If the result of the AND operation is negative, the Sign Flag (SF) will be set to 1. Here, the test instruction performs a bitwise AND operation between the content of the EAX register like before. Similarly, we can execute the following assembly instructions: test eax, eax After that, the jz instruction will get executed and the execution flow will jump to 0xABCD0000 if the ZF flag is set to 1 or the content of the EAX register is zero. If the content of the EAX register is zero, the Zero Flag (ZF) will be set to 1. Here, the test instruction performs a bitwise AND between the content of the EAX register. We often execute a test instruction before a conditional jump instruction. ![]() ![]() So, if there are two operands and we want to test whether any of the operands is zero, we can use the test instruction. The Overflow Flag (OF) and the Carry Flag (CF) are set to zero. But, the operation may modify the Sign Flag (SF), the Zero Flag (ZF), or the Parity Flag (PF). The result of the AND operation is discarded. In x86 and 圆4 assembly, the test instruction takes two operands and it performs a bitwise AND between the two operands.
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