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/* -*- 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.
*
* ----------------------------------------------------------------------- */
/*
* arch/i386/boot/tty.c
*
* 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"
: "=rm" (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! */
}
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