/*      $OpenBSD: db_disasm.c,v 1.25 2024/07/09 01:21:19 jsg Exp $      */
/*      $NetBSD: db_disasm.c,v 1.11 1996/05/03 19:41:58 christos Exp $  */

/*
 * Mach Operating System
 * Copyright (c) 1991,1990 Carnegie Mellon University
 * All Rights Reserved.
 *
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie Mellon
 * the rights to redistribute these changes.
 *
 *      Id: db_disasm.c,v 2.6  92/01/03  20:05:00  dbg (CMU)
 */

/*
 * Instruction disassembler.
 */
#include <sys/param.h>
#include <sys/systm.h>
#include <machine/db_machdep.h>

#include <ddb/db_access.h>
#include <ddb/db_sym.h>
#include <ddb/db_output.h>
#include <ddb/db_interface.h>

/*
 * Size attributes
 */
#define BYTE    0
#define WORD    1
#define LONG    2
#define QUAD    3
#define SNGL    4
#define DBLR    5
#define EXTR    6
#define SDEP    7
#define NONE    8
#define RDEP    9

/*
 * Addressing modes
 */
#define E       1                       /* general effective address */
#define Eind    2                       /* indirect address (jump, call) */
#define Ew      3                       /* address, word size */
#define Eb      4                       /* address, byte size */
#define R       5                       /* register, in 'reg' field */
#define Rw      6                       /* word register, in 'reg' field */
#define Ri      7                       /* register in instruction */
#define S       8                       /* segment reg, in 'reg' field */
#define Si      9                       /* segment reg, in instruction */
#define A       10                      /* accumulator */
#define BX      11                      /* (bx) */
#define CL      12                      /* cl, for shifts */
#define DX      13                      /* dx, for IO */
#define SI      14                      /* si */
#define DI      15                      /* di */
#define CR      16                      /* control register */
#define DR      17                      /* debug register */
#define TR      18                      /* test register */
#define I       19                      /* immediate, unsigned */
#define Is      20                      /* immediate, signed */
#define Ib      21                      /* byte immediate, unsigned */
#define Ibs     22                      /* byte immediate, signed */
#define Iw      23                      /* word immediate, unsigned */
#define O       25                      /* direct address */
#define Db      26                      /* byte displacement from EIP */
#define Dl      27                      /* long displacement from EIP */
#define o1      28                      /* constant 1 */
#define o3      29                      /* constant 3 */
#define OS      30                      /* immediate offset/segment */
#define ST      31                      /* FP stack top */
#define STI     32                      /* FP stack */
#define X       33                      /* extended FP op */
#define XA      34                      /* for 'fstcw %ax' */
#define El      35                      /* address, long size */
#define Ril     36                      /* long register in instruction */
#define Iba     37                      /* byte immediate, don't print if 0xa */
#define MEx     38                      /* memory, or an extension op */

struct inst {
        char *  i_name;                 /* name */
        short   i_has_modrm;            /* has regmodrm byte */
        short   i_size;                 /* operand size */
        int     i_mode;                 /* addressing modes */
        void *  i_extra;                /* pointer to extra opcode table */
};

#define op1(x)          (x)
#define op2(x,y)        ((x)|((y)<<8))
#define op3(x,y,z)      ((x)|((y)<<8)|((z)<<16))

struct finst {
        char *  f_name;                 /* name for memory instruction */
        int     f_size;                 /* size for memory instruction */
        int     f_rrmode;               /* mode for rr instruction */
        void *  f_rrname;               /* name for rr instruction
                                           (or pointer to table) */
};

char *  db_Grp6[] = {
        "sldt",         "str",          "lldt",         "ltr",
        "verr",         "verw",         "",             ""
};

struct inst db_Grp7[] = {
        { "sgdt",   0, NONE, op2(MEx,5), "\0vmcall\0vmlaunch\0vmresume\0vmxoff"},
        { "sidt",   0, NONE, op2(MEx,4), "monitor\0mwait\0clac\0stac"},
        { "lgdt",   0, NONE, op2(MEx,7), "xgetbv\0xsetbv\0\0\0vmfunc\0xend\0xtest" },
        { "lidt",   0, NONE, op1(E),     0 },
        { "smsw",   0, NONE, op1(E),     0 },
        { "",       0, NONE, 0,          0 },
        { "lmsw",   0, NONE, op1(E),     0 },
        { "invlpg", 0, NONE, op2(MEx,2), "swapgs\0rdtscp" },
};

char *  db_Grp8[] = {
        "",             "",             "",             "",
        "bt",           "bts",          "btr",          "btc"
};

struct inst db_Grp9[] = {
        { "fxsave",   0, NONE, op1(E),     0 },
        { "fxrstor",  0, NONE, op1(E),     0 },
        { "ldmxcsr",  0, NONE, op1(E),     0 },
        { "stmxcsr",  0, NONE, op1(E),     0 },
        { "xsave",    0, NONE, op1(E),     0 },
        { "xrstor",   0, NONE, op2(MEx,1), "lfence" },
        { "xsaveopt", 0, NONE, op2(MEx,1), "mfence" },
        { "clflush",  0, NONE, op2(MEx,1), "sfence" },
};

char *  db_GrpA[] = {
        "",             "cmpxchg8b",    "",             "",
        "",             "",             "rdrand",       "rdseed"
};

char *  db_GrpB[] = {
        "xstore-rng",   "xcrypt-ecb",   "xcrypt-cbc",   "xcrypt-ctr",
        "xcrypt-cfb",   "xcrypt-ofb",   "",             ""
};

char *  db_GrpC[] = {
        "montmul",      "xsha1",        "xsha256",      "",
        "",             "",             "",             ""
};

struct inst db_inst_0f0x[] = {
/*00*/  { NULL,    1,  NONE,  op1(Ew),     db_Grp6 },
/*01*/  { "",      1,  RDEP,  0,           db_Grp7 },
/*02*/  { "lar",   1,  LONG,  op2(E,R),    0 },
/*03*/  { "lsl",   1,  LONG,  op2(E,R),    0 },
/*04*/  { "",      0, NONE,  0,       0 },
/*05*/  { "",      0, NONE,  0,       0 },
/*06*/  { "clts",  0, NONE,  0,       0 },
/*07*/  { "",      0, NONE,  0,       0 },

/*08*/  { "invd",  0, NONE,  0,       0 },
/*09*/  { "wbinvd",0, NONE,  0,       0 },
/*0a*/  { "",      0, NONE,  0,       0 },
/*0b*/  { "",      0, NONE,  0,       0 },
/*0c*/  { "",      0, NONE,  0,       0 },
/*0d*/  { "",      0, NONE,  0,       0 },
/*0e*/  { "",      0, NONE,  0,       0 },
/*0f*/  { "",      0, NONE,  0,       0 },
};

struct inst     db_inst_0f2x[] = {
/*20*/  { "mov",   1,  LONG,  op2(CR,E),   0 }, /* use E for reg */
/*21*/  { "mov",   1,  LONG,  op2(DR,E),   0 }, /* since mod == 11 */
/*22*/  { "mov",   1,  LONG,  op2(E,CR),   0 },
/*23*/  { "mov",   1,  LONG,  op2(E,DR),   0 },
/*24*/  { "mov",   1,  LONG,  op2(TR,E),   0 },
/*25*/  { "",      0, NONE,  0,       0 },
/*26*/  { "mov",   1,  LONG,  op2(E,TR),   0 },
/*27*/  { "",      0, NONE,  0,       0 },

