static portBASE_TYPE xComPortISR( xComPort * const pxPort )
{
unsigned short usStatusRegister;
char cChar;
portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE, xContinue = pdTRUE;
/* NOTE: THIS IS NOT AN EFFICIENT ISR AS IT IS DESIGNED SOLELY TO TEST
THE SCHEDULER FUNCTIONALITY. REAL APPLICATIONS SHOULD NOT USE THIS
FUNCTION. */
while( xContinue == pdTRUE )
{
xContinue = pdFALSE;
usStatusRegister = portINPUT_WORD( pxPort->usStatusReg );
if( usStatusRegister & serRX_READY )
{
cChar = ( char ) portINPUT_WORD( pxPort->usRxReg );
xQueueSendFromISR( pxPort->xRxedChars, &cChar, &xHigherPriorityTaskWoken );
/* Also release the semaphore - this does nothing interesting and is just a test. */
xSemaphoreGiveFromISR( pxPort->xTestSem, &xHigherPriorityTaskWoken );
/* We have performed an action this cycle - there may be other to perform. */
xContinue = pdTRUE;
}
if( pxPort->sTxInterruptOn && ( usStatusRegister & serTX_EMPTY ) )
{
if( xQueueReceiveFromISR( pxPort->xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
{
portOUTPUT_WORD( pxPort->usTxReg, ( unsigned short ) cChar );
/* We have performed an action this cycle - there may be others to perform. */
xContinue = pdTRUE;
}
else
{
/* Queue empty, nothing to send */
vInterruptOff( pxPort, serTX_HOLD_EMPTY_INT );
}
}
}
serRESET_PIC( pxPort->usIRQVector );
/* If posting to the queue woke a task that was blocked on the queue we may
want to switch to the woken task - depending on its priority relative to
the task interrupted by this ISR. */
return xHigherPriorityTaskWoken;
}
static void prvExitFunction( void )
{
const uint16_t usTimerDisable = 0x0000;
uint16_t usTimer0Control;
/* Interrupts should be disabled here anyway - but no
harm in making sure. */
portDISABLE_INTERRUPTS();
if( sSchedulerRunning == pdTRUE )
{
/* Put back the switch interrupt routines that was in place
before the scheduler started. */
_dos_setvect( portSWITCH_INT_NUMBER, pxOldSwitchISR );
}
/* Disable the timer used for the tick to ensure the scheduler is
not called before restoring interrupts. There was previously nothing
on this timer so there is no old ISR to restore. */
portOUTPUT_WORD( portTIMER_1_CONTROL_REGISTER, usTimerDisable );
/* Restart the DOS tick. */
usTimer0Control = portINPUT_WORD( portTIMER_0_CONTROL_REGISTER );
usTimer0Control |= portTIMER_INTERRUPT_ENABLE;
portOUTPUT_WORD( portTIMER_0_CONTROL_REGISTER, usTimer0Control );
portENABLE_INTERRUPTS();
}
static void prvExitFunction( void )
{
const unsigned short usTimerDisable = 0x0000;
unsigned short usTimer0Control;
/* Interrupts should be disabled here anyway - but no
harm in making sure. */
portDISABLE_INTERRUPTS();
if( sSchedulerRunning == pdTRUE )
{
/* Put back the switch interrupt routines that was in place
before the scheduler started. */
_dos_setvect( portSWITCH_INT_NUMBER, pxOldSwitchISR );
}
/* Disable the timer used for the tick to ensure the scheduler is
not called before restoring interrupts. There was previously nothing
on this timer so there is no old ISR to restore. */
portOUTPUT_WORD( portTIMER_1_CONTROL_REGISTER, usTimerDisable );
/* Restart the DOS tick. */
usTimer0Control = portINPUT_WORD( portTIMER_0_CONTROL_REGISTER );
usTimer0Control |= portTIMER_INTERRUPT_ENABLE;
portOUTPUT_WORD( portTIMER_0_CONTROL_REGISTER, usTimer0Control );
portENABLE_INTERRUPTS();
/* This will free up all the memory used by the scheduler.
