x86 Opcode Structure and Instruction Overview
30 Aug 2011 Source: Intel x86 Instruction Set Reference. Opcode table presentation inspired by work of Ange Albertini. MMX SSE{2
Intel® 64 and IA-32 Architectures Software Developers Manual
The Intel® 64 and IA-32 Architectures Software · Developer's Manual Volumes 2A
x64 Cheat Sheet
In the following table. ○ Imm refers to a constant value
AMD64 Architecture Programmers Manual Volume 3: General
2 Jun 2023 June 2023. 3.35. Table 1-1 and Table 1-5: Added the caveat “unless ... Opcode. Description. [AMD Public Use]. Page 357. General-Purpose. 317.
Intel® 64 and IA-32 Architectures Software Developers Manual
Table B-27. Formats and Encodings of SSE2 Integer Instructions ... Opcode/. Instruction. Op/. En. 64/32-bit. Mode. CPUID. Feature. Flag. Description. F2 0F D0 /r.
x86 Instruction Encoding
Thus [0f <opcode>] is a two-byte opcode; for example vendor extension. 3DNow! is 0f 0f. ○. 0f 38/3a primarily SSE* → separate opcode maps; additional table
introduction-to-x64-assembly-181178.pdf
x64 is a generic name for the 64-bit extensions to Intel‟s and AMD‟s 32-bit x86 instruction set Table 4 – Common Opcodes. Opcode. Meaning. Opcode. Meaning.
The RISC-V Instruction Set Manual
7 May 2017 Table 12.3: RVC opcode map. Tables 12.4–12.6 list the RVC ... Intel x86 AVX [20] and ARM Neon [11]. We describe a standard framework for ...
ISA Aging: A X86 case study
Table I: x86 instruction encoding example. The ModR/M byte is part of the opcode encoding in this instruction because its subfield Reg/Opc is used as an opcode.
x86 Opcode Structure and Instruction Overview
30 ???. 2011 ?. x86 Opcode Structure and Instruction Overview ... Opcode table presentation inspired by work of Ange Albertini. MMX SSE{2
Intel® 64 and IA-32 Architectures Software Developers Manual
Opcode Column in the Instruction Summary Table (Instructions with VEX prefix) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-3. 3.1.1.3.
4. Instruction tables
11 ???. 2022 ?. breakdown and other tables for x86 family microprocessors from Intel AMD
x86 Instruction Encoding
x86 ISA. ? Insn set backwards-compatible to Intel 8086. • A hybrid CISC Most manuals opcode tables in hex let's look at them in octal :) ...
AMD64 Technology AMD64 Architecture Programmers Manual
Tables xiii. 24594—Rev. 3.33—November 2021. AMD64 Technology. Tables In the legacy x86 architecture addressing relative to the instruction pointer is ...
Appendix A: Intel x86 Instruction Reference
r/m64 is MMX- related and is a shorthand for mmxreg/mem64. A.2 Key to Opcode Descriptions. This appendix also provides the opcodes which NASM will generate for
ref.x86asm.net X86 Opcode Reference 64-bit Edition
ref.x86asm.net. X86 Opcode Reference. 64-bit Edition general system
CPU Opcodes
24 ???. 2018 ?. Must be a reference to an instruction operand. The instruction operand has “rel” type of the matching size. class opcodes.x86.DataOffset.
x64 Cheat Sheet
In 32-bit x86 the base pointer (formerly %ebp
Enumerating x86-64 Instructions
Using the Udis86 library Table 3 shows the numbers for each instruction length. Page 6. 6. Table 3. Instruction Counts for Opcode Lengths. Bytes. Instruction.