/*28*/  { "",      0, NONE,  0,       0 },
/*29*/  { "",      0, NONE,  0,       0 },
/*2a*/  { "",      0, NONE,  0,       0 },
/*2b*/  { "",      0, NONE,  0,       0 },
/*2c*/  { "",      0, NONE,  0,       0 },
/*2d*/  { "",      0, NONE,  0,       0 },
/*2e*/  { "",      0, NONE,  0,       0 },
/*2f*/  { "",      0, NONE,  0,       0 },
};

struct inst     db_inst_0f3x[] = {
/*30*/  { "wrmsr", 0, NONE,  0,           0 },
/*31*/  { "rdtsc", 0, NONE,  0,           0 },
/*32*/  { "rdmsr", 0, NONE,  0,           0 },
/*33*/  { "rdpmc", 0, NONE,  0,           0 },
/*34*/  { "",      0, NONE,  0,           0 },
/*35*/  { "",      0, NONE,  0,           0 },
/*36*/  { "",      0, NONE,  0,           0 },
/*37*/  { "",      0, NONE,  0,           0 },

/*38*/  { "",      0, NONE,  0,           0 },
/*39*/  { "",      0, NONE,  0,           0 },
/*3a*/  { "",      0, NONE,  0,           0 },
/*3b*/  { "",      0, NONE,  0,           0 },
/*3c*/  { "",      0, NONE,  0,           0 },
/*3d*/  { "",      0, NONE,  0,           0 },
/*3e*/  { "",      0, NONE,  0,           0 },
/*3f*/  { "",      0, NONE,  0,           0 },
};

struct inst     db_inst_0f8x[] = {
/*80*/  { "jo",    0, NONE,  op1(Dl),     0 },
/*81*/  { "jno",   0, NONE,  op1(Dl),     0 },
/*82*/  { "jb",    0, NONE,  op1(Dl),     0 },
/*83*/  { "jnb",   0, NONE,  op1(Dl),     0 },
/*84*/  { "jz",    0, NONE,  op1(Dl),     0 },
/*85*/  { "jnz",   0, NONE,  op1(Dl),     0 },
/*86*/  { "jbe",   0, NONE,  op1(Dl),     0 },
/*87*/  { "jnbe",  0, NONE,  op1(Dl),     0 },

/*88*/  { "js",    0, NONE,  op1(Dl),     0 },
/*89*/  { "jns",   0, NONE,  op1(Dl),     0 },
/*8a*/  { "jp",    0, NONE,  op1(Dl),     0 },
/*8b*/  { "jnp",   0, NONE,  op1(Dl),     0 },
/*8c*/  { "jl",    0, NONE,  op1(Dl),     0 },
/*8d*/  { "jnl",   0, NONE,  op1(Dl),     0 },
/*8e*/  { "jle",   0, NONE,  op1(Dl),     0 },
/*8f*/  { "jnle",  0, NONE,  op1(Dl),     0 },
};

struct inst     db_inst_0f9x[] = {
/*90*/  { "seto",  1,  NONE,  op1(Eb),     0 },
/*91*/  { "setno", 1,  NONE,  op1(Eb),     0 },
/*92*/  { "setb",  1,  NONE,  op1(Eb),     0 },
/*93*/  { "setnb", 1,  NONE,  op1(Eb),     0 },
/*94*/  { "setz",  1,  NONE,  op1(Eb),     0 },
/*95*/  { "setnz", 1,  NONE,  op1(Eb),     0 },
/*96*/  { "setbe", 1,  NONE,  op1(Eb),     0 },
/*97*/  { "setnbe",1,  NONE,  op1(Eb),     0 },

/*98*/  { "sets",  1,  NONE,  op1(Eb),     0 },
/*99*/  { "setns", 1,  NONE,  op1(Eb),     0 },
/*9a*/  { "setp",  1,  NONE,  op1(Eb),     0 },
/*9b*/  { "setnp", 1,  NONE,  op1(Eb),     0 },
/*9c*/  { "setl",  1,  NONE,  op1(Eb),     0 },
/*9d*/  { "setnl", 1,  NONE,  op1(Eb),     0 },
/*9e*/  { "setle", 1,  NONE,  op1(Eb),     0 },
/*9f*/  { "setnle",1,  NONE,  op1(Eb),     0 },
};

struct inst     db_inst_0fax[] = {
/*a0*/  { "push",  0, NONE,  op1(Si),     0 },
/*a1*/  { "pop",   0, NONE,  op1(Si),     0 },
/*a2*/  { "cpuid", 0, NONE,  0,       0 },
/*a3*/  { "bt",    1,  LONG,  op2(R,E),    0 },
/*a4*/  { "shld",  1,  LONG,  op3(Ib,R,E), 0 },
/*a5*/  { "shld",  1,  LONG,  op3(CL,R,E), 0 },
/*a6*/  { NULL,    1,  NONE,  0,              db_GrpC },
/*a7*/  { NULL,    1,  NONE,  0,              db_GrpB },

/*a8*/  { "push",  0, NONE,  op1(Si),     0 },
/*a9*/  { "pop",   0, NONE,  op1(Si),     0 },
/*aa*/  { "",      0, NONE,  0,       0 },
/*ab*/  { "bts",   1,  LONG,  op2(R,E),    0 },
/*ac*/  { "shrd",  1,  LONG,  op3(Ib,E,R), 0 },
/*ad*/  { "shrd",  1,  LONG,  op3(CL,E,R), 0 },
/*ae*/  { "",      1,  RDEP,  op1(E),      db_Grp9 },
/*af*/  { "imul",  1,  LONG,  op2(E,R),    0 },
};

struct inst     db_inst_0fbx[] = {
/*b0*/  { "cmpxchg",1, BYTE,     op2(R, E),   0 },
/*b1*/  { "cmpxchg",1, LONG,     op2(R, E),   0 },
/*b2*/  { "lss",   1,  LONG,  op2(E, R),   0 },
/*b3*/  { "btr",   1,  LONG,  op2(R, E),   0 },
/*b4*/  { "lfs",   1,  LONG,  op2(E, R),   0 },
/*b5*/  { "lgs",   1,  LONG,  op2(E, R),   0 },
/*b6*/  { "movzb", 1,  LONG,  op2(Eb, R),  0 },
/*b7*/  { "movzw", 1,  LONG,  op2(Ew, R),  0 },

/*b8*/  { "",      0, NONE,  0,       0 },
/*b9*/  { "",      0, NONE,  0,       0 },
/*ba*/  { NULL,    1,  LONG,  op2(Ib, E),  db_Grp8 },
/*bb*/  { "btc",   1,  LONG,  op2(R, E),   0 },
/*bc*/  { "bsf",   1,  LONG,  op2(E, R),   0 },
/*bd*/  { "bsr",   1,  LONG,  op2(E, R),   0 },
/*be*/  { "movsb", 1,  LONG,  op2(Eb, R),  0 },
/*bf*/  { "movsw", 1,  LONG,  op2(Ew, R),  0 },
};

struct inst     db_inst_0fcx[] = {
/*c0*/  { "xadd",  1,  BYTE,     op2(R, E),   0 },
/*c1*/  { "xadd",  1,  LONG,     op2(R, E),   0 },
/*c2*/  { "",      0, NONE,      0,           0 },
/*c3*/  { "",      0, NONE,      0,           0 },
/*c4*/  { "",      0, NONE,      0,           0 },
/*c5*/  { "",      0, NONE,      0,           0 },
/*c6*/  { "",      0, NONE,      0,           0 },
/*c7*/  { NULL,    1,  NONE,  op1(E),      db_GrpA },