exiting back to dos with INT21 AH=4CH will do this anyway so
it is not necessary to call this. */
vTaskCleanUpResources();
}
xComPortHandle xSerialPortInit( eCOMPort ePort, eBaud eWantedBaud, eParity eWantedParity, eDataBits eWantedDataBits, eStopBits eWantedStopBits, unsigned portBASE_TYPE uxBufferLength )
{
unsigned short usPort;
xComPortHandle pxPort = NULL;
unsigned long ulBaudDiv;
/* BAUDDIV = ( Microprocessor Clock / Baud Rate ) / 16 */
ulBaudDiv = ( configCPU_CLOCK_HZ / prvBaud( eWantedBaud ) ) / 16UL;
/* Only n, 8, 1 is supported so these parameters are not required for this
port. */
( void ) eWantedParity;
( void ) eWantedDataBits;
( void ) eWantedStopBits;
/* Currently only n,8,1 is supported. */
usPort = ( unsigned short ) ePort;
if( usPort < serMAX_PORTS )
{
pxPort = &( xPorts[ usPort ] );
portENTER_CRITICAL();
{
unsigned short usInWord;
/* Create the queues used by the com test task. */
pxPort->xRxedChars = xQueueCreate( uxBufferLength, ( unsigned portBASE_TYPE ) sizeof( char ) );
pxPort->xCharsForTx = xQueueCreate( uxBufferLength, ( unsigned portBASE_TYPE ) sizeof( char ) );
/* Create the test semaphore. This does nothing useful except test a feature of the scheduler. */
vSemaphoreCreateBinary( pxPort->xTestSem );
/* There is no ISR here already to restore later. */
setvect( ( short ) pxPort->usIRQVector, xISRs[ usPort ] );
usInWord = portINPUT_WORD( pxPort->usIntReg );
usInWord &= ~serINTERRUPT_MASK;
usInWord |= serINTERRUPT_PRIORITY;
portOUTPUT_WORD( pxPort->usIntReg, usInWord );
portOUTPUT_WORD( pxPort->usBaudReg, ( unsigned short ) ulBaudDiv );
portOUTPUT_WORD( pxPort->usCtrlReg, serENABLE_INTERRUPTS | serMODE | serENABLE_TX_MACHINES | serENABLE_RX_MACHINES );
portOUTPUT_WORD( pxPort->usStatusReg, serCLEAR_ALL_STATUS_BITS );
}
portEXIT_CRITICAL();
}
return pxPort;
} /*lint !e715 Some parameters are not used as only a subset of the serial port functionality is currently implemented. */
void vSerialClose( xComPortHandle xPort )
{
unsigned short usOutput;
/* Turn off the interrupts. We may also want to delete the queues and/or
re-install the original ISR. */
portENTER_CRITICAL();
{
usOutput = portINPUT_WORD( xPort->usCtrlReg );
usOutput &= ~serENABLE_INTERRUPTS;
usOutput &= ~serENABLE_TX_MACHINES;
usOutput &= ~serENABLE_RX_MACHINES;
portOUTPUT_WORD( xPort->usCtrlReg, usOutput );
usOutput = portINPUT_WORD( xPort->usIntReg );
usOutput |= serINTERRUPT_MASK;
portOUTPUT_WORD( xPort->usIntReg, usOutput );
}
portEXIT_CRITICAL();
}
static void prvSetTickFrequency( uint32_t ulTickRateHz )
{
const uint16_t usMaxCountRegister = 0xff5a;
const uint16_t usTimerPriorityRegister = 0xff32;
const uint16_t usTimerEnable = 0xC000;
const uint16_t usRetrigger = 0x0001;
const uint16_t usTimerHighPriority = 0x0000;
uint16_t usTimer0Control;
/* ( CPU frequency / 4 ) / clock 2 max count [inpw( 0xff62 ) = 7] */
const uint32_t ulClockFrequency = 0x7f31a0;
uint32_t ulTimerCount = ulClockFrequency / ulTickRateHz;
portOUTPUT_WORD( portTIMER_1_CONTROL_REGISTER, usTimerEnable | portTIMER_INTERRUPT_ENABLE | usRetrigger );
portOUTPUT_WORD( usMaxCountRegister, ( uint16_t ) ulTimerCount );
portOUTPUT_WORD( usTimerPriorityRegister, usTimerHighPriority );
/* Stop the DOS tick - don't do this if you want to maintain a TOD clock. */
usTimer0Control = portINPUT_WORD( portTIMER_0_CONTROL_REGISTER );
usTimer0Control &= ~portTIMER_INTERRUPT_ENABLE;
portOUTPUT_WORD( portTIMER_0_CONTROL_REGISTER, usTimer0Control );
}
