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Index > Main > Signed vs unsigned comparison (was 'What am i missing')

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bitshifter



Joined: 04 Dec 2007
Posts: 764
Location: Massachusetts, USA
bitshifter
Code:
        mov     cx,1000h
        mov     ax,9fc0h
        sub     ax,cx

        cmp     ax,27e0h
        jl      lies
        jb      truth
    


EDIT by DOS386 : enhanced subject

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Post 19 Aug 2010, 01:18
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sinsi



Joined: 10 Aug 2007
Posts: 709
Location: Adelaide
sinsi
signed vs unsigned?
Post 19 Aug 2010, 01:52
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LocoDelAssembly
Your code has a bug


Joined: 06 May 2005
Posts: 4633
Location: Argentina
LocoDelAssembly
bitshifter,

Does this **really** has something to do with compiler internals or I can move this to Main?
Post 19 Aug 2010, 02:07
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bitshifter



Joined: 04 Dec 2007
Posts: 764
Location: Massachusetts, USA
bitshifter
ooh, its because the value has sign bit set...

facepalm Embarassed

ok to move... (or destroy)
Post 19 Aug 2010, 02:21
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Tyler



Joined: 19 Nov 2009
Posts: 1216
Location: NC, USA
Tyler
jl is signed jb isn't

With jl 1111111b would be less than 0, while with jb, it would be opposite.

Edit: You beat me to it.
Post 19 Aug 2010, 02:30
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