/*c8*/  { "bswap", 0, LONG,  op1(Ril),    0 },
/*c9*/  { "bswap", 0, LONG,  op1(Ril),    0 },
/*ca*/  { "bswap", 0, LONG,  op1(Ril),    0 },
/*cb*/  { "bswap", 0, LONG,  op1(Ril),    0 },
/*cc*/  { "bswap", 0, LONG,  op1(Ril),    0 },
/*cd*/  { "bswap", 0, LONG,  op1(Ril),    0 },
/*ce*/  { "bswap", 0, LONG,  op1(Ril),    0 },
/*cf*/  { "bswap", 0, LONG,  op1(Ril),    0 },
};

struct inst *db_inst_0f[] = {
        db_inst_0f0x,
        NULL,
        db_inst_0f2x,
        db_inst_0f3x,
        NULL,
        NULL,
        NULL,
        NULL,
        db_inst_0f8x,
        db_inst_0f9x,
        db_inst_0fax,
        db_inst_0fbx,
        db_inst_0fcx,
        NULL,
        NULL,
        NULL
};

char *  db_Esc92[] = {
        "fnop",         "",             "",             "",
        "",             "",             "",             ""
};
char *  db_Esc94[] = {
        "fchs",         "fabs",         "",             "",
        "ftst",         "fxam",         "",             ""
};
char *  db_Esc95[] = {
        "fld1",         "fldl2t",       "fldl2e",       "fldpi",
        "fldlg2",       "fldln2",       "fldz",         ""
};
char *  db_Esc96[] = {
        "f2xm1",        "fyl2x",        "fptan",        "fpatan",
        "fxtract",      "fprem1",       "fdecstp",      "fincstp"
};
char *  db_Esc97[] = {
        "fprem",        "fyl2xp1",      "fsqrt",        "fsincos",
        "frndint",      "fscale",       "fsin",         "fcos"
};

char *  db_Esca5[] = {
        "",             "fucompp",      "",             "",
        "",             "",             "",             ""
};

char *  db_Escb4[] = {
        "fneni",        "fndisi",       "fnclex",       "fninit",
        "fsetpm",       "",             "",             ""
};

char *  db_Esce3[] = {
        "",             "fcompp",       "",             "",
        "",             "",             "",             ""
};

char *  db_Escf4[] = {
        "fnstsw",       "",             "",             "",
        "",             "",             "",             ""
};

struct finst db_Esc8[] = {
/*0*/   { "fadd",   SNGL,  op2(STI,ST), 0 },
/*1*/   { "fmul",   SNGL,  op2(STI,ST), 0 },
/*2*/   { "fcom",   SNGL,  op2(STI,ST), 0 },
/*3*/   { "fcomp",  SNGL,  op2(STI,ST), 0 },
/*4*/   { "fsub",   SNGL,  op2(STI,ST), 0 },
/*5*/   { "fsubr",  SNGL,  op2(STI,ST), 0 },
/*6*/   { "fdiv",   SNGL,  op2(STI,ST), 0 },
/*7*/   { "fdivr",  SNGL,  op2(STI,ST), 0 },
};

struct finst db_Esc9[] = {
/*0*/   { "fld",    SNGL,  op1(STI),    0 },
/*1*/   { "",       NONE,  op1(STI),    "fxch" },
/*2*/   { "fst",    SNGL,  op1(X),      db_Esc92 },
/*3*/   { "fstp",   SNGL,  op1(X),      0 },
/*4*/   { "fldenv", NONE,  op1(X),      db_Esc94 },
/*5*/   { "fldcw",  NONE,  op1(X),      db_Esc95 },
/*6*/   { "fnstenv",NONE,  op1(X),      db_Esc96 },
/*7*/   { "fnstcw", NONE,  op1(X),      db_Esc97 },
};

struct finst db_Esca[] = {
/*0*/   { "fiadd",  LONG,  0,           0 },
/*1*/   { "fimul",  LONG,  0,           0 },
/*2*/   { "ficom",  LONG,  0,           0 },
/*3*/   { "ficomp", LONG,  0,           0 },
/*4*/   { "fisub",  LONG,  0,           0 },
/*5*/   { "fisubr", LONG,  op1(X),      db_Esca5 },
/*6*/   { "fidiv",  LONG,  0,           0 },
/*7*/   { "fidivr", LONG,  0,           0 }
};

struct finst db_Escb[] = {
/*0*/   { "fild",   LONG,  0,           0 },
/*1*/   { "",       NONE,  0,           0 },
/*2*/   { "fist",   LONG,  0,           0 },
/*3*/   { "fistp",  LONG,  0,           0 },
/*4*/   { "",       WORD,  op1(X),      db_Escb4 },
/*5*/   { "fld",    EXTR,  0,           0 },
/*6*/   { "",       WORD,  0,           0 },
/*7*/   { "fstp",   EXTR,  0,           0 },
};

struct finst db_Escc[] = {
/*0*/   { "fadd",   DBLR,  op2(ST,STI), 0 },
/*1*/   { "fmul",   DBLR,  op2(ST,STI), 0 },
/*2*/   { "fcom",   DBLR,  0,           0 },
/*3*/   { "fcomp",  DBLR,  0,           0 },
/*4*/   { "fsub",   DBLR,  op2(ST,STI), "fsubr" },
/*5*/   { "fsubr",  DBLR,  op2(ST,STI), "fsub" },
/*6*/   { "fdiv",   DBLR,  op2(ST,STI), "fdivr" },
/*7*/   { "fdivr",  DBLR,  op2(ST,STI), "fdiv" },
};

struct finst db_Escd[] = {
/*0*/   { "fld",    DBLR,  op1(STI),    "ffree" },
/*1*/   { "",       NONE,  0,           0 },
/*2*/   { "fst",    DBLR,  op1(STI),    0 },
/*3*/   { "fstp",   DBLR,  op1(STI),    0 },
/*4*/   { "frstor", NONE,  op1(STI),    "fucom" },
/*5*/   { "",       NONE,  op1(STI),    "fucomp" },
/*6*/   { "fnsave", NONE,  0,           0 },
/*7*/   { "fnstsw", NONE,  0,           0 },
};

struct finst db_Esce[] = {
/*0*/   { "fiadd",  WORD,  op2(ST,STI), "faddp" },
/*1*/   { "fimul",  WORD,  op2(ST,STI), "fmulp" },
/*2*/   { "ficom",  WORD,  0,           0 },
/*3*/   { "ficomp", WORD,  op1(X),      db_Esce3 },
/*4*/   { "fisub",  WORD,  op2(ST,STI), "fsubrp" },
/*5*/   { "fisubr", WORD,  op2(ST,STI), "fsubp" },
/*6*/   { "fidiv",  WORD,  op2(ST,STI), "fdivrp" },
/*7*/   { "fidivr", WORD,  op2(ST,STI), "fdivp" },
};

struct finst db_Escf[] = {
/*0*/   { "fild",   WORD,  0,           0 },
/*1*/   { "",       WORD,  0,           0 },
/*2*/   { "fist",   WORD,  0,           0 },
/*3*/   { "fistp",  WORD,  0,           0 },
/*4*/   { "fbld",   NONE,  op1(XA),     db_Escf4 },
/*5*/   { "fild",   QUAD,  0,           0 },
/*6*/   { "fbstp",  NONE,  0,           0 },
/*7*/   { "fistp",  QUAD,  0,           0 },
};

struct finst *db_Esc_inst[] = {
        db_Esc8, db_Esc9, db_Esca, db_Escb,
        db_Escc, db_Escd, db_Esce, db_Escf
};

char *  db_Grp1[] = {
        "add",
        "or",
        "adc",
        "sbb",
        "and",
        "sub",
        "xor",
        "cmp"
};

char *  db_Grp2[] = {
        "rol",
        "ror",
        "rcl",
        "rcr",
        "shl",
        "shr",
        "shl",
        "sar"
};

struct inst db_Grp3[] = {
        { "test",  1, NONE, op2(I,E), 0 },
        { "test",  1, NONE, op2(I,E), 0 },
        { "not",   1, NONE, op1(E),   0 },
        { "neg",   1, NONE, op1(E),   0 },
        { "mul",   1, NONE, op2(E,A), 0 },
        { "imul",  1, NONE, op2(E,A), 0 },
        { "div",   1, NONE, op2(E,A), 0 },
        { "idiv",  1, NONE, op2(E,A), 0 },
};

