINSEM_TXSTART_P);
        OSUnprotect();

        ToggleTPTx();
        
        /* wait till ISR is done.                       */        
        OS_WaitBinSem(BINSEM_TXDONE_P, OSNO_TIMEOUT, TaskTxb);
        
        /* since we're using only a binsem to indicate  */
        /*  data being available in _any_ buffer, and   */
        /*  since more than a single byte may have been */
        /*  put into any buffer, and since we just got  */
        /*  (i.e. stripped) a maximum of one byte from  */
        /*  each buffer, then buffers may still be non- */
        /*  empty, and we must stay alive until they're */
        /*  completely empty -- all four of 'em.        */
        #if   TRANSMITTERS == 1
        if   ( TX1BCB.count != 0 )
        #elif TRANSMITTERS == 2
        if ( ( TX1BCB.count != 0 ) || ( TX2BCB.count != 0 ) )
        #elif TRANSMITTERS == 3
        if ( ( TX1BCB.count != 0 ) || ( TX2BCB.count != 0 ) \
         ||  ( TX3BCB.count != 0 ) )
        #elif TRANSMITTERS == 4
        if ( ( TX1BCB.count != 0 ) || ( TX2BCB.count != 0 ) \
         ||  ( TX3BCB.count != 0 ) || ( TX4BCB.count != 0 ) )
        #endif
            OSSignalBinSem(BINSEM_TXBUFF_P);
    }    
}
#endif

#endif