Programming

17313 readers

150 users here now

Welcome to the main community in programming.dev! Feel free to post anything relating to programming here!

Cross posting is strongly encouraged in the instance. If you feel your post or another person's post makes sense in another community cross post into it.

Hope you enjoy the instance!

Rules

Follow the programming.dev instance rules
Keep content related to programming in some way
If you're posting long videos try to add in some form of tldr for those who don't want to watch videos

Wormhole

Follow the wormhole through a path of communities !webdev@programming.dev

founded 1 year ago

MODERATORS

snowe@programming.dev

Ategon@programming.dev

MaungaHikoi@lemmy.nz

not di does not seem to perform bitwise negation (lemmy.world)

submitted 9 months ago* (last edited 9 months ago) by qaz@lemmy.world to c/programming@programming.dev

5 comments fedilink hide all child comments

I've been trying to debug a program I'm working on and have managed to narrow it down to a single not statement. I fail to understand how this could fail. My current suspicion is the fact that I'm using a 16 bit (aka short) register. Should I even be using this?


Before `not di`	`1101111110000000`
Expected after `not di`	`0010000001111111`
Actually after `not di`	`10000001111111`

Code

.certain:
not di ; ← this line is the problem
bsf ax, di

GDB output

(gdb) p/t (short) $di $4 = 1101111110000000
(gdb) nexti
(gdb) p/t (short) $di $5 = 10000001111111

you are viewing a single comment's thread
view the rest of the comments

[–] mrkite@programming.dev 20 points 9 months ago (4 children)

Your result is correct, is just not displaying the leading zeros.

[–] qaz@lemmy.world 2 points 9 months ago (2 children)

Do you perhaps know how to show the leading zeros?

[–] mrkite@programming.dev 3 points 9 months ago (1 children)

I'm not great with gdb but I think using the x cmd shows them.

[–] qaz@lemmy.world 1 points 9 months ago

Yes, but that doesn't seem to work with registers

load more comments (1 replies)