struct inst     db_Grp4[] = {
        { "inc",   1, BYTE, op1(E),   0 },
        { "dec",   1, BYTE, op1(E),   0 },
        { "",      1, NONE, 0,   0 },
        { "",      1, NONE, 0,   0 },
        { "",      1, NONE, 0,   0 },
        { "",      1, NONE, 0,   0 },
        { "",      1, NONE, 0,   0 },
        { "",      1, NONE, 0,   0 }
};

struct inst     db_Grp5[] = {
        { "inc",   1, LONG, op1(E),   0 },
        { "dec",   1, LONG, op1(E),   0 },
        { "call",  1, NONE, op1(Eind),0 },
        { "lcall", 1, NONE, op1(Eind),0 },
        { "jmp",   1, NONE, op1(Eind),0 },
        { "ljmp",  1, NONE, op1(Eind),0 },
        { "push",  1, LONG, op1(E),   0 },
        { "",      1, NONE, 0,   0 }
};

struct inst db_inst_table[256] = {
/*00*/  { "add",   1,  BYTE,  op2(R, E),  0 },
/*01*/  { "add",   1,  LONG,  op2(R, E),  0 },
/*02*/  { "add",   1,  BYTE,  op2(E, R),  0 },
/*03*/  { "add",   1,  LONG,  op2(E, R),  0 },
/*04*/  { "add",   0, BYTE,  op2(I, A),  0 },
/*05*/  { "add",   0, LONG,  op2(Is, A), 0 },
/*06*/  { "push",  0, NONE,  op1(Si),    0 },
/*07*/  { "pop",   0, NONE,  op1(Si),    0 },

/*08*/  { "or",    1,  BYTE,  op2(R, E),  0 },
/*09*/  { "or",    1,  LONG,  op2(R, E),  0 },
/*0a*/  { "or",    1,  BYTE,  op2(E, R),  0 },
/*0b*/  { "or",    1,  LONG,  op2(E, R),  0 },
/*0c*/  { "or",    0, BYTE,  op2(I, A),  0 },
/*0d*/  { "or",    0, LONG,  op2(I, A),  0 },
/*0e*/  { "push",  0, NONE,  op1(Si),    0 },
/*0f*/  { "",      0, NONE,  0,      0 },

/*10*/  { "adc",   1,  BYTE,  op2(R, E),  0 },
/*11*/  { "adc",   1,  LONG,  op2(R, E),  0 },
/*12*/  { "adc",   1,  BYTE,  op2(E, R),  0 },
/*13*/  { "adc",   1,  LONG,  op2(E, R),  0 },
/*14*/  { "adc",   0, BYTE,  op2(I, A),  0 },
/*15*/  { "adc",   0, LONG,  op2(Is, A), 0 },
/*16*/  { "push",  0, NONE,  op1(Si),    0 },
/*17*/  { "pop",   0, NONE,  op1(Si),    0 },

/*18*/  { "sbb",   1,  BYTE,  op2(R, E),  0 },
/*19*/  { "sbb",   1,  LONG,  op2(R, E),  0 },
/*1a*/  { "sbb",   1,  BYTE,  op2(E, R),  0 },
/*1b*/  { "sbb",   1,  LONG,  op2(E, R),  0 },
/*1c*/  { "sbb",   0, BYTE,  op2(I, A),  0 },
/*1d*/  { "sbb",   0, LONG,  op2(Is, A), 0 },
/*1e*/  { "push",  0, NONE,  op1(Si),    0 },
/*1f*/  { "pop",   0, NONE,  op1(Si),    0 },

/*20*/  { "and",   1,  BYTE,  op2(R, E),  0 },
/*21*/  { "and",   1,  LONG,  op2(R, E),  0 },
/*22*/  { "and",   1,  BYTE,  op2(E, R),  0 },
/*23*/  { "and",   1,  LONG,  op2(E, R),  0 },
/*24*/  { "and",   0, BYTE,  op2(I, A),  0 },
/*25*/  { "and",   0, LONG,  op2(I, A),  0 },
/*26*/  { "",      0, NONE,  0,      0 },
/*27*/  { "daa",   0, NONE,  0,      0 },

/*28*/  { "sub",   1,  BYTE,  op2(R, E),  0 },
/*29*/  { "sub",   1,  LONG,  op2(R, E),  0 },
/*2a*/  { "sub",   1,  BYTE,  op2(E, R),  0 },
/*2b*/  { "sub",   1,  LONG,  op2(E, R),  0 },
/*2c*/  { "sub",   0, BYTE,  op2(I, A),  0 },
/*2d*/  { "sub",   0, LONG,  op2(Is, A), 0 },
/*2e*/  { "",      0, NONE,  0,      0 },
/*2f*/  { "das",   0, NONE,  0,      0 },

/*30*/  { "xor",   1,  BYTE,  op2(R, E),  0 },
/*31*/  { "xor",   1,  LONG,  op2(R, E),  0 },
/*32*/  { "xor",   1,  BYTE,  op2(E, R),  0 },
/*33*/  { "xor",   1,  LONG,  op2(E, R),  0 },
/*34*/  { "xor",   0, BYTE,  op2(I, A),  0 },
/*35*/  { "xor",   0, LONG,  op2(I, A),  0 },
/*36*/  { "",      0, NONE,  0,      0 },
/*37*/  { "aaa",   0, NONE,  0,      0 },

/*38*/  { "cmp",   1,  BYTE,  op2(R, E),  0 },
/*39*/  { "cmp",   1,  LONG,  op2(R, E),  0 },
/*3a*/  { "cmp",   1,  BYTE,  op2(E, R),  0 },
/*3b*/  { "cmp",   1,  LONG,  op2(E, R),  0 },
/*3c*/  { "cmp",   0, BYTE,  op2(I, A),  0 },
/*3d*/  { "cmp",   0, LONG,  op2(Is, A), 0 },
/*3e*/  { "",      0, NONE,  0,      0 },
/*3f*/  { "aas",   0, NONE,  0,      0 },

/*40*/  { "inc",   0, LONG,  op1(Ri),    0 },
/*41*/  { "inc",   0, LONG,  op1(Ri),    0 },
/*42*/  { "inc",   0, LONG,  op1(Ri),    0 },
/*43*/  { "inc",   0, LONG,  op1(Ri),    0 },
/*44*/  { "inc",   0, LONG,  op1(Ri),    0 },
/*45*/  { "inc",   0, LONG,  op1(Ri),    0 },
/*46*/  { "inc",   0, LONG,  op1(Ri),    0 },
/*47*/  { "inc",   0, LONG,  op1(Ri),    0 },

/*48*/  { "dec",   0, LONG,  op1(Ri),    0 },
/*49*/  { "dec",   0, LONG,  op1(Ri),    0 },
/*4a*/  { "dec",   0, LONG,  op1(Ri),    0 },
/*4b*/  { "dec",   0, LONG,  op1(Ri),    0 },
/*4c*/  { "dec",   0, LONG,  op1(Ri),    0 },
/*4d*/  { "dec",   0, LONG,  op1(Ri),    0 },
/*4e*/  { "dec",   0, LONG,  op1(Ri),    0 },
/*4f*/  { "dec",   0, LONG,  op1(Ri),    0 },

