PPC: Add PPC disassembler.

1 files changed, 578 insertions, 0 deletions

diff --git a/lib/dis_ppc.lua b/lib/dis_ppc.lua
new file mode 100644
index 00000000..13d87c70
--- /dev/null
+++ b/lib/dis_ppc.lua
@@ -0,0 +1,578 @@
+----------------------------------------------------------------------------
+-- LuaJIT PPC disassembler module.
+--
+-- Copyright (C) 2005-2010 Mike Pall. All rights reserved.
+-- Released under the MIT/X license. See Copyright Notice in luajit.h
+----------------------------------------------------------------------------
+-- This is a helper module used by the LuaJIT machine code dumper module.
+--
+-- It disassembles all common, non-privileged 32/64 bit PowerPC instructions
+-- plus the e500 SPE instructions and some Cell/Xenon extensions.
+--
+-- NYI: VMX, VMX128
+------------------------------------------------------------------------------
+
+local type = type
+local sub, byte, format = string.sub, string.byte, string.format
+local match, gmatch, gsub = string.match, string.gmatch, string.gsub
+local concat = table.concat
+local bit = require("bit")
+local band, bor, tohex = bit.band, bit.bor, bit.tohex
+local lshift, rshift, arshift = bit.lshift, bit.rshift, bit.arshift
+
+------------------------------------------------------------------------------
+-- Primary and extended opcode maps
+------------------------------------------------------------------------------
+
+local map_crops = {
+  shift = 1, mask = 1023,
+  [0] = "mcrfXX",
+  [33] = "crnor|crnotCCC=", [129] = "crandcCCC",
+  [193] = "crxor|crclrCCC%", [225] = "crnandCCC",
+  [257] = "crandCCC", [289] = "creqv|crsetCCC%",
+  [417] = "crorcCCC", [449] = "cror|crmoveCCC=",
+  [16] = "b_lrKB", [528] = "b_ctrKB",
+  [150] = "isync",
+}
+
+local map_rld = {
+  shift = 2, mask = 7,
+  [0] = "rldiclRR~HM.", "rldicrRR~HM.", "rldicRR~HM.", "rldimiRR~HM.",
+  {
+    shift = 1, mask = 1,
+    [0] = "rldclRR~HM.", "rldcrRR~HM.",
+  },
+}
+
+local map_ext = setmetatable({
+  shift = 1, mask = 1023,
+
+  [0] = "cmp_YLRR", [32] = "cmpl_YLRR",
+  [4] = "twARR", [68] = "tdARR",
+
+  [8] = "subfcRRR.", [40] = "subfRRR.",
+  [104] = "negRR.", [136] = "subfeRRR.",
+  [200] = "subfzeRR.", [232] = "subfmeRR.",
+  [520] = "subfcoRRR.", [552] = "subfoRRR.",
+  [616] = "negoRR.", [648] = "subfeoRRR.",
+  [712] = "subfzeoRR.", [744] = "subfmeoRR.",
+
+  [9] = "mulhduRRR.", [73] = "mulhdRRR.", [233] = "mulldRRR.",
+  [457] = "divduRRR.", [489] = "divdRRR.",
+  [745] = "mulldoRRR.",
+  [969] = "divduoRRR.", [1001] = "divdoRRR.",
