Hello:

I want to thank all that reply.

I am very new to assembly, so please forgive my stupid questions.

I have downloaded MASM32 and have been trying to compile some of the examples that I have also download from the internet. But, it seems that no matter what .ASM file I try to compile it does not work. Here is an example of a .ASM file that I would like to get working so that I may study, I get several error's.

Can someone please help me to get started. I can't to get anything going.


; rawread.asm
;
; this program reads a DOS cluster using only BIOS disk calls. All
; of the tasks usually done by DOS, e.g. FAT lookup, cluster to
; logical sector translation, logical to physical translation, are
; all done by this program instead. The idea is to be able to create
; a program that can access DOS disks from a bootable floppy without
; having to have DOS.
;
; written on Fri 05-27-1994 by Ed Beroset
;
; well, that's what it used to do. Now it's supposed to do something
; completely different. Its job is to scan the entire surface of the
; hard drive, looking for the specified string. If that string is
; found, it is to print the full path and directory entry, including
; the file date and time.
;
; written on Sun 12-11-1994 by Ed Beroset
;
; but wait! There's more. Now what we have is a number of raw
; routines which could prove useful for manipulating a DOS file
; structure outside of the DOS environment. The main routine still
; should be kept (if renamed), since the order in which these things
; are done is important (e.g. later calls depend on data set up by
; earlier calls).
;
; get filename
; parse filename into subdirs
; locate root dir and cluster size
; follow subdir routing to filename
; report file size, date & time
;
.MODEL small
.STACK 0200h
.586P

.DATA
PartEntry STRUC
Bootable db ? ;80h = bootable, 00h = nonbootable
BeginHead db ? ;beginning head
BeginSector db ? ;beginning sector
BeginCylinder db ? ;beginning cylinder
FileSystem db ? ;name of file system
EndHead db ? ;ending head
EndSector db ? ;ending sector
EndCylinder db ? ;ending cylinder
StartSector dd ? ;starting sector (relative to beg. of disk)
PartSectors dd ? ;number of sectors in partition
PartEntry ENDS

BootSector STRUC
Jump db ? ;E9 xx xx or EB xx 90
JumpTarget dw ? ;E9 xx xx or EB xx 90
OemName db '????????' ;OEM name & version
;Start of BIOS parameter block
BytesPerSec dw ? ;bytes per sector
SecPerClust db ? ;sectors per cluster
ResSectors dw ? ;number of reserved sectors
FATs db ? ;number of file allocation tables
RootDirEnts dw ? ;number of root-dir entries
Sectors dw ? ;total number of sectors
Media db ? ;media descriptor byte
FATsecs dw ? ;number of sectors per FAT
SecPerTrack dw ? ;sectors per track
Heads dw ? ;number of heads
HiddenSecs dd ? ;number of hidden sectors
HugeSectors dd ? ;num sectors if Sectors==0
;End of BIOS parameter block
BootSector ENDS

DirEntry STRUC
FileName db '????????' ;name
Extension db '???' ;extension
Attributes db ? ;attributes
Reserved db 10 dup (?) ;reserved
Time dw ? ;time stamp
Date dw ? ;date stamp
StartCluster dw ? ;starting cluster
FileSize dd ? ;file size
DirEntry ENDS

BootFileName db "CONFIG SYS" ;the boot loader for this OS
MBR DB 0200h DUP (?)
buff DB 0200h * 40h DUP (?)
ClustOffs dd ?

CR EQU 0DH
LF EQU 0AH


.CODE
main PROC
STARTUPCODE ;initialize stuff
call FetchMBR C ;fetch the master boot record
jc @@exit
mov cx,4 ;search up to four partitions
add bx,01aeh ;point to partition table (-10h)
@@FindBootable:
add bx,10h ;point to next entry
cmp BYTE ptr [bx],80h ;is it a bootable partition?
loopnz @@FindBootable
call FetchSector C, \
WORD ptr [(PartEntry PTR bx).BeginHead], \
WORD ptr [(PartEntry PTR bx).BeginSector], \
WORD ptr [(PartEntry PTR bx).BeginCylinder], \
OFFSET MBR, ds ;SEG MBR
;
; here's the point at which our OS loader would begin, with the
; BootSector structure in memory.
;
mov bx, OFFSET MBR
call CalcClustOff C, \
WORD ptr [(BootSector PTR bx).ResSectors], \
WORD ptr [(BootSector PTR bx).FATsecs], \
WORD ptr [(BootSector PTR bx).FATs], \
WORD ptr [(BootSector PTR bx).RootDirEnts], \
WORD ptr [(BootSector PTR bx).BytesPerSec], \
WORD ptr [(BootSector PTR bx).SecPerClust]
mov WORD ptr [ClustOffs],ax
mov WORD ptr [ClustOffs+2],dx
call CalcClust2 C, \
WORD ptr [(BootSector PTR bx).ResSectors], \
WORD ptr [(BootSector PTR bx).FATsecs], \
WORD ptr [(BootSector PTR bx).FATs]
; now dx:ax contains the logical sector for cluster 2
call LsectToGeom C, \
ax, dx, \
WORD ptr [(BootSector PTR bx).HiddenSecs] , \
WORD ptr [((BootSector PTR bx).HiddenSecs)+2],\
[(BootSector PTR bx).Heads], \
[(BootSector PTR bx).SecPerTrack]

