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nasm/disasm.c
H. Peter Anvin 39d6ac6f79 Fix display for fixed xmm0/ymm0, SSE redundant prefixes 
All singleton registers need to be displayable from register flags
alone!

When using the new 0360..0363 codes, make sure we appropriate avoid
displaying the legacy use of the prefixes.
2008-05-21 10:33:19 -07:00

1465 lines
36 KiB
C
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/* disasm.c where all the _work_ gets done in the Netwide Disassembler
*
* The Netwide Assembler is copyright (C) 1996 Simon Tatham and
* Julian Hall. All rights reserved. The software is
* redistributable under the license given in the file "LICENSE"
* distributed in the NASM archive.
*
* initial version 27/iii/95 by Simon Tatham
*/
#include "compiler.h"
#include <stdio.h>
#include <string.h>
#include <limits.h>
#include <inttypes.h>
#include "nasm.h"
#include "disasm.h"
#include "sync.h"
#include "insns.h"
#include "tables.h"
#include "regdis.h"
/*
* Flags that go into the `segment' field of `insn' structures
* during disassembly.
*/
#define SEG_RELATIVE 1
#define SEG_32BIT 2
#define SEG_RMREG 4
#define SEG_DISP8 8
#define SEG_DISP16 16
#define SEG_DISP32 32
#define SEG_NODISP 64
#define SEG_SIGNED 128
#define SEG_64BIT 256
/*
* Prefix information
*/
struct prefix_info {
uint8_t osize; /* Operand size */
uint8_t asize; /* Address size */
uint8_t osp; /* Operand size prefix present */
uint8_t asp; /* Address size prefix present */
uint8_t rep; /* Rep prefix present */
uint8_t seg; /* Segment override prefix present */
uint8_t lock; /* Lock prefix present */
uint8_t vex[3]; /* VEX prefix present */
uint8_t vex_m; /* VEX.M field */
uint8_t vex_v;
uint8_t vex_lp; /* VEX.LP fields */
uint32_t rex; /* REX prefix present */
};
#define getu8(x) (*(uint8_t *)(x))
#if X86_MEMORY
/* Littleendian CPU which can handle unaligned references */
#define getu16(x) (*(uint16_t *)(x))
#define getu32(x) (*(uint32_t *)(x))
#define getu64(x) (*(uint64_t *)(x))
#else
static uint16_t getu16(uint8_t *data)
{
return (uint16_t)data[0] + ((uint16_t)data[1] << 8);
}
static uint32_t getu32(uint8_t *data)
{
return (uint32_t)getu16(data) + ((uint32_t)getu16(data+2) << 16);
}
static uint64_t getu64(uint8_t *data)
{
return (uint64_t)getu32(data) + ((uint64_t)getu32(data+4) << 32);
}
#endif
#define gets8(x) ((int8_t)getu8(x))
#define gets16(x) ((int16_t)getu16(x))
#define gets32(x) ((int32_t)getu32(x))
#define gets64(x) ((int64_t)getu64(x))
/* Important: regval must already have been adjusted for rex extensions */
static enum reg_enum whichreg(int32_t regflags, int regval, int rex)
{
if (!(regflags & (REGISTER|REGMEM)))
return 0; /* Registers not permissible?! */
regflags |= REGISTER;
if (!(REG_AL & ~regflags))
return R_AL;
if (!(REG_AX & ~regflags))
return R_AX;
if (!(REG_EAX & ~regflags))
return R_EAX;
if (!(REG_RAX & ~regflags))
return R_RAX;
if (!(REG_DL & ~regflags))
return R_DL;
if (!(REG_DX & ~regflags))
return R_DX;
if (!(REG_EDX & ~regflags))
return R_EDX;
if (!(REG_RDX & ~regflags))
return R_RDX;
if (!(REG_CL & ~regflags))
return R_CL;
if (!(REG_CX & ~regflags))
return R_CX;
if (!(REG_ECX & ~regflags))
return R_ECX;
if (!(REG_RCX & ~regflags))
return R_RCX;
if (!(FPU0 & ~regflags))
return R_ST0;
if (!(XMM0 & ~regflags))
return R_XMM0;
if (!(YMM0 & ~regflags))
return R_YMM0;
if (!(REG_CS & ~regflags))
return (regval == 1) ? R_CS : 0;
if (!(REG_DESS & ~regflags))
return (regval == 0 || regval == 2
|| regval == 3 ? nasm_rd_sreg[regval] : 0);
if (!(REG_FSGS & ~regflags))