+
+  [10] = "addcRRR.", [138] = "addeRRR.",
+  [202] = "addzeRR.", [234] = "addmeRR.", [266] = "addRRR.",
+  [522] = "addcoRRR.", [650] = "addeoRRR.",
+  [714] = "addzeoRR.", [746] = "addmeoRR.", [778] = "addoRRR.",
+
+  [11] = "mulhwuRRR.", [75] = "mulhwRRR.", [235] = "mullwRRR.",
+  [459] = "divwuRRR.", [491] = "divwRRR.",
+  [747] = "mullwoRRR.",
+  [971] = "divwouRRR.", [1003] = "divwoRRR.",
+
+  [15] = "iselltRRR", [47] = "iselgtRRR", [79] = "iseleqRRR",
+
+  [144] = { shift = 20, mask = 1, [0] = "mtcrfRZ~", "mtocrfRZ~", },
+  [19] = { shift = 20, mask = 1, [0] = "mfcrR", "mfocrfRZ", },
+  [371] = { shift = 11, mask = 1023, [392] = "mftbR", [424] = "mftbuR", },
+  [339] = {
+    shift = 11, mask = 1023,
+    [32] = "mferR", [256] = "mflrR", [288] = "mfctrR", [16] = "mfspefscrR",
+  },
+  [467] = {
+    shift = 11, mask = 1023,
+    [32] = "mtxerR", [256] = "mtlrR", [288] = "mtctrR", [16] = "mtspefscrR",
+  },
+
+  [20] = "lwarxRR0R", [84] = "ldarxRR0R",
+
+  [21] = "ldxRR0R", [53] = "lduxRRR",
+  [149] = "stdxRR0R", [181] = "stduxRRR",
+  [341] = "lwaxRR0R", [373] = "lwauxRRR",
+
+  [23] = "lwzxRR0R", [55] = "lwzuxRRR",
+  [87] = "lbzxRR0R", [119] = "lbzuxRRR",
+  [151] = "stwxRR0R", [183] = "stwuxRRR",
+  [215] = "stbxRR0R", [247] = "stbuxRRR",
+  [279] = "lhzxRR0R", [311] = "lhzuxRRR",
+  [343] = "lhaxRR0R", [375] = "lhauxRRR",
+  [407] = "sthxRR0R", [439] = "sthuxRRR",
+
+  [54] = "dcbst-R0R", [86] = "dcbf-R0R",
+  [150] = "stwcxRR0R.", [214] = "stdcxRR0R.",
+  [246] = "dcbtst-R0R", [278] = "dcbt-R0R",
+  [310] = "eciwxRR0R", [438] = "ecowxRR0R",
+  [470] = "dcbi-RR",
+
+  [598] = {
+    shift = 21, mask = 3,
+    [0] = "sync", "lwsync", "ptesync",
+  },
+  [758] = "dcba-RR",
+  [854] = "eieio", [982] = "icbi-R0R", [1014] = "dcbz-R0R",
+
+  [26] = "cntlzwRR~", [58] = "cntlzdRR~",
+  [122] = "popcntbRR~",
+  [154] = "prtywRR~", [186] = "prtydRR~",
+
+  [28] = "andRR~R.", [60] = "andcRR~R.", [124] = "nor|notRR~R=.",
+  [284] = "eqvRR~R.", [316] = "xorRR~R.",
+  [412] = "orcRR~R.", [444] = "or|mrRR~R=.", [476] = "nandRR~R.",
+  [508] = "cmpbRR~R",
+
+  [512] = "mcrxrX",
+
+  [532] = "ldbrxRR0R", [660] = "stdbrxRR0R",
+
+  [533] = "lswxRR0R", [597] = "lswiRR0A",
+  [661] = "stswxRR0R", [725] = "stswiRR0A",
+
+  [534] = "lwbrxRR0R", [662] = "stwbrxRR0R",
+  [790] = "lhbrxRR0R", [918] = "sthbrxRR0R",
+
+  [535] = "lfsxFR0R", [567] = "lfsuxFRR",
+  [599] = "lfdxFR0R", [631] = "lfduxFRR",
+  [663] = "stfsxFR0R", [695] = "stfsuxFRR",
