How Do You Make An Assembler? [closed]

Question

I'd like to make a simple x86 assembler. I'm wondering if there's any tutorials for making your own assembler. Or if there's a simple assembler that I could study.

Also, I wonder what tools are used in looking at and handling the binary/hex of programs.

Answer 1

This is what you are looking for:

Assemblers And Loaders - By David Salomon. Published February, 1993 - Freely available (download here)

Of course, you are going to need the following:

1. Intel® 64 and IA-32 Architectures Software Developer's Manuals
2. AMD-64 Architecture Programmers manual
3. Linkers and Loaders by John R. Levine (freely available)
4. ELF File Format Specifications : System V ABI Update
5. Microsoft Portable Executable and Common Object File Format Specification

You can always refer to implementations of Opensource Assemblers:

1. Netwide Assembler (NASM)
2. Gnu Assembler (GAS)

Answer 2

Just a very tiny piece of code in Delphi 7.

{$APPTYPE CONSOLE} program assembler; uses sysutils; const s1=#0#77#1#90#59#64#4#80#1#69#3#76#1#1#1#1#14#224#2#15#1#1#1#11#1#1#1#1#1#64#13+ #116#1#16#13#64#3#16#4#2#3#1#8#3#2#10#7#32#4#2#7#3#5#16#4#16#5#1#10#16#13#16#3+ #184#124#184#5#16#3#184#5#2#15#96#3#224#173#52#1#16#3#40#1#16#23#65#1#16#3#80#1+ #16#7#75#1#69#1#82#1#78#1#69#1#76#1#51#1#50#1#46#1#68#1#76#1#76#4#71#1#101#1+ #116#1#83#1#116#1#100#1#72#1#97#1#110#1#100#1#108#1#101#4#87#1#114#1#105#1#116+ #1#101#1#67#1#111#1#110#1#115#1#111#1#108#1#101#1#65#2#72#1#101#1#108#1#108#1+ #111#1#44#1#32#1#87#1#111#1#114#1#108#1#100#1#33#1#13#1#10#5#0; s3=#1#185#1#7#4#136#1#195#1#128#1#227#1#15#1#193#1#216#1#4#1#128#1#251#1#9+ #1#118#1#3#1#128#1#195#1#39#1#128#1#195#1#48#1#136#1#153#1#96#1#16#1#64#2#73#1+ #125#1#228#1#106#2#104#1#112#1#16#1#64#2#106#1#8#1#104#1#96#1#16#1#64#2#106#1+ #245#1#255#1#21#1#40#1#16#1#64#2#80#1#255#1#21#1#44#1#16#1#64#2#195; var   f:file of byte;p,i:integer;o:string;   t:text;line:string; procedure w(s: string); begin   i:=1;   while i<length(s) do begin     inc(p,ord(s[i]));     setlength(o, p);     o[p]:=s[i+1];     inc(i,2);   end; end; procedure al(b: byte); var   a: longword;pc: pchar; begin   a := strtoint(line); pc:=@a;   o := o + chr(b) + pc^ + (pc+1)^ + (pc+2)^ + (pc+3)^; inc(p,5); // mov eax, imm32 end; begin   assign(f,'out.exe');   rewrite(f);   p:=1;   w(s1);   assignfile(t, ''); reset(t);   while not eof(t) do begin     readln(t, line); line := trim(line);     if copy(line,1,8) = 'mov eax,' then begin       system.delete(line,1,8);       al($b8); // mov eax, imm32     end     else if copy(line,1,8) = 'add eax,' then begin       system.delete(line,1,8);       al($05); // add eax, imm32     end     else if copy(line,1,8) = 'and eax,' then begin       system.delete(line,1,8);       al($25); // and eax, imm32     end   end;   closefile(t);   w(s3);   blockwrite(f,o[1],p); close(f); end. 

The assembler understands only three different assembler codes "mov eax,immed32", "add eax,immed32", "and eax,immed32" and no data nor labels. It will produce a tiny Windows PE executable which outputs eax in hex at the end.

Attention: In my case avira free antivirus doesn't like the output. It's a false positive. I had to switch off the real time protection. Check the result with a debugger if you are uncertain if this is malware (It's not!)