![]() ![]() The jump instructions allow the programmer to (indirectly) set the value of the EIP register. ![]() SF ≔ MostSignificantBit( difference), so an unset SF means the difference is non-negative ( minuend ≥ subtrahend ).AL/AX/EAX (only if subtrahend is immediate).Note that the GAS/AT&T syntax can be rather confusing, as for example cmp $0, %rax followed by jl branch will branch if %rax < 0 (and not the opposite as might be expected from the order of the operands). The EFLAGS register is set in the same manner as a sub instruction. If subtrahend is an immediate value it will be sign extended to the length of minuend. The comparison is performed by a (signed) subtraction of subtrahend from minuend, the results of which can be called difference. Performs a comparison operation between minuend and subtrahend. PF is set if rax has an even number of set bits.SF becomes the sign of rax, which is a simple test for non-negativity.passing the same register twice: test rax, rax.PF ≔ BitWiseXorNor( commonBits), so PF is set if and only if commonBits has an even number of 1 bits.ZF ≔ ( commonBits = 0), so a set ZF means, accumulator and reference do not have any set bits in common.Register (where AL/AX/EAX can be encoded specially if reference is an immediate value).Performs a bit-wise logical and on accumulator and reference the result of which we will refer to as commonBits and sets the ZF(zero), SF(sign) and PF (parity) flags based on commonBits. 2.11 Jump if Below or Equal (unsigned comparison)Ĭomparison Instructions test reference, accumulator.2.10 Jump if Below (unsigned comparison).2.7 Jump if Above or Equal (unsigned comparison).2.6 Jump if Above (unsigned comparison). ![]()
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