/*50*/  { "push",  0, LONG,  op1(Ri),    0 },
/*51*/  { "push",  0, LONG,  op1(Ri),    0 },
/*52*/  { "push",  0, LONG,  op1(Ri),    0 },
/*53*/  { "push",  0, LONG,  op1(Ri),    0 },
/*54*/  { "push",  0, LONG,  op1(Ri),    0 },
/*55*/  { "push",  0, LONG,  op1(Ri),    0 },
/*56*/  { "push",  0, LONG,  op1(Ri),    0 },
/*57*/  { "push",  0, LONG,  op1(Ri),    0 },

/*58*/  { "pop",   0, LONG,  op1(Ri),    0 },
/*59*/  { "pop",   0, LONG,  op1(Ri),    0 },
/*5a*/  { "pop",   0, LONG,  op1(Ri),    0 },
/*5b*/  { "pop",   0, LONG,  op1(Ri),    0 },
/*5c*/  { "pop",   0, LONG,  op1(Ri),    0 },
/*5d*/  { "pop",   0, LONG,  op1(Ri),    0 },
/*5e*/  { "pop",   0, LONG,  op1(Ri),    0 },
/*5f*/  { "pop",   0, LONG,  op1(Ri),    0 },

/*60*/  { "pusha", 0, LONG,  0,      0 },
/*61*/  { "popa",  0, LONG,  0,      0 },
/*62*/  { "bound", 1,  LONG,  op2(E, R),  0 },
/*63*/  { "arpl",  1,  NONE,  op2(Rw,Ew), 0 },
/*64*/  { "",      0, NONE,  0,      0 },
/*65*/  { "",      0, NONE,  0,      0 },
/*66*/  { "",      0, NONE,  0,      0 },
/*67*/  { "",      0, NONE,  0,      0 },

/*68*/  { "push",  0, LONG,  op1(I),     0 },
/*69*/  { "imul",  1,  LONG,  op3(I,E,R), 0 },
/*6a*/  { "push",  0, LONG,  op1(Ibs),   0 },
/*6b*/  { "imul",  1,  LONG,  op3(Ibs,E,R),0 },
/*6c*/  { "ins",   0, BYTE,  op2(DX, DI), 0 },
/*6d*/  { "ins",   0, LONG,  op2(DX, DI), 0 },
/*6e*/  { "outs",  0, BYTE,  op2(SI, DX), 0 },
/*6f*/  { "outs",  0, LONG,  op2(SI, DX), 0 },

/*70*/  { "jo",    0, NONE,  op1(Db),     0 },
/*71*/  { "jno",   0, NONE,  op1(Db),     0 },
/*72*/  { "jb",    0, NONE,  op1(Db),     0 },
/*73*/  { "jnb",   0, NONE,  op1(Db),     0 },
/*74*/  { "jz",    0, NONE,  op1(Db),     0 },
/*75*/  { "jnz",   0, NONE,  op1(Db),     0 },
/*76*/  { "jbe",   0, NONE,  op1(Db),     0 },
/*77*/  { "jnbe",  0, NONE,  op1(Db),     0 },

/*78*/  { "js",    0, NONE,  op1(Db),     0 },
/*79*/  { "jns",   0, NONE,  op1(Db),     0 },
/*7a*/  { "jp",    0, NONE,  op1(Db),     0 },
/*7b*/  { "jnp",   0, NONE,  op1(Db),     0 },
/*7c*/  { "jl",    0, NONE,  op1(Db),     0 },
/*7d*/  { "jnl",   0, NONE,  op1(Db),     0 },
/*7e*/  { "jle",   0, NONE,  op1(Db),     0 },
/*7f*/  { "jnle",  0, NONE,  op1(Db),     0 },

/*80*/  { NULL,    1,  BYTE,  op2(I, E),   db_Grp1 },
/*81*/  { NULL,    1,  LONG,  op2(I, E),   db_Grp1 },
/*82*/  { NULL,    1,  BYTE,  op2(I, E),   db_Grp1 },
/*83*/  { NULL,    1,  LONG,  op2(Ibs,E),  db_Grp1 },
/*84*/  { "test",  1,  BYTE,  op2(R, E),   0 },
/*85*/  { "test",  1,  LONG,  op2(R, E),   0 },
/*86*/  { "xchg",  1,  BYTE,  op2(R, E),   0 },
/*87*/  { "xchg",  1,  LONG,  op2(R, E),   0 },

/*88*/  { "mov",   1,  BYTE,  op2(R, E),   0 },
/*89*/  { "mov",   1,  LONG,  op2(R, E),   0 },
/*8a*/  { "mov",   1,  BYTE,  op2(E, R),   0 },
/*8b*/  { "mov",   1,  LONG,  op2(E, R),   0 },
/*8c*/  { "mov",   1,  NONE,  op2(S, Ew),  0 },
/*8d*/  { "lea",   1,  LONG,  op2(E, R),   0 },
/*8e*/  { "mov",   1,  NONE,  op2(Ew, S),  0 },
/*8f*/  { "pop",   1,  LONG,  op1(E),      0 },

/*90*/  { "nop",   0, NONE,  0,       0 },
/*91*/  { "xchg",  0, LONG,  op2(A, Ri),  0 },
/*92*/  { "xchg",  0, LONG,  op2(A, Ri),  0 },
/*93*/  { "xchg",  0, LONG,  op2(A, Ri),  0 },
/*94*/  { "xchg",  0, LONG,  op2(A, Ri),  0 },
/*95*/  { "xchg",  0, LONG,  op2(A, Ri),  0 },
/*96*/  { "xchg",  0, LONG,  op2(A, Ri),  0 },
/*97*/  { "xchg",  0, LONG,  op2(A, Ri),  0 },

/*98*/  { "cbw",   0, SDEP,  0,       "cwde" }, /* cbw/cwde */
/*99*/  { "cwd",   0, SDEP,  0,       "cdq"  }, /* cwd/cdq */
/*9a*/  { "lcall", 0, NONE,  op1(OS),     0 },
/*9b*/  { "wait",  0, NONE,  0,       0 },
/*9c*/  { "pushf", 0, LONG,  0,       0 },
/*9d*/  { "popf",  0, LONG,  0,       0 },
/*9e*/  { "sahf",  0, NONE,  0,       0 },
/*9f*/  { "lahf",  0, NONE,  0,       0 },

/*a0*/  { "mov",   0, BYTE,  op2(O, A),   0 },
/*a1*/  { "mov",   0, LONG,  op2(O, A),   0 },
/*a2*/  { "mov",   0, BYTE,  op2(A, O),   0 },
/*a3*/  { "mov",   0, LONG,  op2(A, O),   0 },
/*a4*/  { "movs",  0, BYTE,  op2(SI,DI),  0 },
/*a5*/  { "movs",  0, LONG,  op2(SI,DI),  0 },
/*a6*/  { "cmps",  0, BYTE,  op2(SI,DI),  0 },
/*a7*/  { "cmps",  0, LONG,  op2(SI,DI),  0 },

/*a8*/  { "test",  0, BYTE,  op2(I, A),   0 },
/*a9*/  { "test",  0, LONG,  op2(I, A),   0 },
/*aa*/  { "stos",  0, BYTE,  op1(DI),     0 },
/*ab*/  { "stos",  0, LONG,  op1(DI),     0 },
/*ac*/  { "lods",  0, BYTE,  op1(SI),     0 },
/*ad*/  { "lods",  0, LONG,  op1(SI),     0 },
/*ae*/  { "scas",  0, BYTE,  op1(SI),     0 },
/*af*/  { "scas",  0, LONG,  op1(SI),     0 },

/*b0*/  { "mov",   0, BYTE,  op2(I, Ri),  0 },
/*b1*/  { "mov",   0, BYTE,  op2(I, Ri),  0 },
/*b2*/  { "mov",   0, BYTE,  op2(I, Ri),  0 },
/*b3*/  { "mov",   0, BYTE,  op2(I, Ri),  0 },
/*b4*/  { "mov",   0, BYTE,  op2(I, Ri),  0 },
/*b5*/  { "mov",   0, BYTE,  op2(I, Ri),  0 },
/*b6*/  { "mov",   0, BYTE,  op2(I, Ri),  0 },
/*b7*/  { "mov",   0, BYTE,  op2(I, Ri),  0 },

