decode_operand(ref ud u,
ref ud_operand operand,
ud_operand_code type,
ud_operand_size size)
{
operand.type = ud_type.UD_NONE;
operand._oprcode = type;
switch (type)
{
case ud_operand_code.OP_A:
decode_a(ref u, ref operand);
break;
case ud_operand_code.OP_MR:
decode_modrm_rm(ref u, ref operand, (byte)reg_class.REGCLASS_GPR,
BitOps.MODRM_MOD(modrm(ref u)) == 3 ?
size.Mx_reg_size() : size.Mx_mem_size());
break;
case ud_operand_code.OP_F:
u.br_far = 1;
if (BitOps.MODRM_MOD(modrm(ref u)) == 3)
{
u.error = 1;
u.errorMessage = "expected modrm.mod != 3\n";
}
decode_modrm_rm(ref u, ref operand, reg_class.REGCLASS_GPR, size);
break;
case ud_operand_code.OP_M:
if (BitOps.MODRM_MOD(modrm(ref u)) == 3)
{
u.error = 1;
u.errorMessage = "expected modrm.mod != 3\n";
}
decode_modrm_rm(ref u, ref operand, reg_class.REGCLASS_GPR, size);
break;
case ud_operand_code.OP_E:
decode_modrm_rm(ref u, ref operand, reg_class.REGCLASS_GPR, size);
break;
case ud_operand_code.OP_G:
decode_modrm_reg(ref u, ref operand, reg_class.REGCLASS_GPR, size);
break;
case ud_operand_code.OP_sI:
case ud_operand_code.OP_I:
decode_imm(ref u, size, ref operand);
break;
case ud_operand_code.OP_I1:
operand.type = ud_type.UD_OP_CONST;
operand.lval.udword = 1;
break;
case ud_operand_code.OP_N:
if (BitOps.MODRM_MOD(modrm(ref u)) != 3)
{
u.error = 1;
u.errorMessage = "expected modrm.mod == 3\n";
}
decode_modrm_rm(ref u, ref operand, reg_class.REGCLASS_MMX, size);
break;
case ud_operand_code.OP_Q:
decode_modrm_rm(ref u, ref operand, reg_class.REGCLASS_MMX, size);
break;
case ud_operand_code.OP_P:
decode_modrm_reg(ref u, ref operand, reg_class.REGCLASS_MMX, size);
break;
case ud_operand_code.OP_U:
if (BitOps.MODRM_MOD(modrm(ref u)) != 3)
{
u.error = 1;
u.errorMessage = "expected modrm.mod == 3\n";
}
decode_modrm_rm(ref u, ref operand, reg_class.REGCLASS_XMM, size);
break;
case ud_operand_code.OP_W:
decode_modrm_rm(ref u, ref operand, reg_class.REGCLASS_XMM, size);
break;
case ud_operand_code.OP_V:
decode_modrm_reg(ref u, ref operand, reg_class.REGCLASS_XMM, size);
break;
case ud_operand_code.OP_H:
decode_vex_vvvv(ref u, ref operand, size);
break;
case ud_operand_code.OP_MU:
decode_modrm_rm(ref u, ref operand, reg_class.REGCLASS_XMM,
BitOps.MODRM_MOD(modrm(ref u)) == 3 ?