+  [727] = "stfdxFR0R", [759] = "stfduxFR0R",
+  [855] = "lfiwaxFR0R",
+  [983] = "stfiwxFR0R",
+
+  [24] = "slwRR~R.",
+
+  [27] = "sldRR~R.", [536] = "srwRR~R.",
+  [792] = "srawRR~R.", [824] = "srawiRR~A.",
+
+  [794] = "sradRR~R.", [826] = "sradiRR~H.", [827] = "sradiRR~H.",
+  [922] = "extshRR~.", [954] = "extsbRR~.", [986] = "extswRR~.",
+
+  [539] = "srdRR~R.",
+},
+{ __index = function(t, x)
+    if band(x, 31) == 15 then return "iselRRRC" end
+  end
+})
+
+local map_ld = {
+  shift = 0, mask = 3,
+  [0] = "ldRRE", "lduRRE", "lwaRRE",
+}
+
+local map_std = {
+  shift = 0, mask = 3,
+  [0] = "stdRRE", "stduRRE",
+}
+
+local map_fps = {
+  shift = 5, mask = 1,
+  {
+    shift = 1, mask = 15,
+    [0] = false, false, "fdivsFFF.", false,
+    "fsubsFFF.", "faddsFFF.", "fsqrtsF-F.", false,
+    "fresF-F.", "fmulsFF-F.", "frsqrtesF-F.", false,
+    "fmsubsFFFF~.", "fmaddsFFFF~.", "fnmsubsFFFF~.", "fnmaddsFFFF~.",
+  }
+}
+
+local map_fpd = {
+  shift = 5, mask = 1,
+  [0] = {
+    shift = 1, mask = 1023,
+    [0] = "fcmpuXFF", [32] = "fcmpoXFF", [64] = "mcrfsXX",
+    [38] = "mtfsb1A.", [70] = "mtfsb0A.", [134] = "mtfsfiA>>-A>",
+    [8] = "fcpsgnFFF.", [40] = "fnegF-F.", [72] = "fmrF-F.",
+    [136] = "fnabsF-F.", [264] = "fabsF-F.",
+    [12] = "frspF-F.",
+    [14] = "fctiwF-F.", [15] = "fctiwzF-F.",
+    [583] = "mffsF.", [711] = "mtfsfZF.",
+    [392] = "frinF-F.", [424] = "frizF-F.",
+    [456] = "fripF-F.", [488] = "frimF-F.",
+    [814] = "fctidF-F.", [815] = "fctidzF-F.", [846] = "fcfidF-F.",
+  },
+  {
+    shift = 1, mask = 15,
+    [0] = false, false, "fdivFFF.", false,
+    "fsubFFF.", "faddFFF.", "fsqrtF-F.", "fselFFFF~.",
+    "freF-F.", "fmulFF-F.", "frsqrteF-F.", false,
+    "fmsubFFFF~.", "fmaddFFFF~.", "fnmsubFFFF~.", "fnmaddFFFF~.",
+  }
+}
+
+local map_spe = {
+  shift = 0, mask = 2047,
+
+  [512] = "evaddwRRR", [514] = "evaddiwRAR~",
+  [516] = "evsubwRRR~", [518] = "evsubiwRAR~",
+  [520] = "evabsRR", [521] = "evnegRR",
+  [522] = "evextsbRR", [523] = "evextshRR", [524] = "evrndwRR",
+  [525] = "evcntlzwRR", [526] = "evcntlswRR",
+
+  [527] = "brincRRR",
+
+  [529] = "evandRRR", [530] = "evandcRRR", [534] = "evxorRRR",
+  [535] = "evor|evmrRRR=", [536] = "evnor|evnotRRR=",
+  [537] = "eveqvRRR", [539] = "evorcRRR", [542] = "evnandRRR",
+
+  [544] = "evsrwuRRR", [545] = "evsrwsRRR",
+  [546] = "evsrwiuRRA", [547] = "evsrwisRRA",
+  [548] = "evslwRRR", [550] = "evslwiRRA",
+  [552] = "evrlwRRR", [553] = "evsplatiRS",
+  [554] = "evrlwiRRA", [555] = "evsplatfiRS",
