| 1 | ; ----------------------------------------------------------------------- |
|---|
| 2 | ; |
|---|
| 3 | ; Copyright 1999-2008 H. Peter Anvin - All Rights Reserved |
|---|
| 4 | ; |
|---|
| 5 | ; This program is free software; you can redistribute it and/or modify |
|---|
| 6 | ; it under the terms of the GNU General Public License as published by |
|---|
| 7 | ; the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, |
|---|
| 8 | ; Boston MA 02110-1301, USA; either version 2 of the License, or |
|---|
| 9 | ; (at your option) any later version; incorporated herein by reference. |
|---|
| 10 | ; |
|---|
| 11 | ; ----------------------------------------------------------------------- |
|---|
| 12 | |
|---|
| 13 | ; |
|---|
| 14 | ; localboot.inc |
|---|
| 15 | ; |
|---|
| 16 | ; Boot from a local disk, or invoke INT 18h. |
|---|
| 17 | ; |
|---|
| 18 | |
|---|
| 19 | ; |
|---|
| 20 | ; Boot a specified local disk. AX specifies the BIOS disk number; or |
|---|
| 21 | ; -1 in case we should execute INT 18h ("next device.") |
|---|
| 22 | ; |
|---|
| 23 | section .text16 |
|---|
| 24 | |
|---|
| 25 | local_boot: |
|---|
| 26 | call vgaclearmode |
|---|
| 27 | RESET_STACK_AND_SEGS dx ; dx <- 0 |
|---|
| 28 | mov fs,dx |
|---|
| 29 | mov gs,dx |
|---|
| 30 | mov si,localboot_msg |
|---|
| 31 | call writestr |
|---|
| 32 | call cleanup_hardware |
|---|
| 33 | cmp ax,-1 |
|---|
| 34 | je .int18 |
|---|
| 35 | |
|---|
| 36 | ; Load boot sector from the specified BIOS device and jump to it. |
|---|
| 37 | mov dl,al |
|---|
| 38 | xor dh,dh |
|---|
| 39 | push dx |
|---|
| 40 | xor ax,ax ; Reset drive |
|---|
| 41 | int 13h |
|---|
| 42 | mov ax,0201h ; Read one sector |
|---|
| 43 | mov cx,0001h ; C/H/S = 0/0/1 (first sector) |
|---|
| 44 | mov bx,trackbuf |
|---|
| 45 | mov bp,retry_count |
|---|
| 46 | .again: |
|---|
| 47 | pusha |
|---|
| 48 | int 13h |
|---|
| 49 | popa |
|---|
| 50 | jnc .ok |
|---|
| 51 | dec bp |
|---|
| 52 | jnz .again |
|---|
| 53 | jmp kaboom ; Failure... |
|---|
| 54 | .ok: |
|---|
| 55 | pop dx |
|---|
| 56 | cli ; Abandon hope, ye who enter here |
|---|
| 57 | mov si,trackbuf |
|---|
| 58 | mov di,07C00h |
|---|
| 59 | mov cx,512 ; Probably overkill, but should be safe |
|---|
| 60 | rep movsd |
|---|
| 61 | mov ss,cx ; SS <- 0 |
|---|
| 62 | mov sp,7C00h |
|---|
| 63 | jmp 0:07C00h ; Jump to new boot sector |
|---|
| 64 | |
|---|
| 65 | .int18: |
|---|
| 66 | int 18h ; Hope this does the right thing... |
|---|
| 67 | jmp kaboom ; If we returned, oh boy... |
|---|
| 68 | |
|---|
| 69 | section .data16 |
|---|
| 70 | localboot_msg db 'Booting from local disk...', CR, LF, 0 |
|---|
| 71 | |
|---|
| 72 | section .text16 |
|---|
| 73 | |
|---|