size.Mx_reg_size() : size.Mx_mem_size());
break;
case ud_operand_code.OP_S:
decode_modrm_reg(ref u, ref operand, reg_class.REGCLASS_SEG, size);
break;
case ud_operand_code.OP_O:
decode_moffset(ref u, size, ref operand);
break;
case ud_operand_code.OP_R0:
case ud_operand_code.OP_R1:
case ud_operand_code.OP_R2:
case ud_operand_code.OP_R3:
case ud_operand_code.OP_R4:
case ud_operand_code.OP_R5:
case ud_operand_code.OP_R6:
case ud_operand_code.OP_R7:
decode_reg(ref u, ref operand, reg_class.REGCLASS_GPR,
(byte)((BitOps.REX_B(u._rex) << 3) | (type - ud_operand_code.OP_R0)), size);
break;
case ud_operand_code.OP_AL:
case ud_operand_code.OP_AX:
case ud_operand_code.OP_eAX:
case ud_operand_code.OP_rAX:
decode_reg(ref u, ref operand, reg_class.REGCLASS_GPR, 0, size);
break;
case ud_operand_code.OP_CL:
case ud_operand_code.OP_CX:
case ud_operand_code.OP_eCX:
decode_reg(ref u, ref operand, reg_class.REGCLASS_GPR, 1, size);
break;
case ud_operand_code.OP_DL:
case ud_operand_code.OP_DX:
case ud_operand_code.OP_eDX:
decode_reg(ref u, ref operand, reg_class.REGCLASS_GPR, 2, size);
break;
case ud_operand_code.OP_ES:
case ud_operand_code.OP_CS:
case ud_operand_code.OP_DS:
case ud_operand_code.OP_SS:
case ud_operand_code.OP_FS:
case ud_operand_code.OP_GS:
/* in 64bits mode, only fs and gs are allowed */
if (u.dis_mode == 64)
{
if (type != ud_operand_code.OP_FS && type != ud_operand_code.OP_GS)
{
u.error = 1;
u.errorMessage = "invalid segment register in 64bits\n";
}
}
operand.type = ud_type.UD_OP_REG;
operand.@base = (type - ud_operand_code.OP_ES) + ud_type.UD_R_ES;
operand.size = 16;
break;
case ud_operand_code.OP_J:
decode_imm(ref u, size, ref operand);
operand.type = ud_type.UD_OP_JIMM;
break;
case ud_operand_code.OP_R:
if (BitOps.MODRM_MOD(modrm(ref u)) != 3)
{
u.error = 1;
u.errorMessage = "expected modrm.mod == 3\n";
}
decode_modrm_rm(ref u, ref operand, reg_class.REGCLASS_GPR, size);
break;
case ud_operand_code.OP_C:
decode_modrm_reg(ref u, ref operand, reg_class.REGCLASS_CR, size);
break;
case ud_operand_code.OP_D:
decode_modrm_reg(ref u, ref operand, reg_class.REGCLASS_DB, size);
break;
case ud_operand_code.OP_I3:
operand.type = ud_type.UD_OP_CONST;
operand.lval.@sbyte = 3;
break;
case ud_operand_code.OP_ST0:
case ud_operand_code.OP_ST1:
case ud_operand_code.OP_ST2:
case ud_operand_code.OP_ST3:
case ud_operand_code.OP_ST4:
case ud_operand_code.OP_ST5:
case ud_operand_code.OP_ST6:
case ud_operand_code.OP_ST7:
operand.type = ud_type.UD_OP_REG;
operand.@base = (type - ud_operand_code.OP_ST0) + ud_type.UD_R_ST0;
operand.size = 80;
break;
case ud_operand_code.OP_L:
decode_vex_immreg(ref u, ref operand, size);
break;
default:
operand.type = ud_type.UD_NONE;
break;
}
return(operand.type);
}
decode_modrm_rm(ref ud u,
ref ud_operand op,
reg_class type, /* register type */
ud_operand_size size) /* operand size */
{
int offset = 0;
byte mod, rm;
/* get mod, r/m and reg fields */
mod = BitOps.MODRM_MOD(modrm(ref u));
rm = (byte)((BitOps.REX_B(u._rex) << 3) | BitOps.MODRM_RM(modrm(ref u)));
/*
* If mod is 11b, then the modrm.rm specifies a register.