return (regval == 4 || regval == 5 ? nasm_rd_sreg[regval] : 0);
if (!(REG_SEG67 & ~regflags))
return (regval == 6 || regval == 7 ? nasm_rd_sreg[regval] : 0);
/* All the entries below look up regval in an 16-entry array */
if (regval < 0 || regval > 15)
return 0;
if (!(REG8 & ~regflags)) {
if (rex & REX_P)
return nasm_rd_reg8_rex[regval];
else
return nasm_rd_reg8[regval];
}
if (!(REG16 & ~regflags))
return nasm_rd_reg16[regval];
if (!(REG32 & ~regflags))
return nasm_rd_reg32[regval];
if (!(REG64 & ~regflags))
return nasm_rd_reg64[regval];
if (!(REG_SREG & ~regflags))
return nasm_rd_sreg[regval & 7]; /* Ignore REX */
if (!(REG_CREG & ~regflags))
return nasm_rd_creg[regval];
if (!(REG_DREG & ~regflags))
return nasm_rd_dreg[regval];
if (!(REG_TREG & ~regflags)) {
if (rex & REX_P)
return 0; /* TR registers are ill-defined with rex */
return nasm_rd_treg[regval];
}
if (!(FPUREG & ~regflags))
return nasm_rd_fpureg[regval & 7]; /* Ignore REX */
if (!(MMXREG & ~regflags))
return nasm_rd_mmxreg[regval & 7]; /* Ignore REX */
if (!(XMMREG & ~regflags))
return nasm_rd_xmmreg[regval];
if (!(YMMREG & ~regflags))
return nasm_rd_ymmreg[regval];
return 0;
}
/*
* Process a DREX suffix
*/
static uint8_t *do_drex(uint8_t *data, insn *ins)
{
uint8_t drex = *data++;
operand *dst = &ins->oprs[ins->drexdst];
if ((drex & 8) != ((ins->rex & REX_OC) ? 8 : 0))
return NULL; /* OC0 mismatch */
ins->rex = (ins->rex & ~7) | (drex & 7);
dst->segment = SEG_RMREG;
dst->basereg = drex >> 4;
return data;
}
/*
* Process an effective address (ModRM) specification.
*/
static uint8_t *do_ea(uint8_t *data, int modrm, int asize,
int segsize, operand * op, insn *ins)
{
int mod, rm, scale, index, base;
int rex;
uint8_t sib = 0;
mod = (modrm >> 6) & 03;
rm = modrm & 07;
if (mod != 3 && rm == 4 && asize != 16)
sib = *data++;
if (ins->rex & REX_D) {
data = do_drex(data, ins);
if (!data)
return NULL;
}
rex = ins->rex;
if (mod == 3) { /* pure register version */
op->basereg = rm+(rex & REX_B ? 8 : 0);
op->segment |= SEG_RMREG;
return data;
}
op->disp_size = 0;
op->eaflags = 0;
if (asize == 16) {
/*
* <mod> specifies the displacement size (none, byte or
* word), and <rm> specifies the register combination.
* Exception: mod=0,rm=6 does not specify [BP] as one might
* expect, but instead specifies [disp16].
*/
op->indexreg = op->basereg = -1;
op->scale = 1; /* always, in 16 bits */
switch (rm) {
case 0:
op->basereg = R_BX;
op->indexreg = R_SI;
break;
case 1:
op->basereg = R_BX;
op->indexreg = R_DI;
break;
case 2:
op->basereg = R_BP;
op->indexreg = R_SI;
break;
case 3:
op->basereg = R_BP;
op->indexreg = R_DI;
break;
case 4:
op->basereg = R_SI;
break;
case 5:
op->basereg = R_DI;
break;
case 6:
op->basereg = R_BP;
break;
case 7:
op->basereg = R_BX;
break;
}
if (rm == 6 && mod == 0) { /* special case */
op->basereg = -1;
if (segsize != 16)
op->disp_size = 16;
mod = 2; /* fake disp16 */
}
switch (mod) {
case 0:
op->segment |= SEG_NODISP;
break;
case 1:
op->segment |= SEG_DISP8;
op->offset = (int8_t)*data++;
break;
case 2:
op->segment |= SEG_DISP16;
op->offset = *data++;
op->offset |= ((unsigned)*data++) << 8;
break;
}
return data;
} else {
/*
* Once again, <mod> specifies displacement size (this time
* none, byte or *dword*), while <rm> specifies the base
* register. Again, [EBP] is missing, replaced by a pure
* disp32 (this time that's mod=0,rm=*5*) in 32-bit mode,
* and RIP-relative addressing in 64-bit mode.
*
* However, rm=4
* indicates not a single base register, but instead the
* presence of a SIB byte...