+  [556] = "evmergehiRRR", [557] = "evmergeloRRR",
+  [558] = "evmergehiloRRR", [559] = "evmergelohiRRR",
+
+  [560] = "evcmpgtuYRR", [561] = "evcmpgtsYRR",
+  [562] = "evcmpltuYRR", [563] = "evcmpltsYRR",
+  [564] = "evcmpeqYRR",
+
+  [632] = "evselRRR", [633] = "evselRRRW",
+  [634] = "evselRRRW", [635] = "evselRRRW",
+  [636] = "evselRRRW", [637] = "evselRRRW",
+  [638] = "evselRRRW", [639] = "evselRRRW",
+
+  [640] = "evfsaddRRR", [641] = "evfssubRRR",
+  [644] = "evfsabsRR", [645] = "evfsnabsRR", [646] = "evfsnegRR",
+  [648] = "evfsmulRRR", [649] = "evfsdivRRR",
+  [652] = "evfscmpgtYRR", [653] = "evfscmpltYRR", [654] = "evfscmpeqYRR",
+  [656] = "evfscfuiR-R", [657] = "evfscfsiR-R",
+  [658] = "evfscfufR-R", [659] = "evfscfsfR-R",
+  [660] = "evfsctuiR-R", [661] = "evfsctsiR-R",
+  [662] = "evfsctufR-R", [663] = "evfsctsfR-R",
+  [664] = "evfsctuizR-R", [666] = "evfsctsizR-R",
+  [668] = "evfststgtYRR", [669] = "evfststltYRR", [670] = "evfststeqYRR",
+
+  [704] = "efsaddRRR", [705] = "efssubRRR",
+  [708] = "efsabsRR", [709] = "efsnabsRR", [710] = "efsnegRR",
+  [712] = "efsmulRRR", [713] = "efsdivRRR",
+  [716] = "efscmpgtYRR", [717] = "efscmpltYRR", [718] = "efscmpeqYRR",
+  [719] = "efscfdR-R",
+  [720] = "efscfuiR-R", [721] = "efscfsiR-R",
+  [722] = "efscfufR-R", [723] = "efscfsfR-R",
+  [724] = "efsctuiR-R", [725] = "efsctsiR-R",
+  [726] = "efsctufR-R", [727] = "efsctsfR-R",
+  [728] = "efsctuizR-R", [730] = "efsctsizR-R",
+  [732] = "efststgtYRR", [733] = "efststltYRR", [734] = "efststeqYRR",
+
+  [736] = "efdaddRRR", [737] = "efdsubRRR",
+  [738] = "efdcfuidR-R", [739] = "efdcfsidR-R",
+  [740] = "efdabsRR", [741] = "efdnabsRR", [742] = "efdnegRR",
+  [744] = "efdmulRRR", [745] = "efddivRRR",
+  [746] = "efdctuidzR-R", [747] = "efdctsidzR-R",
+  [748] = "efdcmpgtYRR", [749] = "efdcmpltYRR", [750] = "efdcmpeqYRR",
+  [751] = "efdcfsR-R",
+  [752] = "efdcfuiR-R", [753] = "efdcfsiR-R",
+  [754] = "efdcfufR-R", [755] = "efdcfsfR-R",
+  [756] = "efdctuiR-R", [757] = "efdctsiR-R",
+  [758] = "efdctufR-R", [759] = "efdctsfR-R",
+  [760] = "efdctuizR-R", [762] = "efdctsizR-R",
+  [764] = "efdtstgtYRR", [765] = "efdtstltYRR", [766] = "efdtsteqYRR",
+
+  [768] = "evlddxRR0R", [769] = "evlddRR8",
+  [770] = "evldwxRR0R", [771] = "evldwRR8",
+  [772] = "evldhxRR0R", [773] = "evldhRR8",
+  [776] = "evlhhesplatxRR0R", [777] = "evlhhesplatRR2",
+  [780] = "evlhhousplatxRR0R", [781] = "evlhhousplatRR2",
+  [782] = "evlhhossplatxRR0R", [783] = "evlhhossplatRR2",
