add Pack ; change api to access reg for StackFrame
2 files changed
tree: 782cd0c87bbdffe5f298abdff4ac12054005ae41
  2. Makefile
  3. gen/
  5. readme.txt
  6. sample/
  7. test/
  8. xbyak.sln
  9. xbyak/

Xbyak 3.80 ; JIT assembler for x86(IA32), x64(AMD64, x86-64) by C++


This is a header file which enables dynamically to assemble x86(IA32), x64(AMD64, x86-64) mnemonic.


header file only you can use Xbyak's functions at once if xbyak.h is included.

Supported Instructions Sets


Supported OS

  • Windows Xp, Vista, Windows 7(32bit, 64bit)
  • Linux(32bit, 64bit)
  • Intel Mac ready

Supported Compilers

  • Visual Studio C++ 2005 Express Ed., VC2008 Pro, VC2010
  • gcc 4.5
  • mingw 3.4.2
  • icc 7.2

Note: Xbyak uses and(), or(), xor(), not() functions, so “-fno-operator-names” option is required on gcc. Or define XBYAK_NO_OP_NAMES and use and_(), or_(), xor_(), not_() instead of them. and_(), or_(), xor_(), not_() are available if XBYAK_NO_OP_NAMES is not defined.


The following files are necessary. Please add the path to your compile directories.

  • xbyak.h
  • xbyak_bin2hex.h
  • xbyak_mnemonic.h


make install

These files are copied into /usr/local/include/xbyak

New Feature

AutoGrow mode is a mode that Xbyak grows memory automatically if necessary. Call ready() before calling getCode() to calc address of jmp.

struct Code : Xbyak::CodeGenerator {
    : Xbyak::CodeGenerator(<default memory size>, Xbyak::AutoGrow)
Code c;
c.ready(); // Don't forget to call this function

Don't use the address returned by getCurr() before calling ready(). It may be invalid address. RESTRICTION : rip addressing is not supported in AutoGrow


Make Xbyak::CodeGenerator and make the class method and get the function pointer by calling cgetCode() and casting the return value.

NASM              Xbyak
mov eax, ebx  --> mov(eax, ebx);
inc ecx           inc(ecx);
ret           --> ret();


(ptr|dword|word|byte) [base + index * (1|2|4|8) + displacement]
                      [rip + 32bit disp] ; x64 only

NASM                   Xbyak
mov eax, [ebx+ecx] --> mov (eax, ptr[ebx+ecx]);
test byte [esp], 4 --> test (byte [esp], 4);

selector is not supported.

you can use ptr for almost memory access unless you specify the size of memory.

dword, word and byte are member variables, then don't use dword as unsigned int, for example.


You can omit a destination for almost 3-op mnemonics.

vaddps(xmm1, xmm2, xmm3); // xmm1 <- xmm2 + xmm3
vaddps(xmm2, xmm3); // xmm2 <- xmm2 + xmm3
vaddps(xmm2, xmm3, ptr [rax]); // use ptr to access memory


  jmp ("L1");

  jmp ("L2");
  a few mnemonics(8-bit displacement jmp)

  jmp ("L3", T_NEAR);
  a lot of mnemonics(32-bit displacement jmp)

Call hasUndefinedLabel() to verify your code has no undefined label. you can use a label for immediate value of mov like as mov (eax, “L2”);

1. support @@, @f, @b like MASM

L("@@"); // <A>
  jmp("@b"); // jmp to <A>
  jmp("@f"); // jmp to <B>
L("@@"); // <B>
  jmp("@b"); // jmp to <B>
  mov(eax, "@b");
  jmp(eax); // jmp to <B>

2. localization of label by calling inLocalLabel(), outLocallabel().

labels begining of period between inLocalLabel() and outLocalLabel() are dealed with local label. inLocalLabel() and outLocalLabel() can be nested.

void func1()
  L(".lp"); // <A> ; local label
    jmp(".lp"); // jmpt to <A>
  L("aaa"); // global label

void func2()
  L(".lp"); // <B> ; local label
    jmp(".lp"); // jmp to <B>

Code size

The default max code size is 2048 bytes. Please set it in constructor of CodeGenerator() if you want to use large size.

class Quantize : public Xbyak::CodeGenerator {
    : CodeGenerator(8192)

use user allocated memory

You can make jit code on prepaired memory.

class Sample : public Xbyak::CodeGenerator {
    Sample(void *userPtr, size_t size)
        : Xbyak::CodeGenerator(size, userPtr)

const size_t codeSize = 1024;
uint8 buf[codeSize + 16];

// get 16-byte aligned address
uint8 *p = Xbyak::CodeArray::getAlignedAddress(buf);

// append executable attribute to the memory
Xbyak::CodeArray::protect(p, codeSize, true);

// construct your jit code on the memory
Sample s(p, codeSize);

See sample/test0.cpp


  • XBYAK32 is defined on 32bit.
  • XBYAK64 is defined on 64bit.
  • XBYAK64_WIN is defined on 64bit Windows(VC)
  • XBYAK64_GCC is defined on 64bit gcc, cygwin


  • test0.cpp ; tiny sample of Xbyak(x86, x64)
  • quantize.cpp ; JIT optimized quantization by fast division(x86 only)
  • calc.cpp ; assemble and estimate a given polynomial(x86, x64)
  • bf.cpp ; JIT brainfuck(x86, x64)


The current version does not support 3D Now!, 80bit FPU load/store and some special mnemonics. Please mail to me if necessary.