*/
int a64 = asize == 64;
op->indexreg = -1;
if (a64)
op->basereg = nasm_rd_reg64[rm | ((rex & REX_B) ? 8 : 0)];
else
op->basereg = nasm_rd_reg32[rm | ((rex & REX_B) ? 8 : 0)];
if (rm == 5 && mod == 0) {
if (segsize == 64) {
op->eaflags |= EAF_REL;
op->segment |= SEG_RELATIVE;
mod = 2; /* fake disp32 */
}
if (asize != 64)
op->disp_size = asize;
op->basereg = -1;
mod = 2; /* fake disp32 */
}
if (rm == 4) { /* process SIB */
scale = (sib >> 6) & 03;
index = (sib >> 3) & 07;
base = sib & 07;
op->scale = 1 << scale;
if (index == 4)
op->indexreg = -1; /* ESP/RSP/R12 cannot be an index */
else if (a64)
op->indexreg = nasm_rd_reg64[index | ((rex & REX_X) ? 8 : 0)];
else
op->indexreg = nasm_rd_reg32[index | ((rex & REX_X) ? 8 : 0)];
if (base == 5 && mod == 0) {
op->basereg = -1;
mod = 2; /* Fake disp32 */
} else if (a64)
op->basereg = nasm_rd_reg64[base | ((rex & REX_B) ? 8 : 0)];
else
op->basereg = nasm_rd_reg32[base | ((rex & REX_B) ? 8 : 0)];
if (segsize == 16)
op->disp_size = 32;
}
switch (mod) {
case 0:
op->segment |= SEG_NODISP;
break;
case 1:
op->segment |= SEG_DISP8;
op->offset = gets8(data);
data++;
break;
case 2:
op->segment |= SEG_DISP32;
op->offset = gets32(data);
data += 4;
break;
}
return data;
}
}
/*
* Determine whether the instruction template in t corresponds to the data
* stream in data. Return the number of bytes matched if so.
*/
#define case4(x) case (x): case (x)+1: case (x)+2: case (x)+3
static int matches(const struct itemplate *t, uint8_t *data,
const struct prefix_info *prefix, int segsize, insn *ins)
{
uint8_t *r = (uint8_t *)(t->code);
uint8_t *origdata = data;
bool a_used = false, o_used = false;
enum prefixes drep = 0;
uint8_t lock = prefix->lock;
int osize = prefix->osize;
int asize = prefix->asize;
int i, c;
struct operand *opx;
int s_field_for = -1; /* No 144/154 series code encountered */
bool vex_ok = false;
for (i = 0; i < MAX_OPERANDS; i++) {
ins->oprs[i].segment = ins->oprs[i].disp_size =
(segsize == 64 ? SEG_64BIT : segsize == 32 ? SEG_32BIT : 0);
}
ins->condition = -1;
ins->rex = prefix->rex;
memset(ins->prefixes, 0, sizeof ins->prefixes);
if (t->flags & (segsize == 64 ? IF_NOLONG : IF_LONG))
return false;
if (prefix->rep == 0xF2)
drep = P_REPNE;
else if (prefix->rep == 0xF3)
drep = P_REP;
while ((c = *r++) != 0) {
opx = &ins->oprs[c & 3];
switch (c) {
case 01:
case 02:
case 03:
while (c--)
if (*r++ != *data++)
return false;
break;
case 04:
switch (*data++) {
case 0x07:
ins->oprs[0].basereg = 0;
break;
case 0x17:
ins->oprs[0].basereg = 2;
break;
case 0x1F:
ins->oprs[0].basereg = 3;
break;
default:
return false;
}
break;
case 05:
switch (*data++) {
case 0xA1:
ins->oprs[0].basereg = 4;
break;
case 0xA9:
ins->oprs[0].basereg = 5;
break;
default:
return false;
}
break;
case 06:
switch (*data++) {
case 0x06:
ins->oprs[0].basereg = 0;
break;
case 0x0E:
ins->oprs[0].basereg = 1;
break;
case 0x16:
ins->oprs[0].basereg = 2;
break;
case 0x1E:
ins->oprs[0].basereg = 3;
break;
default:
return false;
}
break;
case 07:
switch (*data++) {
case 0xA0:
ins->oprs[0].basereg = 4;
break;
case 0xA8:
ins->oprs[0].basereg = 5;
break;
default:
return false;
}
break;
case4(010):
{
int t = *r++, d = *data++;
if (d < t || d > t + 7)
return false;
else {
opx->basereg = (d-t)+
(ins->rex & REX_B ? 8 : 0);
opx->segment |= SEG_RMREG;
}
break;
}
case4(014):
opx->offset = (int8_t)*data++;
opx->segment |= SEG_SIGNED;
break;
case4(020):
opx->offset = *data++;
break;
case4(024):
opx->offset = *data++;
break;
case4(030):
opx->offset = getu16(data);
data += 2;
break;
case4(034):
if (osize == 32) {
opx->offset = getu32(data);
data += 4;
} else {
opx->offset = getu16(data);
data += 2;
}
if (segsize != asize)
