absolute 0484h
BIOS_vidrows resb 1 ; Number of screen rows
- absolute 0600h
+;
+; Memory below this point is reserved for the BIOS and the MBR
+;
+ absolute 1000h
trackbuf equ $ ; Track buffer goes here
trackbufsize equ 16384 ; Safe size of track buffer
-; trackbuf ends at 4600h
+; trackbuf ends at 5000h
absolute 6000h ; Here we keep our BSS stuff
-StackBuf equ $ ; Start the stack here (grow down)
+StackBuf equ $ ; Start the stack here (grow down - 4K)
VKernelBuf: resb vk_size ; "Current" vkernel
alignb 4
AppendBuf resb max_cmd_len+1 ; append=
+KbdMap resb 256 ; Keyboard map
FKeyName resb 10*16 ; File names for F-key help
NumBuf resb 16 ; Buffer to load number
NumBufEnd equ NumBuf+15 ; Pointer to last byte in NumBuf
start:
cli ; No interrupts yet, please
- jmp 0:start1 ; Stupid Intel BIOS jumps to 07C0:0000 not 0000:7C00
-start1: xor ax,ax
- mov ds,ax
- mov es,ax
+ jmp 0:start1 ; Some stupid BIOSes jumps to 07C0:0000 not 0000:7C00
+start1:
+;
+; Set up ES and SS, and the stack
+;
+ xor ax,ax
mov ss,ax
mov sp,StackBuf ; Just below BSS
;
+; DS:SI may contain a partition table entry. Preserve it for us.
+;
+ mov dh,[si] ; "Active flag" (sanity check)
+ mov bp,[si+8] ; LSW of linear offset
+ mov bx,[si+10] ; MSW of linear offset
+
; Now sautee the BIOS floppy info block to that it will support decent-
; size transfers; the floppy block is 11 bytes and is stored in the
; INT 1Eh vector (brilliant waste of resources, eh?)
; Of course, if BIOSes had been properly programmed, we wouldn't have
; had to waste precious boot sector space with this code.
;
- mov bx,fdctab
- lds si,[ss:bx] ; DS:SI -> original
+; This code no longer fits. Hope that noone really needs it anymore.
+;
+%ifdef SUPPORT_BROKEN_BIOSES
+ lds si,[ss:fdctab] ; DS:SI -> original
push ds ; Save on stack in case
push si ; we have to bail
push bx
mov ds,ax ; Now we can point DS to here, too
mov cl,[bsSecPerTrack] ; Patch the sector count
mov [di+4],cl
-; mov byte ptr [di+9],0Fh ; I have no clue what this does???
- mov [bx+2],ax ; Segment 0
- mov [bx],di ; offset floppy_block
+ mov [fdctab+2],ax ; Segment 0
+ mov [fdctab],di ; offset floppy_block
+%else
+ mov ds,ax
+%endif
;
; Ready to enable interrupts, captain
;
sti
;
-; Reset floppy system to load new parameter block
+; Reset floppy system
;
xor dx,dx
int 13h ; AH = 00h already
;
+; The drive number and possibly partition information was passed to us
+; by the BIOS or previous boot loader (MBR). Current "best practice" is to
+; trust that rather than what the superblock contains.
+;
+; Would it be better to zero out bsHidden if we don't have a partition table?
+;
+ push dx
+ mov [bsDriveNumber],dl
+ test dl,80h ; If floppy disk (00-7F), assume no
+ jz not_harddisk ; partition table
+ test dh,7Fh ; Sanity check: "active flag" should
+ jnz no_partition ; be 00 or 80
+ mov [bsHidden1],bp
+ mov [bsHidden2],bx
+no_partition:
+;
+; Get disk drive parameters (don't trust the superblock.) Don't do this for
+; floppy drives -- INT 13:08 on floppy drives will return info about what the
+; *drive* supports, not about the *media*...
+;
+ pop dx ; Restore DL = drive #
+ mov ah,08h
+ int 13h
+ jc no_driveparm
+ and ah,ah
+ jnz no_driveparm
+ inc dh ; Contains # of heads - 1
+ mov [bsHeads],dh
+ and cx,3fh
+ mov [bsSecPerTrack],cx
+no_driveparm:
+not_harddisk:
+;
; Now we have to do some arithmetric to figure out where things are located.
; If Microsoft had had brains they would already have done this for us,
; and stored it in the superblock at format time, but here we go,
; wasting precious boot sector space again...
;
debugentrypt:
- mov al,[bsFATs] ; Number of FATs
- jmpc kaboom ; If the floppy init failed
- ; (too far to be above the mov)
- cbw ; Clear AH (we WILL have < 128 FATs)
+ xor si,si ; Some BIOSes destroy ES for INT 13:08
+ mov es,si ; so we clear it this late
+
+ mov al,[bsFATs] ; Number of FATs (AH == 0)
+ jc kaboom ; If the floppy init failed
mul word [bsFATsecs] ; Get the size of the FAT area
add ax,[bsHidden1] ; Add hidden sectors
adc dx,[bsHidden2]
- add ax,[bsResSectors] ; And reserved sectors (why two?)
