ljx

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dis_x86.lua (32832B)


      1 ----------------------------------------------------------------------------
      2 -- LuaJIT x86/x64 disassembler module.
      3 --
      4 -- Copyright (C) 2005-2016 Mike Pall. All rights reserved.
      5 -- Released under the MIT license. See Copyright Notice in luajit.h
      6 ----------------------------------------------------------------------------
      7 -- This is a helper module used by the LuaJIT machine code dumper module.
      8 --
      9 -- Sending small code snippets to an external disassembler and mixing the
     10 -- output with our own stuff was too fragile. So I had to bite the bullet
     11 -- and write yet another x86 disassembler. Oh well ...
     12 --
     13 -- The output format is very similar to what ndisasm generates. But it has
     14 -- been developed independently by looking at the opcode tables from the
     15 -- Intel and AMD manuals. The supported instruction set is quite extensive
     16 -- and reflects what a current generation Intel or AMD CPU implements in
     17 -- 32 bit and 64 bit mode. Yes, this includes MMX, SSE, SSE2, SSE3, SSSE3,
     18 -- SSE4.1, SSE4.2, SSE4a, AVX, AVX2 and even privileged and hypervisor
     19 -- (VMX/SVM) instructions.
     20 --
     21 -- Notes:
     22 -- * The (useless) a16 prefix, 3DNow and pre-586 opcodes are unsupported.
     23 -- * No attempt at optimization has been made -- it's fast enough for my needs.
     24 ------------------------------------------------------------------------------
     25 
     26 local type = type
     27 local sub, byte, format = string.sub, string.byte, string.format
     28 local match, gmatch, gsub = string.match, string.gmatch, string.gsub
     29 local lower, rep = string.lower, string.rep
     30 local bit = require("bit")
     31 local tohex = bit.tohex
     32 
     33 -- Map for 1st opcode byte in 32 bit mode. Ugly? Well ... read on.
     34 local map_opc1_32 = {
     35 --0x
     36 [0]="addBmr","addVmr","addBrm","addVrm","addBai","addVai","push es","pop es",
     37 "orBmr","orVmr","orBrm","orVrm","orBai","orVai","push cs","opc2*",
     38 --1x
     39 "adcBmr","adcVmr","adcBrm","adcVrm","adcBai","adcVai","push ss","pop ss",
     40 "sbbBmr","sbbVmr","sbbBrm","sbbVrm","sbbBai","sbbVai","push ds","pop ds",
     41 --2x
     42 "andBmr","andVmr","andBrm","andVrm","andBai","andVai","es:seg","daa",
     43 "subBmr","subVmr","subBrm","subVrm","subBai","subVai","cs:seg","das",
     44 --3x
     45 "xorBmr","xorVmr","xorBrm","xorVrm","xorBai","xorVai","ss:seg","aaa",
     46 "cmpBmr","cmpVmr","cmpBrm","cmpVrm","cmpBai","cmpVai","ds:seg","aas",
     47 --4x
     48 "incVR","incVR","incVR","incVR","incVR","incVR","incVR","incVR",
     49 "decVR","decVR","decVR","decVR","decVR","decVR","decVR","decVR",
     50 --5x
     51 "pushUR","pushUR","pushUR","pushUR","pushUR","pushUR","pushUR","pushUR",
     52 "popUR","popUR","popUR","popUR","popUR","popUR","popUR","popUR",
     53 --6x
     54 "sz*pushaw,pusha","sz*popaw,popa","boundVrm","arplWmr",
     55 "fs:seg","gs:seg","o16:","a16",
     56 "pushUi","imulVrmi","pushBs","imulVrms",
     57 "insb","insVS","outsb","outsVS",
     58 --7x
     59 "joBj","jnoBj","jbBj","jnbBj","jzBj","jnzBj","jbeBj","jaBj",
     60 "jsBj","jnsBj","jpeBj","jpoBj","jlBj","jgeBj","jleBj","jgBj",
     61 --8x
     62 "arith!Bmi","arith!Vmi","arith!Bmi","arith!Vms",
     63 "testBmr","testVmr","xchgBrm","xchgVrm",
     64 "movBmr","movVmr","movBrm","movVrm",
     65 "movVmg","leaVrm","movWgm","popUm",
     66 --9x
     67 "nop*xchgVaR|pause|xchgWaR|repne nop","xchgVaR","xchgVaR","xchgVaR",
     68 "xchgVaR","xchgVaR","xchgVaR","xchgVaR",
     69 "sz*cbw,cwde,cdqe","sz*cwd,cdq,cqo","call farViw","wait",
     70 "sz*pushfw,pushf","sz*popfw,popf","sahf","lahf",
     71 --Ax
     72 "movBao","movVao","movBoa","movVoa",
     73 "movsb","movsVS","cmpsb","cmpsVS",
     74 "testBai","testVai","stosb","stosVS",
     75 "lodsb","lodsVS","scasb","scasVS",
     76 --Bx
     77 "movBRi","movBRi","movBRi","movBRi","movBRi","movBRi","movBRi","movBRi",
     78 "movVRI","movVRI","movVRI","movVRI","movVRI","movVRI","movVRI","movVRI",
     79 --Cx
     80 "shift!Bmu","shift!Vmu","retBw","ret","vex*3$lesVrm","vex*2$ldsVrm","movBmi","movVmi",
     81 "enterBwu","leave","retfBw","retf","int3","intBu","into","iretVS",
     82 --Dx
     83 "shift!Bm1","shift!Vm1","shift!Bmc","shift!Vmc","aamBu","aadBu","salc","xlatb",
     84 "fp*0","fp*1","fp*2","fp*3","fp*4","fp*5","fp*6","fp*7",
     85 --Ex
     86 "loopneBj","loopeBj","loopBj","sz*jcxzBj,jecxzBj,jrcxzBj",
     87 "inBau","inVau","outBua","outVua",
     88 "callVj","jmpVj","jmp farViw","jmpBj","inBad","inVad","outBda","outVda",
     89 --Fx
     90 "lock:","int1","repne:rep","rep:","hlt","cmc","testb!Bm","testv!Vm",
     91 "clc","stc","cli","sti","cld","std","incb!Bm","incd!Vm",
     92 }
     93 assert(#map_opc1_32 == 255)
     94 
     95 -- Map for 1st opcode byte in 64 bit mode (overrides only).