opx->disp_size = asize;
break;
case4(040):
opx->offset = getu32(data);
data += 4;
break;
case4(044):
switch (asize) {
case 16:
opx->offset = getu16(data);
data += 2;
if (segsize != 16)
opx->disp_size = 16;
break;
case 32:
opx->offset = getu32(data);
data += 4;
if (segsize == 16)
opx->disp_size = 32;
break;
case 64:
opx->offset = getu64(data);
opx->disp_size = 64;
data += 8;
break;
}
break;
case4(050):
opx->offset = gets8(data++);
opx->segment |= SEG_RELATIVE;
break;
case4(054):
opx->offset = getu64(data);
data += 8;
break;
case4(060):
opx->offset = gets16(data);
data += 2;
opx->segment |= SEG_RELATIVE;
opx->segment &= ~SEG_32BIT;
break;
case4(064):
opx->segment |= SEG_RELATIVE;
if (osize == 16) {
opx->offset = gets16(data);
data += 2;
opx->segment &= ~(SEG_32BIT|SEG_64BIT);
} else if (osize == 32) {
opx->offset = gets32(data);
data += 4;
opx->segment &= ~SEG_64BIT;
opx->segment |= SEG_32BIT;
}
if (segsize != osize) {
opx->type =
(opx->type & ~SIZE_MASK)
| ((osize == 16) ? BITS16 : BITS32);
}
break;
case4(070):
opx->offset = gets32(data);
data += 4;
opx->segment |= SEG_32BIT | SEG_RELATIVE;
break;
case4(0100):
case4(0110):
case4(0120):
case4(0130):
{
int modrm = *data++;
opx->segment |= SEG_RMREG;
data = do_ea(data, modrm, asize, segsize,
&ins->oprs[(c >> 3) & 3], ins);
if (!data)
return false;
opx->basereg = ((modrm >> 3)&7)+
(ins->rex & REX_R ? 8 : 0);
break;
}
case4(0140):
if (s_field_for == (c & 3)) {
opx->offset = gets8(data);
data++;
} else {
opx->offset = getu16(data);
data += 2;
}
break;
case4(0144):
case4(0154):
s_field_for = (*data & 0x02) ? c & 3 : -1;
if ((*data++ & ~0x02) != *r++)
return false;
break;
case4(0150):
if (s_field_for == (c & 3)) {
opx->offset = gets8(data);
data++;
} else {
opx->offset = getu32(data);
data += 4;
}
break;
case4(0160):
ins->rex |= REX_D;
ins->drexdst = c & 3;
break;
case4(0164):
ins->rex |= REX_D|REX_OC;
ins->drexdst = c & 3;
break;
case 0171:
data = do_drex(data, ins);
if (!data)
return false;
break;
case 0172:
{
uint8_t ximm = *data++;
c = *r++;
ins->oprs[c >> 3].basereg = ximm >> 4;
ins->oprs[c >> 3].segment |= SEG_RMREG;
ins->oprs[c & 7].offset = ximm & 15;
}
break;
case 0173:
{
uint8_t ximm = *data++;
c = *r++;
if ((c ^ ximm) & 15)
return false;
ins->oprs[c >> 4].basereg = ximm >> 4;
ins->oprs[c >> 4].segment |= SEG_RMREG;
}
break;
case 0174:
{
uint8_t ximm = *data++;
c = *r++;
ins->oprs[c].basereg = ximm >> 4;
ins->oprs[c].segment |= SEG_RMREG;
}
break;
case4(0200):
case4(0204):
case4(0210):
case4(0214):
case4(0220):
case4(0224):
case4(0230):
case4(0234):
{
int modrm = *data++;
if (((modrm >> 3) & 07) != (c & 07))
return false; /* spare field doesn't match up */
data = do_ea(data, modrm, asize, segsize,
&ins->oprs[(c >> 3) & 07], ins);
if (!data)
return false;
break;
}
case4(0260):
{
int vexm = *r++;
int vexwlp = *r++;
ins->rex |= REX_V;
if ((prefix->rex & (REX_V|REX_D|REX_P)) != REX_V)
return false;
if ((vexm & 0x1f) != prefix->vex_m)
return false;
switch (vexwlp & 030) {
case 000:
if (prefix->rex & REX_W)
return false;
break;
case 010:
if (!(prefix->rex & REX_W))
return false;
break;
default:
break; /* XXX: Need to do anything special here? */
}
if ((vexwlp & 007) != prefix->vex_lp)
return false;
opx->segment |= SEG_RMREG;
opx->basereg = prefix->vex_v;
vex_ok = true;
break;
}
case 0270:
{
int vexm = *r++;
int vexwlp = *r++;
ins->rex |= REX_V;
if ((prefix->rex & (REX_V|REX_D|REX_P)) != REX_V)
return false;
if ((vexm & 0x1f) != prefix->vex_m)
return false;
switch (vexwlp & 030) {
case 000:
if (ins->rex & REX_W)
return false;
break;
case 010:
if (!(ins->rex & REX_W))
return false;
break;
default:
break; /* Need to do anything special here? */
}
if ((vexwlp & 007) != prefix->vex_lp)
