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core-packer/distorm/operands.c

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/*
operands.c

diStorm3 - Powerful disassembler for X86/AMD64
http://ragestorm.net/distorm/
distorm at gmail dot com
Copyright (C) 2003-2012 Gil Dabah

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>
*/


#include "config.h"
#include "operands.h"
#include "x86defs.h"
#include "insts.h"
#include "../mnemonics.h"


/* Maps a register to its register-class mask. */
uint16_t _REGISTERTORCLASS[] = /* Based on _RegisterType enumeration! */
{RM_AX, RM_CX, RM_DX, RM_BX, RM_SP, RM_BP, RM_SI, RM_DI, 0, 0, 0, 0, 0, 0, 0, 0,
 RM_AX, RM_CX, RM_DX, RM_BX, RM_SP, RM_BP, RM_SI, RM_DI, 0, 0, 0, 0, 0, 0, 0, 0,
 RM_AX, RM_CX, RM_DX, RM_BX, RM_SP, RM_BP, RM_SI, RM_DI, 0, 0, 0, 0, 0, 0, 0, 0,
 RM_AX, RM_CX, RM_DX, RM_BX, RM_AX, RM_CX, RM_DX, RM_BX, 0, 0, 0, 0, 0, 0, 0, 0,
 RM_SP, RM_BP, RM_SI, RM_DI,
 0, 0, 0, 0, 0, 0,
 0,
 RM_FPU, RM_FPU, RM_FPU, RM_FPU, RM_FPU, RM_FPU, RM_FPU, RM_FPU,
 RM_MMX, RM_MMX, RM_MMX, RM_MMX, RM_MMX, RM_MMX, RM_MMX, RM_MMX,
 RM_SSE, RM_SSE, RM_SSE, RM_SSE, RM_SSE, RM_SSE, RM_SSE, RM_SSE, RM_SSE, RM_SSE, RM_SSE, RM_SSE, RM_SSE, RM_SSE, RM_SSE, RM_SSE,
 RM_AVX, RM_AVX, RM_AVX, RM_AVX, RM_AVX, RM_AVX, RM_AVX, RM_AVX, RM_AVX, RM_AVX, RM_AVX, RM_AVX, RM_AVX, RM_AVX, RM_AVX, RM_AVX,
 RM_CR, 0, RM_CR, RM_CR, RM_CR, 0, 0, 0, RM_CR,
 RM_DR, RM_DR, RM_DR, RM_DR, 0, 0, RM_DR, RM_DR
};

typedef enum {OPERAND_SIZE_NONE = 0, OPERAND_SIZE8, OPERAND_SIZE16, OPERAND_SIZE32, OPERAND_SIZE64, OPERAND_SIZE80, OPERAND_SIZE128, OPERAND_SIZE256} _OperandSizeType;
static uint16_t _OPSIZETOINT[] = {0, 8, 16, 32, 64, 80, 128, 256};

/* A helper function to fix the 8 bits register if REX is used (to support SIL, DIL, etc). */
static unsigned int _FASTCALL_ operands_fix_8bit_rex_base(unsigned int reg)
{
    if ((reg >= 4) && (reg < 8)) return reg + REGS8_REX_BASE - 4;
    return reg + REGS8_BASE;
}

/* A helper function to set operand's type and size. */
static void _FASTCALL_ operands_set_ts(_Operand* op, _OperandType type, uint16_t size)
{
    op->type = type;
    op->size = size;
}

/* A helper function to set operand's type, size and index. */
static void _FASTCALL_ operands_set_tsi(_Operand* op, _OperandType type, uint16_t size, unsigned int index)
{
    op->type = type;
    op->index = (uint8_t)index;
    op->size = size;
}

/* A helper function to read an unsigned integer from the stream safely. */
static int _FASTCALL_ read_stream_safe_uint(_CodeInfo* ci, void* result, unsigned int size)
{
    ci->codeLen -= size;
    if (ci->codeLen < 0) return FALSE;
    switch (size)
    {
        case 1: *(uint8_t*)result = *(uint8_t*)ci->code; break;
        case 2: *(uint16_t*)result = RUSHORT(ci->code); break;
        case 4: *(uint32_t*)result = RULONG(ci->code); break;
        case 8: *(uint64_t*)result = RULLONG(ci->code); break;
    }
    ci->code += size;
    return TRUE;
}

/* A helper function to read a signed integer from the stream safely. */
static int _FASTCALL_ read_stream_safe_sint(_CodeInfo* ci, int64_t* result, unsigned int size)
{
    ci->codeLen -= size;
    if (ci->codeLen < 0) return FALSE;
    switch (size)
    {
        case 1: *result = *(int8_t*)ci->code; break;
        case 2: *result = RSHORT(ci->code); break;
        case 4: *result = RLONG(ci->code); break;
        case 8: *result = RLLONG(ci->code); break;
    }
    ci->code += size;
    return TRUE;
}