     96 local map_opc1_64 = setmetatable({
     97   [0x06]=false, [0x07]=false, [0x0e]=false,
     98   [0x16]=false, [0x17]=false, [0x1e]=false, [0x1f]=false,
     99   [0x27]=false, [0x2f]=false, [0x37]=false, [0x3f]=false,
    100   [0x60]=false, [0x61]=false, [0x62]=false, [0x63]="movsxdVrDmt", [0x67]="a32:",
    101   [0x40]="rex*",   [0x41]="rex*b",   [0x42]="rex*x",   [0x43]="rex*xb",
    102   [0x44]="rex*r",  [0x45]="rex*rb",  [0x46]="rex*rx",  [0x47]="rex*rxb",
    103   [0x48]="rex*w",  [0x49]="rex*wb",  [0x4a]="rex*wx",  [0x4b]="rex*wxb",
    104   [0x4c]="rex*wr", [0x4d]="rex*wrb", [0x4e]="rex*wrx", [0x4f]="rex*wrxb",
    105   [0x82]=false, [0x9a]=false, [0xc4]="vex*3", [0xc5]="vex*2", [0xce]=false,
    106   [0xd4]=false, [0xd5]=false, [0xd6]=false, [0xea]=false,
    107 }, { __index = map_opc1_32 })
    108 
    109 -- Map for 2nd opcode byte (0F xx). True CISC hell. Hey, I told you.
    110 -- Prefix dependent MMX/SSE opcodes: (none)|rep|o16|repne, -|F3|66|F2
    111 local map_opc2 = {
    112 --0x
    113 [0]="sldt!Dmp","sgdt!Ump","larVrm","lslVrm",nil,"syscall","clts","sysret",
    114 "invd","wbinvd",nil,"ud1",nil,"$prefetch!Bm","femms","3dnowMrmu",
    115 --1x
    116 "movupsXrm|movssXrvm|movupdXrm|movsdXrvm",
    117 "movupsXmr|movssXmvr|movupdXmr|movsdXmvr",
    118 "movhlpsXrm$movlpsXrm|movsldupXrm|movlpdXrm|movddupXrm",
    119 "movlpsXmr||movlpdXmr",
    120 "unpcklpsXrvm||unpcklpdXrvm",
    121 "unpckhpsXrvm||unpckhpdXrvm",
    122 "movlhpsXrm$movhpsXrm|movshdupXrm|movhpdXrm",
    123 "movhpsXmr||movhpdXmr",
    124 "$prefetcht!Bm","hintnopVm","hintnopVm","hintnopVm",
    125 "hintnopVm","hintnopVm","hintnopVm","hintnopVm",
    126 --2x
    127 "movUmx$","movUmy$","movUxm$","movUym$","movUmz$",nil,"movUzm$",nil,
    128 "movapsXrm||movapdXrm",
    129 "movapsXmr||movapdXmr",
    130 "cvtpi2psXrMm|cvtsi2ssXrvVmt|cvtpi2pdXrMm|cvtsi2sdXrvVmt",
    131 "movntpsXmr|movntssXmr|movntpdXmr|movntsdXmr",
    132 "cvttps2piMrXm|cvttss2siVrXm|cvttpd2piMrXm|cvttsd2siVrXm",
    133 "cvtps2piMrXm|cvtss2siVrXm|cvtpd2piMrXm|cvtsd2siVrXm",
    134 "ucomissXrm||ucomisdXrm",
    135 "comissXrm||comisdXrm",
    136 --3x
    137 "wrmsr","rdtsc","rdmsr","rdpmc","sysenter","sysexit",nil,"getsec",
    138 "opc3*38",nil,"opc3*3a",nil,nil,nil,nil,nil,
    139 --4x
    140 "cmovoVrm","cmovnoVrm","cmovbVrm","cmovnbVrm",
    141 "cmovzVrm","cmovnzVrm","cmovbeVrm","cmovaVrm",
    142 "cmovsVrm","cmovnsVrm","cmovpeVrm","cmovpoVrm",
    143 "cmovlVrm","cmovgeVrm","cmovleVrm","cmovgVrm",
    144 --5x
    145 "movmskpsVrXm$||movmskpdVrXm$","sqrtpsXrm|sqrtssXrm|sqrtpdXrm|sqrtsdXrm",
    146 "rsqrtpsXrm|rsqrtssXrvm","rcppsXrm|rcpssXrvm",
    147 "andpsXrvm||andpdXrvm","andnpsXrvm||andnpdXrvm",
    148 "orpsXrvm||orpdXrvm","xorpsXrvm||xorpdXrvm",
    149 "addpsXrvm|addssXrvm|addpdXrvm|addsdXrvm","mulpsXrvm|mulssXrvm|mulpdXrvm|mulsdXrvm",
    150 "cvtps2pdXrm|cvtss2sdXrvm|cvtpd2psXrm|cvtsd2ssXrvm",
    151 "cvtdq2psXrm|cvttps2dqXrm|cvtps2dqXrm",
    152 "subpsXrvm|subssXrvm|subpdXrvm|subsdXrvm","minpsXrvm|minssXrvm|minpdXrvm|minsdXrvm",
    153 "divpsXrvm|divssXrvm|divpdXrvm|divsdXrvm","maxpsXrvm|maxssXrvm|maxpdXrvm|maxsdXrvm",
    154 --6x
    155 "punpcklbwPrvm","punpcklwdPrvm","punpckldqPrvm","packsswbPrvm",
    156 "pcmpgtbPrvm","pcmpgtwPrvm","pcmpgtdPrvm","packuswbPrvm",
    157 "punpckhbwPrvm","punpckhwdPrvm","punpckhdqPrvm","packssdwPrvm",
    158 "||punpcklqdqXrvm","||punpckhqdqXrvm",
    159 "movPrVSm","movqMrm|movdquXrm|movdqaXrm",
    160 --7x
    161 "pshufwMrmu|pshufhwXrmu|pshufdXrmu|pshuflwXrmu","pshiftw!Pvmu",
    162 "pshiftd!Pvmu","pshiftq!Mvmu||pshiftdq!Xvmu",
    163 "pcmpeqbPrvm","pcmpeqwPrvm","pcmpeqdPrvm","emms*|",
    164 "vmreadUmr||extrqXmuu$|insertqXrmuu$","vmwriteUrm||extrqXrm$|insertqXrm$",
    165 nil,nil,
    166 "||haddpdXrvm|haddpsXrvm","||hsubpdXrvm|hsubpsXrvm",
    167 "movVSmMr|movqXrm|movVSmXr","movqMmr|movdquXmr|movdqaXmr",
    168 --8x
    169 "joVj","jnoVj","jbVj","jnbVj","jzVj","jnzVj","jbeVj","jaVj",
    170 "jsVj","jnsVj","jpeVj","jpoVj","jlVj","jgeVj","jleVj","jgVj",
    171 --9x
    172 "setoBm","setnoBm","setbBm","setnbBm","setzBm","setnzBm","setbeBm","setaBm",
    173 "setsBm","setnsBm","setpeBm","setpoBm","setlBm","setgeBm","setleBm","setgBm",
    174 --Ax
    175 "push fs","pop fs","cpuid","btVmr","shldVmru","shldVmrc",nil,nil,
    176 "push gs","pop gs","rsm","btsVmr","shrdVmru","shrdVmrc","fxsave!Dmp","imulVrm",
    177 --Bx
    178 "cmpxchgBmr","cmpxchgVmr","$lssVrm","btrVmr",
    179 "$lfsVrm","$lgsVrm","movzxVrBmt","movzxVrWmt",