X86 Opcode Reference 64-bit Edition
X86 Opcode Reference 64-bit Edition general system x87 FPU MMX SSE(1) SSE2 SSE3 SSSE3 opcodes Copyright © MazeGen First Edition July 2008 Errata: http://ref x86asm net/errata/64/opcode Karel Lejska Bayerova 8 Brno 60200 Czech Republic Product or corporate names may be trademarks or registered trademarks and are
how many bits are needed for the opcode - Lisbdnetcom
Main Opcode bits Operand length bit Register/Opcode modifier defined by primary opcode Addressing mode r/m field Index field Scale field Base field CALL Source: Intel x86 Instruction Set Reference Opcode table presentation inspired by work of Ange Albertini MMX SSE{23} MMX SSE2 MMX SSE{12} MMX SSE{123} 1 st 2nd 1 2nd
CPU Opcodes - Read the Docs
class opcodes x86 Encoding Instruction encoding Variables components – a list of Prefix VEX Opcode ModRM RegisterByte Immediate DataOffset CodeOffset objects that specify the components of encoded instruction class opcodes x86 ISAExtension(name) score A number that can be used to order a list of ISA extensions class opcodes x86 Immediate
X86 Opcode Reference 32-bit Edition - x86asmnet
X86 Opcode Reference 32-bit Edition general system x87 FPU MMX SSE(1) SSE2 SSE3 SSSE3 opcodes Copyright © MazeGen First Edition July 2008 Errata: http://ref x86asm net/errata/32/opcode Karel Lejska Bayerova 8 Brno 60200 Czech Republic Product or corporate names may be trademarks or registered trademarks and are
Brief x86 history (3) - University of Minnesota
x86 instruction format parts Optional prefix bytes One two or three-byte opcode Extra bytes specifying operands Many insns have a mod/reg/RM byte Some addressing modes have an SIB byte Some addressing modes have a constant displacement Sometimes a immediate (constant) operand x86 opcode map Prefix bytes 0x26 0x2e 0x36 0x3e 0x64 0x65: segment
Searches related to opcode table x86 filetype:pdf
Opcode Single byte denoting basic operation; opcode is mandatory A byte => 256 entry primary opcode map; but we have more instructions Escape sequences select alternate opcode maps Legacy escapes: 0f [0f 38 3a] Thus [0f ] is a two-byte opcode; for example vendor extension 3DNow! is 0f 0f
[PDF] x86 Opcode Structure and Instruction Overview
30 août 2011 · x86 Opcode Structure and Instruction Overview Opcode table presentation inspired by work of Ange Albertini MMX SSE{23} MMX SSE2
[PDF] x86 Instruction Encoding
x86 ISA ? Insn set backwards-compatible to Intel 8086 • A hybrid CISC Most manuals opcode tables in hex let's look at them in octal :)
nice and simple x86 opcode table [pdf] : r/programming - Reddit
Here's a Z80 opcode chart I created I always though Z80 opcodes were neater than x86 ones (I mean NOP is 90?!?) but seeing them side by side
[PDF] Appendix A: Intel x86 Instruction Reference
This appendix provides a complete list of the machine instructions which NASM will assemble and a short description of the function of each one
coder32 edition X86 Opcode and Instruction Reference 112
coder32 edition of X86 Opcode and Instruction Reference one byte opcodes; AMD64 Architecture Programmer's Manual Volume 3 Table One-Bytes Opcodes
[PDF] Intel x86 Assembler Instruction Set Opcode Table - PDFCOFFEECOM
Intel x86 Assembler Instruction Set Opcode Table The instruction has no ModR/M byte; the address of the operand is encoded in the instruction; and no
Intel x86 Assembler Instruction Set Opcode Tabledocx
The reg field of the ModR/M byte selects a packed SIMD floating-point register An ModR/M byte follows the opcode and specifies the operand The operand is
Intel x86 Assembler Instruction Set Opcode Table
Intel x86 Assembler Instruction Set Opcode Table The instruction has no ModR/M byte; the address of the operand is encoded in the instruction;
Intel x86 Assembler Instruction Set Opcode Table PDF - Scribd
Intel x86 Assembler Instruction Set Opcode Table docx - Free download as Word Doc ( doc / docx) PDF File ( pdf ) Text File ( txt) or view presentation
What are x86 opcode bytes?
- The x86 opcode bytes are 8-bit equivalents of iii field that we discussed in simplified encoding. This provides for up to 512 different instruction classes, although the x86 does not yet use them all. How many bits are needed for the program counter and the instruction register?
What is an opcode table?
- 2007 by Taylor & Francis Group, LLC. The asse mbler uses an opcode table to extract opcode inf ormation. The op code table is a table storing each mnemon ic, the correspo nding opcode , and any othe r attribut e of the instru ction useful for the asse mbly proce ss.
What is the difference between x86-64 and x87 opcodes?