mov dl,80h
mov bx,offset buff
mov al,[(BootSector PTR MBR).SecPerClust]
mov ah,2h ; get ready to read
int 13h
; now find our desired filename within buffer (which has the root dir)

call FindFile C, \
bx, 200h * 40h, offset BootFileName
xor dh,dh
mov dl,[(BootSector PTR MBR).SecPerClust]
mov si,ax
mov ax,[(DirEntry PTR si).StartCluster]
mul dx
add ax,WORD ptr [ClustOffs]
adc dx,WORD ptr [ClustOffs+2]
; now dx:ax contains logical sector number for start of file

call LsectToGeom C, \
ax, dx, \
WORD ptr [(BootSector PTR MBR).HiddenSecs] , \
WORD ptr [((BootSector PTR MBR).HiddenSecs)+2],\
[(BootSector PTR MBR).Heads], \
[(BootSector PTR MBR).SecPerTrack]
mov dl,80h
mov ax,204h ; read in 2k worth of data
int 13h

@@exit:
EXITCODE ;exit to DOS
ENDP main

;
; FetchMBR - fetches the Master Boot Record from the first physical
; hard disk and stores it in the location MBR.
;
; INPUT: none
; OUTPUT: AX is error code if CY set, ES:BX ==> MBR
; DESTROYED: none
;
FetchMBR PROC C
USES cx, dx ;save registers we'll use
mov dx,80h ;first physical disk
mov cx,1 ;head 1, sector 0
mov bx,ds ;
mov es,bx ;point to boot record buffer
mov bx,OFFSET MBR ;read into boot record
mov ax,0201h ;read one sector
int 13h ;BIOS read
ret ;return to main
FetchMBR ENDP

;
; FetchSector - fetches the physical sector described by the passed
; parameters and stores it in the named buffer
;
; INPUT: head, sector, cylinder, buffer
; OUTPUT: AX is error code if CY set, ES:BX ==> Boot
; DESTROYED: none
;
FetchSector PROC C head:BYTE, sector:BYTE, cylinder:BYTE, buffer:DWORD
USES cx, dx ;save registers we'll use
mov ch, [cylinder] ;
mov cl, [sector] ;
mov dh, [head] ;
mov dl, 80h ;first physical hard drive
les bx, [buffer] ;
mov ax,0201h ;read one sector
int 13h ;BIOS read
ret ;return to main
FetchSector ENDP

;
; GeomToLsect - converts to logical sector number from the physical
; geometry (head, cylinder, track). See LsectToGeom.
;
; INPUT: cx, dx are set with cylinder/track, and head respectively
; HiddenSecs, Heads, SecPerTrack
; OUTPUT: lsect
; DESTROYED: none
;
GeomToLsect PROC C lsect:DWORD, dHiddenSecs:DWORD, \
dHeads:WORD, dSecPerTrack:WORD, buffer:DWORD
USES ax ;save registers we'll use
mov ax, WORD ptr [lsect] ;load lsect into DX:AX
mov dx, WORD ptr [lsect+2] ;
stc ;add one additional
adc ax, WORD ptr [dHiddenSecs] ;add starting sector
adc dx, WORD ptr [dHiddenSecs+2] ;
div [dSecPerTrack] ;
mov cl,dl ;store sector in cl
xor dx,dx ;
div [dHeads] ;
mov dh,dl ;store head in dh
mov ch,al ;store low 8 bits of cylinder in ch
shr ax,1 ;
shr ax,1 ;
and al,0c0h ;pass through two hi bits only
or cl,ah ;mov bits into location
ret ;
GeomToLsect ENDP