    180 "|popcntVrm","ud2Dp","bt!Vmu","btcVmr",
    181 "bsfVrm","bsrVrm|lzcntVrm|bsrWrm","movsxVrBmt","movsxVrWmt",
    182 --Cx
    183 "xaddBmr","xaddVmr",
    184 "cmppsXrvmu|cmpssXrvmu|cmppdXrvmu|cmpsdXrvmu","$movntiVmr|",
    185 "pinsrwPrvWmu","pextrwDrPmu",
    186 "shufpsXrvmu||shufpdXrvmu","$cmpxchg!Qmp",
    187 "bswapVR","bswapVR","bswapVR","bswapVR","bswapVR","bswapVR","bswapVR","bswapVR",
    188 --Dx
    189 "||addsubpdXrvm|addsubpsXrvm","psrlwPrvm","psrldPrvm","psrlqPrvm",
    190 "paddqPrvm","pmullwPrvm",
    191 "|movq2dqXrMm|movqXmr|movdq2qMrXm$","pmovmskbVrMm||pmovmskbVrXm",
    192 "psubusbPrvm","psubuswPrvm","pminubPrvm","pandPrvm",
    193 "paddusbPrvm","padduswPrvm","pmaxubPrvm","pandnPrvm",
    194 --Ex
    195 "pavgbPrvm","psrawPrvm","psradPrvm","pavgwPrvm",
    196 "pmulhuwPrvm","pmulhwPrvm",
    197 "|cvtdq2pdXrm|cvttpd2dqXrm|cvtpd2dqXrm","$movntqMmr||$movntdqXmr",
    198 "psubsbPrvm","psubswPrvm","pminswPrvm","porPrvm",
    199 "paddsbPrvm","paddswPrvm","pmaxswPrvm","pxorPrvm",
    200 --Fx
    201 "|||lddquXrm","psllwPrvm","pslldPrvm","psllqPrvm",
    202 "pmuludqPrvm","pmaddwdPrvm","psadbwPrvm","maskmovqMrm||maskmovdquXrm$",
    203 "psubbPrvm","psubwPrvm","psubdPrvm","psubqPrvm",
    204 "paddbPrvm","paddwPrvm","padddPrvm","ud",
    205 }
    206 assert(map_opc2[255] == "ud")
    207 
    208 -- Map for three-byte opcodes. Can't wait for their next invention.
    209 local map_opc3 = {
    210 ["38"] = { -- [66] 0f 38 xx
    211 --0x
    212 [0]="pshufbPrvm","phaddwPrvm","phadddPrvm","phaddswPrvm",
    213 "pmaddubswPrvm","phsubwPrvm","phsubdPrvm","phsubswPrvm",
    214 "psignbPrvm","psignwPrvm","psigndPrvm","pmulhrswPrvm",
    215 "||permilpsXrvm","||permilpdXrvm",nil,nil,
    216 --1x
    217 "||pblendvbXrma",nil,nil,nil,
    218 "||blendvpsXrma","||blendvpdXrma","||permpsXrvm","||ptestXrm",
    219 "||broadcastssXrm","||broadcastsdXrm","||broadcastf128XrlXm",nil,
    220 "pabsbPrm","pabswPrm","pabsdPrm",nil,
    221 --2x
    222 "||pmovsxbwXrm","||pmovsxbdXrm","||pmovsxbqXrm","||pmovsxwdXrm",
    223 "||pmovsxwqXrm","||pmovsxdqXrm",nil,nil,
    224 "||pmuldqXrvm","||pcmpeqqXrvm","||$movntdqaXrm","||packusdwXrvm",
    225 "||maskmovpsXrvm","||maskmovpdXrvm","||maskmovpsXmvr","||maskmovpdXmvr",
    226 --3x
    227 "||pmovzxbwXrm","||pmovzxbdXrm","||pmovzxbqXrm","||pmovzxwdXrm",
    228 "||pmovzxwqXrm","||pmovzxdqXrm","||permdXrvm","||pcmpgtqXrvm",
    229 "||pminsbXrvm","||pminsdXrvm","||pminuwXrvm","||pminudXrvm",
    230 "||pmaxsbXrvm","||pmaxsdXrvm","||pmaxuwXrvm","||pmaxudXrvm",
    231 --4x
    232 "||pmulddXrvm","||phminposuwXrm",nil,nil,
    233 nil,"||psrlvVSXrvm","||psravdXrvm","||psllvVSXrvm",
    234 --5x
    235 [0x58] = "||pbroadcastdXrlXm",[0x59] = "||pbroadcastqXrlXm",
    236 [0x5a] = "||broadcasti128XrlXm",
    237 --7x
    238 [0x78] = "||pbroadcastbXrlXm",[0x79] = "||pbroadcastwXrlXm",
    239 --8x
    240 [0x8c] = "||pmaskmovXrvVSm",
    241 [0x8e] = "||pmaskmovVSmXvr",
    242 --Dx
    243 [0xdc] = "||aesencXrvm", [0xdd] = "||aesenclastXrvm",
    244 [0xde] = "||aesdecXrvm", [0xdf] = "||aesdeclastXrvm",
    245 --Fx
    246 [0xf0] = "|||crc32TrBmt",[0xf1] = "|||crc32TrVmt",
    247 [0xf7] = "| sarxVrmv| shlxVrmv| shrxVrmv",
    248 },
    249 
    250 ["3a"] = { -- [66] 0f 3a xx
    251 --0x
    252 [0x00]="||permqXrmu","||permpdXrmu","||pblenddXrvmu",nil,
    253 "||permilpsXrmu","||permilpdXrmu","||perm2f128Xrvmu",nil,
    254 "||roundpsXrmu","||roundpdXrmu","||roundssXrvmu","||roundsdXrvmu",
    255 "||blendpsXrvmu","||blendpdXrvmu","||pblendwXrvmu","palignrPrvmu",
    256 --1x
    257 nil,nil,nil,nil,
    258 "||pextrbVmXru","||pextrwVmXru","||pextrVmSXru","||extractpsVmXru",
    259 "||insertf128XrvlXmu","||extractf128XlXmYru",nil,nil,
    260 nil,nil,nil,nil,
    261 --2x
    262 "||pinsrbXrvVmu","||insertpsXrvmu","||pinsrXrvVmuS",nil,
    263 --3x
    264 [0x38] = "||inserti128Xrvmu",[0x39] = "||extracti128XlXmYru",
    265 --4x
    266 [0x40] = "||dppsXrvmu",
    267 [0x41] = "||dppdXrvmu",
    268 [0x42] = "||mpsadbwXrvmu",
    269 [0x44] = "||pclmulqdqXrvmu",
    270 [0x46] = "||perm2i128Xrvmu",
    271 [0x4a] = "||blendvpsXrvmb",[0x4b] = "||blendvpdXrvmb",
    272 [0x4c] = "||pblendvbXrvmb",
    273 --6x
    274 [0x60] = "||pcmpestrmXrmu",[0x61] = "||pcmpestriXrmu",
    275 [0x62] = "||pcmpistrmXrmu",[0x63] = "||pcmpistriXrmu",
    276 [0xdf] = "||aeskeygenassistXrmu",
    277 --Fx
    278 [0xf0] = "||| rorxVrmu",
    279 },
    280 }
    281 
    282 -- Map for VMX/SVM opcodes 0F 01 C0-FF (sgdt group with register operands).