return false;
if (prefix->vex_v != 0)
return false;
vex_ok = true;
break;
}
case 0310:
if (asize != 16)
return false;
else
a_used = true;
break;
case 0311:
if (asize == 16)
return false;
else
a_used = true;
break;
case 0312:
if (asize != segsize)
return false;
else
a_used = true;
break;
case 0313:
if (asize != 64)
return false;
else
a_used = true;
break;
case 0314:
if (prefix->rex & REX_B)
return false;
break;
case 0315:
if (prefix->rex & REX_X)
return false;
break;
case 0316:
if (prefix->rex & REX_R)
return false;
break;
case 0317:
if (prefix->rex & REX_W)
return false;
break;
case 0320:
if (osize != 16)
return false;
else
o_used = true;
break;
case 0321:
if (osize != 32)
return false;
else
o_used = true;
break;
case 0322:
if (osize != (segsize == 16) ? 16 : 32)
return false;
else
o_used = true;
break;
case 0323:
ins->rex |= REX_W; /* 64-bit only instruction */
osize = 64;
o_used = true;
break;
case 0324:
if (!(ins->rex & (REX_P|REX_W)) || osize != 64)
return false;
o_used = true;
break;
case 0330:
{
int t = *r++, d = *data++;
if (d < t || d > t + 15)
return false;
else
ins->condition = d - t;
break;
}
case 0331:
if (prefix->rep)
return false;
break;
case 0332:
if (prefix->rep != 0xF2)
return false;
drep = 0;
break;
case 0333:
if (prefix->rep != 0xF3)
return false;
drep = 0;
break;
case 0334:
if (lock) {
ins->rex |= REX_R;
lock = 0;
}
break;
case 0335:
if (drep == P_REP)
drep = P_REPE;
break;
case 0340:
return false;
case 0360:
if (prefix->osp || prefix->rep)
return false;
break;
case 0361:
if (!prefix->osp || prefix->rep)
return false;
o_used = true;
break;
case 0362:
if (prefix->osp || prefix->rep != 0xf2)
return false;
drep = 0;
break;
case 0363:
if (prefix->osp || prefix->rep != 0xf3)
return false;
drep = 0;
break;
case 0364:
if (prefix->osp)
return false;
break;
case 0365:
if (prefix->asp)
return false;
break;
case 0366:
if (!prefix->osp)
return false;
o_used = true;
break;
case 0367:
if (!prefix->asp)
return false;
a_used = true;
break;
default:
return false; /* Unknown code */
}
}
if (!vex_ok && (ins->rex & REX_V))
return false;
/* REX cannot be combined with DREX or VEX */
if ((ins->rex & (REX_D|REX_V)) && (prefix->rex & REX_P))
return false;
/*
* Check for unused rep or a/o prefixes.
*/
for (i = 0; i < t->operands; i++) {
if (ins->oprs[i].segment != SEG_RMREG)
a_used = true;
}
if (lock) {
if (ins->prefixes[PPS_LREP])
return false;
ins->prefixes[PPS_LREP] = P_LOCK;
}
if (drep) {
if (ins->prefixes[PPS_LREP])
return false;
ins->prefixes[PPS_LREP] = drep;
}
if (!o_used) {
if (osize != ((segsize == 16) ? 16 : 32)) {
enum prefixes pfx = 0;
switch (osize) {
case 16:
pfx = P_O16;
break;
case 32:
pfx = P_O32;
break;
case 64:
pfx = P_O64;
break;
}
if (ins->prefixes[PPS_OSIZE])
return false;
ins->prefixes[PPS_OSIZE] = pfx;
}
}
if (!a_used && asize != segsize) {
if (ins->prefixes[PPS_ASIZE])
return false;
ins->prefixes[PPS_ASIZE] = asize == 16 ? P_A16 : P_A32;
}
/* Fix: check for redundant REX prefixes */
return data - origdata;
}
/* Condition names for disassembly, sorted by x86 code */
static const char * const condition_name[16] = {
"o", "no", "c", "nc", "z", "nz", "na", "a",
"s", "ns", "pe", "po", "l", "nl", "ng", "g"
};
int32_t disasm(uint8_t *data, char *output, int outbufsize, int segsize,
int32_t offset, int autosync, uint32_t prefer)
{
const struct itemplate * const *p, * const *best_p;
const struct disasm_index *ix;
uint8_t *dp;
int length, best_length = 0;
char *segover;
int i, slen, colon, n;
uint8_t *origdata;
int works;
insn tmp_ins, ins;
uint32_t goodness, best;
int best_pref;
struct prefix_info prefix;
bool end_prefix;
memset(&ins, 0, sizeof ins);
/*
* Scan for prefixes.
