Get ZF Value

To obtain the ZF value, you can use the sete command (put the ZF value in Al) or the jnz JNE jump command to obtain it indirectly. See the following code:

Char x S1 = "123 ";
Char * S2 = "1234 ";

_ ASM
{
XOR Al, Al
MoV EDI, S1
MoV ECx,-1
Repnz scasb
Not ECx // get the length of string S1 (including the trailing null character '\ 0 ')
MoV EDI, S1
MoV ESI, S2
Repz cmpsb

Jnz another
MoV eax, 1 // use 1 to indicate that S1 is the same as S2
JMP end
Another:
MoV eax, 0 // use 0 to indicate that S1 is different from S2.
End:
}

NOTE: If ECx is 0, it is inaccurate to determine whether the two strings are the same. In this example, when the repe cmpsb loop ends, ECx is equal to 0, but the two strings are not equal, at this time, ZF = 0.
Therefore, to determine whether the two strings are equal, check whether ZF is always set to 1 instead of ECx.

Get ZF Value