- So when SIB.baseuses a 16-bit register (such as AX), the address size becomes 16-bit. Using a 32-bit displacement will result in the displacement being truncated. Opcode The x86-64 instruction set defines many opcodes and many ways to encode them, depending on several factors. Legacy opcodes Legacy (and x87) opcodes consist of, in this order:
CSci 5980/8980
Manual and Automated Binary Reverse Engineering
Day 2: x86 Overview and Arithmetic
Stephen McCamant
University of MinnesotaOutline
x86-32 Overview x86-32 Arithmetic Basics x86-32 to x86-64 In Compiler ExplorerBrief x86 history (1)Brief x86 history (2)80286 added memory protection not easily usable
by MS-DOS80386 introduced 32-bit mode and pagingBrief x86 history (3)Intel had a history of designing clean-sheet
processors that were undercut by cheaper x86esIts first 32-bit, RISC, VLIW, and 64-bit processors were
never popular on the desktopA backwards-compatible 64-bit extension was designed by AMD undercutting Intel/HP ItaniumLater adopted by Intel making it a de-facto standard Various called x86-64, AMD64, EMT64T, Intel 64, x64Supported modern OSes like Unix and Windows NT80486 was almost the same ISA, but fasterBrief x86 history (3)
Intel had a history of designing clean-sheet
processors that were undercut by cheaper x86esIts first 32-bit, RISC, VLIW, and 64-bit processors were
never popular on the desktopA backwards-compatible 64-bit extension was designed by AMD undercutting Intel/HP ItaniumLater adopted by Intel making it a de-facto standard Various called x86-64, AMD64, EMT64T, Intel 64, x64Cache, pipeliningWhat would have been the 80586 was sold as the
"Pentium"4-bit Intel 4004 and 8-bit 8008 were mostly for calculatorsBrief x86 history (2)80286 added memory protection not easily usable
by MS-DOS80386 introduced 32-bit mode and pagingBrief x86 history (3)Intel had a history of designing clean-sheet
processors that were undercut by cheaper x86esIts first 32-bit, RISC, VLIW, and 64-bit processors were
never popular on the desktopA backwards-compatible 64-bit extension was designed by AMD undercutting Intel/HP ItaniumLater adopted by Intel making it a de-facto standard Various called x86-64, AMD64, EMT64T, Intel 64, x64Supported modern OSes like Unix and Windows NT80486 was almost the same ISA, but fasterBrief x86 history (3)
Intel had a history of designing clean-sheet
processors that were undercut by cheaper x86esIts first 32-bit, RISC, VLIW, and 64-bit processors were
never popular on the desktopA backwards-compatible 64-bit extension was designed by AMD undercutting Intel/HP ItaniumLater adopted by Intel making it a de-facto standard Various called x86-64, AMD64, EMT64T, Intel 64, x64Cache, pipeliningWhat would have been the 80586 was sold as the
"Pentium"8-bit 8080 powered early hobbyist micro computersBrief x86 history (2)80286 added memory protection not easily usable
by MS-DOS80386 introduced 32-bit mode and pagingBrief x86 history (3)Intel had a history of designing clean-sheet
processors that were undercut by cheaper x86esIts first 32-bit, RISC, VLIW, and 64-bit processors were
never popular on the desktopA backwards-compatible 64-bit extension was designed by AMD undercutting Intel/HP ItaniumLater adopted by Intel making it a de-facto standard Various called x86-64, AMD64, EMT64T, Intel 64, x64Supported modern OSes like Unix and Windows NT80486 was almost the same ISA, but fasterBrief x86 history (3)
Intel had a history of designing clean-sheet
processors that were undercut by cheaper x86esIts first 32-bit, RISC, VLIW, and 64-bit processors were
never popular on the desktopA backwards-compatible 64-bit extension was designed by AMD undercutting Intel/HP ItaniumLater adopted by Intel making it a de-facto standard Various called x86-64, AMD64, EMT64T, Intel 64, x64Cache, pipeliningWhat would have been the 80586 was sold as the
"Pentium"16-bit 8086 was binary incompatible (but partially assembly-level compatible) with the 8080Brief x86 history (2)80286 added memory protection not easily usable
by MS-DOS80386 introduced 32-bit mode and pagingBrief x86 history (3)Intel had a history of designing clean-sheet
processors that were undercut by cheaper x86esIts first 32-bit, RISC, VLIW, and 64-bit processors were
never popular on the desktopA backwards-compatible 64-bit extension was designed by AMD undercutting Intel/HP ItaniumLater adopted by Intel making it a de-facto standard Various called x86-64, AMD64, EMT64T, Intel 64, x64Supported modern OSes like Unix and Windows NT80486 was almost the same ISA, but fasterBrief x86 history (3)
