OpenEuphoria

Re: unbuffered getc() ?

• Posted by tubby.toast at ntlworld.com May 12, 2003
• 396 views

Erm, no.  That won't work through the serial port, or will it?  Sorry, I'm
rubbish at explaining things - it's the serial port I'm trying to read from.

chris.

>
> Did you try get_key() and/or wait_key()?
>
> -- Brian
>
> chris wrote:
> >
> > Hi,
> > I am using Euphoria (2.4 alpha) in Linux to interface with a serial LCD
> > screen and keypad.  Sending output is no problem (once I'd remembered to
> > use
> > flush() ) but I'm having trouble reading from the keypad.  I tried
> > something
> > like the following:
> >
> > integer lcd, key
> >
> > lcd=open("/dev/ttyS1","ub")
> > while 1 do
> >     puts(lcd,{#FE,#26})
> > -- this tells the device to return the contents of its key buffer, or if
> > the
> > -- buffer is empty, to return 0x00
> >     flush(lcd)
> >     key=getc(lcd)  --just locks up here!
> >     print(1,key)
> > end while
> >
> > This doesn't work because according to the Euphoria docs:
> >
> > "File input using getc() is buffered, i.e. getc() does not actually go
> > out
> > to the disk for each character. Instead, a large block of characters
> > will be
> > read in at one time and returned to you one by one from a memory buffer.
> > When getc() reads from the keyboard, it will not see any characters
> > until
> > the user presses Enter. Note that the user can type control-Z, which the
> > operating system treats as "end of file". -1 will be returned. "
> >
> > So it seems that getc() won't return anything until Euphoria sees a line
> > feed or an EOF.  So my question (if you've read this far): how can I get
> > a
> > Euphoria program to read a single byte, immediately and without dealing
> > with
> > buffers, from a file descriptor.  Is there a standard C function I can
> > easily wrap? (I'm not very good with C)
> >
> > I hope that made some sort of sense,
> > chris.
> >
> >
>
>
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