[ECOS] tty_write yields written bytes count

[Robin Farine]

On Wed, 2002-02-27 at 23:42, Jonathan Larmour wrote:

[snip]

> 
> I certainly agree with your analysis, but I think there is a simpler
> solution. Haven't tried it admittedly, but tell me what you think!
> 

[snip]

Yes, your solution is a lot more elegant but I don't think it works
correctly (I haven't tried it either :). The problem comes with the
error case. The underlying device will set 'size' to the number of bytes
it could send before the error. Fine. But tty_write() doesn't know at
that time how many lf -> crlf or other translations it did before and
thus it cannot adjust 'bytes_successfull' correctly. That's why I
thought the easier way was to flush the buffer each time a translation
occurs.

Robin 

> Jifl
> 
> Index: tty.c
> ===================================================================
> RCS file: /home/cvs/ecc/ecc/io/serial/current/src/common/tty.c,v
> retrieving revision 1.14
> diff -u -5 -p -r1.14 tty.c
> --- tty.c	2000/11/06 19:40:01	1.14
> +++ tty.c	2002/02/27 22:41:21
> @@ -156,19 +156,18 @@ static Cyg_ErrNo 
>  tty_write(cyg_io_handle_t handle, const void *_buf, cyg_uint32 *len)
>  {
>      cyg_devtab_entry_t *t = (cyg_devtab_entry_t *)handle;
>      struct tty_private_info *priv = (struct tty_private_info *)t->priv;
>      cyg_io_handle_t chan = (cyg_io_handle_t)priv->dev_handle;
> -    cyg_int32 size, bytes_successful, actually_written;
> +    cyg_int32 size, bytes_successful;
>      cyg_uint8 xbuf[BUFSIZE];
>      cyg_uint8 c;
>      cyg_uint8 *buf = (cyg_uint8 *)_buf;
>      Cyg_ErrNo res = -EBADF;
>      // assert(chan)
>      size = 0;
>      bytes_successful = 0;
> -    actually_written = 0;
>      while (bytes_successful++ < *len) {
>          c = *buf++;
>          if ((c == '\n') &&
>              (priv->dev_info.tty_out_flags & CYG_TTY_OUT_FLAGS_CRLF)) {
>              xbuf[size++] = '\r';
> @@ -177,18 +176,17 @@ tty_write(cyg_io_handle_t handle, const 
>          // Always leave room for possible CR/LF expansion
>          if ((size >= (BUFSIZE-1)) ||
>              (bytes_successful == *len)) {
>              res = cyg_io_write(chan, xbuf, &size);
>              if (res != ENOERR) {
> -                *len = actually_written;
> +                *len = bytes_successful-size;
>                  return res;
>              }
> -            actually_written += size;
>              size = 0;
>          }
>      }
> -    *len = actually_written;
> +    *len = bytes_successful;
>      return res;
>  }
>  
>  static Cyg_ErrNo 
>  tty_read(cyg_io_handle_t handle, void *_buf, cyg_uint32 *len)
> 
> 
> Jifl
> -- 
> Red Hat, Rustat House, Clifton Road, Cambridge, UK. Tel: +44 (1223) 271062
> Maybe this world is another planet's Hell -Aldous Huxley || Opinions==mine
> 
> -- 
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> and search the list archive: http://sources.redhat.com/ml/ecos-discuss
> 
> 



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