How Do You Make An Assembler?
X86AssemblyX86 Problem Overview
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.
X86 Solutions
Solution 1 - X86
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:
- Intel® 64 and IA-32 Architectures Software Developer's Manuals
- AMD-64 Architecture Programmers manual
- Linkers and Loaders by John R. Levine (freely available)
- ELF File Format Specifications : System V ABI Update
- Microsoft Portable Executable and Common Object File Format Specification
You can always refer to implementations of Opensource Assemblers:
Solution 2 - X86
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!)
Solution 3 - X86
I wrote one a long time ago. It is as simple as getting the x86 assembler ref guide from Intel, and writing the bytes to a .com file (for windows). I wish i could find my old forum post I made on it. It was written in D++. Just goes to show you can do it in any language. Just tokenize your string and translate it.
Solution 4 - X86
As far as example code goes...
I don't know of any "simple" assemblers, though.