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|
; -----------------------------------------------------------------------
;
; Copyright 2010 Gene Cumm
;
; Portions from diskstart.inc:
; Copyright 1994-2009 H. Peter Anvin - All Rights Reserved
; Copyright 2009-2010 Intel Corporation; author: H. Peter Anvin
;
; This program is free software; you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
; Boston MA 02110-1301, USA; either version 2 of the License, or
; (at your option) any later version; incorporated herein by reference.
;
; -----------------------------------------------------------------------
;
; geodsp1s.asm
;
; Display geometry translation info for diagnosing misconceptions
; 1 sector variant
;
; nasm -Ox -f bin -o geodsp.bin -l geodsp.lst geodsp.asm
;
; nasm -Ox -f elf -o geodsp.o -l geodsp.lst geodsp.asm
; ld -m elf_i386 -T syslinux.ld -M -o geodsp.elf geodsp.o > geodsp.map
; objcopy -O binary geodsp.elf geodsp.raw
;
; # OF=/dev/sdb
; # dd if=core/geodsp.bin of=$OF
; # dd skip=1 seek=1 if=../dbg/lba-img/lba-img.bin of=$OF
; # eject $OF
; # dd count=$() if=/dev/zero of=$OF
;
; # OF=geo-2.255.63.i
; # (dd if=core/geodsp.bin; dd skip=1 if=../dbg/lba-img/lba-img.bin; dd count=$((2*255*63 - 256*63 - 1)) if=/dev/zero )|dd of=$OF
; # OF=geo-20.16.63.i
; # (dd if=core/geodsp.bin; dd skip=1 if=../dbg/lba-img/lba-img.bin; dd count=$((40*16*63 - 256*63 - 1)) if=/dev/zero )|dd of=$OF
;
%include "macros.inc"
; %include "layout.inc"
; global STACK_LEN, STACK_TOP, STACK_BASE
; STACK_LEN equ 4096
STACK_TOP equ 7c00h
; STACK_BASE equ STACK_TOP - STACK_LEN
StackBuf equ STACK_TOP-44-92 ; Start the stack here (grow down - 4K)
DriveNumber equ StackBuf-4 ; Drive number
m_CHS0 equ 00534843h ;'CHS',0
m_EDD0 equ 00444445h ;'EDD',0
m_EDD_SP equ 20444445h ;'EDD '
retry_count equ 16
dbuf equ 8000h
int13_ret equ 7e00h
; extern real_mode_seg
; section .real_mode write nobits align=65536
; global core_real_mode
; core_real_mode resb 65536
; extern xfer_buf_seg
; section .xfer_buf write nobits align=65536
; global core_xfer_buf
; core_xfer_buf resb 65536
section .text
org STACK_TOP
global _start
bootsec equ $
_start:
; In case we want to pull more of the standard diskstart stuff in
; jmp short start ; 2 bytes
; nop ; 1 byte
start:
cli
cld
xor cx,cx
mov ss,cx
mov sp,StackBuf-2 ; Just below BSS (-2 for alignment)
push dx ; Save drive number (in DL)
; Kill everything else and let the BIOS sort it out later
mov es,cx
mov ds,cx
sti
get_geo: ; DL and ES ready
mov ah,08h
mov di,0
int 13h
write_geo:
jc .bad_geo
mov si,s_chs
call writestr_early
call write_chs
call crlf
jmp short .done
.bad_geo:
.done:
mov bx,dbuf
get_h1c: ; 0,1,1
mov cx,0001h
mov dh,01h
call getonesec_chs
call write_chs_lba
get_c1c: ; 1,0,1
mov cx,0101h
mov dh,00h
call getonesec_chs
call write_chs_lba
;
; Do we have EBIOS (EDD)?
;
edd:
.check:
mov bx,55AAh
mov ah,41h ; EDD existence query
mov dl,[DriveNumber]
int 13h
jc .noedd
cmp bx,0AA55h
jne .noedd
test cl,1 ; Extended disk access functionality set
jz .noedd
;
; We have EDD support...
;
mov bx,dbuf
xor edx,edx
mov dword [s_chs],m_EDD_SP
.get_lba63:
mov eax,63 ; Same length as mov al,64; movzx eax,al
call getonesec_ebios
jc .bad_edd ;read error
call write_edd_lba
.get_lba16065:
mov eax,16065
call getonesec_ebios
jc .bad_edd ;read error
call write_edd_lba
.good_edd:
mov dword [s_type],m_EDD0
.bad_edd:
.noedd:
.end:
write_final_type:
mov si,s_typespec
call writestr_early
jmp short kaboom
;
; getonesec_ebios:
;
; getonesec implementation for EBIOS (EDD)
;
getonesec_ebios:
mov cx,retry_count
.retry:
; Form DAPA on stack
push edx
push eax
push es
push bx
push word 1
push word 16
mov si,sp
pushad
mov ah,42h ; Extended Read
call xint13
popad
lea sp,[si+16] ; Remove DAPA
jc .error
ret
.error:
; Some systems seem to get "stuck" in an error state when
; using EBIOS. Doesn't happen when using CBIOS, which is
; good, since some other systems get timeout failures
; waiting for the floppy disk to spin up.
pushad ; Try resetting the device
xor ax,ax
call xint13
popad
loop .retry ; CX-- and jump if not zero
; Total failure.
stc
ret
;
; getonesec_chs:
;
; CX,DH specifies CHS address
;
getonesec_chs: ; We could use an xchg and get a loop
; mov cx,retry_count
.retry:
pushad
mov ax,0201h ; Read one sector
call xint13
popad
jc .error
ret
.error:
; loop .retry
; Fall through to disk_error
;
; kaboom: write a message and bail out.
;
global kaboom
disk_error:
kaboom:
.patch:
mov si,bailmsg
call writestr_early
xor eax,eax
.again: int 16h ; Wait for keypress
; NB: replaced by int 18h if
; chosen at install time..
int 19h ; And try once more to boot...
.norge: hlt ; If int 19h returned; this is the end
jmp short .norge
;
; INT 13h wrapper function
;
xint13:
mov dl,[DriveNumber]
int 13h
mov [int13_ret],ax
ret
;
;
; writestr_early: write a null-terminated string to the console
; This assumes we're on page 0. This is only used for early
; messages, so it should be OK.
;
writestr_early:
pushad
.loop: lodsb
and al,al
jz .return
call writechr
jmp short .loop
.return: popad
ret
%include "geodsplib.inc"
bailmsg equ s_end
; This fails if the boot sector overflowsg
zb 1BEh-($-$$)
ptable zb 40h ; Partition table
bootsignature dw 0xAA55
sector_2:
|
