Contents
Is the test eax, eax the same as?
The test eax, eax is the same as and eax, eax (bitwise and) except that it doesn’t store the result in eax. So eax isn’t affected by the test, but the zero-flag is, for example. The test eax, eax is necessary to make the jne work in the first place.
Is the test eax, eax after a strcmp the same?
Register eax will contain the return code from strcmp, after the call. The test eax, eax is the same as and eax, eax (bitwise and) except that it doesn’t store the result in eax. So eax isn’t affected by the test, but the zero-flag is, for example. The test eax, eax is necessary to make the jne work in the first place.
What does it mean to jump if EAX is 0?
It tests whether eax is 0, or above, or below. In this case, the jump is taken if eax is 0. The meaning of test is to AND the arguments together, and check the result for zero. So this code tests if EAX is zero or not. je will jump if zero.
Which is the best comparison of operating systems?
These tables provide a comparison of operating systems, of computer devices, as listing general and technical information for a number of widely used and currently available PC or handheld (including smartphone and tablet computer) operating systems.
What happens when EAX is set to zero?
Performs the logical bitwise or operation. If EAX is zero, the result will be all zeroes, and the zero flag will be set, which most likely will is the whole point. It’s hard to see exactly what the significance of this is without knowing the wider context of what is happening.
Which is the shortest instruction, test or eax?
As a result, shorter instructions are generally preferred The most commonly used one is TEST. AND eax, eax can also be used, since it’s exactly the same as TEST except it destroys the destination (but that’s irrelevant in cases where source and dest are the same register like this).