    283 local map_opcvm = {
    284 [0xc1]="vmcall",[0xc2]="vmlaunch",[0xc3]="vmresume",[0xc4]="vmxoff",
    285 [0xc8]="monitor",[0xc9]="mwait",
    286 [0xd8]="vmrun",[0xd9]="vmmcall",[0xda]="vmload",[0xdb]="vmsave",
    287 [0xdc]="stgi",[0xdd]="clgi",[0xde]="skinit",[0xdf]="invlpga",
    288 [0xf8]="swapgs",[0xf9]="rdtscp",
    289 }
    290 
    291 -- Map for FP opcodes. And you thought stack machines are simple?
    292 local map_opcfp = {
    293 -- D8-DF 00-BF: opcodes with a memory operand.
    294 -- D8
    295 [0]="faddFm","fmulFm","fcomFm","fcompFm","fsubFm","fsubrFm","fdivFm","fdivrFm",
    296 "fldFm",nil,"fstFm","fstpFm","fldenvVm","fldcwWm","fnstenvVm","fnstcwWm",
    297 -- DA
    298 "fiaddDm","fimulDm","ficomDm","ficompDm",
    299 "fisubDm","fisubrDm","fidivDm","fidivrDm",
    300 -- DB
    301 "fildDm","fisttpDm","fistDm","fistpDm",nil,"fld twordFmp",nil,"fstp twordFmp",
    302 -- DC
    303 "faddGm","fmulGm","fcomGm","fcompGm","fsubGm","fsubrGm","fdivGm","fdivrGm",
    304 -- DD
    305 "fldGm","fisttpQm","fstGm","fstpGm","frstorDmp",nil,"fnsaveDmp","fnstswWm",
    306 -- DE
    307 "fiaddWm","fimulWm","ficomWm","ficompWm",
    308 "fisubWm","fisubrWm","fidivWm","fidivrWm",
    309 -- DF
    310 "fildWm","fisttpWm","fistWm","fistpWm",
    311 "fbld twordFmp","fildQm","fbstp twordFmp","fistpQm",
    312 -- xx C0-FF: opcodes with a pseudo-register operand.
    313 -- D8
    314 "faddFf","fmulFf","fcomFf","fcompFf","fsubFf","fsubrFf","fdivFf","fdivrFf",
    315 -- D9
    316 "fldFf","fxchFf",{"fnop"},nil,
    317 {"fchs","fabs",nil,nil,"ftst","fxam"},
    318 {"fld1","fldl2t","fldl2e","fldpi","fldlg2","fldln2","fldz"},
    319 {"f2xm1","fyl2x","fptan","fpatan","fxtract","fprem1","fdecstp","fincstp"},
    320 {"fprem","fyl2xp1","fsqrt","fsincos","frndint","fscale","fsin","fcos"},
    321 -- DA
    322 "fcmovbFf","fcmoveFf","fcmovbeFf","fcmovuFf",nil,{nil,"fucompp"},nil,nil,
    323 -- DB
    324 "fcmovnbFf","fcmovneFf","fcmovnbeFf","fcmovnuFf",
    325 {nil,nil,"fnclex","fninit"},"fucomiFf","fcomiFf",nil,
    326 -- DC
    327 "fadd toFf","fmul toFf",nil,nil,
    328 "fsub toFf","fsubr toFf","fdivr toFf","fdiv toFf",
    329 -- DD
    330 "ffreeFf",nil,"fstFf","fstpFf","fucomFf","fucompFf",nil,nil,
    331 -- DE
    332 "faddpFf","fmulpFf",nil,{nil,"fcompp"},
    333 "fsubrpFf","fsubpFf","fdivrpFf","fdivpFf",
    334 -- DF
    335 nil,nil,nil,nil,{"fnstsw ax"},"fucomipFf","fcomipFf",nil,
    336 }
    337 assert(map_opcfp[126] == "fcomipFf")
    338 
    339 -- Map for opcode groups. The subkey is sp from the ModRM byte.
    340 local map_opcgroup = {
    341   arith = { "add", "or", "adc", "sbb", "and", "sub", "xor", "cmp" },
    342   shift = { "rol", "ror", "rcl", "rcr", "shl", "shr", "sal", "sar" },
    343   testb = { "testBmi", "testBmi", "not", "neg", "mul", "imul", "div", "idiv" },
    344   testv = { "testVmi", "testVmi", "not", "neg", "mul", "imul", "div", "idiv" },
    345   incb = { "inc", "dec" },
    346   incd = { "inc", "dec", "callUmp", "$call farDmp",
    347 	   "jmpUmp", "$jmp farDmp", "pushUm" },
    348   sldt = { "sldt", "str", "lldt", "ltr", "verr", "verw" },
    349   sgdt = { "vm*$sgdt", "vm*$sidt", "$lgdt", "vm*$lidt",
    350 	   "smsw", nil, "lmsw", "vm*$invlpg" },
    351   bt = { nil, nil, nil, nil, "bt", "bts", "btr", "btc" },
    352   cmpxchg = { nil, "sz*,cmpxchg8bQmp,cmpxchg16bXmp", nil, nil,
    353 	      nil, nil, "vmptrld|vmxon|vmclear", "vmptrst" },
    354   pshiftw = { nil, nil, "psrlw", nil, "psraw", nil, "psllw" },
    355   pshiftd = { nil, nil, "psrld", nil, "psrad", nil, "pslld" },
    356   pshiftq = { nil, nil, "psrlq", nil, nil, nil, "psllq" },
    357   pshiftdq = { nil, nil, "psrlq", "psrldq", nil, nil, "psllq", "pslldq" },
    358   fxsave = { "$fxsave", "$fxrstor", "$ldmxcsr", "$stmxcsr",
    359 	     nil, "lfenceDp$", "mfenceDp$", "sfenceDp$clflush" },
    360   prefetch = { "prefetch", "prefetchw" },
    361   prefetcht = { "prefetchnta", "prefetcht0", "prefetcht1", "prefetcht2" },
    362 }
    363 
    364 ------------------------------------------------------------------------------
    365 
    366 -- Maps for register names.
