Jun 19, 2017 · The repz prefix (alternately spelled repe) means to increment rsi and rdi then repeat cmps as long as [rsi] and [rdi] compare equal. The rflags register will be set on each …

Oct 5, 2016 · The issue of the repz ret has been covered here as well as in other sources [2, 3] quite satisfactorily. However, reading neither of these sources, I found answers to the …

Sep 29, 2017 · 2) repeat and decrease ecx until ecx equal to 0 or ZF set in the CMPS,SCAS instructions and called repz or repe. The 0xF3 binary prefix is used as: 1) repeat and decrease …

repz ret: why all the hassle? has some extra details about the specific micro-architectural reasons why that gives K8 and Barcelona a hard time. Avoiding 1-byte ret as a possible branch target: …

Jan 19, 2010 · The REPZ and REPNZ prefixes are synonymous forms of the REPE and REPNE prefixes, respectively.) Share.

Feb 24, 2016 · Let's talk about the prefix REPZ now. From vol. 1, §7.3.9.2: The following repeat prefixes can be used in conjunction with a count in the ECX register to cause a string …

Prefixes (other than lock) that don't apply to an instruction are ignored in practice by existing CPUs.. The documentation says using rep with instructions it doesn't apply to is "reserved and …

Looking at the following assembly code: MOV ESI, DWORD PTR [EBP + C] MOV ECX, EDI MOV EAX, EAX SHR ECX, 2 LEA EDI, DWORD PTR[EBX + 18] REP MOVS DWORD PTR …

Nov 6, 2014 · I am trying to reverse engineer a binary and the following instruction is confusing me, can anyone clarify what exactly this does? =>0x804854e: repnz scas al,BYTE PTR …

May 12, 2014 · The solution is simple, you just need to put the repz and the ret on two consecutive lines. Also note that this optimization is obsolete, AMD now recommends to use …