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5.3.4 A Sample Program (FICOM.H)
The following program is an example of a C language program
which he l ps users to understand the data format and the data
interfacing method, and also to develop their own programs.
[Interrupt Usage and Selection between COM1 and COM2]
#define COM1 0
#define COM2 0
/* Base addresses of serial ports */
#define COM1BASE 0x03f8
#define COM2BASE 0xx02f8
#define COMBASE ( (comport = = COM1)?COM1BASE:
COM2BASE)
/* Registers */
#defineTHR (COMBASE +0) /* Transmit Holding Register */
#defineRBR (COMBASE +0) /* Receive Buffer Register */
#defineIER (COMBASE +1) /* Interrupt Enable Register */
#defineIIR (COMBASE +2) /* Interrupt Identification Register*/
#defineLCR (COMBASE +3) /* Line Control Register */
#defineMCR (COMBASE +4) /* Modem Control Register */
#defineLSR (COMBASE +5) /* Line Status Register */
#defineMSR (COMBASE +6) /* Modem Status Register */
44 45
/* Parameters to bioscom function */
#define DATABIT7 0X02 /* Data bit */
#define DATABIT8 0X03
#define STOPBIT1 0X00 /* Stop bit */
#define STOPBIT2 0X04
#define NOPARITY 0X00 /* Parity bit */
#define ODDPARITY 0X08
#define EVENPARITY 0X18
#define BAUD1200 0X80 /* Baud rate */
#define BAUD2400 0Xa0
#define BAUD4800 0Xc0
#define BAUD9600 0Xe0
/* 8259 PIC (Programmable Interrupt Controller */
#defineIMR 0x21 /* I/O address of 0CW1 (IMR) of 8529 PIC */
#define0CW 0x20 /* I/O address of 0CW2 of 8259 PIC */
/* 0CW: Operation Command Word */
/* IMR: Interrupt Mask Register */
# define MASKON 0x e7 /* Mask IRQ3/IRQ4 on → IMR */
* define MASKOFF 0x18 /* Mask IRQ3/IRQ4 off → IMR */
#define EOI 0x20 /* Non-specific End of Interrupt command →
0CW2*/
/* Interrupt Request Numbers */
#define IRQ0 0x 08 /* Interrupt Vector for Timer */
#define IRQ3 0x 0b /* Interrupt Vector for COM2 */
#define IRQ4 0x 0c /* Interrupt Vector for COM1 */
#define IRQ8 0x 70 /* Interrupt Vector for RTC (Real TIme Clock) */
#define IRQ16 0x 1C /* Interrupt Vector to called Timer */
#define IRQNUM ( ( comport = = COM1)? IRQ4 : IRQ3)