*/
memset(&prefix, 0, sizeof prefix);
prefix.asize = segsize;
prefix.osize = (segsize == 64) ? 32 : segsize;
segover = NULL;
origdata = data;
end_prefix = false;
while (!end_prefix) {
switch (*data) {
case 0xF2:
case 0xF3:
prefix.rep = *data++;
break;
case 0xF0:
prefix.lock = *data++;
break;
case 0x2E:
segover = "cs", prefix.seg = *data++;
break;
case 0x36:
segover = "ss", prefix.seg = *data++;
break;
case 0x3E:
segover = "ds", prefix.seg = *data++;
break;
case 0x26:
segover = "es", prefix.seg = *data++;
break;
case 0x64:
segover = "fs", prefix.seg = *data++;
break;
case 0x65:
segover = "gs", prefix.seg = *data++;
break;
case 0x66:
prefix.osize = (segsize == 16) ? 32 : 16;
prefix.osp = *data++;
break;
case 0x67:
prefix.asize = (segsize == 32) ? 16 : 32;
prefix.asp = *data++;
break;
case 0xC4:
case 0xC5:
if (segsize == 64 || (data[1] & 0xc0) == 0xc0) {
prefix.vex[0] = *data++;
prefix.vex[1] = *data++;
if (prefix.vex[0] == 0xc4)
prefix.vex[2] = *data++;
}
prefix.rex = REX_V;
if (prefix.vex[0] == 0xc4) {
prefix.rex |= (~prefix.vex[1] >> 5) & 7; /* REX_RXB */
prefix.rex |= (prefix.vex[2] >> (7-3)) & REX_W;
prefix.vex_m = prefix.vex[1] & 0x1f;
prefix.vex_v = (~prefix.vex[2] >> 3) & 15;
prefix.vex_lp = prefix.vex[2] & 7;
} else {
prefix.rex |= (~prefix.vex[1] >> (7-2)) & REX_R;
prefix.vex_m = 1;
prefix.vex_v = (~prefix.vex[1] >> 3) & 15;
prefix.vex_lp = prefix.vex[1] & 7;
}
end_prefix = true;
break;
case REX_P + 0x0:
case REX_P + 0x1:
case REX_P + 0x2:
case REX_P + 0x3:
case REX_P + 0x4:
case REX_P + 0x5:
case REX_P + 0x6:
case REX_P + 0x7:
case REX_P + 0x8:
case REX_P + 0x9:
case REX_P + 0xA:
case REX_P + 0xB:
case REX_P + 0xC:
case REX_P + 0xD:
case REX_P + 0xE:
case REX_P + 0xF:
if (segsize == 64) {
prefix.rex = *data++;
if (prefix.rex & REX_W)
prefix.osize = 64;
}
end_prefix = true;
break;
default:
end_prefix = true;
break;
}
}
best = -1; /* Worst possible */
best_p = NULL;
best_pref = INT_MAX;
dp = data;
ix = itable + *dp++;
while (ix->n == -1) {
ix = (const struct disasm_index *)ix->p + *dp++;
}
p = (const struct itemplate * const *)ix->p;
for (n = ix->n; n; n--, p++) {
if ((length = matches(*p, data, &prefix, segsize, &tmp_ins))) {
works = true;
/*
* Final check to make sure the types of r/m match up.
* XXX: Need to make sure this is actually correct.
*/
for (i = 0; i < (*p)->operands; i++) {
if (!((*p)->opd[i] & SAME_AS) &&
(
/* If it's a mem-only EA but we have a
register, die. */
((tmp_ins.oprs[i].segment & SEG_RMREG) &&
!(MEMORY & ~(*p)->opd[i])) ||
/* If it's a reg-only EA but we have a memory
ref, die. */
(!(tmp_ins.oprs[i].segment & SEG_RMREG) &&
!(REG_EA & ~(*p)->opd[i]) &&
!((*p)->opd[i] & REG_SMASK)) ||
/* Register type mismatch (eg FS vs REG_DESS):
die. */
((((*p)->opd[i] & (REGISTER | FPUREG)) ||
(tmp_ins.oprs[i].segment & SEG_RMREG)) &&
!whichreg((*p)->opd[i],
tmp_ins.oprs[i].basereg, tmp_ins.rex))
)) {
works = false;
break;
}
}
/*
* Note: we always prefer instructions which incorporate
* prefixes in the instructions themselves. This is to allow
* e.g. PAUSE to be preferred to REP NOP, and deal with
* MMX/SSE instructions where prefixes are used to select
* between MMX and SSE register sets or outright opcode
* selection.