Intel had a history of designing clean-sheet
processors that were undercut by cheaper x86esIts first 32-bit, RISC, VLIW, and 64-bit processors were
never popular on the desktopA backwards-compatible 64-bit extension was designed by AMD undercutting Intel/HP ItaniumLater adopted by Intel making it a de-facto standard Various called x86-64, AMD64, EMT64T, Intel 64, x64Cache, pipeliningWhat would have been the 80586 was sold as the
"Pentium"Cheaper-package 8088 edition of 8086 selected byIBM for the original IBM PCBrief x86 history (2)
80286 added memory protection not easily usable
by MS-DOS80386 introduced 32-bit mode and pagingBrief x86 history (3)Intel had a history of designing clean-sheet
processors that were undercut by cheaper x86esIts first 32-bit, RISC, VLIW, and 64-bit processors were
never popular on the desktopA backwards-compatible 64-bit extension was designed by AMD undercutting Intel/HP ItaniumLater adopted by Intel making it a de-facto standard Various called x86-64, AMD64, EMT64T, Intel 64, x64Supported modern OSes like Unix and Windows NT80486 was almost the same ISA, but fasterBrief x86 history (3)
Intel had a history of designing clean-sheet
processors that were undercut by cheaper x86esIts first 32-bit, RISC, VLIW, and 64-bit processors were
never popular on the desktopA backwards-compatible 64-bit extension was designed by AMD undercutting Intel/HP ItaniumLater adopted by Intel making it a de-facto standard Various called x86-64, AMD64, EMT64T, Intel 64, x64Cache, pipeliningWhat would have been the 80586 was sold as the
"Pentium"Brief x86 history (3)Intel had a history of designing clean-sheet
processors that were undercut by cheaper x86esIts first 32-bit, RISC, VLIW, and 64-bit processors were
never popular on the desktopA backwards-compatible 64-bit extension was designed by AMD undercutting Intel/HP ItaniumLater adopted by Intel making it a de-facto standard Various called x86-64, AMD64, EMT64T, Intel 64, x64The x86 ISA: CISC vs. RISCCalled CISC because it predates the 80s/90s RISC
revolutionPre-RISC ISAs were for human assembly programmers RISC CPUs had simpler instructions, moving complexity to compilers(Note, ISAs grew more complex over time anyway)ISA is the only aspect of x86 that did not change
x86-64 compilers mostly use the RISC-like instructions The internals of modern x86 CPUs are RISC-likex86 ISA attributesVariable-length byte-granularity instructions
Most instructions overwrite one operand
"Two-address" instead of "three-address" styleMost instructions allow one operand in memory
Versus load-store style of RISC
Rich addressing modes
Branching using condition codesx86 instruction encodingVariable length instructions are a "prefix code":
Values of bytes tell how many more to read
Short encodings (some 1 byte) for simple/common
instructionsLong encodings for rare/newer instructions and complex operandsOverall limit of 15 bytes for any instruction x86 instruction format partsOptional prefix bytes
One, two, or three-byte opcode
Extra bytes specifying operands
Many insns have a "mod/reg/RM" byte
Some addressing modes have an "SIB" byte
Some addressing modes have a constant displacement Sometimes a immediate (constant) operandx86 opcode mapPrefix bytes0x26, 0x2e, 0x36, 0x3e, 0x64, 0x65: segment
overridesA mostly-obsolete memory management feature0x66 operand size override
In 32-bit mode, operand is 16-bit (and vice-versa)0x67 address size override (rarely used)
0xf0 lock: block concurrent access
0xf2, 0xf3: repne and rep/repe, repeat string
operationx86 condition codesSix one-bit flags set based on math or comparison
results:CF: (unsigned) carry outOF: (signed) overflow
ZF: result is zero
SF: result is negative ("sign")
PF: parity of result (mostly historical)
AF: adjustment needed for BCD (mostly historical)
More about these when we cover branchesx86-32 operand sizesMany general-purpose/integer arithmetic insns can
operate on 8, 16, or 32-bit valuesSometimes the byte insn has an even opcode and the 32-bit opcode is one higherFor a 16-bit version, use the 32-bit opcode with a0x66 prefix bytePre-386, these opcodes were 16-bitx86-32 general-purpose registers
8, 32-bit registers for integers or pointers
In encoding order:???,???,???,???,???,???,
