;
; ****************************************************************************
-; NOTE TO SELF: Last PXELINUX merge pxelinux.asm,v 1.49 2001/04/05 06:20:48 hpa
-; Integrate PXELINUX changes since that version, please
+%macro TRACER 1
+; call debug_tracer
+; db %1
+%endmacro
;
; Some semi-configurable constants... change on your own risk. Most are imposed
KernelSize resd 1 ; Size of kernel (bytes)
RootDir resd 1 ; Root directory location (LBA)
RootDirLen resd 1 ; Root directory length
+RootDirClust resd 1 ; Root directory length in clusters
SavedSSSP resw 1 ; Our SS:SP while running a COMBOOT image
FBytes equ $ ; Used by open/getc
FBytes1 resw 1
PktTimeout resw 1 ; Timeout for current packet
KernelExtPtr resw 1 ; During search, final null pointer
LocalBootType resw 1 ; Local boot return code
-RootDirClust resw 1 ; Root directory length in clusters
TextAttrBX equ $
TextAttribute resb 1 ; Text attribute for message file
TextPage resb 1 ; Active display page
bi_reserved: times 10 dd 0xdeadbeef ; Reserved
_start1: xor ax,ax
- mov es,ax
mov ss,ax
- mov ds,ax
mov sp,_start ; Set up stack
+ mov ds,ax
+ mov es,ax
+ mov fs,ax
+ mov gs,ax
sti
cld
+ ; Show signs of life
+ mov si,isolinux_banner
+ call writestr
+ call crlf ; For now...
+
;
; Before modifying any memory, get the checksum of bytes 64-2048
;
loop .loop
mov [FirstSecSum],edi
- ; Show signs of life
- mov si,isolinux_banner
- call writestr
- call crlf ; For now...
-
; Set up boot file sizes
mov eax,[bi_length]
sub eax,SECTORSIZE-3
call writestr
integrity_ok:
+ mov si,allread_msg
+ call writemsg
jmp all_read ; Jump to main code
- ; INT 13h, AX=4B01h, DL=7Fh failed. Try to scan the entire 80h-FFh from
- ; the end.
+ ; INT 13h, AX=4B01h, DL=7Fh failed. Try to scan the
+ ; entire 80h-FFh from the end.
spec_query_failed:
mov si,spec_err_msg
call writemsg
writechr_simple:
pushfd
- popad
+ pushad
mov ah,0Eh
xor bx,bx
int 10h
verify_msg: db 'Image checksum verified.', CR, LF, 0
checkerr_msg: db 'Load checksum error, goodbye...', CR, LF, 0
diskerr_msg: db 'CD-ROM disk error ', 0
-
+allread_msg db 'Main image read, jumping to main code...', CR, LF, 0
+crlf_msg db CR, LF, 0
alignb 8, db 0
FirstSecSum: dd 0 ; Checksum of bytes 64-2048
; ----------------------------------------------------------------------------
all_read:
- ; Patch the writechr routine to point to the full code
- mov word [writechr+1], writechr_full-(writechr+3)
-
;
; Now, we need to sniff out the actual filesystem data structures.
; mkisofs gave us a pointer to the primary volume descriptor
mov bx,trackbuf
call getonesec
+ mov si,dbg_rootdir_msg ; ***
+ call writemsg ; ***
mov eax,[trackbuf+156+2]
mov [RootDir],eax
+ call writehex8 ; ***
+ call crlf ; ***
mov eax,[trackbuf+156+10]
mov [RootDirLen],eax
add eax,SECTORSIZE-1
shr eax,SECTORSIZE_LG2
- mov [RootDirClust],ax
+ mov [RootDirClust],eax
;
; Initialize screen (if we're using one)
;
-
; Get ROM 8x16 font in case we switch to graphics mode
xor cx,cx
mov ax,1130h
; Now set up screen parameters
call adjust_screen
+ ; Patch the writechr routine to point to the full code
+ mov word [writechr+1], writechr_full-(writechr+3)
+
;
; Tell the user we got this far
;
mov si,copyright_str
call writestr
+; Test tracers
+ TRACER 'T'
+ TRACER '>'
+
;
; Clear Files structures
;
;
; Locate the configuration file
;
+ mov si,dbg_config_msg ; ***
+ call writemsg ; ***
+
mov di,isolinux_cfg
call open
jz near no_config_file ; Not found or empty
+ mov si,dbg_configok_msg ; ***
+ call writemsg ; ***
+
;
; Now we have the config file open
;
;
searchdir:
+ TRACER 'S'
push es
push ds
- pop es ; DS = ES
+ pop es ; ES = DS
call allocate_file ; Temporary file structure for directory
jnz .failure
mov si,bx
- movzx eax,word [RootDirClust]
+ mov eax,[RootDirClust]
mov [bx+file_left],eax
mov eax,[RootDir]
mov [bx+file_sector],eax
mov edx,[RootDirLen]
- mov si,trackbuf+SECTORSIZE
.getsome:
; Get a chunk of the directory
+ mov si,trackbuf
+ TRACER 'g'
pushad
- mov si,bx
- mov bx,trackbuf+SECTORSIZE
+ xchg bx,si
mov cx,[BufSafe]
dec cx ; ... minus one sector
call getfssec
popad
.compare:
+ movzx eax,byte [si] ; Length of directory entry
+ cmp al,33
+ jb .next_sector
+ TRACER 'c'
test [si+25], byte 8Eh ; Unwanted file attributes!
jnz .not_file
+ pusha
movzx cx,byte [si+32] ; File identifier length
- push si
- lea si,[si+33] ; File identifier offset
+ add si,byte 33 ; File identifier offset
+ TRACER 'i'
call iso_compare_names
- pop si
+ popa
je .success
.not_file:
- xor eax,eax
- mov al,[si]
sub edx,eax ; Decrease bytes left
jbe .failure
add si,ax ; Advance pointer
- ; Are we getting close to the end of the buffer
- cmp si,trackbuf+trackbufsize-SECTORSIZE
+.check_overrun:
+ ; Did we finish the buffer?
