include/opcode/i386.h

   1 /* opcode/i386.h -- Intel 80386 opcode macros
   2    Copyright (C) 1989-2021 Free Software Foundation, Inc.
   3
   4    This file is part of GAS, the GNU Assembler, and GDB, the GNU Debugger.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software
  18    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  19    MA 02110-1301, USA.  */
  20
  21 /* The SystemV/386 SVR3.2 assembler, and probably all AT&T derived
  22    ix86 Unix assemblers, generate floating point instructions with
  23    reversed source and destination registers in certain cases.
  24    Unfortunately, gcc and possibly many other programs use this
  25    reversed syntax, so we're stuck with it.
  26
  27    eg. `fsub %st(3),%st' results in st = st - st(3) as expected, but
  28    `fsub %st,%st(3)' results in st(3) = st - st(3), rather than
  29    the expected st(3) = st(3) - st
  30
  31    This happens with all the non-commutative arithmetic floating point
  32    operations with two register operands, where the source register is
  33    %st, and destination register is %st(i).
  34
  35    The affected opcode map is dceX, dcfX, deeX, defX.  */
  36
  37 #ifndef OPCODE_I386_H
  38 #define OPCODE_I386_H
  39
  40 #ifndef SYSV386_COMPAT
  41 /* Set non-zero for broken, compatible instructions.  Set to zero for
  42    non-broken opcodes at your peril.  gcc generates SystemV/386
  43    compatible instructions.  */
  44 #define SYSV386_COMPAT 1
  45 #endif
  46
  47 #define MOV_AX_DISP32 0xa0
  48 #define POP_SEG_SHORT 0x07
  49 #define POP_SEG386_SHORT 0xfa1
  50 #define JUMP_PC_RELATIVE 0xeb
  51 #define INT_OPCODE  0xcd
  52 #define INT3_OPCODE 0xcc
  53 /* The opcode for the fwait instruction, which disassembler treats as a
  54    prefix when it can.  */
  55 #define FWAIT_OPCODE 0x9b
  56
  57 /* Instruction prefixes.
  58    NOTE: For certain SSE* instructions, 0x66,0xf2,0xf3 are treated as
  59    part of the opcode.  Other prefixes may still appear between them
  60    and the 0x0f part of the opcode.  */
  61 #define ADDR_PREFIX_OPCODE 0x67
  62 #define DATA_PREFIX_OPCODE 0x66
  63 #define LOCK_PREFIX_OPCODE 0xf0
  64 #define CS_PREFIX_OPCODE 0x2e
  65 #define DS_PREFIX_OPCODE 0x3e
  66 #define ES_PREFIX_OPCODE 0x26
  67 #define FS_PREFIX_OPCODE 0x64
  68 #define GS_PREFIX_OPCODE 0x65
  69 #define SS_PREFIX_OPCODE 0x36
  70 #define REPNE_PREFIX_OPCODE 0xf2
  71 #define REPE_PREFIX_OPCODE  0xf3
  72 #define XACQUIRE_PREFIX_OPCODE 0xf2
  73 #define XRELEASE_PREFIX_OPCODE 0xf3
  74 #define BND_PREFIX_OPCODE 0xf2
  75 #define NOTRACK_PREFIX_OPCODE 0x3e
  76
  77 #define TWO_BYTE_OPCODE_ESCAPE 0x0f
  78 #define NOP_OPCODE (char) 0x90
  79
  80 /* register numbers */
  81 #define EAX_REG_NUM 0
  82 #define ECX_REG_NUM 1
  83 #define EDX_REG_NUM 2
  84 #define EBX_REG_NUM 3
  85 #define ESP_REG_NUM 4
  86 #define EBP_REG_NUM 5
  87 #define ESI_REG_NUM 6
  88 #define EDI_REG_NUM 7
  89
  90 /* modrm_byte.regmem for twobyte escape */
  91 #define ESCAPE_TO_TWO_BYTE_ADDRESSING ESP_REG_NUM
  92 /* index_base_byte.index for no index register addressing */
  93 #define NO_INDEX_REGISTER ESP_REG_NUM
  94 /* index_base_byte.base for no base register addressing */
  95 #define NO_BASE_REGISTER EBP_REG_NUM
  96 #define NO_BASE_REGISTER_16 6
  97
  98 /* modrm.mode = REGMEM_FIELD_HAS_REG when a register is in there */
  99 #define REGMEM_FIELD_HAS_REG 0x3/* always = 0x3 */
 100 #define REGMEM_FIELD_HAS_MEM (~REGMEM_FIELD_HAS_REG)
 101
 102 /* Extract fields from the mod/rm byte.  */
 103 #define MODRM_MOD_FIELD(modrm) (((modrm) >> 6) & 3)
 104 #define MODRM_REG_FIELD(modrm) (((modrm) >> 3) & 7)
 105 #define MODRM_RM_FIELD(modrm)  (((modrm) >> 0) & 7)
 106
 107 /* Extract fields from the sib byte.  */
 108 #define SIB_SCALE_FIELD(sib) (((sib) >> 6) & 3)
 109 #define SIB_INDEX_FIELD(sib) (((sib) >> 3) & 7)
 110 #define SIB_BASE_FIELD(sib)  (((sib) >> 0) & 7)
 111
 112 /* x86-64 extension prefix.  */
 113 #define REX_OPCODE      0x40
 114
 115 /* Non-zero if OPCODE is the rex prefix.  */
 116 #define REX_PREFIX_P(opcode) (((opcode) & 0xf0) == REX_OPCODE)
 117
 118 /* Indicates 64 bit operand size.  */
 119 #define REX_W   8
 120 /* High extension to reg field of modrm byte.  */
 121 #define REX_R   4
 122 /* High extension to SIB index field.  */
 123 #define REX_X   2
 124 /* High extension to base field of modrm or SIB, or reg field of opcode.  */
 125 #define REX_B   1
 126
 127 /* max operands per insn */
 128 #define MAX_OPERANDS 5
 129
 130 /* max immediates per insn (lcall, ljmp, insertq, extrq) */
 131 #define MAX_IMMEDIATE_OPERANDS 2
 132
 133 /* max memory refs per insn (string ops) */
 134 #define MAX_MEMORY_OPERANDS 2
 135
 136 /* max size of insn mnemonics.  */
 137 #define MAX_MNEM_SIZE 20
 138
 139 /* max size of register name in insn mnemonics.  */
 140 #define MAX_REG_NAME_SIZE 8
 141
 142 #endif /* OPCODE_I386_H */