/*b8*/  { "mov",   0, LONG,  op2(I, Ri),  0 },
/*b9*/  { "mov",   0, LONG,  op2(I, Ri),  0 },
/*ba*/  { "mov",   0, LONG,  op2(I, Ri),  0 },
/*bb*/  { "mov",   0, LONG,  op2(I, Ri),  0 },
/*bc*/  { "mov",   0, LONG,  op2(I, Ri),  0 },
/*bd*/  { "mov",   0, LONG,  op2(I, Ri),  0 },
/*be*/  { "mov",   0, LONG,  op2(I, Ri),  0 },
/*bf*/  { "mov",   0, LONG,  op2(I, Ri),  0 },

/*c0*/  { NULL,    1,  BYTE,  op2(Ib, E),  db_Grp2 },
/*c1*/  { NULL,    1,  LONG,  op2(Ib, E),  db_Grp2 },
/*c2*/  { "ret",   0, NONE,  op1(Iw),     0 },
/*c3*/  { "ret",   0, NONE,  0,       0 },
/*c4*/  { "les",   1,  LONG,  op2(E, R),   0 },
/*c5*/  { "lds",   1,  LONG,  op2(E, R),   0 },
/*c6*/  { "mov",   1,  BYTE,  op2(I, E),   0 },
/*c7*/  { "mov",   1,  LONG,  op2(I, E),   0 },

/*c8*/  { "enter", 0, NONE,  op2(Iw, Ib), 0 },
/*c9*/  { "leave", 0, NONE,  0,           0 },
/*ca*/  { "lret",  0, NONE,  op1(Iw),     0 },
/*cb*/  { "lret",  0, NONE,  0,       0 },
/*cc*/  { "int",   0, NONE,  op1(o3),     0 },
/*cd*/  { "int",   0, NONE,  op1(Ib),     0 },
/*ce*/  { "into",  0, NONE,  0,       0 },
/*cf*/  { "iret",  0, NONE,  0,       0 },

/*d0*/  { NULL,    1,  BYTE,  op2(o1, E),  db_Grp2 },
/*d1*/  { NULL,    1,  LONG,  op2(o1, E),  db_Grp2 },
/*d2*/  { NULL,    1,  BYTE,  op2(CL, E),  db_Grp2 },
/*d3*/  { NULL,    1,  LONG,  op2(CL, E),  db_Grp2 },
/*d4*/  { "aam",   1,  NONE,  op1(Iba),    0 },
/*d5*/  { "aad",   1,  NONE,  op1(Iba),    0 },
/*d6*/  { ".byte\t0xd6",0, NONE, 0,       0 },
/*d7*/  { "xlat",  0, BYTE,  op1(BX),     0 },

/* d8 to df block is ignored: direct test in code handles them */
/*d8*/  { "",      1,  NONE,  0,              db_Esc8 },
/*d9*/  { "",      1,  NONE,  0,              db_Esc9 },
/*da*/  { "",      1,  NONE,  0,              db_Esca },
/*db*/  { "",      1,  NONE,  0,              db_Escb },
/*dc*/  { "",      1,  NONE,  0,              db_Escc },
/*dd*/  { "",      1,  NONE,  0,              db_Escd },
/*de*/  { "",      1,  NONE,  0,              db_Esce },
/*df*/  { "",      1,  NONE,  0,              db_Escf },

/*e0*/  { "loopne",0, NONE,  op1(Db),     0 },
/*e1*/  { "loope", 0, NONE,  op1(Db),     0 },
/*e2*/  { "loop",  0, NONE,  op1(Db),     0 },
/*e3*/  { "jcxz",  0, SDEP,  op1(Db),     "jecxz" },
/*e4*/  { "in",    0, BYTE,  op2(Ib, A),  0 },
/*e5*/  { "in",    0, LONG,  op2(Ib, A) , 0 },
/*e6*/  { "out",   0, BYTE,  op2(A, Ib),  0 },
/*e7*/  { "out",   0, LONG,  op2(A, Ib) , 0 },

/*e8*/  { "call",  0, NONE,  op1(Dl),     0 },
/*e9*/  { "jmp",   0, NONE,  op1(Dl),     0 },
/*ea*/  { "ljmp",  0, NONE,  op1(OS),     0 },
/*eb*/  { "jmp",   0, NONE,  op1(Db),     0 },
/*ec*/  { "in",    0, BYTE,  op2(DX, A),  0 },
/*ed*/  { "in",    0, LONG,  op2(DX, A) , 0 },
/*ee*/  { "out",   0, BYTE,  op2(A, DX),  0 },
/*ef*/  { "out",   0, LONG,  op2(A, DX) , 0 },

/*f0*/  { "",      0, NONE,  0,      0 },
/*f1*/  { "",      0, NONE,  0,      0 },
/*f2*/  { "",      0, NONE,  0,      0 },
/*f3*/  { "",      0, NONE,  0,      0 },
/*f4*/  { "hlt",   0, NONE,  0,      0 },
/*f5*/  { "cmc",   0, NONE,  0,      0 },
/*f6*/  { "",      1,  BYTE,  0,             db_Grp3 },
/*f7*/  { "",      1,  LONG,  0,             db_Grp3 },

/*f8*/  { "clc",   0, NONE,  0,      0 },
/*f9*/  { "stc",   0, NONE,  0,      0 },
/*fa*/  { "cli",   0, NONE,  0,      0 },
/*fb*/  { "sti",   0, NONE,  0,      0 },
/*fc*/  { "cld",   0, NONE,  0,      0 },
/*fd*/  { "std",   0, NONE,  0,      0 },
/*fe*/  { "",      1,  RDEP,  0,             db_Grp4 },
/*ff*/  { "",      1,  RDEP,  0,             db_Grp5 },
};

struct inst     db_bad_inst =
        { "???",   0, NONE,  0,       0 }
;

#define f_mod(byte)     ((byte)>>6)
#define f_reg(byte)     (((byte)>>3)&0x7)
#define f_rm(byte)      ((byte)&0x7)

#define sib_ss(byte)    ((byte)>>6)
#define sib_index(byte) (((byte)>>3)&0x7)
#define sib_base(byte)  ((byte)&0x7)

struct i_addr {
        int             is_reg; /* if reg, reg number is in 'disp' */
        int             disp;
        char *          base;
        char *          index;
        int             ss;
};

char *  db_index_reg_16[8] = {
        "%bx,%si",
        "%bx,%di",
        "%bp,%si",
        "%bp,%di",
        "%si",
        "%di",
        "%bp",
        "%bx"
};

char *  db_reg[3][8] = {
        { "%al",  "%cl",  "%dl",  "%bl",  "%ah",  "%ch",  "%dh",  "%bh" },
        { "%ax",  "%cx",  "%dx",  "%bx",  "%sp",  "%bp",  "%si",  "%di" },
        { "%eax", "%ecx", "%edx", "%ebx", "%esp", "%ebp", "%esi", "%edi" }
};

char *  db_seg_reg[8] = {
        "%es", "%cs", "%ss", "%ds", "%fs", "%gs", "", ""
};

/*
 * lengths for size attributes
 */
int db_lengths[] = {
        1,      /* BYTE */
        2,      /* WORD */
        4,      /* LONG */
        8,      /* QUAD */
        4,      /* SNGL */
        8,      /* DBLR */
        10,     /* EXTR */
};

