linux/arch/x86/boot/tty.c
Steven Rostedt 5cf02b7baf x86: use limited register constraint for setnz
Impact: build fix with certain compilers

GCC can decide to use %dil when "r" is used, which is not valid for
setnz.

This bug was brought out by Stephen Rothwell's merging of the
branch tracer into linux-next.

[ Thanks to Uros Bizjak for recommending 'q' over 'Q' ]

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-25 15:38:03 +01:00

111 lines
1.9 KiB
C

/* -*- linux-c -*- ------------------------------------------------------- *
*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright 2007 rPath, Inc. - All Rights Reserved
*
* This file is part of the Linux kernel, and is made available under
* the terms of the GNU General Public License version 2.
*
* ----------------------------------------------------------------------- */
/*
* Very simple screen I/O
* XXX: Probably should add very simple serial I/O?
*/
#include "boot.h"
/*
* These functions are in .inittext so they can be used to signal
* error during initialization.
*/
void __attribute__((section(".inittext"))) putchar(int ch)
{
unsigned char c = ch;
if (c == '\n')
putchar('\r'); /* \n -> \r\n */
/* int $0x10 is known to have bugs involving touching registers
it shouldn't. Be extra conservative... */
asm volatile("pushal; pushw %%ds; int $0x10; popw %%ds; popal"
: : "b" (0x0007), "c" (0x0001), "a" (0x0e00|ch));
}
void __attribute__((section(".inittext"))) puts(const char *str)
{
int n = 0;
while (*str) {
putchar(*str++);
n++;
}
}
/*
* Read the CMOS clock through the BIOS, and return the
* seconds in BCD.
*/
static u8 gettime(void)
{
u16 ax = 0x0200;
u16 cx, dx;
asm volatile("int $0x1a"
: "+a" (ax), "=c" (cx), "=d" (dx)
: : "ebx", "esi", "edi");
return dx >> 8;
}
/*
* Read from the keyboard
*/
int getchar(void)
{
u16 ax = 0;
asm volatile("int $0x16" : "+a" (ax));
return ax & 0xff;
}
static int kbd_pending(void)
{
u8 pending;
asm volatile("int $0x16; setnz %0"
: "=qm" (pending)
: "a" (0x0100));
return pending;
}
void kbd_flush(void)
{
for (;;) {
if (!kbd_pending())
break;
getchar();
}
}
int getchar_timeout(void)
{
int cnt = 30;
int t0, t1;
t0 = gettime();
while (cnt) {
if (kbd_pending())
return getchar();
t1 = gettime();
if (t0 != t1) {
cnt--;
t0 = t1;
}
}
return 0; /* Timeout! */
}