???,???Without the "e", refers to the low 16-bits of the32-bit registerEvery register is special
Most insns with variable operands have an extra
byte to specify them3 fields: 2-bit Mod, 3-bit Reg/Opcode, 3-bit R/MThe Mod and R/M fields specify an operand that
could be in memory:If Mod=11 (byte?0xc0), R/M specifies a registerElse if R/M = 100, see next slide Else, register addr maybe with 8 or 32-bit displacement The Reg field is the other operand, or a sub-opcodeExample ModR/M addressing modes
Opcode 0xff/000 means 32-bit increment
More complex addressing modes use another byte
"SIB": 2-bit scale, 3-bit index register, 3-bit base registerBase and index are added together, with the index multiplied by 1, 2, 4, or 8Think: array indexingBase or index can also be omittedOutline
x86-32 Overview x86-32 Arithmetic Basics x86-32 to x86-64In Compiler ExplorerLEA for arithmetic
The computations used for addressing modes are
also available as a separate instruction???No memory access, just stores computed value in another registerWhy? Addition of registers with constants and small multiplesThree-address, unlike regular arithmetic
Does not set condition codes8 core binary operators ???("subtract with borrow"),???,???,???,??????is like???, but the result is discarded, useful only for flagsShift-family operationsOpcodes 0xc0, 0xc1, 0xd0, 0xd1, 0xd2, 0xd3
In encoding order:???,???,???,???,???/???,
???, (???),???The amount operand can be:An 8-bit immediate (0xc0 and 0xc1)
One position (0xd0 and 0xd1)
The low bits of???(0xd2 and 0xd3)Shift-family operations (cont"d) ???,???are circular bit rotation???,???are?????-bit rotations that also incorporate CF???is logical (unsigned) right shift, while???is arithmetic (signed) right shiftThere is no logical/arithmetic distinction for left shift,and only the 100 position is documented110, which would be???, is an undoc. synonym of 100Unary-family operations
Opcodes 0xf6, 0xf7, 0xfe, and 0xff encode several
arithmetic operators with only a ModR/M operand???and???are increment and decrement???is bitwise not and???is unary negation
Multiplication
Widening multiply has unsigned (???) and signed
(????) versions, and a unary encoding:One factor is always in???The other factor is a register or memory location
The product is in???????Same-size????also has more flexible binary encodingsDivision and remainderDivision and remainder are always computed
togetherThere are unsigned (???) and signed (????)versions, with a unary encoding:The dividend is in???????The divisor is a register or memory location
The quotient is in???The remainder is in???x87-style floating pointIn the 8086-80386 era, hardware floating point
required a separate chipThe 8087 was more transistors and more expensive than the 8086Pioneering but now-unusual design80-bit extended register size
Stack-structured register file
Opcodes 0xd8-0xdf, mnemonics starting with "f"SIMD extensionsSince the Pentium era, repeated extensions have
added SIMD supportSingle Instruction Multiple Data: wide registers treated like small arraysMMX, SSE, AVXMostly separate register file and instructions
Two and three-byte opcodes with 0x66, 0xf2, and
0xf3 reused to specify operand sizeOutline
x86-32 Overview x86-32 Arithmetic Basics x86-32 to x86-64In Compiler Explorerx86-64 extension overview
Extended registers to 64 bits
64-bit versions of most operations
Main use case was 64 bit pointers, but still 32-bit intsDoubled number of GPRs from 8 to 16Most RISC ISAs have 32
Mostly backwards-compatibleREX encoding
How to signal 64-bit ops, and name new registers?
Switch opcodes 0x40-0x4f into a new kind of prefix byte with four extra bitsBit 3 is set to 1 (e.g. 0x48) to indicate a 64-bit operationOther bits become the 4th bit of register numbers, i.e. set means new registersx86-64 registersAll the new register names start with "r"
x86-32 "e" registers extend to 64-bit by changing "e" to "r"The new registers are r8 through r15 Low 32-, 16-, and 8-bit parts are available with more systematic names?,?, or?suffixImplicit zero extension
Operations on 8- and 16-bit subregisters leave the rest unchangedConvenient for storing other data in high half32-bit operations in x86-64 are different: they
always set the high half to zeroConvenient for mixing 32-bit and 64-bit computations Exception: 0x90 ("xchg eax, eax") is still a no-opOutline x86-32 Overview x86-32 Arithmetic Basics x86-32 to x86-64In Compiler Explorer
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