- adc dx,byte 0
+ add ax,[bsResSectors] ; And reserved sectors
+ adc dx,si ; SI == 0
mov [RootDir1],ax ; Location of root directory
mov [RootDir2],dx
mov [EndofDirSec],bx ; End of a single directory sector
add [DataArea1],ax
- adc word [DataArea2],byte 0
+ adc word [DataArea2],si ; SI == 0
pop dx ; Reload root directory starting point
pop ax
; kaboom: write a message and bail out.
;
kaboom:
- mov si,bailmsg
- call writestr ; Returns with AL = 0
- cbw ; Sets AH = 0 (shorter than XOR)
- int 16h ; Wait for keypress
mov sp,StackBuf-2*3 ; Reset stack
pop si ; BIOS floppy block address
cli
pop word [si] ; Restore location
pop word [si+2]
sti
- int 19h ; And try once more to boot...
+; mov si,bailmsg
+; call writestr ; Returns with AL = 0
+; cbw ; AH <- 0
+; int 16h ; Wait for keypress
+; int 19h ; And try once more to boot...
+ int 18h ; Bail. Hope this does something useful.
norge: jmp short norge ; If int 19h returned; this is the end
;
disk_error: dec si ; SI holds the disk retry counter
jz kaboom
xchg ax,bx ; Shorter than MOV
- pop bx
- pop cx
- pop dx
+ pop bx ; <I>
+ pop cx ; <H>
+ pop dx ; <G>
jmp short disk_try_again
;
; getonesec: like getlinsec, but pre-sets the count to 1
; On return, BX points to the first byte after the transferred
; block.
;
+; When compiling with the STUPID option, this is replaced by a
+; routine which loads one sector at a time.
+;
getlinsec:
mov si,[bsSecPerTrack]
div si ; Convert linear to sector/track
xor dx,dx ; 32-bit track number
div word [bsHeads] ; Convert track to head/cyl
;
- ; Now we have AX = cyl, DX = head, CX = sector (0-based)
- ; for the very first sector, SI = bsSecPerTrack
+ ; Now we have AX = cyl, DX = head, CX = sector (0-based),
+ ; BP = sectors to transfer, SI = bsSecPerTrack,
+ ; ES:BX = data target
;
-gls_nexttrack: push si
- push bp
+gls_nextchunk: push si ; <A> bsSecPerTrack
+ push bp ; <B> Sectors to transfer
+%ifdef STUPID
+ mov bp,1
+ nop ; Minimize size of patch
+ nop
+ nop
+ nop
+ nop
+%else
sub si,cx ; Sectors left on track
cmp bp,si
- jna gls_lasttrack
+ jna gls_lastchunk
mov bp,si ; No more than a trackful, please!
-gls_lasttrack: push ax ; Cylinder #
- push dx ; Head #
- push bp ; Number of sectors we're transferring
+gls_lastchunk:
+%endif
+ push ax ; <C> Cylinder #
+ push dx ; <D> Head #
+ push bp ; <E> Number of sectors we're transferring
- push cx
+ push cx ; <F> Sector #
mov cl,6 ; Because IBM was STOOPID
shl ah,cl ; and thought 8 bits were enough
; then thought 10 bits were enough...
- pop cx ; Sector #
+ pop cx ; <F> Sector #
+ push cx
inc cx ; Sector numbers are 1-based
or cl,ah
mov ch,al
; Do the disk transfer... save the registers in case we fail :(
;
mov si,retry_count ; # of times to retry a disk access
-disk_try_again: push dx
- push cx
- push bx
- push ax
- push si
+disk_try_again: push dx ; <G>
+ push cx ; <H>
+ push bx ; <I>
+ push ax ; <J>
+ push si ; <K>
int 13h
- pop si
- pop bx
+ pop si ; <K>
+ pop bx ; <J>
jc disk_error
;
-; It seems the following test fails on some machines (buggy BIOS?)
-; Especially Phoenix BIOS 4.03 seems to fail if this is enabled
-;
-; cmp al,bl ; Check that we got what we asked for
-; jne disk_error
-;
; Disk access successful
;
- pop bx ; Buffer location
- pop si ; Not needed anymore
- pop si ; Neither is this
- pop si ; Sector transferred count
- mov ax,si ; Reduce sector left count
+ pop bx ; <I> Buffer location
+ pop ax ; <H> No longer needed
+ pop ax ; <G> No longer needed
+ pop cx ; <F> Sector #
+ pop di ; <E> Sector transferred count
+ mov ax,di ; Reduce sector left count
mul word [bsBytesPerSec] ; Figure out how much to advance ptr
add bx,ax ; Update buffer location
- pop dx ; Head #
- pop ax ; Cyl #
+ pop dx ; <D> Head #
+ pop ax ; <C> Cyl #
+ pop bp ; <B> Sectors left to transfer
+ pop si ; <A> Number of sectors/track
+ sub bp,di ; Reduce with # of sectors just read
+ jz return ; Done!
