Ham Radio 2000 #1/Ham Radio 2000.iso/ham2000/hf/dsp/dsp4tool/serial.c

C/C++ Source or Header | 1993-07-20 | 4.7 KB | 232 lines

/*  SERIAL.C -- IBM Serial Port handler (with interrupts)
 *
 *  Copyright (C) 1989,1990,1991 by Alef Null. All rights reserved.
 *  Author(s): J Vuori, E Torsti
 *  Modification(s):
 *    1989-Sep: COM1, COM2 and baud rate selection with
 *          OpenSerial(int port, int baud)
 *    1991-Apr: DTR line control function added
 */


#define BUFLEN    4096    // buffer lenght


#include <dos.h>
#include <conio.h>
#include <stdlib.h>
#include <malloc.h>
#include <stdio.h>
#include "serial.h"


/* ring buffer definitions */
#define NEXT(p) if (++(p) >= &buffer[BUFLEN]) (p) = buffer
static volatile unsigned char *head, *tail;
static        unsigned char *buffer;


/* i/o-port definitions */
#define PIC_MASK  0x21    // 8259 mask register
#define PIC_EOI   0x20    // 8259 EOI command
static const struct {
    int data,        // 8250 data register
    ier,        //    interrupt enable register
    lcr,        //    line control register
    mcr,        //    modem control register
    stat;        //    status register
    int intno;        // interrupt number
    int mask;        // PIC mask
} *comport, comports[2] = {
    /* COM1 */
    0x3f8, 0x3f9, 0x3fb, 0x3fc, 0x3fd,
    0x0c,
    0x10,

    /* COM2 */
    0x2f8, 0x2f9, 0x2fb, 0x2fc, 0x2fd,
    0x0b,
    0x08,
};


#if defined(__TURBOC__)
    /* store for old interrupt vector */
    static void (interrupt far *OldHandler)(void);

    /*
     * 8250 UART Interrupt server routine
     */
    static void interrupt far ReadChr(void) {
    *head = (unsigned char)inp(comport->data);
    NEXT(head);

    outp(PIC_EOI, 0x20);
    }
#else
    /* store for old interrupt vector */
    static void (interrupt far cdecl *OldHandler)(void);

    #pragma intrinsic(inp, outp)    // produces more beautiful code with this

    /*
     * 8250 UART Interrupt server routine
     */
    #pragma check_stack(off)        // because stack check is not allowed in interrupt service routine
    static void cdecl interrupt far ReadChr(void) {
    *head = (unsigned char)inp(comport->data);
    NEXT(head);

    outp(PIC_EOI, 0x20);
    }
    #pragma check_stack()
#endif


/*
 * Initializes serial communication
 *
 * enter with:
 *  port - 1 = COM1, 2 = COM2
 *
 * returns:
 *  NULL if failed
 */
int OpenSerial(int port, int baud) {
    comport = &comports[port-1];

    /* allocate receiving buffer */
    if ((buffer = (unsigned char *)malloc(BUFLEN)) != NULL) {
    /* reset buffer */
    head = tail = buffer;

    /* set interrupt vector */
    OldHandler = _dos_getvect(comport->intno);
    _dos_setvect(comport->intno, ReadChr);

    /* set 8250 UART chip */
    SetBaudRate(baud);
    SetDTR(0);
    outp(comport->ier, 0x01);            // enable rec interrupt

    inp(comport->data);                // make UART happy

    /* set 8259 PIC chip */
    outp(PIC_MASK, inp(PIC_MASK) & ~comport->mask); // remove interrupt mask

    return(-1);
    } else
    return(0);
}


/*
 * Terminates serial communication
 */
void CloseSerial(void) {
    /* set 8259 PIC chip */
    outp(PIC_MASK, inp(PIC_MASK) | comport->mask);  // set mask

    /* reset interrupt vector */
    _dos_setvect(comport->intno, OldHandler);

    free(buffer);
}


/*
 * Reads one character from serial port,
 * returns -1 if there are no characters waiting
 */
int ReadSerial(void) {
    register int c;

    if (head != tail) {
    c = *tail;
    NEXT(tail);
    return(c);
    } else
    return(-1);
}


/*
 * Writes one character to serial port
 */
int WriteSerial(int c) {
    while(!(inp(comport->stat) & 0x20));    // wait TBE status

    //printf("%02X ", c & 0xff);
    return(outp(comport->data, c));
}


/*
 * Controls DTR-line
 */
void SetDTR(int state) {
    outp(comport->mcr, state ? 0x0f : 0x0e);
}


/*
 * Controls baud rate
 */
void SetBaudRate(int baud) {
    outp(comport->lcr, 0x83);
    outp(comport->data, (12L*9600L/(long)baud) & 0xff);
    outp(comport->ier,    (12L*9600L/(long)baud) >> 8);
    outp(comport->lcr, 0x03);                // 8, n, 1
}


/*
 * Check if break condition detected
 */
int IfBreak(void) {
    return (inp(comport->stat) & 0x10);
}


#if defined(DEBUG)
    #include <stdio.h>
    #include <signal.h>

    #define PORT    1
    #define BAUD    9600

    /*
     * CTRL-C handler
     */
    void handler(void) {
    CloseSerial();
    printf("disconnected\n");
    exit(-1);
    }


    int main(void) {
    int c;

    signal(SIGINT, handler);
    if (!OpenSerial(PORT, BAUD)) {
        fprintf(stderr, "Can't open serial port COM%d\n", PORT);
        return(-1);
    }

    printf("Simple serial port terminal [COM%1d, %4d] (%s)\n", PORT, BAUD, __DATE__);
    printf("Press CTRL-C to exit\n\n");

    while (1) {
        while ((c = ReadSerial()) == -1)
        if (kbhit())
            WriteSerial(getch());

        putchar(c & 0x7f);
    }

    CloseSerial();
    return(0);
    }
#endif