Be more explicit about errors, so we can debug problems.

diff --git a/syslinux.asm b/syslinux.asm
index e793029..bea50a3 100644 (file)
--- a/syslinux.asm
+++ b/syslinux.asm
@@ -2,7 +2,7 @@
 ; $Id$
 ; -----------------------------------------------------------------------
 ;   
-;   Copyright 1998 H. Peter Anvin - All Rights Reserved
+;   Copyright 1998-2001 H. Peter Anvin - All Rights Reserved
 ;
 ;   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
@@ -151,7 +151,6 @@ dpbFreeCnt: resw 1
 got_cmdline:
                mov dl,[DriveNo]
                inc dl                          ; 1-based
-               mov bx,DPB
                mov ah,32h
                int 21h                         ; Get Drive Parameter Block
                
@@ -169,12 +168,14 @@ hugeclust_error:
                jmp die
 filesystem_error:
                mov dx,msg_filesystem_err
-               jmp die
+               jmp doserr
 sectorsize_error:
                mov dx,msg_sectorsize_err
                jmp die
 
 drive_ok:
+               push cs
+               pop ds
 
 ;
 ; Writing LDLINUX.SYS
@@ -188,7 +189,7 @@ write_file:
                ; 0. Set the correct filename
 
                mov al,[DriveNo]
-               add [ldlinux_sys_str],al
+               add byte [ldlinux_sys_str],al
 
                ; 1. If the file exists, strip its attributes and delete
 
@@ -219,7 +220,8 @@ write_file:
                cmp ax,ldlinux_size
                je .no_file_write_error
 .file_write_error:
-               jmp file_write_error
+               mov dx, msg_fwrite_err
+               jmp doserr
 .no_file_write_error:
 
                mov bx,[FileHandle]
@@ -254,20 +256,19 @@ lock_drive:
                mov dx,01h                      ; Allow write mappings/allow new mappings
                pusha
                int 21h
-               popa
                jc .disk_lock_error_nocleanup
+               popa
 
                xor dx,dx
                inc bh                          ; Lock level 2
                pusha
                int 21h
-               popa
                jc .disk_lock_error
+               popa
 
                inc bh                          ; Lock level 3
                pusha
                int 21h
-               popa
                jnc .done
 
 .disk_lock_error:
@@ -285,10 +286,13 @@ lock_drive:
                loop .lock_cleanup
 
 .disk_lock_error_nocleanup:
+               popa
                mov dx, msg_lock_err
-               jmp die
+               jmp doserr
 
 .done:
+               popa
+
 .plain_dos:    ; Plain DOS -> no locking
 
 ;
@@ -331,7 +335,7 @@ read_bootsect:
                jmp short write_bootsect
 disk_read_error:
                mov dx,msg_read_err
-               jmp die
+               jmp doserr
 
 ;
 ; Writing boot sector
@@ -379,9 +383,45 @@ all_done:  mov ax,4C00h                    ; Exit good status
 ;
 ; Error routine jump
 ;
-file_write_error:
 disk_write_error:
                mov dx,msg_write_err
+
+doserr:
+               push cs
+               pop ds
+               push dx                         ; Error message
+               push ax                         ; Error code
+               mov dx, msg_error_sp
+               mov ah,09h
+               int 21h
+               pop ax
+               
+               mov cx,4
+               mov bx,hexdigits
+               mov si,ax
+.digit:
+               rol si,1
+               rol si,1
+               rol si,1
+               rol si,1
+               mov ax,si
+               and al,0Fh
+               xlatb
+               mov ah,02h                      ; Display character
+               mov dl,al
+               int 21h
+               loop .digit
+
+               mov dx,msg_colon
+               mov ah,09h
+               int 21h
+
+               jmp short die_common
+
+               section .data
+hexdigits:     db '0123456789ABCDEF'
+
+               section .text
 die:
                push cs
                pop ds
@@ -389,7 +429,9 @@ die:
                mov dx, msg_error
                mov ah,09h
                int 21h
-               pop dx
+
+die_common:
+               pop dx                          ; Error message
 
                mov ah,09h                      ; Write string
                int 21h
@@ -404,13 +446,16 @@ die:
                %include "stupid.inc"
 
                section .data
+msg_error_sp:          db 'ERROR $'
+msg_colon:             db ': $'
 msg_error:             db 'ERROR: $'
 msg_ancient_err:       db 'DOS version 3.20 or later required', 0Dh, 0Ah, '$'
 msg_filesystem_err:    db 'Filesystem not found on disk', 0Dh, 0Ah, '$'
 msg_sectorsize_err:    db 'Sector sizes other than 512 bytes not supported', 0Dh, 0Ah, '$'
 msg_hugeclust_err:     db 'Clusters larger than 16K not supported', 0Dh, 0Ah, '$'
 msg_read_err:          db 'Boot sector read failed', 0Dh, 0Ah, '$'
-msg_write_err:         db 'Disk write failed', 0Dh, 0Ah, '$'
+msg_write_err:         db 'Boot sector write failed', 0Dh, 0Ah, '$'
+msg_fwrite_err:                db 'LDLINUX.SYS write failed', 0Dh, 0Ah, '$'
 msg_lock_err:          db 'Unable to lock drive for exclusive access', 0Dh, 0Ah, '$'
 
                section .data