+ add cx,di
+ cmp cx,si
+ jb gls_nextchunk
inc dx ; Next track on cyl
cmp dx,[bsHeads] ; Was this the last one?
jb gls_nonewcyl
inc ax ; If so, new cylinder
xor dx,dx ; First head on new cylinder
-gls_nonewcyl: pop bp ; Sectors left to transfer
- xor cx,cx ; First sector on new track
- sub bp,si ; Reduce with # of sectors just read
- pop si
- ja gls_nexttrack
+gls_nonewcyl: sub cx,si ; First sector on new track
+ jmp short gls_nextchunk
return: ret
-bailmsg db 'Boot failed: press any key to retry', 0Dh, 0Ah, 0
+; bailmsg db 'Error!', 0Dh, 0Ah, 0
bs_checkpt equ $ ; Must be <= 1E3h
; they probably won't be trying to install Linux on them...
;
; The code is still ripe with 16-bitisms, though. Not worth the hassle
-; to take'm out.
+; to take'm out. In fact, we may want to put them back if we're going
+; to boot ELKS at some point.
;
mov si,linuxauto_cmd ; Default command: "linux auto"
mov di,default_cmd
mov cx,linuxauto_len
rep movsb
+
+ mov di,KbdMap ; Default keymap 1:1
+ xor al,al
+ mov cx,256
+mkkeymap: stosb
+ inc al
+ loop mkkeymap
+
;
; Load configuration file
;
je near pc_prompt
cmp ax,'fo' ; FOnt
je near pc_font
+ cmp ax,'kb' ; KBd
+ je near pc_kbd
cmp ax,'di' ; DIsplay
je near pc_display
cmp ax,'la' ; LAbel
mov [KbdTimeOut],bx
jmp short parse_config_2
-pc_display: mov di,trackbuf
- push di
- call getline ; Get filename to display
- pop si
- mov di,MNameBuf ; Mangled name buffer
- push di
- call mangle_name ; Mangle file name
- pop di
- call searchdir ; Search for file
+pc_display: call pc_getfile ; "display" command
jz parse_config_2 ; File not found?
call get_msg_file ; Load and display file
parse_config_2: jmp parse_config
rep movsb
jmp short parse_config_2
-pc_font: mov di,trackbuf ; "font" command
+pc_font: call pc_getfile ; "font" command
+ jz parse_config_2 ; File not found?
+ call loadfont ; Load and install font
+ jmp short parse_config_3
+
+pc_kbd: call pc_getfile ; "kbd" command
+ jz parse_config_3
+ call loadkeys
+parse_config_3: jmp parse_config
+
+;
+; pc_getfile: For command line options that take file argument, this
+; routine decodes the file argument and runs it through searchdir
+;
+pc_getfile: mov di,trackbuf
push di
- call getline ; Get font filename
+ call getline
pop si
- mov di,MNameBuf ; Mangled name buffer
+ mov di,MNameBuf
push di
- call mangle_name ; Mangle file name
+ call mangle_name
pop di
- call searchdir ; Search for file
- jz parse_config_3 ; File not found?
- call loadfont ; Load and install font
-parse_config_3: jmp parse_config
+ jmp searchdir ; Tailcall
;
; commit_vk: Store the current VKernelBuf into buffer segment
int 16h
and al,al
jz func_key
+ mov bx,KbdMap ; Keyboard map translation
+ xlatb
cmp al,' ' ; ASCII?
jb not_ascii
ja enter_char
jz ac_ret ; If no pending keystroke
xor ax,ax ; Load pending keystroke
int 16h
+ mov bx,KbdMap
+ xlatb
cmp al,27 ; <ESC> aborts (DOS geeks)
je ac2
cmp al,3 ; So does Ctrl-C (UNIX geeks)
jmp short adjust_screen
;
+; loadkeys: Load a LILO-style keymap; SI and DX:AX set by searchdir
+;
+loadkeys:
+ and dx,dx ; Should be 256 bytes exactly
+ jne loadkeys_ret
+ cmp ax,256
+ jne loadkeys_ret
+
+ mov bx,trackbuf
+ mov cx,1 ; 1 cluster should be >= 256 bytes
+ call getfssec
+
+ mov si,trackbuf
+ mov di,KbdMap
+ mov cx,256 >> 2
+ rep movsd
+
+loadkeys_ret: ret
+
+;
; get_msg_file: Load a text file and write its contents to the screen,
; interpreting color codes. Is called with SI and DX:AX
; set by routine searchdir
db 'de' ; default
db 'ti' ; timeout
db 'fo' ; font
+ db 'kb' ; kbd
db 'di' ; display
db 'pr' ; prompt
db 'la' ; label
kern_cmd_len equ ldlinux_end-command_line
ldlinux_len equ ldlinux_end-ldlinux_magic
;
-; Put the FAT right after the code, aligned on a sector boundary
+; Put the getcbuf right after the code, aligned on a sector boundary
;
end_of_code equ (ldlinux_end-bootsec)+7C00h
-FAT equ (end_of_code + 511) & 0FE00h
-;
-; Put getc buffer right after FAT (the FAT buffer is 6K, the max size
-; of a 12-bit FAT)
-;
-getcbuf equ FAT+6*1024
+getcbuf equ (end_of_code + 511) & 0FE00h
projects / profile / ivi / syslinux.git / commitdiff