typedef struct Iarg Iarg;

typedef struct Iarg Iarg;
typedef struct Inst Inst;
typedef struct Bus Bus;
typedef struct Cpu Cpu;
typedef struct Pit Pit;

enum {
RAX,
RCX,
RDX,
RBX,
RSP,
RBP,
RSI,
RDI,

RES,
RCS,
RSS,
RDS,
RFS,
RGS,

R0S, /* 0 segment */

RIP,
RFL,

NREG,
};

struct Iarg
{
Cpu *cpu;

uchar tag;
uchar len;
uchar atype;

union {
uchar reg;
struct {
uchar sreg;
ulong seg, off;
};
ulong val;
};
};

struct Inst
{
uchar op;
uchar code;
uchar olen;
uchar alen;

Iarg *a1, *a2, *a3;

uchar rep;

uchar mod;
uchar reg;
uchar rm;

uchar scale;
uchar index;
uchar base;

uchar sreg;
uchar dsreg;

ulong off;
long disp;
};

struct Bus
{
void *aux;
ulong (*r)(void *aux, ulong off, int len);
void (*w)(void *aux, ulong off, ulong data, int len);
};

struct Cpu
{
ulong reg[NREG];

/* instruction counter */
ulong ic;

/* mem[16], one entry for each 64k block */
Bus *mem;

/* port[1], in/out */
Bus *port;

int trap;
ulong oldip;
jmp_buf jmp;

/* default operand, address and stack pointer length */
uchar olen, alen, slen;

/* argument buffers */
ulong iabuf;
Iarg abuf[0x80];
};

struct Pit
{
ulong count;

/* set by setgate(), cleared by clockpit() */
uchar gateraised;

/* signals */
uchar gate;
uchar out;

/* mode and flags */
uchar count0;

uchar bcd;
uchar amode;
uchar omode;

/* latch for wpit initial count */
uchar wcount;
uchar wlatched;
uchar wlatch[2];

/* latch for rpit status/count */
uchar rcount;
uchar rlatched;
uchar rlatch[2];
};

/* processor flags */
enum {
CF = 1<<0, /* carry flag */
PF = 1<<2, /* parity flag */
AF = 1<<4, /* aux carry flag */
ZF = 1<<6, /* zero flag */
SF = 1<<7, /* sign flag */
TF = 1<<8, /* trap flag */
IF = 1<<9, /* interrupts enabled flag */
DF = 1<<10, /* direction flag */
OF = 1<<11, /* overflow flag */
IOPL= 3<<12, /* I/O privelege level */
NT = 1<<14, /* nested task */
RF = 1<<16, /* resume flag */
VM = 1<<17, /* virtual-8086 mode */
AC = 1<<18, /* alignment check */
VIF = 1<<19, /* virtual interrupt flag */
VIP = 1<<20, /* virtual interrupt pending */
ID = 1<<21, /* ID flag */
};

/* interrupts/traps */
enum {
EDIV0,
EDEBUG,
ENMI,
EBRK,
EINTO,
EBOUND,
EBADOP,
ENOFPU,
EDBLF,
EFPUSEG,
EBADTSS,
ENP,
ESTACK,
EGPF,
EPF,

EHALT = 256, /* pseudo-interrupts */
EMEM,
EIO,
};

/* argument tags */
enum {
TREG,
TMEM,
TCON,

TH = 0x80, /* special flag for AH,BH,CH,DH */
};

/* argument types */
enum {
ANONE, /* no argument */
A0, /* constant 0 */
A1, /* constant 1 */
A2, /* constant 2 */
A3, /* constant 3 */
A4, /* constant 4 */
AAp, /* 32-bit or 48-bit direct address */
AEb, /* r/m8 from modrm byte */
AEv, /* r/m16 or r/m32 from modrm byte */
AEw, /* r/m16 */
AFv, /* flag word */
AGb, /* r8 from modrm byte */
AGv, /* r16 or r32 from modrm byte */
AGw, /* r/m16 */
AIb, /* immediate byte */
AIc, /* immediate byte sign-extended */
AIw, /* immediate 16-bit word */
AIv, /* immediate 16-bit or 32-bit word */
AJb, /* relative offset byte */
AJv, /* relative offset 16-bit or 32-bit word */
AJr, /* r/m16 or r/m32 register */
AM, /* memory address from modrm */
AMa, /* something for bound */
AMa2,
AMp, /* 32-bit or 48-bit memory address */
AOb, /* immediate word-sized offset to a byte */
AOv, /* immediate word-size offset to a word */
ASw, /* segment register selected by r field of modrm */
AXb, /* byte at DS:SI */
AXv, /* word at DS:SI */
AYb, /* byte at ES:DI */
AYv, /* word at ES:DI */

AAL,
ACL,
ADL,
ABL,
AAH,
ACH,
ADH,
ABH,

AAX,
ACX,
ADX,
ABX,
ASP,
ABP,
ASI,
ADI,

AES,
ACS,
ASS,
ADS,
AFS,
AGS,

NATYPE,
};

/* operators */
enum {
OBAD,
O0F,
OAAA,
OAAD,
OAAM,
OAAS,
OADC,
OADD,
OAND,
OARPL,
OASIZE,
OBOUND,
OBT,
OBTS,
OBTR,
OBTC,
OBSF,
OBSR,
OCALL,
OCBW,
OCLC,
OCLD,
OCLI,
OCMC,
OCMOV,
OCMP,
OCMPS,
OCPUID,
OCWD,
ODAA,
ODAS,
ODEC,
ODIV,
OENTER,
OGP1,
OGP2,
OGP3b,
OGP3v,
OGP4,
OGP5,
OGP8,
OGP10,
OGP12,
OHLT,
OIDIV,
OIMUL,
OIN,
OINC,
OINS,
OINT,
OIRET,
OJUMP,
OLAHF,
OLEA,
OLEAVE,
OLFP,
OLOCK,
OLODS,
OLOOP,
OLOOPNZ,
OLOOPZ,
OMOV,
OMOVS,
OMOVZX,
OMOVSX,
OMUL,
ONEG,
ONOP,
ONOT,
OOR,
OOSIZE,
OOUT,
OOUTS,
OPOP,
OPOPA,
OPOPF,
OPUSH,
OPUSHA,
OPUSHF,
ORCL,
ORCR,
OREPE,
OREPNE,
ORET,
ORETF,
OROL,
OROR,
OSAHF,
OSAR,
OSBB,
OSCAS,
OSEG,
OSET,
OSHL,
OSHLD,
OSHR,
OSHRD,
OSTC,
OSTD,
OSTI,
OSTOS,
OSUB,
OTEST,
OWAIT,
OXCHG,
OXLAT,
OXOR,
NUMOP,
};