/* Name : Sample Comm's Program - 1024 Byte Buffer - buff1024.c */
/* Written By : Craig Peacock <[email protected]> */
#include <dos.h>
#include <stdio.h>
#include <conio.h>

#define PORT1 0x3F8 /* Port Address Goes Here */
#define INTVECT 0x0C /* Com Port's IRQ here (Must also change PIC setting) */

/* Defines Serial Ports Base Address */
/* COM1 0x3F8 */
/* COM2 0x2F8 */
/* COM3 0x3E8 */
/* COM4 0x2E8 */

int bufferin = 0;
int bufferout = 0;
char ch;
char buffer[1025];

void interrupt(*oldport1isr)();

void interrupt PORT1INT() /* Interrupt Service Routine (ISR) for PORT1 */
{
　int c;
　do
　{
　　c = inportb(PORT1 + 5);
　　if (c &1)
　　{
　　　buffer[bufferin] = inportb(PORT1);
　　　bufferin++;
　　　if (bufferin == 1024)
　　　{
　　　　bufferin = 0;
　　　}
　　}
　}
　while (c &1);
　　outportb(0x20, 0x20);
}

void main(void)
{
　int c;
　outportb(PORT1 + 1, 0); /* Turn off interrupts - Port1 */

　oldport1isr = getvect(INTVECT); /* Save old Interrupt Vector of later
　recovery */

　setvect(INTVECT, PORT1INT); /* Set Interrupt Vector Entry */
　/* COM1 - 0x0C */
　/* COM2 - 0x0B */
　/* COM3 - 0x0C */
　/* COM4 - 0x0B */

　/* PORT 1 - Communication Settings */

　outportb(PORT1 + 3, 0x80); /* SET DLAB ON */
　outportb(PORT1 + 0, 0x0C); /* Set Baud rate - Divisor Latch Low Byte */
　/* Default 0x03 = 38,400 BPS */
　/* 0x01 = 115,200 BPS */
　/* 0x02 = 57,600 BPS */
　/* 0x06 = 19,200 BPS */
　/* 0x0C = 9,600 BPS */
　/* 0x18 = 4,800 BPS */
　/* 0x30 = 2,400 BPS */
　outportb(PORT1 + 1, 0x00); /* Set Baud rate - Divisor Latch High Byte */
　outportb(PORT1 + 3, 0x03); /* 8 Bits, No Parity, 1 Stop Bit */
　outportb(PORT1 + 2, 0xC7); /* FIFO Control Register */
　outportb(PORT1 + 4, 0x0B); /* Turn on DTR, RTS, and OUT2 */

　outportb(0x21, (inportb(0x21) &0xEF)); /* Set Programmable Interrupt Controller */
　/* COM1 (IRQ4) - 0xEF */
　/* COM2 (IRQ3) - 0xF7 */
　/* COM3 (IRQ4) - 0xEF */
　/* COM4 (IRQ3) - 0xF7 */

　outportb(PORT1 + 1, 0x01); /* Interrupt when data received */

　printf("/nSample Comm's Program. Press ESC to quit /n");

　do
　{
　　if (bufferin != bufferout)
　　{
　　　ch = buffer[bufferout];
　　　bufferout++;
　　　if (bufferout == 1024)
　　　{
　　　　bufferout = 0;
　　　}
　　　printf("%c", ch);
　　}

　if (kbhit())
　{
　　c = getch();
　　outportb(PORT1, c);
　}
}
while (c != 27);

outportb(PORT1 + 1, 0);
/* Turn off interrupts - Port1 */
outportb(0x21, (inportb(0x21) | 0x10)); /* MASK IRQ using PIC */
/* COM1 (IRQ4) - 0x10 */
/* COM2 (IRQ3) - 0x08 */
/* COM3 (IRQ4) - 0x10 */
/* COM4 (IRQ3) - 0x08 */
setvect(INTVECT, oldport1isr); /* Restore old interrupt vector */
}