*/
if (works) {
int i, nprefix;
goodness = ((*p)->flags & IF_PFMASK) ^ prefer;
nprefix = 0;
for (i = 0; i < MAXPREFIX; i++)
if (tmp_ins.prefixes[i])
nprefix++;
if (nprefix < best_pref ||
(nprefix == best_pref && goodness < best)) {
/* This is the best one found so far */
best = goodness;
best_p = p;
best_pref = nprefix;
best_length = length;
ins = tmp_ins;
}
}
}
}
if (!best_p)
return 0; /* no instruction was matched */
/* Pick the best match */
p = best_p;
length = best_length;
slen = 0;
/* TODO: snprintf returns the value that the string would have if
* the buffer were long enough, and not the actual length of
* the returned string, so each instance of using the return
* value of snprintf should actually be checked to assure that
* the return value is "sane." Maybe a macro wrapper could
* be used for that purpose.
*/
for (i = 0; i < MAXPREFIX; i++)
switch (ins.prefixes[i]) {
case P_LOCK:
slen += snprintf(output + slen, outbufsize - slen, "lock ");
break;
case P_REP:
slen += snprintf(output + slen, outbufsize - slen, "rep ");
break;
case P_REPE:
slen += snprintf(output + slen, outbufsize - slen, "repe ");
break;
case P_REPNE:
slen += snprintf(output + slen, outbufsize - slen, "repne ");
break;
case P_A16:
slen += snprintf(output + slen, outbufsize - slen, "a16 ");
break;
case P_A32:
slen += snprintf(output + slen, outbufsize - slen, "a32 ");
break;
case P_A64:
slen += snprintf(output + slen, outbufsize - slen, "a64 ");
break;
case P_O16:
slen += snprintf(output + slen, outbufsize - slen, "o16 ");
break;
case P_O32:
slen += snprintf(output + slen, outbufsize - slen, "o32 ");
break;
case P_O64:
slen += snprintf(output + slen, outbufsize - slen, "o64 ");
break;
default:
break;
}
i = (*p)->opcode;
if (i >= FIRST_COND_OPCODE) {
slen += snprintf(output + slen, outbufsize - slen, "%s%s",
nasm_cond_insn_names[i-FIRST_COND_OPCODE],
condition_name[ins.condition]);
} else {
slen += snprintf(output + slen, outbufsize - slen, "%s",
nasm_insn_names[i]);
}
colon = false;
length += data - origdata; /* fix up for prefixes */
for (i = 0; i < (*p)->operands; i++) {
opflags_t t = (*p)->opd[i];
const operand *o = &ins.oprs[i];
int64_t offs;
if (t & SAME_AS) {
o = &ins.oprs[t & ~SAME_AS];
t = (*p)->opd[t & ~SAME_AS];
}
output[slen++] = (colon ? ':' : i == 0 ? ' ' : ',');
offs = o->offset;
if (o->segment & SEG_RELATIVE) {
offs += offset + length;
/*
* sort out wraparound
*/
if (!(o->segment & (SEG_32BIT|SEG_64BIT)))
offs &= 0xffff;
else if (segsize != 64)
offs &= 0xffffffff;
/*
* add sync marker, if autosync is on
*/
if (autosync)
add_sync(offs, 0L);
}
if (t & COLON)
colon = true;
else
colon = false;
if ((t & (REGISTER | FPUREG)) ||
(o->segment & SEG_RMREG)) {
enum reg_enum reg;
reg = whichreg(t, o->basereg, ins.rex);
if (t & TO)
slen += snprintf(output + slen, outbufsize - slen, "to ");
slen += snprintf(output + slen, outbufsize - slen, "%s",
nasm_reg_names[reg-EXPR_REG_START]);
} else if (!(UNITY & ~t)) {
output[slen++] = '1';
} else if (t & IMMEDIATE) {
if (t & BITS8) {
slen +=
snprintf(output + slen, outbufsize - slen, "byte ");
if (o->segment & SEG_SIGNED) {
if (offs < 0) {
offs *= -1;
output[slen++] = '-';
} else
output[slen++] = '+';
}
} else if (t & BITS16) {
slen +=
snprintf(output + slen, outbufsize - slen, "word ");
} else if (t & BITS32) {
slen +=
snprintf(output + slen, outbufsize - slen, "dword ");
} else if (t & BITS64) {
slen +=
snprintf(output + slen, outbufsize - slen, "qword ");
} else if (t & NEAR) {
slen +=
snprintf(output + slen, outbufsize - slen, "near ");
} else if (t & SHORT) {