*
*/
if (mod == 3)
{
decode_reg(ref u, ref op, type, rm, size);
return;
}
/*
* !11b => Memory Address
*/
op.type = ud_type.UD_OP_MEM;
op.size = (byte)resolve_operand_size(ref u, size);
if (u.adr_mode == 64)
{
op.@base = ud_type.UD_R_RAX + rm;
if (mod == 1)
{
offset = 8;
}
else if (mod == 2)
{
offset = 32;
}
else if (mod == 0 && (rm & 7) == 5)
{
op.@base = ud_type.UD_R_RIP;
offset = 32;
}
else
{
offset = 0;
}
/*
* Scale-Index-Base (SIB)
*/
if ((rm & 7) == 4)
{
inp_next(ref u);
op.@base = ud_type.UD_R_RAX + (BitOps.SIB_B(inp_curr(ref u)) | (BitOps.REX_B(u._rex) << 3));
op.index = ud_type.UD_R_RAX + (BitOps.SIB_I(inp_curr(ref u)) | (BitOps.REX_X(u._rex) << 3));
/* special conditions for base reference */
if (op.index == ud_type.UD_R_RSP)
{
op.index = ud_type.UD_NONE;
op.scale = (byte)ud_type.UD_NONE;
}
else
{
op.scale = (byte)((1 << BitOps.SIB_S(inp_curr(ref u))) & ~1);
}
if (op.@base == ud_type.UD_R_RBP || op.@base == ud_type.UD_R_R13)
{
if (mod == 0)
{
op.@base = ud_type.UD_NONE;
}
if (mod == 1)
{
offset = 8;
}
else
{
offset = 32;
}
}
}
else
{
op.scale = 0;
op.index = ud_type.UD_NONE;
}
}
else if (u.adr_mode == 32)
{
op.@base = ud_type.UD_R_EAX + rm;
if (mod == 1)
{
offset = 8;
}
else if (mod == 2)
{
offset = 32;
}
else if (mod == 0 && rm == 5)
{
op.@base = ud_type.UD_NONE;
offset = 32;
}
else
{
offset = 0;
}
/* Scale-Index-Base (SIB) */
if ((rm & 7) == 4)
{
inp_next(ref u);
op.scale = (byte)((1 << BitOps.SIB_S(inp_curr(ref u))) & ~1);
op.index = ud_type.UD_R_EAX + (BitOps.SIB_I(inp_curr(ref u)) | (BitOps.REX_X(u.pfx_rex) << 3));
op.@base = ud_type.UD_R_EAX + (BitOps.SIB_B(inp_curr(ref u)) | (BitOps.REX_B(u.pfx_rex) << 3));
if (op.index == ud_type.UD_R_ESP)
{
op.index = ud_type.UD_NONE;
op.scale = (byte)ud_type.UD_NONE;
}
/* special condition for base reference */
if (op.@base == ud_type.UD_R_EBP)
{
if (mod == 0)
{
op.@base = ud_type.UD_NONE;
}
if (mod == 1)
{
offset = 8;
}
else
{
offset = 32;
}
}
}
else
{
op.scale = 0;
op.index = ud_type.UD_NONE;
}
}
else
{
ud_type[] bases = { ud_type.UD_R_BX, ud_type.UD_R_BX, ud_type.UD_R_BP, ud_type.UD_R_BP,
ud_type.UD_R_SI, ud_type.UD_R_DI, ud_type.UD_R_BP, ud_type.UD_R_BX };
ud_type[] indices = { ud_type.UD_R_SI, ud_type.UD_R_DI, ud_type.UD_R_SI, ud_type.UD_R_DI,
ud_type.UD_NONE, ud_type.UD_NONE, ud_type.UD_NONE, ud_type.UD_NONE };
op.@base = bases[rm & 7];
op.index = indices[rm & 7];
op.scale = 0;
if (mod == 0 && rm == 6)
{
offset = 16;
op.@base = ud_type.UD_NONE;
}
else if (mod == 1)
{
offset = 8;
}
else if (mod == 2)
{
offset = 16;
}
}
if (offset > 0)
{
decode_mem_disp(ref u, offset, ref op);
}
else
{
op.offset = 0;
}
}
