Demo/PIC18_WizC/serial/isrSerialTx.c

/*
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    This file is part of the FreeRTOS distribution.

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    the terms of the GNU General Public License (version 2) as published by the
    Free Software Foundation and modified by the FreeRTOS exception.
    **NOTE** The exception to the GPL is included to allow you to distribute a
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    FreeRTOS is distributed in the hope that it will be useful,    but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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    Temple Place, Suite 330, Boston, MA  02111-1307  USA.


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

/*
Changes from V3.0.0
	+ ISRcode pulled inline to reduce stack-usage.

	+ Added functionality to only call vTaskSwitchContext() once
	  when handling multiple interruptsources in a single interruptcall.

	+ Filename changed to a .c extension to allow stepping through code
	  using F7.

Changes from V3.0.1
*/

#ifndef _FREERTOS_SERIAL_ISRSERIALTX_C
#define _FREERTOS_SERIAL_ISRSERIALTX_C

#define serINTERRUPT_DISABLED	( 0 )


{
	/*
	 * Was the interrupt the Tx register becoming empty?
	 */
	if( bTXIF && bTXIE)
	{
		/*
		 * Queue to interface between comms API and interrupt routine.
		*/
		extern xQueueHandle xCharsForTx;

		/*
		 * Because we are not allowed to use local variables here,
		 * PRODL and PRODH are (ab)used as temporary storage. This
		 * is allowed because these SFR's will be restored before
		 * exiting the ISR.
		 */
		extern char				cChar;
		#pragma locate cChar		&PRODL
		extern portBASE_TYPE		pxTaskWoken;
		#pragma locate pxTaskWoken	&PRODH

		if( xQueueReceiveFromISR( xCharsForTx, &cChar, &pxTaskWoken ) == pdTRUE )
		{
			/*
			 * Send the next character queued for Tx.
			 */
			TXREG = cChar;
		}
		else
		{
			/*
			 * Queue empty, nothing to send.
			 */
			bTXIE = serINTERRUPT_DISABLED;
		}

		/*
		 * If we woke another task, ask for a contextswitch
		 */
		if( pxTaskWoken == pdTRUE )
		{
			uxSwitchRequested = pdTRUE;
		}
	}
}

#endif	/* _FREERTOS_SERIAL_ISRSERIALTX_C */