CODEWITHSUNDEEP
assemblyx86tasm
pts
pts

Reputation: 87291

creating a 32-bit binary file with nonzero org with TASM+TLINK

I'm looking for the equivalent of the following assembly program with TASM, i.e. creating a 32-bit binary file with nonzero org. Here is how it works with NASM:

; $ nasm -O0 -f bin -o id.bin id.nasm
bits 32
cpu 386
org 432100h
mov eax, foo
push eax
foo:
; $ ndisasm -b 32 id.bin
; 00000000  B806214300        mov eax,0x432106
; 00000005  50                push eax

Is it possible to do the same with a combination of TASM and TLINK? How would the .asm file look like? What are the compilation command lines?

Please note:

Some context: I have a moderately complex x86 32-bit assembly program with binary file output, and I'm curious if it would be possible to port it to TASM.

Upvotes: 4

Views: 120

Answers (2)

pts
pts

Reputation: 87291

I ended up writing my own linker, folink2 for this (see C89 impelementation, TASM 2.0 implementation for DOS 8086).

The linker just copies the raw data bytes (expanding RLE-compressed LIDATA records) from the .obj file to the raw binary output file, and it checks that there are no relocations (fixupps).

Here is an example 32-bit program (also available here), written in TASM assembly (works with TASM 1.0 or later):

ideal
program_base equ 8048000h  ; Typical Linux i386 executable program.
p386n
segment _TEXT use32  ; The segment name is arbitrary.
assume cs:_TEXT, ds:_TEXT, es:_TEXT, ss:_TEXT
org program_base

file_header:
Elf32_Ehdr:     OSABI_Linux equ 3
                db 7Fh,'ELF',1,1,1,OSABI_Linux,0,0,0,0,0,0,0,0,2,0,3,0
                dd 1,_start,Elf32_Phdr-file_header,0,0
                dw Elf32_Phdr-file_header,20h,1,0,0,0
Elf32_Phdr:     dd 1,0,program_base,0,prebss-program_base,mem_end-program_base,7,1000h

_start:         mov eax, 4  ; SYS_read.
                mov ebx, 1  ; STDOUT_FILENO.
                mov ecx, offset msg
                mov edx, msg_end-msg
                int 80h  ; Linux i386 syscall.

                mov eax, 1  ; SYS_exit.
                xor ebx, ebx  ; EXIT_SUCCESS == 0.
                int 80h  ; Linux i386 syscall.

msg:            db 'Hello, World!', 10
msg_end:

prebss:         db ((file_header-$) and 3) dup (?)
bss:

; These variables are initialized to zero by the Linux kernel.
; No extra bytes are generated for them.
unused_array:   db 42 dup (?)
unused_var:     dw ?

mem_end:
ends
end

After generating the file.obj with tasm file.asm, the folink2 linker can be used to generate the raw binary file: folink2t.com file.obj file.

The same linker can be used for 16-bit x86 raw binary output, see example TASM source.

Upvotes: 3

pts
pts

Reputation: 87291

I managed to make it work with TASM+WLINK (rather than TASM+TLINK), using TASM 4.1 and the WLINK from OpenWatcom v2.

Here is my id.asm file:

.386   
.model flat
.stack 100h  ; Dummy, to pacify TASM.
mov eax, offset foo  
push eax
foo:
end foo  ; Dummy reference to foo, to pacify TASM.

Here is how I compile it:

tasm /t id.asm
wlink format raw bin option offset=0x432100 option quiet name idw.bin file id.obj
ndisasm -b 32 idw.bin

Output:

00000000  B806214300        mov eax,0x432106
00000005  50                push eax

Here is an alternative id.asm file, using TASM ideal mode:

p386n
model flat
stack 100h  ; Dummy, to pacify TASM.
codeseg
mov eax, offset foo
push eax
foo:   
end foo  ; Dummy, to pacify TASM.

Unfortunately most early versions of WLINK (such as in Watcom C/C++ 11.0B, the last release before OpenWatcom) don't support format raw.

Upvotes: 2

Related Questions