    367 local map_regs = {
    368   B = { "al", "cl", "dl", "bl", "ah", "ch", "dh", "bh",
    369 	"r8b", "r9b", "r10b", "r11b", "r12b", "r13b", "r14b", "r15b" },
    370   B64 = { "al", "cl", "dl", "bl", "spl", "bpl", "sil", "dil",
    371 	  "r8b", "r9b", "r10b", "r11b", "r12b", "r13b", "r14b", "r15b" },
    372   W = { "ax", "cx", "dx", "bx", "sp", "bp", "si", "di",
    373 	"r8w", "r9w", "r10w", "r11w", "r12w", "r13w", "r14w", "r15w" },
    374   D = { "eax", "ecx", "edx", "ebx", "esp", "ebp", "esi", "edi",
    375 	"r8d", "r9d", "r10d", "r11d", "r12d", "r13d", "r14d", "r15d" },
    376   Q = { "rax", "rcx", "rdx", "rbx", "rsp", "rbp", "rsi", "rdi",
    377 	"r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15" },
    378   M = { "mm0", "mm1", "mm2", "mm3", "mm4", "mm5", "mm6", "mm7",
    379 	"mm0", "mm1", "mm2", "mm3", "mm4", "mm5", "mm6", "mm7" }, -- No x64 ext!
    380   X = { "xmm0", "xmm1", "xmm2", "xmm3", "xmm4", "xmm5", "xmm6", "xmm7",
    381 	"xmm8", "xmm9", "xmm10", "xmm11", "xmm12", "xmm13", "xmm14", "xmm15" },
    382   Y = { "ymm0", "ymm1", "ymm2", "ymm3", "ymm4", "ymm5", "ymm6", "ymm7",
    383 	"ymm8", "ymm9", "ymm10", "ymm11", "ymm12", "ymm13", "ymm14", "ymm15" },
    384 }
    385 local map_segregs = { "es", "cs", "ss", "ds", "fs", "gs", "segr6", "segr7" }
    386 
    387 -- Maps for size names.
    388 local map_sz2n = {
    389   B = 1, W = 2, D = 4, Q = 8, M = 8, X = 16, Y = 32,
    390 }
    391 local map_sz2prefix = {
    392   B = "byte", W = "word", D = "dword",
    393   Q = "qword",
    394   M = "qword", X = "xword", Y = "yword",
    395   F = "dword", G = "qword", -- No need for sizes/register names for these two.
    396 }
    397 
    398 ------------------------------------------------------------------------------
    399 
    400 -- Output a nicely formatted line with an opcode and operands.
    401 local function putop(ctx, text, operands)
    402   local code, pos, hex = ctx.code, ctx.pos, ""
    403   local hmax = ctx.hexdump
    404   if hmax > 0 then
    405     for i=ctx.start,pos-1 do
    406       hex = hex..format("%02X", byte(code, i, i))
    407     end
    408     if #hex > hmax then hex = sub(hex, 1, hmax)..". "
    409     else hex = hex..rep(" ", hmax-#hex+2) end
    410   end
    411   if operands then text = text.." "..operands end
    412   if ctx.o16 then text = "o16 "..text; ctx.o16 = false end
    413   if ctx.a32 then text = "a32 "..text; ctx.a32 = false end
    414   if ctx.rep then text = ctx.rep.." "..text; ctx.rep = false end
    415   if ctx.rex then
    416     local t = (ctx.rexw and "w" or "")..(ctx.rexr and "r" or "")..
    417 	      (ctx.rexx and "x" or "")..(ctx.rexb and "b" or "")..
    418 	      (ctx.vexl and "l" or "")
    419     if ctx.vexv and ctx.vexv ~= 0 then t = t.."v"..ctx.vexv end
    420     if t ~= "" then text = ctx.rex.."."..t.." "..gsub(text, "^ ", "")
    421     elseif ctx.rex == "vex" then text = gsub("v"..text, "^v ", "") end
    422     ctx.rexw = false; ctx.rexr = false; ctx.rexx = false; ctx.rexb = false
    423     ctx.rex = false; ctx.vexl = false; ctx.vexv = false
    424   end
    425   if ctx.seg then
    426     local text2, n = gsub(text, "%[", "["..ctx.seg..":")
    427     if n == 0 then text = ctx.seg.." "..text else text = text2 end
    428     ctx.seg = false
    429   end
    430   if ctx.lock then text = "lock "..text; ctx.lock = false end
    431   local imm = ctx.imm
    432   if imm then
    433     local sym = ctx.symtab[imm]
    434     if sym then text = text.."\t->"..sym end
    435   end
    436   ctx.out(format("%08x  %s%s\n", ctx.addr+ctx.start, hex, text))
    437   ctx.mrm = false
    438   ctx.vexv = false
    439   ctx.start = pos
    440   ctx.imm = nil
    441 end
    442 
    443 -- Clear all prefix flags.
    444 local function clearprefixes(ctx)
    445   ctx.o16 = false; ctx.seg = false; ctx.lock = false; ctx.rep = false
    446   ctx.rexw = false; ctx.rexr = false; ctx.rexx = false; ctx.rexb = false
    447   ctx.rex = false; ctx.a32 = false; ctx.vexl = false
    448 end
    449 
    450 -- Fallback for incomplete opcodes at the end.
    451 local function incomplete(ctx)
    452   ctx.pos = ctx.stop+1
    453   clearprefixes(ctx)
    454   return putop(ctx, "(incomplete)")
    455 end
    456 
    457 -- Fallback for unknown opcodes.
    458 local function unknown(ctx)
    459   clearprefixes(ctx)
    460   return putop(ctx, "(unknown)")
    461 end
    462 
    463 -- Return an immediate of the specified size.
