Learning to Read X86 Assembly Language

Post by pjmlp » Mon, Nov 28, 2016, 7:37 AM UTC

userbinator wrote: post #76

qwertyuiop924 wrote: post #8

Earlier quoted context omitted.

They're not as common reasons. But yes, if you want to program your TRS-80 (but only the original: later ones were 6502), or your ZX* (How many of you lot know the ZX line? Spectrum? No?), or your Game Gear, or your Master System, or any of the various CP/M machines, you have to learn Z80.

How many of you lot know the ZX line? Spectrum? No? The ZX Spectrum and its clones were very popular in the UK, Eastern Europe, and the former USSR.

Post by pcwalton » Mon, Nov 28, 2016, 7:44 AM UTC

gens wrote: post #135

adamnemecek wrote: post #123

Earlier quoted context omitted.

I wouldn't be surprised if the reason was that people at Bell labs were mimicking some older syntax.

I remember reading a long time ago about the syntaxes and the author said that it is because AT&T assembled faster. Makes sense considering that the intel syntax requires some backtracking (or more of temporary data). (please don't upvote if you agree, i'm at 69 points :)

Post by Annatar » Mon, Nov 28, 2016, 8:06 AM UTC

haberman wrote: post #116

userbinator wrote: post #70

What a train wreck! It’s hard to imagine a more confusing state of affairs. I'd say that's more attributed to someone many many years ago deciding they would not follow the official Intel syntax (for what reason I do not know), and somehow convincing the rest of the community to follow them. That's actually one of the things that could make for a very interesting article: how one processor family got two different an…

This. The AT&T syntax for x86 thing is a huge mistake. All the official docs are Intel syntax. Intel syntax is easier to read and write. Half the gotchas in this article are problems that don't exist in Intel syntax, like the instruction suffixes. The instruction suffixes get even weirder when you get to the sign extending instructions. I wrote an article about this here: http://blog.reverberate.org/2009/07/giving-up…

Post by userbinator » Mon, Nov 28, 2016, 8:44 AM UTC

Annatar wrote: post #155

haberman wrote: post #116

Earlier quoted context omitted.

This. The AT&T syntax for x86 thing is a huge mistake. All the official docs are Intel syntax. Intel syntax is easier to read and write. Half the gotchas in this article are problems that don't exist in Intel syntax, like the instruction suffixes. The instruction suffixes get even weirder when you get to the sign extending instructions. I wrote an article about this here: http://blog.reverberate.org/2009/07/giving-up…

The AT&T syntax for x86 thing is a huge mistake. For someone who grew up on normal processors (MC68000 and UltraSPARC) AT&T syntax is the best thing since sliced bread: it's perfectly logical to move something to somewhere, instead of "move to somewhere something".

    cmp eax, 5     ; eax - 5
    jg morethan5   ; eax > 5 ? then jump.
    sub eax, ecx     ; eax = eax - ecx

    sub A, B    ; B = A - B ??

Post by Annatar » Mon, Nov 28, 2016, 8:59 AM UTC

qwertyuiop924 wrote: post #42

wolfgke wrote: post #40

Earlier quoted context omitted.

> an absolutely ugly jumble of [...] religious backwards compatability, odd hacks, and various extensions Like POSIX, MS-Windows, X11, WinAPI, C++, HTML5, ... ;-)

Hey, I didn't say it was the only one. Although POSIX and HTML5 hold up a bit better than Win32 and C++, IMHO. Especially POSIX (it's not great, but it works pretty well). But I've heard X11 is absolutely miserable, so the windows folks don't have a monopoly on satanically evil APIs with religious backwards-compatability.