Xchg Ax Ax

XCHG — Exchange Register/Memory with Register

felixcloutier.comXCHG (E)AX, (E)AX (encoded instruction byte is 90H) is an alias for NOP regardless of data size prefixes, including REX.W.


An Assembly program to exchange two variables using XCHG …

cssimplified.comInstruction XCHG is used to EXCHANGE memory variables in the following permutations above. REG stands for Registers (Eg. AX, BX, CX, DX). memory stands for Variable or Address. immediate stands for Numbers or Values. Let us understand the meanings of the above permutations.


XCHG Exchange Operands – c-jump

c-jump.comExchanging an operand with AX may be accomplished with a single-byte opcode, saving fetch time and code space. All good assemblers recognize these cases and optimize for them, but if you are hand-assembling INLINE statements for some high-level language, keep the single-byte special cases in mind.


8086 Data Transfer Instructions – Assembly Language …

microcontrollerslab.comThe code given above first sets AX to 5C21 and CX to 3D05. After execution of fourth instruction XCHG AX, CX, the contents of AX and CX are exchanged. AX becomes CX and CX becomes AX. Then XCHG AH, CL exchanges the most significant bits of AH with lower bits of CL.


X86 Assembly/Data Transfer – Wikibooks, open books for an …

en.wikibooks.org2020-11-06 · The cmpxchg instruction has one implicit operand: the al / ax / eax depending on the size of arg1. The instruction compares arg1 to al / ax / eax. If they are equal, arg1 becomes arg2. (arg1 = arg2) Otherwise, al / ax / eax becomes arg1.


Data Movement Instructions

kader05cuet.files.wordpress.com• Example: XCHG AX, BX ; Exchanges the content of AX with BX. XCHG [DI], AL ; Exchanges the content of memory location [DI] with AL XLAT • The XLAT (translate) instruction converts of the AL register into a number stored in a memory table. • This instruction performs the direct table lookup technique often used to convert one code to another. • An XLAT instruction first adds the …


39942 – Nonoptimal code – leaveq; xchg %ax,%ax; retq

gcc.gnu.org(In reply to comment #8) > From config/i386/i386.c: > /* AMD Athlon works faster > when RET is not destination of conditional jump or directly preceded > by other jump instruction. We avoid the penalty by inserting NOP just > before the RET instructions in such cases. */ …


disassembly – Assembly that just seems to be a jumble …

reverseengineering.stackexchange.comNo, before the add it does xchg ax, si but ax at this point is not the initial ax. There are multiple code paths that lead to it, for example with dx = cx = 0 (so only 16 bit numbers as input), ax at that point contains dx instead (which is 0). Do note that mul outputs to dx:ax so the other code paths are more complicated. – Johann Aydinbas Feb 27 ’19 at 0:12. add a comment | 2. It looks …


Reversing Assembly – Nightmare – Nightmare – Nightmare

guyinatuxedo.github.io080483fb <main>: 80483fb: 8d 4c 24 04 lea ecx,[esp+0x4] 80483ff: 83 e4 f0 and esp,0xfffffff0 8048402: ff 71 fc push DWORD PTR [ecx-0x4] 8048405: 55 push ebp 8048406: 89 e5 mov ebp,esp 8048408: 51 push ecx 8048409: 83 ec 14 sub esp,0x14 804840c: c7 45 f4 0a 00 00 00 mov DWORD PTR [ebp-0xc],0xa 8048413: 83 7d f4 0a cmp DWORD PTR [ebp-0xc],0xa 8048417: 75 10 jne 8048429 …


80386 Programmer’s Reference Manual — Opcode XCHG

fermimn.edu.it11 rows · Description XCHG exchanges two operands. The operands can be in either order. If a …


x86 – How does xchg work in Intel Assembly Language …

stackoverflow.comxchg only stores one element, and it can’t magically look back in time to know where the value in eax came from and swap two memory locations with one xchg instruction. The only way to swap 1,2 to 2,1 in one instruction would be a 64-bit rotate, like rol qword ptr [arrayD], 32 (x86-64 only).


Winter: x86 Instruction Set Reference

c9x.meOpcode Mnemonic Description; 90+rw: XCHG AX, 16: Exchange r16 with AX. 90+rw: XCHG r16, X: Exchange AX with r16. 90+rd: XCHG EAX, r32: Exchange r32 with EAX. 90+rd


Microprocessor Engineering Q1: Find The Values Of …

chegg.comLet AX= 1234H, BX=5678H, CX=0AOBH. XCHG AX,BX, BX= MOV AX,CL ; AX= XOR CL.BL; CX= Q2: Write A Code That Will Exchange The Values Of Al With Bl And Ch With Dh Using Exchange Instruction. Let AX= 1111-, BX=2222H, CX=4444H, DX=5555H. Q3: Use Lea Instruction…


Output – SizeCoding

sizecoding.org2020-10-17 · Here’s an obligatory "Hello World" program in text mode, using a "high level" MS-DOS function. With a small optimization already included (using XCHG BP,AX instead of MOV AH,09h), this snippet is 20 bytes in size.


