113 lines
1.9 KiB
C
113 lines
1.9 KiB
C
/* -*- linux-c -*- ------------------------------------------------------- *
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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* Copyright 2007 rPath, Inc. - All Rights Reserved
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*
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* This file is part of the Linux kernel, and is made available under
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* the terms of the GNU General Public License version 2.
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*
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* ----------------------------------------------------------------------- */
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/*
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* arch/i386/boot/tty.c
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*
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* Very simple screen I/O
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* XXX: Probably should add very simple serial I/O?
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*/
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#include "boot.h"
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/*
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* These functions are in .inittext so they can be used to signal
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* error during initialization.
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*/
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void __attribute__((section(".inittext"))) putchar(int ch)
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{
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unsigned char c = ch;
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if (c == '\n')
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putchar('\r'); /* \n -> \r\n */
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/* int $0x10 is known to have bugs involving touching registers
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it shouldn't. Be extra conservative... */
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asm volatile("pushal; pushw %%ds; int $0x10; popw %%ds; popal"
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: : "b" (0x0007), "c" (0x0001), "a" (0x0e00|ch));
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}
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void __attribute__((section(".inittext"))) puts(const char *str)
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{
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int n = 0;
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while (*str) {
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putchar(*str++);
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n++;
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}
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}
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/*
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* Read the CMOS clock through the BIOS, and return the
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* seconds in BCD.
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*/
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static u8 gettime(void)
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{
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u16 ax = 0x0200;
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u16 cx, dx;
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asm("int $0x1a"
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: "+a" (ax), "=c" (cx), "=d" (dx)
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: : "ebx", "esi", "edi");
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return dx >> 8;
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}
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/*
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* Read from the keyboard
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*/
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int getchar(void)
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{
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u16 ax = 0;
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asm("int $0x16" : "+a" (ax));
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return ax & 0xff;
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}
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static int kbd_pending(void)
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{
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u8 pending;
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asm("int $0x16; setnz %0"
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: "=rm" (pending)
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: "a" (0x0100));
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return pending;
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}
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void kbd_flush(void)
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{
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for (;;) {
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if (!kbd_pending())
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break;
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getchar();
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}
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}
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int getchar_timeout(void)
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{
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int cnt = 30;
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int t0, t1;
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t0 = gettime();
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while (cnt) {
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if (kbd_pending())
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return getchar();
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t1 = gettime();
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if (t0 != t1) {
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cnt--;
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t0 = t1;
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}
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}
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return 0; /* Timeout! */
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}
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