+  [784] = "evlwhexRR0R", [785] = "evlwheRR4",
+  [788] = "evlwhouxRR0R", [789] = "evlwhouRR4",
+  [790] = "evlwhosxRR0R", [791] = "evlwhosRR4",
+  [792] = "evlwwsplatxRR0R", [793] = "evlwwsplatRR4",
+  [796] = "evlwhsplatxRR0R", [797] = "evlwhsplatRR4",
+
+  [800] = "evstddxRR0R", [801] = "evstddRR8",
+  [802] = "evstdwxRR0R", [803] = "evstdwRR8",
+  [804] = "evstdhxRR0R", [805] = "evstdhRR8",
+  [816] = "evstwhexRR0R", [817] = "evstwheRR4",
+  [820] = "evstwhoxRR0R", [821] = "evstwhoRR4",
+  [824] = "evstwwexRR0R", [825] = "evstwweRR4",
+  [828] = "evstwwoxRR0R", [829] = "evstwwoRR4",
+
+  [1027] = "evmhessfRRR", [1031] = "evmhossfRRR", [1032] = "evmheumiRRR",
+  [1033] = "evmhesmiRRR", [1035] = "evmhesmfRRR", [1036] = "evmhoumiRRR",
+  [1037] = "evmhosmiRRR", [1039] = "evmhosmfRRR", [1059] = "evmhessfaRRR",
+  [1063] = "evmhossfaRRR", [1064] = "evmheumiaRRR", [1065] = "evmhesmiaRRR",
+  [1067] = "evmhesmfaRRR", [1068] = "evmhoumiaRRR", [1069] = "evmhosmiaRRR",
+  [1071] = "evmhosmfaRRR", [1095] = "evmwhssfRRR", [1096] = "evmwlumiRRR",
+  [1100] = "evmwhumiRRR", [1101] = "evmwhsmiRRR", [1103] = "evmwhsmfRRR",
+  [1107] = "evmwssfRRR", [1112] = "evmwumiRRR", [1113] = "evmwsmiRRR",
+  [1115] = "evmwsmfRRR", [1127] = "evmwhssfaRRR", [1128] = "evmwlumiaRRR",
+  [1132] = "evmwhumiaRRR", [1133] = "evmwhsmiaRRR", [1135] = "evmwhsmfaRRR",
+  [1139] = "evmwssfaRRR", [1144] = "evmwumiaRRR", [1145] = "evmwsmiaRRR",
+  [1147] = "evmwsmfaRRR",
+
+  [1216] = "evaddusiaawRR", [1217] = "evaddssiaawRR",
+  [1218] = "evsubfusiaawRR", [1219] = "evsubfssiaawRR",
+  [1220] = "evmraRR",
+  [1222] = "evdivwsRRR", [1223] = "evdivwuRRR",
+  [1224] = "evaddumiaawRR", [1225] = "evaddsmiaawRR",
+  [1226] = "evsubfumiaawRR", [1227] = "evsubfsmiaawRR",
+
+  [1280] = "evmheusiaawRRR", [1281] = "evmhessiaawRRR",
+  [1283] = "evmhessfaawRRR", [1284] = "evmhousiaawRRR",
+  [1285] = "evmhossiaawRRR", [1287] = "evmhossfaawRRR",
+  [1288] = "evmheumiaawRRR", [1289] = "evmhesmiaawRRR",
+  [1291] = "evmhesmfaawRRR", [1292] = "evmhoumiaawRRR",
+  [1293] = "evmhosmiaawRRR", [1295] = "evmhosmfaawRRR",
+  [1320] = "evmhegumiaaRRR", [1321] = "evmhegsmiaaRRR",
+  [1323] = "evmhegsmfaaRRR", [1324] = "evmhogumiaaRRR",
+  [1325] = "evmhogsmiaaRRR", [1327] = "evmhogsmfaaRRR",
+  [1344] = "evmwlusiaawRRR", [1345] = "evmwlssiaawRRR",
+  [1352] = "evmwlumiaawRRR", [1353] = "evmwlsmiaawRRR",
+  [1363] = "evmwssfaaRRR", [1368] = "evmwumiaaRRR",
+  [1369] = "evmwsmiaaRRR", [1371] = "evmwsmfaaRRR",
