Unbufferred file I/O

[Ben Smith]

In article <2961 at crash.cts.com> cline at pnet01.cts.com (Ben Humphreys) writes:
| As I have not been able to get any versions of talk to run on my SCO system, I
| was forced to use write.  But write is a bummer because it is bufferred.  

The I/O has to be set to "cbreak" mode. See the termio  & ioctl sections of your
UNIX manual.  The following program demonstrates the use of "cbreak":

/* 1ch - sets terminal echo off and does decimal code echo of each keypress
   until newline is received  - ben smith (uunet!idsnh!ben) - this program
   is being placed in the public domain by the author (bss) */

#include <stdio.h>
#include <termio.h>

char *descr[33] /* control character descriptions */
	=	{
		"   NULL",
		"^A SOH ",
		"^B STX ",
		"^C ETX ",
		"^D EOT ",
		"^E ENQ ",
		"^F ACK ",
		"^G BEL ",
		"^H BS  ",
		"^I HT  ",
		"^J LF  ",
		"^K VT  ",
		"^L FF  ",
		"^M CR  ",
		"^N SO  ",
		"^O SI  ",
		"^P DLE ",
		"^Q DC1 ",
		"^R DC2 ",
		"^S DC3 ",
		"^T DC4 ",
		"^U NAK ",
		"^V SYN ",
		"^W ETB ",
		"^X CAN ",
		"^Y EM  ",
		"^Z SUB ",
		"^[ ESC ",
		"^\\ FS  ",
		"^] GS  ",
		"^^ RS  ",
		"   SP  "
		};

main()
{
int inchar, c;
struct termio old, new;

/* save old terminal config */
ioctl(0,TCGETA,&old);

/* set up new terminal config */
/* first make a copy to modify */
ioctl(0,TCGETA,&new);
/* then AND the controls */
new.c_lflag &= !(ICANON);
new.c_cc[4] = new.c_cc[5] = '\01';  /* delay and buffer size */
/* and send out new config */
ioctl(0,TCSETAW,&new);

/* now for the real part of the program - processing the keypresses */
do
	{
	c = getchar();
	if ((c > 32 && c < 127) || (c > 160 && c < 255))
		printf("decimal %3d   octal %3o   hex %2X = %c\n",c,c,c,c);
	else if (c >= 0 && c <= 32)
		printf("decimal %3d   octal %3o   hex %2X = %s\n",c,c,c,descr[c]);
	else if (c >= 128 && c <= 160)
		printf("decimal %3d   octal %3o   hex %2X = %s\n",
			c,c,c,descr[c-128]);
	else if (c == 127 || c == 255)
		printf("decimal %3d   octal %3o   hex %2X = DEL\n",c,c,c);
	}while (c != '\n');

/* reinstate old parameters before leaving */
ioctl(0,TCSETAW,&old);
}