slen +=
snprintf(output + slen, outbufsize - slen, "short ");
}
slen +=
snprintf(output + slen, outbufsize - slen, "0x%"PRIx64"",
offs);
} else if (!(MEM_OFFS & ~t)) {
slen +=
snprintf(output + slen, outbufsize - slen,
"[%s%s%s0x%"PRIx64"]",
(segover ? segover : ""),
(segover ? ":" : ""),
(o->disp_size == 64 ? "qword " :
o->disp_size == 32 ? "dword " :
o->disp_size == 16 ? "word " : ""), offs);
segover = NULL;
} else if (!(REGMEM & ~t)) {
int started = false;
if (t & BITS8)
slen +=
snprintf(output + slen, outbufsize - slen, "byte ");
if (t & BITS16)
slen +=
snprintf(output + slen, outbufsize - slen, "word ");
if (t & BITS32)
slen +=
snprintf(output + slen, outbufsize - slen, "dword ");
if (t & BITS64)
slen +=
snprintf(output + slen, outbufsize - slen, "qword ");
if (t & BITS80)
slen +=
snprintf(output + slen, outbufsize - slen, "tword ");
if (t & BITS128)
slen +=
snprintf(output + slen, outbufsize - slen, "oword ");
if (t & BITS256)
slen +=
snprintf(output + slen, outbufsize - slen, "yword ");
if (t & FAR)
slen += snprintf(output + slen, outbufsize - slen, "far ");
if (t & NEAR)
slen +=
snprintf(output + slen, outbufsize - slen, "near ");
output[slen++] = '[';
if (o->disp_size)
slen += snprintf(output + slen, outbufsize - slen, "%s",
(o->disp_size == 64 ? "qword " :
o->disp_size == 32 ? "dword " :
o->disp_size == 16 ? "word " :
""));
if (o->eaflags & EAF_REL)
slen += snprintf(output + slen, outbufsize - slen, "rel ");
if (segover) {
slen +=
snprintf(output + slen, outbufsize - slen, "%s:",
segover);
segover = NULL;
}
if (o->basereg != -1) {
slen += snprintf(output + slen, outbufsize - slen, "%s",
nasm_reg_names[(o->basereg-EXPR_REG_START)]);
started = true;
}
if (o->indexreg != -1) {
if (started)
output[slen++] = '+';
slen += snprintf(output + slen, outbufsize - slen, "%s",
nasm_reg_names[(o->indexreg-EXPR_REG_START)]);
if (o->scale > 1)
slen +=
snprintf(output + slen, outbufsize - slen, "*%d",
o->scale);
started = true;
}
if (o->segment & SEG_DISP8) {
const char *prefix;
uint8_t offset = offs;
if ((int8_t)offset < 0) {
prefix = "-";
offset = -offset;
} else {
prefix = "+";
}
slen +=
snprintf(output + slen, outbufsize - slen, "%s0x%"PRIx8"",
prefix, offset);
} else if (o->segment & SEG_DISP16) {
const char *prefix;
uint16_t offset = offs;
if ((int16_t)offset < 0 && started) {
offset = -offset;
prefix = "-";
} else {
prefix = started ? "+" : "";
}
slen +=
snprintf(output + slen, outbufsize - slen,
"%s0x%"PRIx16"", prefix, offset);
} else if (o->segment & SEG_DISP32) {
if (prefix.asize == 64) {
const char *prefix;
uint64_t offset = (int64_t)(int32_t)offs;
if ((int32_t)offs < 0 && started) {
offset = -offset;
prefix = "-";
} else {
prefix = started ? "+" : "";
}
slen +=
snprintf(output + slen, outbufsize - slen,
"%s0x%"PRIx64"", prefix, offset);
} else {
const char *prefix;
uint32_t offset = offs;
if ((int32_t) offset < 0 && started) {
offset = -offset;
prefix = "-";
} else {
prefix = started ? "+" : "";
}
slen +=
snprintf(output + slen, outbufsize - slen,
"%s0x%"PRIx32"", prefix, offset);
}
}
output[slen++] = ']';
} else {
slen +=
snprintf(output + slen, outbufsize - slen, "<operand%d>",
i);
}
}
output[slen] = '\0';
if (segover) { /* unused segment override */
char *p = output;
int count = slen + 1;
while (count--)
p[count + 3] = p[count];
strncpy(output, segover, 2);
output[2] = ' ';
}
return length;
}
int32_t eatbyte(uint8_t *data, char *output, int outbufsize)
{
snprintf(output, outbufsize, "db 0x%02X", *data);
return 1;
}
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