+  [1408] = "evmheusianwRRR", [1409] = "evmhessianwRRR",
+  [1411] = "evmhessfanwRRR", [1412] = "evmhousianwRRR",
+  [1413] = "evmhossianwRRR", [1415] = "evmhossfanwRRR",
+  [1416] = "evmheumianwRRR", [1417] = "evmhesmianwRRR",
+  [1419] = "evmhesmfanwRRR", [1420] = "evmhoumianwRRR",
+  [1421] = "evmhosmianwRRR", [1423] = "evmhosmfanwRRR",
+  [1448] = "evmhegumianRRR", [1449] = "evmhegsmianRRR",
+  [1451] = "evmhegsmfanRRR", [1452] = "evmhogumianRRR",
+  [1453] = "evmhogsmianRRR", [1455] = "evmhogsmfanRRR",
+  [1472] = "evmwlusianwRRR", [1473] = "evmwlssianwRRR",
+  [1480] = "evmwlumianwRRR", [1481] = "evmwlsmianwRRR",
+  [1491] = "evmwssfanRRR", [1496] = "evmwumianRRR",
+  [1497] = "evmwsmianRRR", [1499] = "evmwsmfanRRR",
+}
+
+local map_pri = {
+  [0] = false,  false,          "tdiARI",       "twiARI",
+  map_spe,      false,          false,          "mulliRRI",
+  "subficRRI",  false,          "cmpl_iYLRU",   "cmp_iYLRI",
+  "addicRRI",   "addic.RRI",    "addi|liRR0I",  "addis|lisRR0I",
+  "b_KBJ",      "sc",            "bKJ",         map_crops,
+  "rlwimiRR~AAA.", "rlwinmRR~AAA.", false,      "rlwnmRR~RAA.",
+  "oriNRR~U",   "orisRR~U",     "xoriRR~U",     "xorisRR~U",
+  "andi.RR~U",  "andis.RR~U",   map_rld,        map_ext,
+  "lwzRRD",     "lwzuRRD",      "lbzRRD",       "lbzuRRD",
+  "stwRRD",     "stwuRRD",      "stbRRD",       "stbuRRD",
+  "lhzRRD",     "lhzuRRD",      "lhaRRD",       "lhauRRD",
+  "sthRRD",     "sthuRRD",      "lmwRRD",       "stmwRRD",
+  "lfsFRD",     "lfsuFRD",      "lfdFRD",       "lfduFRD",
+  "stfsFRD",    "stfsuFRD",     "stfdFRD",      "stfduFRD",
+  false,        false,          map_ld,         map_fps,
+  false,        false,          map_std,        map_fpd,
+}
+
+------------------------------------------------------------------------------
+
+local map_gpr = {
+  [0] = "r0", "sp", "r2", "r3", "r4", "r5", "r6", "r7",
+  "r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15",
+  "r16", "r17", "r18", "r19", "r20", "r21", "r22", "r23",
+  "r24", "r25", "r26", "r27", "r28", "r29", "r30", "r31",
+}
+
+local map_cond = { [0] = "lt", "gt", "eq", "so", "ge", "le", "ne", "ns", }
+
+-- Format a condition bit.
+local function condfmt(cond)
+  if cond <= 3 then
+    return map_cond[band(cond, 3)]
+  else
+    return format("4*cr%d+%s", rshift(cond, 2), map_cond[band(cond, 3)])
+  end
+end
+
+------------------------------------------------------------------------------
+
+-- Output a nicely formatted line with an opcode and operands.