;
; LsectToGeom - converts from logical sector number to the physical
; geometry (head, cylinder, track) in the form required
; by the BIOS (Int 13h) disk read and write calls.
;
; INPUT: lsect, HiddenSecs, Heads, SecPerTrack
; OUTPUT: cx, dx are set with cylinder/track, and head respectively
; DESTROYED: none
;
LsectToGeom PROC C lsect:DWORD, lHiddenSecs:DWORD, \
lHeads:WORD, lSecPerTrack:WORD, buffer:DWORD
USES ax ;save registers we'll use
mov ax, WORD ptr [lsect] ;load lsect into DX:AX
mov dx, WORD ptr [lsect+2] ;
stc ;add one additional
adc ax, WORD ptr [lHiddenSecs] ;add starting sector
adc dx, WORD ptr [lHiddenSecs+2] ;
div [lSecPerTrack] ;
mov cl,dl ;store sector in cl
xor dx,dx ;
div [lHeads] ;
mov dh,dl ;store head in dh
mov ch,al ;store low 8 bits of cylinder in ch
shr ax,1 ;
shr ax,1 ;
and al,0c0h ;pass through two hi bits only
or cl,ah ;mov bits into location
ret ;
LsectToGeom ENDP

;
; CalcClust2 - calculates the starting logical sector number of
; cluster 2, (the beginning of data space for
; partitions).
;
; INPUT: ResSectors, FATsecs, FATs
; OUTPUT: dx:ax contains the starting logical sector number
; DESTROYED: none
;
CalcClust2 PROC C cResSectors:WORD, cFATsecs:WORD, cFATs:BYTE
xor dx,dx ;
mov ax,[cFATsecs] ;
mul [cFATs] ;
add ax,[cResSectors] ;
adc dx,0 ;
ret
CalcClust2 ENDP

;
; CalcClustOff - calculates the starting logical sector number of
; cluster 0, which isn't really a cluster, but the
; number returned is useful for calculations converting
; cluster number to logical sector
;
; INPUT: ResSectors, FATsecs, FATs
; OUTPUT: dx:ax contains the starting logical sector number
; DESTROYED: none
;
CalcClustOff PROC C dResSectors:WORD, dFATsecs:WORD, dFATs:BYTE, \
dRootDirEnts:WORD, dBytesPerSec:WORD, dSecPerClust:BYTE
LOCAL clustLo:WORD, clustHi:WORD
xor dh,dh
mov ax,[dFatSecs]
mov dl,[dFATs]
mul dx
add ax,[dResSectors]
adc dx,0
; call CalcClust2 C, [dResSectors], [dFATsecs], [dFATs]
; now dx:ax = FATs * FATsecs + ResSectors
mov [clustLo],ax
mov [clustHi],dx
mov dx,20h ; bytes per dir entry
mov ax,[dRootDirEnts] ;
mul dx ; multiply 'em out
div [dBytesPerSec] ; and divide by bytes/sec
add [clustLo],ax ;
adc [clustHi],dx ; create the aggregate
mov al,[dSecPerClust] ;
xor ah,ah ;
shl ax,1 ; AX = SecPerClust * 2
sub [clustLo],ax ;
sbb [clustHi],0 ; propagate carry flag
mov ax,[clustLo] ;
mov dx,[clustHi] ;
ret
CalcClustOff ENDP

;
; FindFile - given a memory buffer containing the directory data
; and a static file name for which to search, this routine
; finds the file and returns a pointer to its directory
; entry in ds:si
;
; INPUT: dirbuffer, filespec
; OUTPUT: ax contains pointer to directory entry (or NULL)
; DESTROYED: none
;
FindFile PROC C dirbuffer:WORD, limit:WORD, filespec:WORD
USES cx, dx, di, si, es
mov cx,ds ;
mov es,cx ; es and ds point to same segment
cld ; always count forward
mov ax,[dirbuffer] ; load 'em up
add [limit],ax
mov dx,[filespec] ;
keepsearching:
mov cx,11 ; size of dos filename (8.3)
mov si,dx ;
mov di,ax ;
repe cmpsb ; compare 'em
jz foundit ;
add ax,20h ; size of directory entry
cmp ax,[limit]
jb keepsearching
xor ax,ax

foundit:
ret
FindFile ENDP
END
Posted on 2003-05-18 08:47:49 by damica
This is DOS code. You will need to use the older DOS linker.
The linker included in MASM32 is for Windows code. I just
did a quick search for the older linker but didn't find it. I'm
sure someone else here knows where to get it.
Posted on 2003-05-18 09:19:23 by anon
Iczelion has it on his page. Here's a direct link: http://spiff.tripnet.se/~iczelion/files/Lnk563.exe

If you want to learn how to use assembly in Windows, check out the tutorials on this forum.
Posted on 2003-05-18 12:29:42 by Qweerdy