+ cmp si,trackbuf+trackbufsize
jb .compare ; No, keep going
- ; Close to end of buffer. Copy fractional sector to top of
- ; buffer, and load another chunk.
- push di
- lea di,[si-(trackbufsize-SECTORSIZE)]
- mov cx,trackbuf+trackbufsize
- sub cx,si
- push di
- rep movsb
- pop si ; SI <- new pointer location
- pop di
- jmp short .getsome ; Get another chunk
+ jmp short .getsome ; Get some more directory
+
+.next_sector:
+ ; Advance to the beginning of next sector
+ add si,SECTORSIZE-1
+ and si,~(SECTORSIZE-1)
+ jmp short .check_overrun
.failure: xor ax,ax ; ZF = 1
pop es
mov edx,eax
shr edx,16
and bx,bx ; ZF = 0
+ mov si,bx
pop es
ret
; ZF clear
;
allocate_file:
+ TRACER 'a'
push cx
mov bx,Files
mov cx,MAX_OPEN
.check: cmp dword [bx], byte 0
je .found
- add bx,open_file_t_size
+ add bx,open_file_t_size ; ZF = 0
loop .check
- xor cx,cx ; ZF = 1
+ ; ZF = 0 if we fell out of the loop
.found: pop cx
ret
; the filesystem; CX indicates its length, and ';' terminates.
; DI is expected to end with a null.
;
+; Note: clobbers AX, CX, SI, DI
+;
iso_compare_names:
- push ax
.loop: jcxz .si_end
lodsb
dec cx
mov ah,[di]
inc di
+ and al,al
+ jz .si_end_dec_di
+ cmp al,';'
+ je .si_end_dec_di
or ax,2020h ; Convert both to lowercase
cmp ah,al
- jne .done ; ZF = 0
- cmp al,';'
- je .si_end
- and al,al
- jnz .loop
+ je .loop
+ ret ; Failure, ZF = 0
+.si_end_dec_di:
+ dec di ; Re-read "current" character
.si_end:
cmp [di], byte 0
; Now ZF is set according to the final result
.done:
- pop ax
ret
;
jmp short .curxyok
;
+; debug hack to print a character with minimal code impact
+;
+debug_tracer: pushad
+ pushfd
+ mov bp,sp
+ mov bx,[bp+9*4] ; Get return address
+ mov al,[cs:bx] ; Get data byte
+ inc word [bp+9*4] ; Return to after data byte
+ call writechr
+ popfd
+ popad
+ ret
+
+;
; pollchar: check if we have an input character pending (ZF = 0)
;
pollchar:
; CF = 1 -> Hit EOF
;
getfssec:
+ TRACER 'F'
+
push ds
push cs
pop ds ; DS <- CS
mov bp,cx
push cx
+ push si
mov eax,[si+file_sector]
- call getfssec
+ TRACER 'l'
+ call getlinsec
xor ecx,ecx
+ pop si
pop cx
add [si+file_sector],ecx
.not_eof:
pop ds
+ TRACER 'f'
ret
copyright_str db ' Copyright (C) 1994-', year, ' H. Peter Anvin'
db CR, LF, 0
boot_prompt db 'boot: ', 0
-wipe_char db 08h, ' ', 08h, 0
+wipe_char db BS, ' ', BS, 0
err_notfound db 'Could not find kernel image: ',0
err_notkernel db CR, LF, 'Invalid or corrupt kernel image.', CR, LF, 0
err_not386 db 'It appears your computer uses a 286 or lower CPU.'
dot_msg db '.', 0
fourbs_msg db BS, BS, BS, BS, 0
aborted_msg db ' aborted.' ; Fall through to crlf_msg!
-crlf_msg db CR, LF, 0
crff_msg db CR, FF, 0
default_str db 'default', 0
default_len equ ($-default_str)
isolinux_cfg db 'isolinux.cfg', 0
+dbg_rootdir_msg db 'Root directory at LBA = ', 0
+dbg_config_msg db 'About to load config file...', CR, LF, 0
+dbg_configok_msg db 'Configuration file opened...', CR, LF, 0
;
; Command line options we'd like to take a look at
;
; **** BIOS expects our "sector size" to be.
;
ClustSize dw SECTORSIZE ; Bytes/cluster
-SecPerClust dw SECTORSIZE/512 ; Same as bsSecPerClust, but a word
+SecPerClust dw 1 ; Same as bsSecPerClust, but a word
BufSafe dw trackbufsize/SECTORSIZE ; Clusters we can load into trackbuf
-BufSafeSec dw trackbufsize/512 ; = how many sectors?
+BufSafeSec dw trackbufsize/SECTORSIZE ; = how many sectors?
BufSafeBytes dw trackbufsize ; = how many bytes?
EndOfGetCBuf dw getcbuf+trackbufsize ; = getcbuf+BufSafeBytes
ClustPerMoby dw 65536/SECTORSIZE ; Clusters per 64K
projects / platform / upstream / syslinux.git / commitdiff