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ASYNCPEC.C
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C/C++ Source or Header
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1993-08-14
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11KB
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305 lines
/************************************************************/
/************************************************************/
/* asyncpec.c asynchronous com routine for Microsoft C 5.1 */
/* Copyright 1989, Quinn-Curtis */
/************************************************************/
/************************************************************/
#include <bios.h>
#include <dos.h>
#include <string.h>
#define timeout 10000 /* Readln_com times out at 10000 milliseconds*/
#define max_buffer 1000 /* Circular buffer size */
#define near_full 900 /* When buffer_length exceeds near_full */
/* RTS line is disabled */
#define near_empty 100 /* When buffer drops below near_empty */
/* RTS line is enabled */
int com_flag = 0; /*Com open flag*/
int overrun_flag;
char com_buffer[max_buffer]; /*Circular com buffer*/
int com_port; /* Current Com port (0 or 1) */
int intlev; /* Hardware interrut level for com port */
int buffer_in; /* Pointer for input to com buffer */
int buffer_out; /* Pointer for output from com buffer */
int buffer_length; /* Current number of characters in com buffer */
int bf_hndshk; /* Handshake flag for control lines */
int thr, rbr, ier, lcr,
mcr, lsr, msr; /*Async com board registers*/
void (interrupt far *oldfunc)(); /* Holds old interrupt vector */
void delay(int d)
/* d = delay in milliseconds on 10 MHz AT */
{ int i;
int j;
int k;
j = 0;
for (k=0; k<d; k++)
for (i=1; i<200; i++)
j += 1;
}
void interrupt far com_isr()
{
if (com_flag == 1) {
/*Get character - store in circular buffer*/
com_buffer[buffer_in] = inp(rbr);
/*Increment buffer_in pointer*/
buffer_in += 1;
/*Wrap buffer pointer around to start if > max_buffer*/
if (buffer_in == max_buffer) buffer_in = 0;
/*Current number of characters in buffer incremented 1*/
buffer_length += 1;
if (buffer_length > max_buffer) {
buffer_length = max_buffer;
overrun_flag = 1;
}
/*Disable RTS if buffer_length exceeds near_full constant*/
if (buffer_length > near_full) {
outp(mcr, 9); /*Disable rts , leave dtr and out2 set*/
bf_hndshk = 1; /*Buffer full handshake = true*/
}
}
outp(0x20,0x20); /* End of Interrupt to 8259 */
}
void reset_buffer()
/* This procedure will reset the com buffer */
{
bf_hndshk = 0; /*Buffer full handshake false*/
buffer_in = 0; /*Set circular buffer input to 0*/
buffer_out = 0; /*Set circular buffer output to 0*/
buffer_length = 0; /*Set buffer_length to 0*/
overrun_flag = 0; /*Set overrun flag to false */
}
void open_com(int Cport, /*Com port # - 0 or 1 */
int baud, /*baud rate - 110,150,300..9600*/
int parity, /*parity 0 = no parity */
/* 1 = even parity */
/* 2 = odd parity */
int stopbits, /*stop bits - 1 or 2 */
int numbits, /*word length - 7 or 8 */
int *error_code )
{
int comdata;
int ptemp;
*error_code = 0;
com_port = Cport;
comdata = 0;
if ((numbits == 7) || (numbits == 8))
comdata = comdata | (numbits-5) ;
else *error_code = 5;
if ((stopbits == 2) || (stopbits == 1))
comdata = comdata | (stopbits-1) << 2 ;
else *error_code = 4;
if ((parity == 1) || (parity == 3) || (parity == 0))
comdata = comdata | (parity << 3) ;
else *error_code = 3;
switch (baud){
case 110: comdata = comdata | 0x00;
break;
case 150: comdata = comdata | 0x20;
break;
case 300: comdata = comdata | 0x40;
break;
case 600: comdata = comdata | 0x60;
break;
case 1200: comdata = comdata | 0x80;
break;
case 2400: comdata = comdata | 0xA0;
break;
case 4800: comdata = comdata | 0xC0;
break;
case 9600 : comdata = comdata | 0xE0;
break;
default : *error_code = 2;
break;
}
if ((Cport <0) || (Cport >1 ))
*error_code = 1;
if (*error_code == 0)
_bios_serialcom( 0,Cport, comdata);
if (Cport == 0) {
thr = 0x3f8; /*Set register varibles*/
rbr = 0x3f8; /*for port locations of*/
ier = 0x3f9; /*serial com port #1*/
lcr = 0x3fb;
