projects / linux-2.6-block.git / blame
| Commit | Line | Data |
|---|---|---|
| 1543610a PA |
1 | /* -*- linux-c -*- ------------------------------------------------------- * |
| 2 | * | |
| 3 | * Copyright (C) 1991, 1992 Linus Torvalds | |
| 4 | * Copyright 2007 rPath, Inc. - All Rights Reserved | |
| 5 | * | |
| 6 | * This file is part of the Linux kernel, and is made available under | |
| 7 | * the terms of the GNU General Public License version 2. | |
| 8 | * | |
| 9 | * ----------------------------------------------------------------------- */ | |
| 10 | ||
| 11 | /* | |
| 1543610a PA |
12 | * Very simple screen I/O |
| 13 | * XXX: Probably should add very simple serial I/O? | |
| 14 | */ | |
| 15 | ||
| 16 | #include "boot.h" | |
| 17 | ||
| 18 | /* | |
| 19 | * These functions are in .inittext so they can be used to signal | |
| 20 | * error during initialization. | |
| 21 | */ | |
| 22 | ||
| 23 | void __attribute__((section(".inittext"))) putchar(int ch) | |
| 24 | { | |
| 25 | unsigned char c = ch; | |
| 26 | ||
| 27 | if (c == '\n') | |
| 28 | putchar('\r'); /* \n -> \r\n */ | |
| 29 | ||
| 30 | /* int $0x10 is known to have bugs involving touching registers | |
| 31 | it shouldn't. Be extra conservative... */ | |
| 8c027ae2 | 32 | asm volatile("pushal; pushw %%ds; int $0x10; popw %%ds; popal" |
| 1543610a PA |
33 | : : "b" (0x0007), "c" (0x0001), "a" (0x0e00|ch)); |
| 34 | } | |
| 35 | ||
| 36 | void __attribute__((section(".inittext"))) puts(const char *str) | |
| 37 | { | |
| 38 | int n = 0; | |
| 39 | while (*str) { | |
| 40 | putchar(*str++); | |
| 41 | n++; | |
| 42 | } | |
| 43 | } | |
| 44 | ||
| 45 | /* | |
| 46 | * Read the CMOS clock through the BIOS, and return the | |
| 47 | * seconds in BCD. | |
| 48 | */ | |
| 49 | ||
| 50 | static u8 gettime(void) | |
| 51 | { | |
| 52 | u16 ax = 0x0200; | |
| 53 | u16 cx, dx; | |
| 54 | ||
| b015124e PA |
55 | asm volatile("int $0x1a" |
| 56 | : "+a" (ax), "=c" (cx), "=d" (dx) | |
| 57 | : : "ebx", "esi", "edi"); | |
| 1543610a PA |
58 | |
| 59 | return dx >> 8; | |
| 60 | } | |
| 61 | ||
| 62 | /* | |
| 63 | * Read from the keyboard | |
| 64 | */ | |
| 65 | int getchar(void) | |
| 66 | { | |
| 67 | u16 ax = 0; | |
| b015124e | 68 | asm volatile("int $0x16" : "+a" (ax)); |
| 1543610a PA |
69 | |
| 70 | return ax & 0xff; | |
| 71 | } | |
| 72 | ||
| 73 | static int kbd_pending(void) | |
| 74 | { | |
| 75 | u8 pending; | |
| b015124e | 76 | asm volatile("int $0x16; setnz %0" |
| 5cf02b7b | 77 | : "=qm" (pending) |
| b015124e | 78 | : "a" (0x0100)); |
| 1543610a PA |
79 | return pending; |
| 80 | } | |
| 81 | ||
| 82 | void kbd_flush(void) | |
| 83 | { | |
| 84 | for (;;) { | |
| 85 | if (!kbd_pending()) | |
| 86 | break; | |
| 87 | getchar(); | |
| 88 | } | |
| 89 | } | |
| 90 | ||
| 91 | int getchar_timeout(void) | |
| 92 | { | |
| 93 | int cnt = 30; | |
| 94 | int t0, t1; | |
| 95 | ||
| 96 | t0 = gettime(); | |
| 97 | ||
| 98 | while (cnt) { | |
| 99 | if (kbd_pending()) | |
| 100 | return getchar(); | |
| 101 | ||
| 102 | t1 = gettime(); | |
| 103 | if (t0 != t1) { | |
| 104 | cnt--; | |
| 105 | t0 = t1; | |
| 106 | } | |
| 107 | } | |
| 108 | ||
| 109 | return 0; /* Timeout! */ | |
| 110 | } |