From: Adam Shelly <adam.shelly@...>
Date: 2007-10-04T15:34:08+09:00
Subject: Re: Non-blocking 'gets' ?

On 10/3/07, Stephen Ware <sgware@gmail.com> wrote:
> Is there a way to perform a non-blocking gets or getc?  As in a method
> that reads a character from stdin if there is one in the buffer or
> returns nil otherwise?

If I was programming a Windows console app in C, I would use kbhit()
to check if there was a character in the buffer.   So I decided this
was a good time to try writing my first ruby c extension.

on Windows, save and complie conio.c into conio.dll, and then the
following example should work.
-Adam

--- test_conio.rb ---
require 'conio'
#background work:
  Thread.new { print('.') or sleep(1) while true }
#check for input in this thread
  Thread.new do
    while 1
      while !CONIO::kbhit?; end  #--wait for key, nonblocking
     #s = STDIN::getc            #--this blocks until return pressed
      s = CONIO::getch           #--this doesn't
      p "#{s} (#{s.chr})"
      exit if s==?q
    end
  end
#do some foreground work
  puts("waiting") or sleep(10) while 1

---
---conio.c---
/* conio.c -- Windows conio functions
   3 Oct 2007, Adam Shelly
   Ruby license applies
 */
#include "ruby.h"
#include <conio.h>

static VALUE c_kbhit(VALUE self)
{
	return _kbhit()? Qtrue : Qfalse;
}

static VALUE c_getch(VALUE self)
{
	int n = _getch();
	return INT2FIX(n);
}
static VALUE c_ungetch(VALUE self, VALUE cv)
{
	int c = FIX2INT(cv);
	int n = _ungetch(c);
	return INT2FIX(n);
}

VALUE mConio;

__declspec( dllexport ) void Init_conio()
{
 mConio = rb_define_module("CONIO");
 rb_define_module_function(mConio, "kbhit?", c_kbhit, 0);
 rb_define_module_function(mConio, "getch", c_getch, 0);
 rb_define_module_function(mConio, "ungetch", c_ungetch, 1);
}