port.c

一系列包含串口、Modem、收发传真、终端仿真等方面的编程例子

/* Copyright (C) 1992 Peter Edward Cann, all rights reserved */

#include<stdio.h>
#include<bios.h>
#include<dos.h>
#include"port.h"

int index, basereg;
unsigned char diffintmask, irqnum;
void (interrupt far *oldvect)();

unsigned char buf[TBUFSIZ];

void interrupt far inthndl(_es, _ds, _di, _si, _bp, _sp,
			  _bx, _dx, _cx, _ax, _ip, _cs, _flags)
	unsigned _es, _ds, _di, _si, _bp, _sp;
	unsigned _bx, _dx, _cx, _ax, _ip, _cs, _flags;
	{
	if(inp(basereg+STATREG)&0x01)
		{
		buf[index++]=inp(basereg)&0xff;
		index=index%TBUFSIZ;
		}
	outp(INTBASE1, INTACK);
	outp(INTBASE2, INTACK);
	}

unsigned char lctl;
unsigned int speed, comnum;
char databits, parity, stopbits;

unsigned char newintmask, oldintmask, lctl, dlmsb, dllsb;
unsigned intnum;
unsigned char oldlctl, olddllsb, olddlmsb, oldintctl, oldmctl;

setport()
	{
	newintmask=0;
	switch(comnum)
		{
		case 0:
			irqnum=4;
			diffintmask=0xff&~0x10;
			basereg=0x3f8;
			break;
		case 1:
			irqnum=3;
			diffintmask=0xff&~0x08;
			basereg=0x2f8;
			break;
		case 2:
			irqnum=4;
			diffintmask=0xff&~0x10;
			basereg=0x3e8;
			break;
		case 3:
			irqnum=3;
			diffintmask=0xff&~0x08;
			basereg=0x2e8;
			break;
		case 4:
			irqnum=2;
			diffintmask=0xff&~0x02;
			basereg=0x3e8;
			break;
		case 5:
			irqnum=2;
			diffintmask=0xff&~0x02;
			basereg=0x2e8;
			break;
		case 6:
			irqnum=5;
			diffintmask=0xff&~0x20;
			basereg=0x3e8;
			break;
		case 7:
			irqnum=5;
			diffintmask=0xff&~0x20;
			basereg=0x2e8;
			break;
		default:
			printf("Bad port choice.\n");
			exit(4);
		}
	intnum=irqnum+8;
	switch(speed)
		{
		case 300:
			dlmsb=0;
			dllsb=0xc0;
			break;
		case 1200:
			dlmsb=0;
			dllsb=0x60;
			break;
		case 2400:
			dlmsb=0;
			dllsb=0x30;
			break;
		case 9600:
			dlmsb=0;
			dllsb=0x0c;
			break;
		case 19200:
			dlmsb=0;
			dllsb=0x06;
			break;
		case 38400:
			dlmsb=0;
			dllsb=0x03;
			break;
		case 57600:
			dlmsb=0;
			dllsb=0x02;
			break;
		default:
			printf("Bad speed %d.\n", speed);
			exit(5);
		}
	lctl=0;
	switch(parity)
		{
		case 'e':
		case 'E':
			lctl |= PARITYEN | PARITYEVEN;
			break;
		case 'o':
		case 'O':
			lctl|=PARITYEN;
			break;
		case 'n':
		case 'N':
			break;
		default:
			printf("Bad parity.\n");
			exit(7);
		}
	switch(databits)
		{
		case '7':
			lctl|=DB7;
			break;
		case '8':
			lctl|=DB8;
			break;
		default:
			printf("Bad data bits.\n");
			exit(8);
		}
	switch(stopbits)
		{
		case '1':
			break;
		case '2':
			lctl|=STOP2;
			break;
		default:
			printf("Bad stop bits.\n");
			exit(9);
		}
	}

readset()
	{
	oldlctl=inp(basereg+LCTLREG);
	outp(basereg+LCTLREG, DLAB);
	olddllsb=inp(basereg+DLLSBREG);
	olddlmsb=inp(basereg+DLMSBREG);
	outp(basereg+LCTLREG, oldlctl);
	oldvect=_dos_getvect(intnum);
	oldmctl=inp(basereg+MCTLREG);
	oldintmask=(intnum==10)?inp(INTMASK2):inp(INTMASK1);
	}
	
setup()
	{
	outp(basereg+LCTLREG, DLAB);
	outp(basereg+DLLSBREG, dllsb);
	outp(basereg+DLMSBREG, dlmsb);
	outp(basereg+LCTLREG, lctl);
	_dos_setvect(intnum, inthndl);
	oldintctl=inp(basereg+INTCTLREG);
	outp(basereg+INTCTLREG, 0x01);
	inp(basereg); /* Clear interrupt */
	outp(basereg+MCTLREG, 0x0b);
	newintmask=diffintmask;
	newintmask&=oldintmask;
	if(intnum==10)
		outp(INTMASK2, newintmask);
	else
		outp(INTMASK1, newintmask);
	outp(INTBASE1, INTACK);
	outp(INTBASE2, INTACK);
	}

cleanup(flags)
	int flags;
	{
	if(!(flags&INHINT))
		{
		if(intnum==10)
			outp(INTMASK2, oldintmask);
		else
			outp(INTMASK1, oldintmask);
		outp(basereg+INTCTLREG, oldintctl);
		_dos_setvect(intnum, oldvect);
		outp(basereg+MCTLREG, 0x03);
		}
	if(!(flags&INHCTL))
		{
		outp(basereg+LCTLREG, DLAB);
		outp(basereg+DLLSBREG, olddllsb);
		outp(basereg+DLMSBREG, olddlmsb);
		outp(basereg+LCTLREG, oldlctl);
		outp(basereg+MCTLREG, oldmctl);
		}
	}