modified new BSD License


  • 2013/Mar/27 ver 3.80 support mov(reg, “label”);
  • 2013/Mar/13 ver 3.76 add cqo(), jcxz(), jecxz(), jrcxz()
  • 2013/Jan/15 ver 3.75 add setSize() to modify generated code
  • 2013/Jan/12 ver 3.74 add CodeGenerator::reset() ; add Allocator::useProtect()
  • 2013/Jan/06 ver 3.73 use unordered_map if possible
  • 2012/Dec/04 ver 3.72 eax, ebx, ... are member variables of CodeGenerator(revert), Xbyak::util::eax, ... are static const.
  • 2012/Nov/17 ver 3.71 and_(), or_(), xor_(), not_() are available if XBYAK_NO_OP_NAMES is not defined.
  • 2012/Nov/17 change eax, ebx, ptr and so on in CodeGenerator as static member and alias of them are defined in Xbyak::util.
  • 2012/Nov/09 ver 3.70 XBYAK_NO_OP_NAMES macro is added to use and_() instead of and() (thanks to Mattias)
  • 2012/Nov/01 ver 3.62 add fwait/fnwait/finit/fninit
  • 2012/Nov/01 ver 3.61 add fldcw/fstcw
  • 2012/May/03 ver 3.60 change interface of Allocator
  • 2012/Mar/23 ver 3.51 fix userPtr mode
  • 2012/Mar/19 ver 3.50 support AutoGrow mode
  • 2011/Nov/09 ver 3.05 fix bit property of rip addresing / support movsxd
  • 2011/Aug/15 ver 3.04 fix dealing with imm8 such as add(dword [ebp-8], 0xda); (thanks to lolcat)
  • 2011/Jun/16 ver 3.03 fix __GNUC_PREREQ macro for Mac gcc(thanks to t_teruya)
  • 2011/Apr/28 ver 3.02 do not use xgetbv on Mac gcc
  • 2011/May/24 ver 3.01 fix typo of OSXSAVE
  • 2011/May/23 ver 3.00 add vcmpeqps and so on
  • 2011/Feb/16 ver 2.994 beta add vmovq for 32-bit mode(I forgot it)
  • 2011/Feb/16 ver 2.993 beta remove cvtReg to avoid thread unsafe
  • 2011/Feb/10 ver 2.992 beta support one argument syntax for fadd like nasm
  • 2011/Feb/07 ver 2.991 beta fix pextrw reg, xmm, imm(Thanks to Gabest)
  • 2011/Feb/04 ver 2.99 beta support AVX
  • 2010/Dec/08 ver 2.31 fix ptr [rip + 32bit offset], support rdtscp
  • 2010/Oct/19 ver 2.30 support pclmulqdq, aesdec, aesdeclast, aesenc, aesenclast, aesimc, aeskeygenassist
  • 2010/Jun/07 ver 2.29 fix call()
  • 2010/Jun/17 ver 2.28 move some member functions to public
  • 2010/Jun/01 ver 2.27 support encoding of mov(reg64, imm) like yasm(not nasm)
  • 2010/May/24 ver 2.26 fix sub(rsp, 1000)
  • 2010/Apr/26 ver 2.25 add jc/jnc(I forgot to implement them...)
  • 2010/Apr/16 ver 2.24 change the prototype of rewrite() method
  • 2010/Apr/15 ver 2.23 fix align() and xbyak_util.h for Mac
  • 2010/Feb/16 ver 2.22 fix inLocalLabel()/outLocalLabel()
  • 2009/Dec/09 ver 2.21 support cygwin(gcc 4.3.2)
  • 2009/Nov/28 support a part of FPU
  • 2009/Jun/25 fix mov(qword[rax], imm); (thanks to Martin)
  • 2009/Mar/10 fix redundant REX.W prefix on jmp/call reg64
  • 2009/Feb/24 add movq reg64, mmx/xmm; movq mmx/xmm, reg64
  • 2009/Feb/13 movd(xmm7, dword[eax]) drops 0x66 prefix (thanks to Gabest)
  • 2008/Dec/30 fix call in short relative address(thanks to kato san)
  • 2008/Sep/18 support @@, @f, @b and localization of label(thanks to nobu-q san)
  • 2008/Sep/18 support (ptr[rip + 32bit offset]) (thanks to Dango-Chu san)
  • 2008/Jun/03 fix align(). mov(ptr[eax],1) throws ERR_MEM_SIZE_IS_NOT_SPECIFIED.
  • 2008/Jun/02 support memory interface allocated by user
  • 2008/May/26 fix protect() to avoid invalid setting(thanks to shinichiro_h san)
  • 2008/Apr/30 add cmpxchg16b, cdqe
  • 2008/Apr/29 support x64
  • 2008/Apr/14 code refactoring
  • 2008/Mar/12 add bsr/bsf
  • 2008/Feb/14 fix output of sub eax, 1234 (thanks to Robert)
  • 2007/Nov/5 support lock, xadd, xchg
  • 2007/Nov/2 support SSSE3/SSE4 (thanks to Dango-Chu san)
  • 2007/Feb/4 fix the bug that exception doesn't occur under the condition which the offset of jmp mnemonic without T_NEAR is over 127.
  • 2007/Jan/21 fix the bug to create address like [disp] select smaller representation for mov (eax|ax|al, [disp])
  • 2007/Jan/4 first version


MITSUNARI Shigeo(herumi at nifty dot com)