    464 local function getimm(ctx, pos, n)
    465   if pos+n-1 > ctx.stop then return incomplete(ctx) end
    466   local code = ctx.code
    467   if n == 1 then
    468     local b1 = byte(code, pos, pos)
    469     return b1
    470   elseif n == 2 then
    471     local b1, b2 = byte(code, pos, pos+1)
    472     return b1+b2*256
    473   else
    474     local b1, b2, b3, b4 = byte(code, pos, pos+3)
    475     local imm = b1+b2*256+b3*65536+b4*16777216
    476     ctx.imm = imm
    477     return imm
    478   end
    479 end
    480 
    481 -- Process pattern string and generate the operands.
    482 local function putpat(ctx, name, pat)
    483   local operands, regs, sz, mode, sp, rm, sc, rx, sdisp
    484   local code, pos, stop, vexl = ctx.code, ctx.pos, ctx.stop, ctx.vexl
    485 
    486   -- Chars used: 1DFGIMPQRSTUVWXYabcdfgijlmoprstuvwxyz
    487   for p in gmatch(pat, ".") do
    488     local x = nil
    489     if p == "V" or p == "U" then
    490       if ctx.rexw then sz = "Q"; ctx.rexw = false
    491       elseif ctx.o16 then sz = "W"; ctx.o16 = false
    492       elseif p == "U" and ctx.x64 then sz = "Q"
    493       else sz = "D" end
    494       regs = map_regs[sz]
    495     elseif p == "T" then
    496       if ctx.rexw then sz = "Q"; ctx.rexw = false else sz = "D" end
    497       regs = map_regs[sz]
    498     elseif p == "B" then
    499       sz = "B"
    500       regs = ctx.rex and map_regs.B64 or map_regs.B
    501     elseif match(p, "[WDQMXYFG]") then
    502       sz = p
    503       if sz == "X" and vexl then sz = "Y"; ctx.vexl = false end
    504       regs = map_regs[sz]
    505     elseif p == "P" then
    506       sz = ctx.o16 and "X" or "M"; ctx.o16 = false
    507       if sz == "X" and vexl then sz = "Y"; ctx.vexl = false end
    508       regs = map_regs[sz]
    509     elseif p == "S" then
    510       name = name..lower(sz)
    511     elseif p == "s" then
    512       local imm = getimm(ctx, pos, 1); if not imm then return end
    513       x = imm <= 127 and format("+0x%02x", imm)
    514 		     or format("-0x%02x", 256-imm)
    515       pos = pos+1
    516     elseif p == "u" then
    517       local imm = getimm(ctx, pos, 1); if not imm then return end
    518       x = format("0x%02x", imm)
    519       pos = pos+1
    520     elseif p == "b" then
    521       local imm = getimm(ctx, pos, 1); if not imm then return end
    522       x = regs[imm/16+1]
    523       pos = pos+1
    524     elseif p == "w" then
    525       local imm = getimm(ctx, pos, 2); if not imm then return end
    526       x = format("0x%x", imm)
    527       pos = pos+2
    528     elseif p == "o" then -- [offset]
    529       if ctx.x64 then
    530 	local imm1 = getimm(ctx, pos, 4); if not imm1 then return end
    531 	local imm2 = getimm(ctx, pos+4, 4); if not imm2 then return end
    532 	x = format("[0x%08x%08x]", imm2, imm1)
    533 	pos = pos+8
    534       else
    535 	local imm = getimm(ctx, pos, 4); if not imm then return end
    536 	x = format("[0x%08x]", imm)
    537 	pos = pos+4
    538       end
    539     elseif p == "i" or p == "I" then
    540       local n = map_sz2n[sz]
    541       if n == 8 and ctx.x64 and p == "I" then
    542 	local imm1 = getimm(ctx, pos, 4); if not imm1 then return end
    543 	local imm2 = getimm(ctx, pos+4, 4); if not imm2 then return end
    544 	x = format("0x%08x%08x", imm2, imm1)
    545       else
    546 	if n == 8 then n = 4 end
    547 	local imm = getimm(ctx, pos, n); if not imm then return end
    548 	if sz == "Q" and (imm < 0 or imm > 0x7fffffff) then
    549 	  imm = (0xffffffff+1)-imm
    550 	  x = format(imm > 65535 and "-0x%08x" or "-0x%x", imm)
    551 	else
    552 	  x = format(imm > 65535 and "0x%08x" or "0x%x", imm)
    553 	end
    554       end
    555       pos = pos+n
    556     elseif p == "j" then
    557       local n = map_sz2n[sz]
    558       if n == 8 then n = 4 end
    559       local imm = getimm(ctx, pos, n); if not imm then return end
    560       if sz == "B" and imm > 127 then imm = imm-256
    561       elseif imm > 2147483647 then imm = imm-4294967296 end
    562       pos = pos+n
    563       imm = imm + pos + ctx.addr
    564       if imm > 4294967295 and not ctx.x64 then imm = imm-4294967296 end
    565       ctx.imm = imm
    566       if sz == "W" then
    567 	x = format("word 0x%04x", imm%65536)
    568       elseif ctx.x64 then
    569 	local lo = imm % 0x1000000
    570 	x = format("0x%02x%06x", (imm-lo) / 0x1000000, lo)
    571       else
    572 	x = "0x"..tohex(imm)
    573       end
    574     elseif p == "R" then
    575       local r = byte(code, pos-1, pos-1)%8
    576       if ctx.rexb then r = r + 8; ctx.rexb = false end
    577       x = regs[r+1]
    578     elseif p == "a" then x = regs[1]
    579     elseif p == "c" then x = "cl"
    580     elseif p == "d" then x = "dx"
    581     elseif p == "1" then x = "1"
    582     else
    583       if not mode then
    584 	mode = ctx.mrm
    585 	if not mode then
    586 	  if pos > stop then return incomplete(ctx) end
    587 	  mode = byte(code, pos, pos)
    588 	  pos = pos+1
    589 	end
    590 	rm = mode%8; mode = (mode-rm)/8
    591 	sp = mode%8; mode = (mode-sp)/8
    592 	sdisp = ""
    593 	if mode < 3 then
    594 	  if rm == 4 then
    595 	    if pos > stop then return incomplete(ctx) end
    596 	    sc = byte(code, pos, pos)
    597 	    pos = pos+1
    598 	    rm = sc%8; sc = (sc-rm)/8
    599 	    rx = sc%8; sc = (sc-rx)/8
    600 	    if ctx.rexx then rx = rx + 8; ctx.rexx = false end
    601 	    if rx == 4 then rx = nil end
    602 	  end
    603 	  if mode > 0 or rm == 5 then
    604 	    local dsz = mode
    605 	    if dsz ~= 1 then dsz = 4 end
    606 	    local disp = getimm(ctx, pos, dsz); if not disp then return end
    607 	    if mode == 0 then rm = nil end
    608 	    if rm or rx or (not sc and ctx.x64 and not ctx.a32) then
    609 	      if dsz == 1 and disp > 127 then
    610 		sdisp = format("-0x%x", 256-disp)
    611 	      elseif disp >= 0 and disp <= 0x7fffffff then
    612 		sdisp = format("+0x%x", disp)
    613 	      else
    614 		sdisp = format("-0x%x", (0xffffffff+1)-disp)
    615 	      end
    616 	    else
    617 	      sdisp = format(ctx.x64 and not ctx.a32 and
    618 		not (disp >= 0 and disp <= 0x7fffffff)
    619 		and "0xffffffff%08x" or "0x%08x", disp)
    620 	    end
    621 	    pos = pos+dsz
    622 	  end
    623 	end
    624 	if rm and ctx.rexb then rm = rm + 8; ctx.rexb = false end
    625 	if ctx.rexr then sp = sp + 8; ctx.rexr = false end
    626       end
    627       if p == "m" then
    628 	if mode == 3 then x = regs[rm+1]
    629 	else
    630 	  local aregs = ctx.a32 and map_regs.D or ctx.aregs
    631 	  local srm, srx = "", ""
    632 	  if rm then srm = aregs[rm+1]
    633 	  elseif not sc and ctx.x64 and not ctx.a32 then srm = "rip" end
    634 	  ctx.a32 = false
    635 	  if rx then
    636 	    if rm then srm = srm.."+" end
    637 	    srx = aregs[rx+1]
    638 	    if sc > 0 then srx = srx.."*"..(2^sc) end
    639 	  end
    640 	  x = format("[%s%s%s]", srm, srx, sdisp)
    641 	end
    642 	if mode < 3 and
    643 	   (not match(pat, "[aRrgp]") or match(pat, "t")) then -- Yuck.
