Serial port under wine

[Paul Sheer]

I am trying to write a simple serial port library
that has the same lowest-common-denominator interface
under both Windows and Linux. I developed it under wine
using mingw32 - i want my apps that use it to work under
both windows and linux (these are command-line apps only).

i noticed that wine does not seem to report errors
from GetOverLapped.. and Wait..Object in a way that
makes sense. By ignoring errors, and just looking at
the dwRead result, i got it to work.

my attempt at a posix-like read function is below
(the linux version follows further down)

best wishes

-paul

---------

int serial_port_read (struct serial_port *p, unsigned char *buf, int
buf_len, int milli_timeout)
{
    static int c = 0;
    DWORD dwStart, dwRead, r;
    int l, total = 0;
    dwStart = GetTickCount ();
    while (buf_len > 0) {
    l = serial_port_chars_avail (p);
    if (l < 0)
        return total > 0 ? total : SERIAL_PORT_ERROR;
    if (l == 0 && GetTickCount () - dwStart >= milli_timeout)
        return total > 0 ? total : SERIAL_PORT_TIMEOUT;
/* Like POSIX read(), we return without blocking if we have read at
least one character: */
    if (l == 0 && total >= 1)
        return total;
/* Read minimum of one character, and a maximum of buf_len
characters: */
    CLIP (l, 1, buf_len);
    dwRead = 0;
    if (!ReadFile (p->hComm, buf, l, &dwRead, &p->osRead)) {
        if ((r = GetLastError ()) == ERROR_IO_PENDING) {
    	dwRead = 0;
    	GetOverlappedResult (p->hComm, &p->osRead, &dwRead, TRUE);
        }
    }
    total += dwRead;
    buf_len -= dwRead;
    buf += dwRead;
    }
    return total;
}

------------

int serial_port_read (struct serial_port *p, unsigned char *buf, int
buf_len, int milli_timeout)
{
    int c;
    struct timeval tv;
    fd_set rd;
    if (!buf_len)
    return 0;
    FD_ZERO (&rd);
    FD_SET (p->fd, &rd);
    switch (select (p->fd + 1, &rd, NULL, NULL, milli_timeout < 0 ? NULL
: (tv.tv_sec = milli_timeout / 1000,
    								    tv.tv_usec = milli_timeout % 1000,
    								    &tv))) {
    case 1:
    c = read (p->fd, buf, buf_len);
    if (!c) {
        p->error = 0;
        return SERIAL_PORT_HANGUP;
    }
    if (c < 0) {
        p->error = errno;
        return SERIAL_PORT_ERROR;
    }
    return c;
    case 0:
    return SERIAL_PORT_TIMEOUT;
    default:
    p->error = errno;
    return SERIAL_PORT_ERROR;
    }
}