`not di` does not seem to perform bitwise negation

Submitted ⁨⁨9⁩ ⁨months⁩ ago⁩ by ⁨qaz@lemmy.world⁩ to ⁨programming@programming.dev⁩

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 ; &lt;- 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

source

Comments

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mrkite@programming.dev ⁨9⁩ ⁨months⁩ ago
Your result is correct, is just not displaying the leading zeros.

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- qaz@lemmy.world ⁨9⁩ ⁨months⁩ ago
  Thanks, I somehow completely missed that.
  
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- qaz@lemmy.world ⁨9⁩ ⁨months⁩ ago
  Do you perhaps know how to show the leading zeros?
  
  source
  - mrkite@programming.dev ⁨9⁩ ⁨months⁩ ago
    I’m not great with gdb but I think using the x cmd shows them.
    
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