Hexspeak&leetspeak

在看一些开源项目的时候，经常会遇到一些奇怪的 magic numbers，比如 0xdeedbeef，它们经常出现，但是有什么含义呢？

wiki 上对 Hexspeak 的解释如下：

Hexspeak, like leetspeak, is a novelty form of variant English spelling using the hexadecimal digits. Created by programmers as memorable magic numbers, hexspeak words can serve as a clear and unique identifier with which to mark memory or data.

简而言之，hexspeak，就是一种程序员发明的，用 16 进制数来表达的一种变体的英文拼写。

翻译规则

16 进制的书写由0123456789ABCDEF15 个字符来完成，仅仅使用ABCDEF几个字母就已经可以拼写出很多单词了。剩余的0123456789可以将它们转化成对应的字母，比如：

0可以当作字母O，
1可以当作字母L或者I，
5可以当作字母S,
7可以当作字母T,
12可以当作字母R,
6或者9可以当作字母G或者g,
5可以当作字母S,
2、4、8则可使用谐音，如to、for、ate

通过这种方式就可以表达出更多含义了。

常见的 magic numbers

许多计算机处理器、操作系统和调试器都会使用幻数，尤其是将其作为调试值。下面是 wiki 中收录的一些常见幻数：

Code	Description
`0x0000000FF1CE`	(“office”) is used as the last part of product codes (GUID) for Microsoft Office components (visible in registry under the `HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall` registry key).
`0x00BAB10C`	(“über (ooba) block”) is used as the magic number for the ZFS uberblock.
`0x1BADB002`	(“1 bad boot”[1]) Multiboot header magic number.[2]
`0x4B1D`	(“forbid”) was a password in some calibration consoles for developers to peer deeper into control registers outside the normal calibration memory range.[citation needed]
`0x8BADF00D`	(“ate bad food”) is used by Apple in iOS crash reports, when an application takes too long to launch, terminate, or respond to system events.[3]
`0xABADBABE`	(“a bad babe”) was/is used by Microsoft’s Windows 7 to trigger a debugger break-point, probably when a USB device is attached[4]
`0xB105F00D`	(“BIOS food”) is the value of the low bytes of last four registers on ARM PrimeCell compatible components (the component_id registers), used to identify correct behaviour of a memory-mapped component.
`0xB16B00B5`	(“big boobs”) was required by Microsoft’s Hyper-V hypervisor to be used by Linux guests as their “guest signature”.[5] One proposal suggested changing it to `0x0DEFACED` (“defaced”).[6] But in actuality, it was initially changed to decimal and then replaced entirely.[7]
`0x0B00B135`	(“boobies”) was likewise required by Microsoft’s Hyper-V hypervisor to be used by a user of XEN as their user id.[8] It was removed on January 22, 2010.[9]
`0xBAAAAAAD`	(“baaaaaad”) is used by Apple’s iOS exception report to indicate that the log is a stackshot of the entire system, not a crash report.[10]
`0xBAADF00D`	(“bad food”) is used by Microsoft’s LocalAlloc(LMEM_FIXED) to indicate uninitialised allocated heap memory when the debug heap is used.[11]
`0xBAD22222`	(“bad too repeatedly”) is used by Apple’s iOS exception log to indicate that a VoIP application has been terminated by iOS because it resumed too frequently.[10]
`0xBADDCAFE`	(“bad cafe”) is used by Libumem to indicate uninitialized memory area.
`0xCAFEB0BA`	(“cafe boba”) is used by datp as canned return value for QKit MFCC keyword detection for Host GUI development since his colleague likes coffee (and maybe boba, too).
`0xB0BABABE`	(“boba babe”) is used by pton as Host GUI Ack to QKit MFCC keyword detection response.
`0xBEEFBABE`	(“beef babe”) is used by the 1997 video game Frogger to detect a stack buffer overflow.
`0xB000 0xDEAD`	(“boo dead”) was displayed by PA-RISC based HP 3000 and HP 9000 computers upon encountering a “system halt” (aka “low level halt”).[12]
`0xC00010FF`	(“cool off”) is used by Apple in iOS crash reports, when application was killed in response to a thermal event.[3]
`C15C:0D06:F00D`	(“cisco dog food”) used in the IPv6 address of www.cisco.com on World IPv6 Day. “Dog food” refers to Cisco eating its own dog food with IPv6.
`0xCAFEBABE`	(“cafe babe”) is used by Plan 9’s libc as a poison value for memory pools.[13] It is also used by Mach-O to identify Universal object files, and by the Java programming language to identify Java bytecode class files. It was originally created by NeXTSTEP developers as a reference to the baristas at Peet’s Coffee & Tea.[14]
`0xCAFED00D`	(“cafe dude”) is used by Java as a magic number for their pack200 compression.[15]
`0xCEFAEDFE`	(“face feed”) is used by Mach-O to identify flat (single architecture) object files. In little endian this reads `FEEDFACE`, “Feed Face”.
`0x0D15EA5E`	(“zero disease”) is a flag that indicates regular boot on the Nintendo GameCube and Wii consoles.[16][17]
`0xDABBAD00`	(“dabba doo”) is the name of a blog on computer security.[18]