mcr = 0x3fc;
lsr = 0x3fd;
msr = 0x3fe;
} else {
thr = 0x2f8; /*Set register variables*/
rbr = 0x2f8; /*for port locations of*/
ier = 0x2f9; /*serial com port #2*/
lcr = 0x2fb;
mcr = 0x2fc;
lsr = 0x2fd;
msr = 0x2fe;
}
intlev = 0xC - Cport;
oldfunc = _dos_getvect(intlev);
_dos_setvect(intlev, com_isr);
_disable(); /*No interrupts*/
ptemp = inp(lcr) & 0x7f;
outp(lcr,ptemp);
ptemp = inp(lsr); /*Reset any pending errors*/
ptemp = inp(rbr); /*Read any pending character*/
if (Cport == 0) { /*Set irq on 8259 controller*/
ptemp = inp(0x21) & 0xef;
outp(0x21,ptemp);
}
else {
ptemp = inp(0x21) & 0xf7;
outp(0x21,ptemp);
}
outp(ier,1); /*Enable data ready interrupt*/
ptemp = inp(mcr) | 0xb;
outp(mcr,ptemp);
_enable(); /*Turn on interrupts*/
*error_code = 0; /*Set error code to 0*/
com_flag = 1; /*Com inititalization flag true*/
reset_buffer();
}
void close_com()
/* This procedure disables the com port interrupt. */
{ int ptemp;
if (com_flag==1) {
_disable(); /*No interrupts*/
ptemp = inp(0x21) | 0x18;
outp(0x21,ptemp); /*Set mask register to turn off interrupt*/
ptemp = inp(lcr) | 0x7f;
outp(lcr,ptemp); /*Turn off 8250 data ready interrupt*/
outp(ier,0);
outp(mcr,0); /*Disable out2 on 8250*/
_dos_setvect(intlev, oldfunc); /* return to old interrupt vector */
_enable(); /*Turn on interrupts*/
com_flag = 0;
}
}
void check_com(char *c, int *error_code) /*error code for check_com */
/* 0 = no error */
/* 6 = no character available */
/* 7 = buffer overflow */
/* 10 = com port not initialized */
/*This procedure returns 1 character from the com_buffer, at the array element*/
/*pointed to by the circular buffer pointer buffer_out. */
{
if (com_flag == 0) /*Make sure com port has been initialized*/
*error_code = 10;
else
{
if (buffer_length == 0) /*Check to see if any characters in buffer*/
*error_code = 6;
else {
if (overrun_flag == 1) /*buffer overflow */
*error_code = 7;
else *error_code = 0;
*c = (com_buffer[buffer_out]); /*Get charater out of buffer*/
buffer_out += 1; /*Increment buffer_out_pointer*/
/*Wrap buffer_out pointer around if > */
/*max_buffer*/
if (buffer_out == max_buffer) buffer_out = 0;
buffer_length -= 1; /*Decrement buffer_length*/
/*Enable RTS if buffer_length < near_empty*/
if (bf_hndshk && (buffer_length < near_empty)) {
outp(mcr,0xb);
bf_hndshk = 0;
}
}
}
}
void send_com(char c, /*Character to send out com port*/
int *error_code) /*Error code for send_com */
/* 0 = no error */
/* 8 = time out error */
/* 10 = com port not initialized*/
/*This procedure sends a character out the com port. */
{
int handshake;
int counter;
if (com_flag == 0) /*Make sure com port has been initialized*/
*error_code = 10;
else
{
counter = 0; /* Initialize time out counter */
handshake = 0x20; /* Use the following handshake values: */
/* handshake = 0x30; /* Use the following handshake values: */
/* 0x0 no handshake */
/* 0x10 CTS handshaking */
/* 0x20 DSR handshaking */
/* 0x30 CTS and DSR handshaking */
do {
counter += 1;
delay(1); /*delay 1 millisecond - causes timeout at 10 seconds*/
}
while
((((inp(msr) & handshake) != handshake) || /*Check handshake*/
((inp(lsr) & 0x20) != 0x20)) && /*Check that transmit reg empty*/
(counter < timeout)); /* Give up after 10 seconds */
if (counter == timeout)
*error_code = 8;
else
{
_disable(); /*No interrpts*/
outp(thr,c); /*Transmit character*/
_enable(); /*Interrupts on*/
*error_code = 0;
}
}
}
void writeln_com(char *str, /*string to send out com port*/
int *error_code) /*error code for writeln_com*/
{ int length;
int i;
length = strlen( str );
for (i=0; i < length; i++){
send_com( str[i], error_code );
}
send_com(13,error_code);
/* send_com(10,error_code); */ /* Send linefeed if required */
}
void readln_com(char *str, /*string to received from com port*/
int *error_code) /*error code for writeln_com*/
{ int i=0;
char c;
int counter = 0;
do {
check_com(&c,error_code);
if (*error_code == 0) {
str[i]=c;
i += 1;
} else {
delay(1);
counter += 1;
}
} while ((i < 255) && (c != 13) && (counter < timeout));
if (counter == timeout) *error_code = 8;
str[i] = 0;
}