Make awaitkey() poll once even if the timeout is 0. This also fixes a problem

where a keypress within the last polling interval would not be noticed.
Add a new function, conisshift(), which is used to detect whether a shift key
is pressed.  Use this via awaitkey() to allow interrupting the boot by holding
down shift (similar to LILO).

This allows setting the timeout to 0 and still being able to use the boot
program.

sys/arch/i386/stand/lib/conio.S

@@ -1,4 +1,4 @@
-/*	$NetBSD: conio.S,v 1.2 2003/02/01 14:48:18 dsl Exp $	*/
+/*	$NetBSD: conio.S,v 1.3 2005/01/27 18:20:45 mycroft Exp $	*/
 
 /* PC console handling
   originally from: FreeBSD:sys/i386/boot/netboot/start2.S
@@ -71,7 +71,38 @@ ENTRY(congetc)
 	ret
 
 /**************************************************************************
-ISKEY - Check for keyboard interrupt
+ISSHIFT - Check for keyboard interrupt; via shift key
+**************************************************************************/
+ENTRY(conisshift)
+	push	%ebp
+	mov	%esp,%ebp
+	push	%ebx
+	push	%esi
+	push	%edi
+
+	call	_C_LABEL(prot_to_real)	# enter real mode
+	.code16
+
+	xor	%bx,%bx
+	movb	$0x2,%ah
+	int	$0x16
+	testb	$3,%al
+	setnz	%bl
+
+	calll	_C_LABEL(real_to_prot) # back to protected mode
+	.code32
+
+	xor	%eax,%eax
+	movb	%bl,%al
+
+	pop	%edi
+	pop	%esi
+	pop	%ebx
+	pop	%ebp
+	ret
+
+/**************************************************************************
+ISKEY - Check for keyboard input
 **************************************************************************/
 ENTRY(coniskey)
 	push	%ebp
@@ -86,10 +117,7 @@ ENTRY(coniskey)
 	xor	%bx,%bx
 	movb	$0x1,%ah
 	int	$0x16
-	movb	$0,%bl
+	setnz	%bl
-	jz	1f
-	incb	%bl
-1:
 
 	calll	_C_LABEL(real_to_prot) # back to protected mode
 	.code32

sys/arch/i386/stand/lib/libi386.h

@@ -1,4 +1,4 @@
-/*	$NetBSD: libi386.h,v 1.17 2004/08/23 09:41:59 junyoung Exp $	*/
+/*	$NetBSD: libi386.h,v 1.18 2005/01/27 18:20:45 mycroft Exp $	*/
 
 /*
  * Copyright (c) 1996
@@ -64,7 +64,7 @@ void initio(int);
 #define CONSDEV_COM2KBD 7
 #define CONSDEV_COM3KBD 8
 #define CONSDEV_AUTO (-1)
-int iskey(void);
+int iskey(int);
 char awaitkey(int, int);
 
 /* this is in "user code"! */
@@ -108,6 +108,7 @@ void cominit(int);
 int computc(int, int);
 int comstatus(int);
 int congetc(void);
+int conisshift(void);
 int coniskey(void);
 void conputc(int);
 

sys/arch/i386/stand/lib/pcio.c

@@ -1,4 +1,4 @@
-/*	$NetBSD: pcio.c,v 1.18 2004/08/15 22:04:45 dsl Exp $	 */
+/*	$NetBSD: pcio.c,v 1.19 2005/01/27 18:20:45 mycroft Exp $	 */
 
 /*
  * Copyright (c) 1996, 1997
@@ -40,6 +40,7 @@
 
 extern void conputc __P((int));
 extern int congetc __P((void));
+extern int conisshift __P((void));
 extern int coniskey __P((void));
 extern struct x86_boot_params boot_params;
 
@@ -282,14 +283,14 @@ getchar()
 }
 
 int
-iskey()
+iskey(int intr)
 {
 #ifdef SUPPORT_SERIAL
 	switch (iodev) {
 	    default: /* to make gcc -Wall happy... */
 	    case CONSDEV_PC:
 #endif
-		return (coniskey());
+		return ((intr && conisshift()) || coniskey());
 #ifdef SUPPORT_SERIAL
 	    case CONSDEV_COM0:
 	    case CONSDEV_COM1:
@@ -313,7 +314,7 @@ awaitkey(timeout, tell)
 
 	i = timeout * POLL_FREQ;
 
-	while (i) {
+	for (;;) {
 		if (tell && (i % POLL_FREQ) == 0) {
 			char numbuf[20];
 			int len, j;
@@ -325,16 +326,18 @@ awaitkey(timeout, tell)
 			numbuf[len + j] = '\0';
 			printf(numbuf);
 		}
-		if (iskey()) {
+		if (iskey(1)) {
 			/* flush input buffer */
-			while (iskey())
+			while (iskey(0))
 				c = getchar();
 			if (c == 0)
 				c = -1;
 			goto out;
 		}
-		delay(1000000 / POLL_FREQ);
+		if (i--)
-		i--;
+			delay(1000000 / POLL_FREQ);
+		else
+			break;
 	}
 
 out: