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* Compile
options needed: none
-
The following program is a simple example which sends and receives
one character to/from COM1:
*/
#include
<stdio.h>
#include <bios.h>
void
main(void)
{
unsigned com1_status;
unsigned com1_send;
unsigned com1_rec;
unsigned com1_init;
int result, mask;
/* open serial port at 1200 baud, 8 data bits,
** No parity, 1 stop bit */
com1_init = _bios_serialcom(_COM_INIT, 0,
_COM_CHR8 | _COM_NOPARITY | _COM_STOP1 | _COM_1200);
printf("Init status: 0x%4.4X\n", com1_init);
/* send an '*' to com1 */
com1_send = _bios_serialcom(_COM_SEND, 0, '*');
printf("Send status: 0x%4.4X\n", com1_send);
mask = 0x6100;
/* value used to mask:
* bits 0-7 are related to modems,
* bits 8-15 are for port status,
* check to see that the following bits are set:
* 8 (data ready)
* 13 (Transmission-hold register empty)
* 14 (Transmission-shift register empty)
*/
/* check the status */
com1_status = _bios_serialcom(_COM_STATUS, 0, 0);
printf("COM1 status: 0x%4.4X\n", com1_status);
/* wait until a character is ready */
do {
/* check the status */
com1_status = _bios_serialcom(_COM_STATUS, 0, 0);
/* mask off the low order byte of com1_status */
com1_status = com1_status & 0xFF00;
} while( (mask & com1_status) == 0);
/* get a character */
com1_rec = _bios_serialcom(_COM_RECEIVE, 0, 0);
printf("Read status: 0x%4.4X\n", com1_rec);
/* print the character we just received */
result = com1_rec & 0x00FF;
printf("Character: 0x%2.2X = %c\n", result, (char)result);
}
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