*** Listing 2 ***

/*
 * hn_port.c - MS-DOS version of port-level i/o for the HNL
 *
 * Copyright(c) 1988 by Hobart Corporation.
 * Used with permission.
 */


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <glc.h>		/* Greenleaf declarations */
#include <hn.h>
#include <hn_errno.h>

#define DIM(a) (sizeof(a) / sizeof(a[0]))

static int port_name_to_number(char *name)
    {
    struct pair
        {
        char *name;
        int number;
        };
    static struct pair table[] =
        {{"AUX", COM1}, {"COM1", COM1}, {"COM2", COM2}};
    int i;

    for (i = 0; i < DIM(table); ++i)
        if (strcmpi(table[i].name, name) == 0)
            return table[i].number;
    return -1;
    }

hn_port *hn_popen(char *dev, hn_bps bps, hn_parity par,
        unsigned data_bits, unsigned stop_bits)
    {
    static unsigned actual_bps[] = {1200, 2400, 4800, 9600};
    static unsigned dos_bps[] = {1200, 2400, 4800, 9600};
    static unsigned dos_parity[] = {P_NONE, P_ODD, P_EVEN};
    hn_port *p = NULL;
    int err = HN_ENONE, number;

    if ((number = port_name_to_number(dev)) < 0)
        err = HN_EDEVNAME;
    else if (bps >= DIM(dos_bps))
        err = HN_EBPS;
    else if (par >= DIM(dos_parity))
        err = HN_EPARITY;
    else if (data_bits != 7 && data_bits != 8)
        err = HN_EDATABITS;
    else if (stop_bits != 1 && stop_bits != 2)
        err = HN_ESTOPBITS;
    else
        err = asiopen(number, ASINOUT | ASCII, 2048, 2048,
                dos_bps[bps], dos_parity[par], stop_bits,
                data_bits, OFF, OFF);
    if (err == HN_ENONE)
        {
        if ((p = malloc(sizeof(hn_port))) == NULL)
            err = HN_ENOPORTS;
        else
            err = asihold(number, ASINOUT);
        }
    if (err != HN_ENONE)
        {
        if (number >= 0)
            asiquit(number);
        if (p != NULL)
            free(p);
        hn_errno = err;
        return NULL;
        }
    p->number = number;
    p->errno = HN_ENONE;
    return p;
    }

int hn_pclose(hn_port *p)
    {
    int err = HN_ENONE;

    if (p != NULL)
        {
        if ((err = asiquit(p->number)) != HN_ENONE)
            {
            hn_errno = err;
            return EOF;
            }
        free(p);
        }
    return 0;
    }

int hn_penable(hn_port *p)
    {
    if ((p->errno = asiresume(p->number, ASINOUT)) == HN_ENONE)
        return 0;
    hn_errno = p->errno;
    return EOF;
    }

int hn_pdisable(hn_port *p)
    {
    if ((p->errno = asihold(p->number, ASINOUT)) == HN_ENONE)
        return 0;
    hn_errno = p->errno;
    return EOF;
    }

int hn_pgetc(hn_port *p)
    {
    int c;

    if ((c = asigetc(p->number)) >= 0)
        return c;
    if (c != HN_EBUFEMPTY)
        hn_errno = p->errno = c;
    return EOF;
    }

int hn_pputc(int c, hn_port *p)
    {
    if ((p->errno = asiputc(p->number, c)) == HN_ENONE)
        return c;
    hn_errno = p->errno;
    return EOF;
    }

int hn_pflush(hn_port *p)
    {
    while (!istxempty(p->number))
        ;
    return 0;
    }