`0xDEAD2BAD`	(“dead too bad”) was used to mark allocated areas of memory that had not yet been initialised on Sequent Dynix/ptx systems.
`0xDEADBAAD`	(“dead bad”) is used by the Android libc abort() function when native heap corruption is detected.
`0xDEADBABE`	(“dead babe”) is used by IBM Jikes RVM as a sanity check of the stack of the primary thread.[19]
`0xDEADBEAF`	(“dead beaf”) is part of the signature code of Jazz Jackrabbit 2 tileset files.[20] Level files have less room for their signatures and use `0xBABE` (“babe”) instead.[21] It is also the header of campaign gamesaves used in the Halo game series.
`deadbeef-dead-beef-dead-beef00000075`	(“dead beef”) is the GUID assigned to hung/dead virtual machines in Citrix XenServer.
`0xDEADBEEF`	(“dead beef”) is frequently used to indicate a software crash or deadlock in embedded systems. `0xDEADBEEF` was originally used to mark newly allocated areas of memory that had not yet been initialized—when scanning a memory dump, it is easy to see the `0xDEADBEEF`. It is used by IBM RS/6000 systems, Mac OS on 32-bit PowerPC processors, and the Commodore Amiga as a magic debug value. On Sun Microsystems’ Solaris, it marks freed kernel memory. The DEC Alpha SRM console has a background process that traps memory errors, identified by PS as “BeefEater waiting on 0xdeadbeef”.[22]
`0xDEADC0DE`	(“dead code”) is used as a marker in OpenWrt firmware to signify the beginning of the to-be created jffs2 filesystem at the end of the static firmware.
`0xDEADDEAD`	(“dead dead”) is the bug check (STOP) code displayed when invoking a Blue Screen of Death either by telling the kernel via the attached debugger, or by using a special keystroke combination.[23] This is usually seen by driver developers, as it is used to get a memory dump on Windows NT based systems. An alternative to `0xDEADDEAD` is the bug check code `0x000000E2`,[24] as they are both called MANUALLY_INITIATED_CRASH as seen on the Microsoft Developer Network.
`0xDEADD00D`	(“dead dude”) is used by Android in the Dalvik virtual machine to indicate a VM abort.
`0xDEADFA11`	(“dead fall” or “dead fail”) is used by Apple in iOS crash reports, when the user force quits an application.[3]
`0xDEAD10CC`	(“dead lock”) is used by Apple in iOS crash reports, when an application holds on to a system resource while running in the background.[3]
`0xDEADFEED`	(“dead feed”) is used by Apple in iOS crash reports, when a timeout occurs spawning a service.
`0xDECAFBAD`	(“decaf bad”) is often found in coding as an easily recognized magic number when hex dumping memory.
`0xDEFEC8ED`	(“defecated”) is the magic number for OpenSolaris core dumps.[25]
`0xD0D0CACA`	(“doo-doo caca”) is the uninitialized value of GPIO values on the Nvidia Tegra X1.[citation needed]
`0xE011CFD0`	(“docfile0”) is used as a magic number for Microsoft Office files. In little endian this reads `D0CF11E0`, “docfile0”.[26]
`0xF1AC`	(“FLAC”) is used as the Free Lossless Audio Codec’s audio format tag.[27]
`face:b00c`	(“facebook”) used in the IPv6 addresses of www.facebook.com.[28]
`0xFACEFEED`	(“face feed”) is used by Alpha servers running Windows NT. The Alpha Hardware Abstraction Layer (HAL) generates this error when it encounters a hardware failure.[29]
`0xFBADBEEF`	(“bad beef”) is used in the WebKit and Blink layout engines to indicate a known, unrecoverable error such as out of memory.[30]
`0xFEE1DEAD`	(“feel dead”) is used as a magic number in the Linux reboot system call.[31]
`0xFEEDBABE`	(“feed babe”) is the magic number used to indicate the beginning of an OpenRG flash partition descriptor.[32]
`0xFEEDC0DE`	(“feed code”) is used as filling pattern by the OS-9 operating system when initializing its RAM.[33]
`0xFEEDFACECAFEBEEF`	(“feed face cafe beef”) is the magic number used to send as a password via serial wire to rescue some NXP created controller devices from boot failures.[34][35][36]
`0xFFBADD11`	(“bad DLL”): Used by Windows internally.[citation needed]
`0xF00DBABE`	(“food babe”): The Ledger Nano hardware cryptocurrency wallet used this magic number in the process of signing that was exploited.[37]

在上面就有我们经常可以看到的0xDEADBEEF的解释了。

扩展

在某些不同的语言中，可能存在扩展的用法；

比如在 C 语言中，我们经常用后缀L来表示一个数是long类型，使用LL来表示long long，这样就可以写出0xDEADCELL(dead cell) 或者0xFEEDBULL(feed bull) 这样的 hexspeak 了；

翻译规则

常见的 magic numbers

扩展

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