Is there a good debugger for use under windows with fasm?

fasm doesn't support debugging formats so the executables are always stripped. To debug I suggest you to use OllyDbg.

Hwere are a few Free ones


OllyDbg

Windbg [32] [64]

Microsoft WinDbg isn't bad either: http://www.microsoft.com/whdc/devtools/debugging/default.mspx

It does some kind of analysis? The problem with fasm is that you can't add debugging info so if the debugger does not perform any analisys of the program is pretty hard to follow the debugging (not impossible of course).

BTW, why every post repeats the previous?

Last time I checked it didn't really do any analysis, but I'm used to work with softice, so... it's not that necessary for normal debugging. Having some kind of symbol information is nice though, and it's a shame that FASM can't add it.

That is why i perfer ollydbg

Also, another little trick is to follow through the code with your finger. you'd be surprised how many bugs you can catch by manual execution of the program.

I use Ollydbg all the time. You can add symbolic information by putting the list of labels in the export section. Be sure to sort all the entries in the export section and be aware that the entries and sort are case sensitive.

Ollydbg also keeps track of the entries according to address, so if multiple labels in the code refer to the same program address then be sure to use NOP after these labels to insure that all labels have unique addresses. This messes up optimization, but it makes following the code easier since what Ollydbg displays matches the source code.

If there are labels in the code starting with a dot, then be sure to prepend the dot label name in the export section with the previous non-dot label in code. This is because dot labels are considered local to the previous non-dot label and you need to be sure that all label names being exported are unique.

handyman: thanks for the tip, but gosh - it'd be a lot easier if FASM could generate some debug info

I think Tomasz couldn't decide what format to support, so he'd possibly have to invent his own. (And there was also a weird macro hack, see here).

Anyways, if you refuse to debug pure code via stopping at int3 then try YASM (CodeView8, Dwarf2, or Stabs), which I'm almost definitely sure would work with OpenWatcom's debugger.

I suspect the reason for the lack of an official fasm symbolic debug format is far worse than you believe

http://board.flatassembler.net/topic.php?t=4191&start=25#32063




Given that fasm may now be abandonware ???????? (I hope not), perhaps it may never happen.

It's hardly abandonware (few months, heck I procrastinate way worse, heh), but he's busy with school, getting a degree and whatnot.