+local function putop(ctx, text, operands)
+  local pos = ctx.pos
+  local extra = ""
+  if ctx.rel then
+    local sym = ctx.symtab[ctx.rel]
+    if sym then extra = "\t->"..sym end
+  end
+  if ctx.hexdump > 0 then
+    ctx.out(format("%08x  %s  %-7s %s%s\n",
+            ctx.addr+pos, tohex(ctx.op), text, concat(operands, ", "), extra))
+  else
+    ctx.out(format("%08x  %-7s %s%s\n",
+            ctx.addr+pos, text, concat(operands, ", "), extra))
+  end
+  ctx.pos = pos + 4
+end
+
+-- Fallback for unknown opcodes.
+local function unknown(ctx)
+  return putop(ctx, ".long", { "0x"..tohex(ctx.op) })
+end
+
+-- Disassemble a single instruction.
+local function disass_ins(ctx)
+  local pos = ctx.pos
+  local b0, b1, b2, b3 = byte(ctx.code, pos+1, pos+4)
+  local op = bor(lshift(b0, 24), lshift(b1, 16), lshift(b2, 8), b3)
+  local operands = {}
+  local last = nil
+  local rs = 21
+  ctx.op = op
+  ctx.rel = nil
+
+  local opat = map_pri[rshift(b0, 2)]
+  while type(opat) ~= "string" do
+    if not opat then return unknown(ctx) end
+    opat = opat[band(rshift(op, opat.shift), opat.mask)]
+  end
+  local name, pat = match(opat, "^([a-z0-9_.]*)(.*)")
+  local altname, pat2 = match(pat, "|([a-z0-9_.]*)(.*)")
+  if altname then pat = pat2 end
+
+  for p in gmatch(pat, ".") do
+    local x = nil
+    if p == "R" then
+      x = map_gpr[band(rshift(op, rs), 31)]
+      rs = rs - 5
+    elseif p == "F" then
+      x = "f"..band(rshift(op, rs), 31)
+      rs = rs - 5
+    elseif p == "A" then
+      x = band(rshift(op, rs), 31)
+      rs = rs - 5
+    elseif p == "S" then
+      x = arshift(lshift(op, 27-rs), 27)
+      rs = rs - 5
+    elseif p == "I" then
+      x = arshift(lshift(op, 16), 16)
+    elseif p == "U" then
+      x = band(op, 0xffff)
+    elseif p == "D" or p == "E" then
+      local disp = arshift(lshift(op, 16), 16)
+      if p == "E" then disp = band(disp, -4) end
+      if last == "r0" then last = "0" end
+      operands[#operands] = format("%d(%s)", disp, last)
+    elseif p >= "2" and p <= "8" then
+      local disp = band(rshift(op, rs), 31) * p
+      if last == "r0" then last = "0" end
+      operands[#operands] = format("%d(%s)", disp, last)
+    elseif p == "H" then
+      x = band(rshift(op, rs), 31) + lshift(band(op, 2), 4)
+      rs = rs - 5
+    elseif p == "M" then
+      x = band(rshift(op, rs), 31) + band(op, 0x20)
+    elseif p == "C" then
+      x = condfmt(band(rshift(op, rs), 31))
+      rs = rs - 5
+    elseif p == "B" then
+      local bo = rshift(op, 21)
+      local cond = band(rshift(op, 16), 31)
+      local cn = ""
+      rs = rs - 10
+      if band(bo, 4) == 0 then
+        cn = band(bo, 2) == 0 and "dnz" or "dz"
+        if band(bo, 0x10) == 0 then
+          cn = cn..(band(bo, 8) == 0 and "f" or "t")
+          if band(bo, 1) ~= 0 then
+            name = name..(band(op, 0x8000) ~= 0 and "-" or "+")
+          end
+        elseif band(bo, 8) ~= 0 then
+          name = name..(band(bo, 1) == 0 and "-" or "+")
+        elseif band(bo, 1) ~= 0 then
+          name = name..(band(op, 0x8000) ~= 0 and "-" or "+")
+        end
