How to set conditional breakpoint to modify ZF (Zero flag)

Question

In IDA I need to set a breakpoint that once it hit, I want to check if ZF is equal to 1, if it does, I want to change it to 0.

I don't know how to do it:

I searched for example scripts in IDC or IDAPython but I didn't find something that shows it.
How can I do it?

Answer 1

shift + f2

Message("zf flag when bp hit = %x\n" , GetRegValue("zf"));
SetRegValue(0,"zf");
Message("zf flag after setting it %x\n" , GetRegValue("zf"));

result

zf flag when bp hit = 1
zf flag after setting it 0

Answer 2

Since in your case the final value of ZF will be zero, there is no need to check the initial value but simply always zero it:

ZF=0,0

The ,0 at the end will ensure that the result of expression is 0 so IDA will continue execution of the program.