    644 	  x = map_sz2prefix[sz].." "..x
    645 	end
    646       elseif p == "r" then x = regs[sp+1]
    647       elseif p == "g" then x = map_segregs[sp+1]
    648       elseif p == "p" then -- Suppress prefix.
    649       elseif p == "f" then x = "st"..rm
    650       elseif p == "x" then
    651 	if sp == 0 and ctx.lock and not ctx.x64 then
    652 	  x = "CR8"; ctx.lock = false
    653 	else
    654 	  x = "CR"..sp
    655 	end
    656       elseif p == "v" then
    657 	if ctx.vexv then
    658 	  x = regs[ctx.vexv+1]; ctx.vexv = false
    659 	end
    660       elseif p == "y" then x = "DR"..sp
    661       elseif p == "z" then x = "TR"..sp
    662       elseif p == "l" then vexl = false
    663       elseif p == "t" then
    664       else
    665 	error("bad pattern `"..pat.."'")
    666       end
    667     end
    668     if x then operands = operands and operands..", "..x or x end
    669   end
    670   ctx.pos = pos
    671   return putop(ctx, name, operands)
    672 end
    673 
    674 -- Forward declaration.
    675 local map_act
    676 
    677 -- Fetch and cache MRM byte.
    678 local function getmrm(ctx)
    679   local mrm = ctx.mrm
    680   if not mrm then
    681     local pos = ctx.pos
    682     if pos > ctx.stop then return nil end
    683     mrm = byte(ctx.code, pos, pos)
    684     ctx.pos = pos+1
    685     ctx.mrm = mrm
    686   end
    687   return mrm
    688 end
    689 
    690 -- Dispatch to handler depending on pattern.
    691 local function dispatch(ctx, opat, patgrp)
    692   if not opat then return unknown(ctx) end
    693   if match(opat, "%|") then -- MMX/SSE variants depending on prefix.
    694     local p
    695     if ctx.rep then
    696       p = ctx.rep=="rep" and "%|([^%|]*)" or "%|[^%|]*%|[^%|]*%|([^%|]*)"
    697       ctx.rep = false
    698     elseif ctx.o16 then p = "%|[^%|]*%|([^%|]*)"; ctx.o16 = false
    699     else p = "^[^%|]*" end
    700     opat = match(opat, p)
    701     if not opat then return unknown(ctx) end
    702 --    ctx.rep = false; ctx.o16 = false
    703     --XXX fails for 66 f2 0f 38 f1 06  crc32 eax,WORD PTR [esi]
    704     --XXX remove in branches?
    705   end
    706   if match(opat, "%$") then -- reg$mem variants.
    707     local mrm = getmrm(ctx); if not mrm then return incomplete(ctx) end
    708     opat = match(opat, mrm >= 192 and "^[^%$]*" or "%$(.*)")
    709     if opat == "" then return unknown(ctx) end
    710   end
    711   if opat == "" then return unknown(ctx) end
    712   local name, pat = match(opat, "^([a-z0-9 ]*)(.*)")
    713   if pat == "" and patgrp then pat = patgrp end
    714   return map_act[sub(pat, 1, 1)](ctx, name, pat)
    715 end
    716 
    717 -- Get a pattern from an opcode map and dispatch to handler.
    718 local function dispatchmap(ctx, opcmap)
    719   local pos = ctx.pos
    720   local opat = opcmap[byte(ctx.code, pos, pos)]
    721   pos = pos + 1
    722   ctx.pos = pos
    723   return dispatch(ctx, opat)
    724 end
    725 
    726 -- Map for action codes. The key is the first char after the name.
    727 map_act = {
    728   -- Simple opcodes without operands.
    729   [""] = function(ctx, name, pat)
    730     return putop(ctx, name)
    731   end,
    732 
    733   -- Operand size chars fall right through.
    734   B = putpat, W = putpat, D = putpat, Q = putpat,
    735   V = putpat, U = putpat, T = putpat,
    736   M = putpat, X = putpat, P = putpat,
    737   F = putpat, G = putpat, Y = putpat,
    738 
    739   -- Collect prefixes.
    740   [":"] = function(ctx, name, pat)
    741     ctx[pat == ":" and name or sub(pat, 2)] = name
    742     if ctx.pos - ctx.start > 5 then return unknown(ctx) end -- Limit #prefixes.
    743   end,
    744 
    745   -- Chain to special handler specified by name.
    746   ["*"] = function(ctx, name, pat)
    747     return map_act[name](ctx, name, sub(pat, 2))
    748   end,
    749 
    750   -- Use named subtable for opcode group.
    751   ["!"] = function(ctx, name, pat)
    752     local mrm = getmrm(ctx); if not mrm then return incomplete(ctx) end
    753     return dispatch(ctx, map_opcgroup[name][((mrm-(mrm%8))/8)%8+1], sub(pat, 2))
    754   end,
    755 
    756   -- o16,o32[,o64] variants.