+        if band(bo, 0x10) == 0 then x = condfmt(cond) end
+      elseif band(bo, 0x10) == 0 then
+        cn = map_cond[band(cond, 3) + (band(bo, 8) == 0 and 4 or 0)]
+        if band(bo, 2) ~= 0 then
+          name = name..(band(bo, 1) == 0 and "-" or "+")
+        elseif band(bo, 1) ~= 0 then
+          name = name..(band(op, 0x8000) ~= 0 and "-" or "+")
+        end
+        if cond > 3 then x = "cr"..rshift(cond, 2) end
+      end
+      name = gsub(name, "_", cn)
+    elseif p == "J" then
+      x = arshift(lshift(op, 27-rs), 29-rs)*4
+      if band(op, 2) == 0 then x = ctx.addr + pos + x end
+      ctx.rel = x
+      x = "0x"..tohex(x)
+    elseif p == "K" then
+      if band(op, 1) ~= 0 then name = name.."l" end
+      if band(op, 2) ~= 0 then name = name.."a" end
+    elseif p == "X" or p == "Y" then
+      x = band(rshift(op, rs+2), 7)
+      if x == 0 and p == "Y" then x = nil else x = "cr"..x end
+      rs = rs - 5
+    elseif p == "W" then
+      x = "cr"..band(op, 7)
+    elseif p == "Z" then
+      x = band(rshift(op, rs-4), 255)
+      rs = rs - 10
+    elseif p == ">" then
+      operands[#operands] = rshift(operands[#operands], 1)
+    elseif p == "0" then
+      if last == "r0" then
+        operands[#operands] = nil
+        if altname then name = altname end
+      end
+    elseif p == "L" then
+      name = gsub(name, "_", band(op, 0x00200000) ~= 0 and "d" or "w")
+    elseif p == "." then
+      if band(op, 1) == 1 then name = name.."." end
+    elseif p == "N" then
+      if op == 0x60000000 then name = "nop"; break end
+    elseif p == "~" then
+      local n = #operands
+      operands[n-1],  operands[n] = operands[n], operands[n-1]
+    elseif p == "=" then
+      local n = #operands
+      if last == operands[n-1] then
+        operands[n] = nil
+        name = altname
+      end
+    elseif p == "%" then
+      local n = #operands
+      if last == operands[n-1] and last == operands[n-2] then
+        operands[n] = nil
+        operands[n-1] = nil
+        name = altname
+      end
+    elseif p == "-" then
+      rs = rs - 5
+    else
+      assert(false)
+    end
+    if x then operands[#operands+1] = x; last = x end
+  end
+
+  return putop(ctx, name, operands)
+end
+
+------------------------------------------------------------------------------
+
+-- Disassemble a block of code.
+local function disass_block(ctx, ofs, len)
+  if not ofs then ofs = 0 end
+  local stop = len and ofs+len or #ctx.code
+  stop = stop - stop % 4
+  ctx.pos = ofs - ofs % 4
+  ctx.rel = nil
+  while ctx.pos < stop do disass_ins(ctx) end
+end
+
+-- Extended API: create a disassembler context. Then call ctx:disass(ofs, len).
+local function create_(code, addr, out)
+  local ctx = {}
+  ctx.code = code
+  ctx.addr = addr or 0
+  ctx.out = out or io.write
+  ctx.symtab = {}
+  ctx.disass = disass_block
+  ctx.hexdump = 8
+  return ctx
+end
+
+-- Simple API: disassemble code (a string) at address and output via out.
+local function disass_(code, addr, out)
+  create_(code, addr, out):disass()
+end
+
+
+-- Public module functions.
+module(...)
+
+create = create_
+disass = disass_
+