> E.g. xchg ax,ax which does nothing in one byte. Luckily …

news.ycombinator.comxchg ax,ax simply is encoded as 0x90, which is the same as nop (the same holds for. xchg eax, eax in x86-32). > But what about xchg bx,bx, xchg cx,cx and so on? This (cleverly?) cannot be encoded in one byte. Here you have to use at least two bytes (0x87 followed by the ModR/M byte in x86-16; the same holds for their 32 bit counterparts xchg ebx, ebx; xchg ecx, ecx etc. in x86-32): > http …


80386 Programmer’s Reference Manual — Opcode XCHG

pdos.csail.mit.eduXCHG — Exchange Register/Memory with Register Opcode Instruction Clocks Description 90 + r XCHG AX,r16 3 Exchange word register with AX 90 + r XCHG r16,AX 3 Exchange word register with AX 90 + r XCHG EAX,r32 3 Exchange dword register with EAX 90 + r XCHG r32,EAX 3 Exchange dword register with EAX 86 /r XCHG r/m8,r8 3 Exchange byte register with EA byte 86 /r XCHG r8,r/m8 3/5 …


Why do we need the "nop" I.e. No operation instruction in …

electronics.stackexchange.comAnd since xchg ax, ax doesn’t really make sense as an instruction, you can see how the designers of the 8086 saved on transistors and pathways in instruction decoding by exploiting the fact that 0x90 maps naturally to something that’s entirely "noppy". On the other hand, the i8051 has an entirely designed-in opcode for nop – 0x00. Kinda practical. The instruction design is basically using the …



ce701avm.files.wordpress.comXCHG AX, DX Exchange word in AX with word in DX XCHG BL, CH Exchange byte in BL with byte in CH XCHG AL, PRICES [BX] Exchange byte in AL with byte in memory at EA = PRICE [BX] in DS. LEA – LEA Register, Source This instruction determines the offset of …


Linking and Loading

ics.uci.eduExample program Compute 5 + 6 #include <stdio.h> int main(int ac, char **av) {int a = 5, b = 6; return a + b;} We build it like I’m on 64 bit system, but want 32bit code, hence -m32 -fno-pic – disables position independent code gcc -m32 -fno-pic hello-int.c


Instruction Set of 8086 with Examples – Electronics and …

electronicsandcommunications.comXCHG AX, BX XCHG BX, DX XCHG AL, BL XCHG AH BH XCHG Register, Memory XCHG AX, [1000] XCHG BX, [1016] XCHG CX, [1032] XCHG DX, [1048] XCHG Memory, Register XCHG [1000], AX XCHG [1016], CX XCHG [1032], BX XCHG [1048], DX IN and OUT Instructions: IN instruction is used to receive data from the peripheral devices to the processor and OUT instruction is used to send data …


Chapter 5The proessor status and the FLAGS registers

slideshare.net2017-11-21 · A) ADD AX,BX ;AX=7FFFh and BX=0001h B) SUB AL, BL ;AL=01h and BL=FFh C) DEC AL ;AL=00h D) NEG AL ;AL=7Fh E) XCHG AX, BX ;AX=1ABCh, BX= 712Ah F) ADD AL, BL ;AL=80h, BL=FFh G) SUB AX, BX ; AX=0000h, BX= 8000h H) NEG AX AX=0001h ADD AX,BX ;AX=7FFFh and BX=0001h 7=0111 , F=1111 0111 1111 1111 1111 +0000 0000 0000 0001 1000 0000 0000 0000 …


XCHG – Exchange – Instructions

sites.google.com87 / r XCHG r16,r/m16 Exchange word from r/m16 with r16 87 / r XCHG r/m32,r32 Exchange r32 with doubleword from r/m32 87 / r XCHG r32,r/m32 Exchange doubleword from r/m32 with r32


MOV Instruction The mov instruction also allows us to copy …

coursehero.comXCHG Instruction Swaps two values . The general form is xchg operand1, operand2 Can be in the following form: xchg reg, mem xchg reg, reg The order of the operand is not important ie: xchg ax, bx == xchg bx, ax xchg instruction does not modify any flags


Answered: By providing a clear difference between… | bartleby

bartleby.com2020-06-23 · MOV AX, WORD1 XCHG WORD2, AX MOV WORD1, AX. Question. Asked Jun 23, 2020. 9 views. By providing a clear difference between the MOV and XCHG operators, explain the outcome of the following sequential statements with respect to the MOV and XCHG operators. MOV AX, WORD1 XCHG WORD2, AX MOV WORD1, AX. check_circle Expert Answer. Step 1. The difference between MOV and XCHG


Format String Exploit – CTF Wiki

ctf-wiki.github.io→ 0xf7e44670 <printf+0> call 0xf7f1ab09 <__x86.get_pc_thunk.ax> ↳ 0xf7f1ab09 <__x86.get_pc_thunk.ax+0> mov eax, DWORD PTR [esp] 0xf7f1ab0c <__x86.get_pc_thunk.ax+ …


; Pyrit; a 256-byte intro by Rrrola <rrrola@gmail.com …

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