 |
Cheat Engine
The Official Site of Cheat Engine
|
| View previous topic :: View next topic |
| Author |
Message |
malis2007
How do I cheat?
![]() Reputation: 0
Joined: 31 Jul 2017
Posts: 1
|
 Posted: Fri Aug 11, 2017 9:47 pm Post subject: need help understanding the carry flag.. |
 |
|
Hello there 
i have a problem understanding the carry flag :/
i added these lines to the SUB instruction in the CE's step 2 TUT
| Code: | pushad
pushfd
mov eax,2
add eax,1
popfd
popad |
after the add instruction, why is the carry flag being set? (CF=1)
>>image in attachment <<
and why is it cleared (CF=0) when i replaced this code:
with either 7,A or even F the carry flag is cleared? (CF=0)
e.g.
>> image in attachment <<
Thanks for reading, and your help inadvanced..
| Description: |
pushad
pushfd
mov eax,F
add eax,1
popfd
popad |
|
| Filesize: |
100.5 KB |
| Viewed: |
3651 Time(s) |
|
| Description: |
pushad
pushfd
mov eax,2
add eax,1
popfd
popad |
|
| Filesize: |
100.2 KB |
| Viewed: |
3651 Time(s) |
|
|
|
| Back to top |
|
 |
OldCheatEngineUser
Whateven rank
 Reputation: 20
Joined: 01 Feb 2016
Posts: 1587
|
| Posted: Fri Aug 11, 2017 10:12 pm Post subject: |
|
|
| Quote: | Carry Flag
The rules for turning on the carry flag in binary/integer math are two:
The carry flag is set if the addition of two numbers causes a carry out of the most significant (leftmost) bits added. 1111 + 0001 = 0000
(carry flag is turned on)
The carry (borrow) flag is also set if the subtraction of two numbers requires a borrow into the most significant (leftmost) bits subtracted. 0000 - 0001 = 1111
(carry flag is turned on) Otherwise, the carry flag is turned off (zero).
0111 + 0001 = 1000 (carry flag is turned off [zero])
1000 - 0001 = 0111 (carry flag is turned off [zero])
|
_________________
About Me;
I Use CE Since Version 1.X, And Still Learning How To Use It Well!
Jul 26, 2020
| STN wrote: | | i am a sweetheart. |
|
|
| Back to top |
|
|
FreeER
Grandmaster Cheater Supreme
![]() Reputation: 53
Joined: 09 Aug 2013
Posts: 1091
|
| Posted: Sat Aug 12, 2017 7:32 am Post subject: |
|
|
@OldCheatEngineUser the second image is 2 + 1, 00000010 + 00000001 = 00000011, at what point is that causing a carry out, or a borrow, from the most significant bit?
You can see the >> on the popfd so the add has been run but the flag restore has not.
Hello again @malis2007 I'm sure it's something that'll seem simple once it's pointed out but I'm not seeing it either lol
|
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
|
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