    757   sz = function(ctx, name, pat)
    758     if ctx.o16 then ctx.o16 = false
    759     else
    760       pat = match(pat, ",(.*)")
    761       if ctx.rexw then
    762 	local p = match(pat, ",(.*)")
    763 	if p then pat = p; ctx.rexw = false end
    764       end
    765     end
    766     pat = match(pat, "^[^,]*")
    767     return dispatch(ctx, pat)
    768   end,
    769 
    770   -- Two-byte opcode dispatch.
    771   opc2 = function(ctx, name, pat)
    772     return dispatchmap(ctx, map_opc2)
    773   end,
    774 
    775   -- Three-byte opcode dispatch.
    776   opc3 = function(ctx, name, pat)
    777     return dispatchmap(ctx, map_opc3[pat])
    778   end,
    779 
    780   -- VMX/SVM dispatch.
    781   vm = function(ctx, name, pat)
    782     return dispatch(ctx, map_opcvm[ctx.mrm])
    783   end,
    784 
    785   -- Floating point opcode dispatch.
    786   fp = function(ctx, name, pat)
    787     local mrm = getmrm(ctx); if not mrm then return incomplete(ctx) end
    788     local rm = mrm%8
    789     local idx = pat*8 + ((mrm-rm)/8)%8
    790     if mrm >= 192 then idx = idx + 64 end
    791     local opat = map_opcfp[idx]
    792     if type(opat) == "table" then opat = opat[rm+1] end
    793     return dispatch(ctx, opat)
    794   end,
    795 
    796   -- REX prefix.
    797   rex = function(ctx, name, pat)
    798     if ctx.rex then return unknown(ctx) end -- Only 1 REX or VEX prefix allowed.
    799     for p in gmatch(pat, ".") do ctx["rex"..p] = true end
    800     ctx.rex = "rex"
    801   end,
    802 
    803   -- VEX prefix.
    804   vex = function(ctx, name, pat)
    805     if ctx.rex then return unknown(ctx) end -- Only 1 REX or VEX prefix allowed.
    806     ctx.rex = "vex"
    807     local pos = ctx.pos
    808     if ctx.mrm then
    809       ctx.mrm = nil
    810       pos = pos-1
    811     end
    812     local b = byte(ctx.code, pos, pos)
    813     if not b then return incomplete(ctx) end
    814     pos = pos+1
    815     if b < 128 then ctx.rexr = true end
    816     local m = 1
    817     if pat == "3" then
    818       m = b%32; b = (b-m)/32
    819       local nb = b%2; b = (b-nb)/2
    820       if nb == 0 then ctx.rexb = true end
    821       local nx = b%2; b = (b-nx)/2
    822       if nx == 0 then ctx.rexx = true end
    823       b = byte(ctx.code, pos, pos)
    824       if not b then return incomplete(ctx) end
    825       pos = pos+1
    826       if b >= 128 then ctx.rexw = true end
    827     end
    828     ctx.pos = pos
    829     local map
    830     if m == 1 then map = map_opc2
    831     elseif m == 2 then map = map_opc3["38"]
    832     elseif m == 3 then map = map_opc3["3a"]
    833     else return unknown(ctx) end
    834     local p = b%4; b = (b-p)/4
    835     if p == 1 then ctx.o16 = "o16"
    836     elseif p == 2 then ctx.rep = "rep"
    837     elseif p == 3 then ctx.rep = "repne" end
    838     local l = b%2; b = (b-l)/2
    839     if l ~= 0 then ctx.vexl = true end
    840     ctx.vexv = (-1-b)%16
    841     return dispatchmap(ctx, map)
    842   end,
    843 
    844   -- Special case for nop with REX prefix.
    845   nop = function(ctx, name, pat)
    846     return dispatch(ctx, ctx.rex and pat or "nop")
    847   end,
    848 
    849   -- Special case for 0F 77.
    850   emms = function(ctx, name, pat)
    851     if ctx.rex ~= "vex" then
    852       return putop(ctx, "emms")
    853     elseif ctx.vexl then
    854       ctx.vexl = false
    855       return putop(ctx, "zeroall")
    856     else
    857       return putop(ctx, "zeroupper")
    858     end
    859   end,
    860 }
    861 
    862 ------------------------------------------------------------------------------
    863 
    864 -- Disassemble a block of code.
    865 local function disass_block(ctx, ofs, len)
    866   if not ofs then ofs = 0 end
    867   local stop = len and ofs+len or #ctx.code
    868   ofs = ofs + 1
    869   ctx.start = ofs
    870   ctx.pos = ofs
    871   ctx.stop = stop
    872   ctx.imm = nil
    873   ctx.mrm = false
    874   clearprefixes(ctx)
    875   while ctx.pos <= stop do dispatchmap(ctx, ctx.map1) end
    876   if ctx.pos ~= ctx.start then incomplete(ctx) end
    877 end
    878 
    879 -- Extended API: create a disassembler context. Then call ctx:disass(ofs, len).
    880 local function create(code, addr, out)
    881   local ctx = {}
    882   ctx.code = code
    883   ctx.addr = (addr or 0) - 1
    884   ctx.out = out or io.write
    885   ctx.symtab = {}
    886   ctx.disass = disass_block
    887   ctx.hexdump = 16
    888   ctx.x64 = false
    889   ctx.map1 = map_opc1_32
    890   ctx.aregs = map_regs.D
    891   return ctx
    892 end
    893 
    894 local function create64(code, addr, out)
    895   local ctx = create(code, addr, out)
    896   ctx.x64 = true
    897   ctx.map1 = map_opc1_64
    898   ctx.aregs = map_regs.Q
    899   return ctx
    900 end
    901 
    902 -- Simple API: disassemble code (a string) at address and output via out.
    903 local function disass(code, addr, out)
    904   create(code, addr, out):disass()
    905 end
    906 
    907 local function disass64(code, addr, out)
    908   create64(code, addr, out):disass()
    909 end
    910 
    911 -- Return register name for RID.
    912 local function regname(r)
    913   if r < 8 then return map_regs.D[r+1] end
    914   return map_regs.X[r-7]
    915 end
    916 
    917 local function regname64(r)
    918   if r < 16 then return map_regs.Q[r+1] end
    919   return map_regs.X[r-15]
    920 end
    921 
    922 -- Public module functions.
    923 return {
    924   create = create,
    925   create64 = create64,
    926   disass = disass,
    927   disass64 = disass64,
    928   regname = regname,
    929   regname64 = regname64
    930 }
    931