#define get_value_inc(result, loc, size, is_signed) \
        do { \
                result = db_get_value((loc), (size), (is_signed)); \
                (loc) += (size); \
        } while (0)


vaddr_t db_read_address(vaddr_t, int, int, struct i_addr *);
void db_print_address(char *, int, struct i_addr *);
vaddr_t db_disasm_esc(vaddr_t, int, int, int, char *);

/*
 * Read address at location and return updated location.
 */
vaddr_t
db_read_address(vaddr_t loc, int short_addr, int regmodrm,
    struct i_addr *addrp)
{
        int             mod, rm, sib, index, disp;

        mod = f_mod(regmodrm);
        rm  = f_rm(regmodrm);

        if (mod == 3) {
                addrp->is_reg = 1;
                addrp->disp = rm;
                return (loc);
        }
        addrp->is_reg = 0;
        addrp->index = 0;

        if (short_addr) {
                addrp->index = 0;
                addrp->ss = 0;
                switch (mod) {
                    case 0:
                        if (rm == 6) {
                                get_value_inc(disp, loc, 2, 0);
                                addrp->disp = disp;
                                addrp->base = 0;
                        } else {
                                addrp->disp = 0;
                                addrp->base = db_index_reg_16[rm];
                        }
                        break;
                    case 1:
                        get_value_inc(disp, loc, 1, 1);
                        disp &= 0xffff;
                        addrp->disp = disp;
                        addrp->base = db_index_reg_16[rm];
                        break;
                    case 2:
                        get_value_inc(disp, loc, 2, 0);
                        addrp->disp = disp;
                        addrp->base = db_index_reg_16[rm];
                        break;
                }
        } else {
                if (rm == 4) {
                        get_value_inc(sib, loc, 1, 0);
                        rm = sib_base(sib);
                        index = sib_index(sib);
                        if (index != 4)
                                addrp->index = db_reg[LONG][index];
                        addrp->ss = sib_ss(sib);
                }

                switch (mod) {
                    case 0:
                        if (rm == 5) {
                                get_value_inc(addrp->disp, loc, 4, 0);
                                addrp->base = 0;
                        } else {
                                addrp->disp = 0;
                                addrp->base = db_reg[LONG][rm];
                        }
                        break;
                    case 1:
                        get_value_inc(disp, loc, 1, 1);
                        addrp->disp = disp;
                        addrp->base = db_reg[LONG][rm];
                        break;
                    case 2:
                        get_value_inc(disp, loc, 4, 0);
                        addrp->disp = disp;
                        addrp->base = db_reg[LONG][rm];
                        break;
                }
        }
        return (loc);
}

void
db_print_address(char *seg, int size, struct i_addr *addrp)
{
        if (addrp->is_reg) {
                db_printf("%s", db_reg[size][addrp->disp]);
                return;
        }

        if (seg)
                db_printf("%s:", seg);

        db_printsym((vaddr_t)addrp->disp, DB_STGY_ANY, db_printf);
        if (addrp->base != 0 || addrp->index != 0) {
                db_printf("(");
                if (addrp->base)
                        db_printf("%s", addrp->base);
                if (addrp->index)
                        db_printf(",%s,%d", addrp->index, 1<<addrp->ss);
                db_printf(")");
        }
}

/*
 * Disassemble floating-point ("escape") instruction
 * and return updated location.
 */
vaddr_t
db_disasm_esc(vaddr_t loc, int inst, int short_addr, int size, char *seg)
{
        int             regmodrm;
        struct finst    *fp;
        int             mod;
        struct i_addr   address;
        char *          name;

        get_value_inc(regmodrm, loc, 1, 0);
        fp = &db_Esc_inst[inst - 0xd8][f_reg(regmodrm)];
        mod = f_mod(regmodrm);
        if (mod != 3) {
                if (*fp->f_name == '\0') {
                        db_printf("<bad instruction>");
                        return (loc);
                }

                /*
                 * Normal address modes.
                 */
                loc = db_read_address(loc, short_addr, regmodrm, &address);
                db_printf("%s", fp->f_name);
                switch(fp->f_size) {
                    case SNGL:
                        db_printf("s");
                        break;
                    case DBLR:
                        db_printf("l");
                        break;
                    case EXTR:
                        db_printf("t");
                        break;
                    case WORD:
                        db_printf("s");
                        break;
                    case LONG:
                        db_printf("l");
                        break;
                    case QUAD:
                        db_printf("q");
                        break;
                    default:
                        break;
                }
                db_printf("\t");
                db_print_address(seg, BYTE, &address);
        } else {
                /*
                 * 'reg-reg' - special formats
                 */
                switch (fp->f_rrmode) {
                    case op2(ST,STI):
                        name = (fp->f_rrname) ? fp->f_rrname : fp->f_name;
                        db_printf("%s\t%%st,%%st(%d)",name,f_rm(regmodrm));
                        break;
                    case op2(STI,ST):
                        name = (fp->f_rrname) ? fp->f_rrname : fp->f_name;
                        db_printf("%s\t%%st(%d),%%st",name, f_rm(regmodrm));
                        break;
                    case op1(STI):
                        name = (fp->f_rrname) ? fp->f_rrname : fp->f_name;
                        db_printf("%s\t%%st(%d)",name, f_rm(regmodrm));
                        break;
                    case op1(X):
                        name = ((char * const *)fp->f_rrname)[f_rm(regmodrm)];
                        if (*name == '\0')
                                goto bad;
                        db_printf("%s", name);
                        break;
                    case op1(XA):
                        name = ((char * const *)fp->f_rrname)[f_rm(regmodrm)];
                        if (*name == '\0')
                                goto bad;
                        db_printf("%s\t%%ax", name);
                        break;
                    default:
                    bad:
                        db_printf("<bad instruction>");
                        break;
                }
        }

        return (loc);
}

/*
 * Disassemble instruction at 'loc'.  'altfmt' specifies an
 * (optional) alternate format.  Return address of start of
 * next instruction.
 */
vaddr_t
db_disasm(vaddr_t loc, int altfmt)
{
        int     inst;
        int     size;
        int     short_addr;
        char *  seg;
        struct inst *   ip;
        char *  i_name;
        int     i_size;
        int     i_mode;
        int     regmodrm = 0;
        int     first;
        int     displ;
        int     prefix;
        int     imm;
        int     imm2;
        int     len;
        struct i_addr   address;
        char    tmpfmt[24];

        get_value_inc(inst, loc, 1, 0);
        short_addr = 0;
        size = LONG;
        seg = 0;

        /*
         * Get prefixes
         */
        prefix = 1;
        do {
                switch (inst) {
                    case 0x66:          /* data16 */
                        size = WORD;
                        break;
                    case 0x67:
                        short_addr = 1;
                        break;
                    case 0x26:
                        seg = "%es";
                        break;
                    case 0x36:
                        seg = "%ss";
                        break;
                    case 0x2e:
                        seg = "%cs";
                        break;
                    case 0x3e:
                        seg = "%ds";
                        break;
                    case 0x64:
                        seg = "%fs";
                        break;
                    case 0x65:
                        seg = "%gs";
                        break;
                    case 0xf0:
                        db_printf("lock ");
                        break;
                    case 0xf2:
                        db_printf("repne ");
                        break;
                    case 0xf3:
                        db_printf("repe ");     /* XXX repe VS rep */
                        break;
                    default:
                        prefix = 0;
                        break;
                }
                if (prefix)
                        get_value_inc(inst, loc, 1, 0);
        } while (prefix);

        if (inst >= 0xd8 && inst <= 0xdf) {
                loc = db_disasm_esc(loc, inst, short_addr, size, seg);
                db_printf("\n");
                return (loc);
        }

        if (inst == 0x0f) {
                get_value_inc(inst, loc, 1, 0);
                ip = db_inst_0f[inst>>4];
                if (ip == 0)
                        ip = &db_bad_inst;
                else
                        ip = &ip[inst&0xf];
        } else {
                ip = &db_inst_table[inst];
        }

        if (ip->i_has_modrm) {
                get_value_inc(regmodrm, loc, 1, 0);
                loc = db_read_address(loc, short_addr, regmodrm, &address);
        }

        i_name = ip->i_name;
        i_size = ip->i_size;
        i_mode = ip->i_mode;

        if (i_size == RDEP) {
                /* sub-table to handle dependency on reg from ModR/M byte */
                ip = (struct inst *)ip->i_extra;
                ip = &ip[f_reg(regmodrm)];
                i_name = ip->i_name;
                i_mode = ip->i_mode;
                i_size = ip->i_size;
        } else if (i_name == NULL) {
                i_name = ((char **)ip->i_extra)[f_reg(regmodrm)];
        } else if (ip->i_extra == db_Grp3) {
                ip = (struct inst *)ip->i_extra;
                ip = &ip[f_reg(regmodrm)];
                i_name = ip->i_name;
                i_mode = ip->i_mode;
        }

        /* ModR/M-specific operation? */
        if ((i_mode & 0xFF) == MEx) {
                if (f_mod(regmodrm) != 3)
                        i_mode = op1(E);
                else {
                        /* unknown extension? */
                        if (f_rm(regmodrm) > (i_mode >> 8))
                                i_name = "";
                        else {
                                /* skip to the specific op */
                                int i = f_rm(regmodrm);
                                i_name = ip->i_extra;
                                while (i-- > 0)
                                        while (*i_name++)
                                                ;
                        }
                        i_mode = 0;
                }
        }

        if (i_size == SDEP) {
                if (size == WORD)
                        db_printf("%s", i_name);
                else
                        db_printf("%s", (char *)ip->i_extra);
        } else {
                db_printf("%s", i_name);
                if (i_size != NONE) {
                        if (i_size == BYTE) {
                                db_printf("b");
                                size = BYTE;
                        } else if (i_size == WORD) {
                                db_printf("w");
                                size = WORD;
                        } else if (size == WORD) {
                                db_printf("w");
                        } else {
                                db_printf("l");
                        }
                }
        }
        db_printf("\t");
        for (first = 1;
             i_mode != 0;
             i_mode >>= 8, first = 0) {
                if (!first)
                        db_printf(",");

                switch (i_mode & 0xFF) {
                    case E:
                        db_print_address(seg, size, &address);
                        break;
                    case Eind:
                        db_printf("*");
                        db_print_address(seg, size, &address);
                        break;
                    case El:
                        db_print_address(seg, LONG, &address);
                        break;
                    case Ew:
                        db_print_address(seg, WORD, &address);
                        break;
                    case Eb:
                        db_print_address(seg, BYTE, &address);
                        break;
                    case R:
                        db_printf("%s", db_reg[size][f_reg(regmodrm)]);
                        break;
                    case Rw:
                        db_printf("%s", db_reg[WORD][f_reg(regmodrm)]);
                        break;
                    case Ri:
                        db_printf("%s", db_reg[size][f_rm(inst)]);
                        break;
                    case Ril:
                        db_printf("%s", db_reg[LONG][f_rm(inst)]);
                        break;
                    case S:
                        db_printf("%s", db_seg_reg[f_reg(regmodrm)]);
                        break;
                    case Si:
                        db_printf("%s", db_seg_reg[f_reg(inst)]);
                        break;
                    case A:
                        db_printf("%s", db_reg[size][0]);       /* acc */
                        break;
                    case BX:
                        if (seg)
                                db_printf("%s:", seg);
                        db_printf("(%s)", short_addr ? "%bx" : "%ebx");
                        break;
                    case CL:
                        db_printf("%%cl");
                        break;
                    case DX:
                        db_printf("%%dx");
                        break;
                    case SI:
                        if (seg)
                                db_printf("%s:", seg);
                        db_printf("(%s)", short_addr ? "%si" : "%esi");
                        break;
                    case DI:
                        db_printf("%%es:(%s)", short_addr ? "%di" : "%edi");
                        break;
                    case CR:
                        db_printf("%%cr%d", f_reg(regmodrm));
                        break;
                    case DR:
                        db_printf("%%dr%d", f_reg(regmodrm));
                        break;
                    case TR:
                        db_printf("%%tr%d", f_reg(regmodrm));
                        break;
                    case I:
                        len = db_lengths[size];
                        get_value_inc(imm, loc, len, 0);
                        db_printf("$%s", db_format(tmpfmt, sizeof tmpfmt,
                            imm, DB_FORMAT_N, 1, 0));
                        break;
                    case Is:
                        len = db_lengths[size];
                        get_value_inc(imm, loc, len, 1);
                        db_printf("$%s", db_format(tmpfmt, sizeof tmpfmt,
                            imm, DB_FORMAT_R, 1, 0));
                        break;
                    case Ib:
                        get_value_inc(imm, loc, 1, 0);
                        db_printf("$%s", db_format(tmpfmt, sizeof tmpfmt,
                            imm, DB_FORMAT_N, 1, 0));
                        break;
                    case Iba:
                        get_value_inc(imm, loc, 1, 0);
                        if (imm != 0x0a)
                                db_printf("$%s", db_format(tmpfmt, sizeof tmpfmt,
                                    imm, DB_FORMAT_N, 1, 0));
                        break;
                    case Ibs:
                        get_value_inc(imm, loc, 1, 1);
                        if (size == WORD)
                                imm &= 0xFFFF;
                        db_printf("$%s", db_format(tmpfmt, sizeof tmpfmt,
                            imm, DB_FORMAT_R, 1, 0));
                        break;
                    case Iw:
                        get_value_inc(imm, loc, 2, 0);
                        db_printf("$%s", db_format(tmpfmt, sizeof tmpfmt,
                            imm, DB_FORMAT_N, 1, 0));
                        break;
                    case O:
                        if (short_addr)
                                get_value_inc(displ, loc, 2, 1);
                        else
                                get_value_inc(displ, loc, 4, 1);
                        if (seg)
                                db_printf("%s:%s", seg, db_format(tmpfmt,
                                    sizeof tmpfmt, displ, DB_FORMAT_R, 1, 0));
                        else
                                db_printsym((vaddr_t)displ, DB_STGY_ANY,
                                    db_printf);
                        break;
                    case Db:
                        get_value_inc(displ, loc, 1, 1);
                        displ += loc;
                        if (size == WORD)
                                displ &= 0xFFFF;
                        db_printsym((vaddr_t)displ, DB_STGY_XTRN, db_printf);
                        break;
                    case Dl:
                        len = db_lengths[size];
                        get_value_inc(displ, loc, len, 0);
                        displ += loc;
                        if (size == WORD)
                                displ &= 0xFFFF;
                        db_printsym((vaddr_t)displ, DB_STGY_XTRN, db_printf);
                        break;
                    case o1:
                        db_printf("$1");
                        break;
                    case o3:
                        db_printf("$3");
                        break;
                    case OS:
                        len = db_lengths[size];
                        get_value_inc(imm, loc, len, 0);        /* offset */
                        get_value_inc(imm2, loc, 2, 0); /* segment */
                        db_printf("$%s", db_format(tmpfmt, sizeof tmpfmt,
                            imm2, DB_FORMAT_N, 1, 0));
                        db_printf(",%s", db_format(tmpfmt, sizeof tmpfmt,
                            imm, DB_FORMAT_N, 1, 0));
                        break;
                }
        }

        if (altfmt == 0 && (inst == 0xe9 || inst == 0xeb)) {
                /*
                 * GAS pads to longword boundary after unconditional jumps.
                 */
                loc = (loc + (4-1)) & ~(4-1);
        }
        db_printf("\n");
        return (loc);
}