/*
 * SIB decoding is the most confusing part when decoding IA-32 instructions.
 * This explanation should clear up some stuff.
 *
 * ! When base == 5, use EBP as the base register !
 * if (rm == 4) {
 *    if mod == 01, decode SIB byte and ALSO read a 8 bits displacement.
 *    if mod == 10, decode SIB byte and ALSO read a 32 bits displacement.
 *    if mod == 11 <-- EXCEPTION, this is a general-purpose register and mustn't lead to SIB decoding!
 *    ; So far so good, now the confusing part comes in with mod == 0 and base=5, but no worry.
 *    if (mod == 00) {
 *     decode SIB byte WITHOUT any displacement.
 *     EXCEPTION!!! when base == 5, read a 32 bits displacement, but this time DO NOT use (EBP) BASE at all!
 *    }
 *
 *    NOTE: base could specify None (no base register) if base==5 and mod==0, but then you also need DISP32.
 * }
 */
static void operands_extract_sib(_DInst* di, _OperandNumberType opNum,
                                 _PrefixState* ps, _DecodeType effAdrSz,
                                 unsigned int sib, unsigned int mod)
{
    unsigned int scale = 0, index = 0, base = 0;
    unsigned int vrex = ps->vrex;
    uint8_t* pIndex = NULL;

    _Operand* op = &di->ops[opNum];

    /*
     * SIB bits:
     * |7---6-5----3-2---0|
     * |SCALE| INDEX| BASE|
     * |------------------|
     */
    scale = (sib >> 6) & 3;
    index = (sib >> 3) & 7;
    base = sib & 7;

    /*
     * The following fields: base/index/scale/disp8/32 are ALL optional by specific rules!
     * The idea here is to keep the indirection as a simple-memory type.
     * Because the base is optional, and we might be left with only one index.
     * So even if there's a base but no index, or vice versa, we end up with one index register.
     */

    /* In 64 bits the REX prefix might affect the index of the SIB byte. */
    if (vrex & PREFIX_EX_X) {
        ps->usedPrefixes |= INST_PRE_REX;
        index += EX_GPR_BASE;
    }

    if (index == 4) { /* No index is used. Use SMEM. */
        op->type = O_SMEM;
        pIndex = &op->index;
    } else {
        op->type = O_MEM;
        pIndex = &di->base;
        /* No base, unless it is updated below. E.G: [EAX*4] has no base reg. */
    }

    if (base != 5) {
        if (vrex & PREFIX_EX_B) ps->usedPrefixes |= INST_PRE_REX;
        *pIndex = effAdrSz == Decode64Bits ? REGS64_BASE : REGS32_BASE;
        *pIndex += (uint8_t)(base + ((vrex & PREFIX_EX_B) ? EX_GPR_BASE : 0));
    } else if (mod != 0) {
        /*
         * if base == 5 then you have to decode according to MOD.
         * mod(00) - disp32.
         * mod(01) - disp8 + rBP
         * mod(10) - disp32 + rBP
         * mod(11) - not possible, it's a general-purpose register.
         */

        if (vrex & PREFIX_EX_B) ps->usedPrefixes |= INST_PRE_REX;
        if (effAdrSz == Decode64Bits) *pIndex = REGS64_BASE + 5 + ((vrex & PREFIX_EX_B) ? EX_GPR_BASE : 0);
        else *pIndex = REGS32_BASE + 5 + ((vrex & PREFIX_EX_B) ? EX_GPR_BASE : 0);
    } else if (index == 4) {
         /* 32bits displacement only. */
        op->type = O_DISP;
        return;
    }

    if (index != 4) { /* In 64 bits decoding mode, if index == R12, it's valid! */
        if (effAdrSz == Decode64Bits) op->index = (uint8_t)(REGS64_BASE + index);
        else op->index = (uint8_t)(REGS32_BASE + index);
        di->scale = scale != 0 ? (1 << scale) : 0;
    }
}

/*
 * This seems to be the hardest part in decoding the operands.
 * If you take a look carefully at Table 2-2. 32-Bit Addressing Forms with the ModR/M Byte,
 * you will understand it's easy to decode the operands.

 * First we check the DT, so we can decide according to which Table in the documentation we are supposed to decode.
 * Then we follow the specific table whether it's 16 bits or 32/64 bits.

 * Don't forget that Operand Size AND Address Size prefixes may change the decoding!

 * Some instructions force the use of RM16 or other specific types, so take it into account.
 */
static int operands_extract_modrm(_CodeInfo* ci,
                                  _DInst* di, _OpType type,
                                  _OperandNumberType opNum, _PrefixState* ps,
                                  _DecodeType effOpSz, _DecodeType effAdrSz,
                                  int* lockableInstruction, unsigned int mod, unsigned int rm,
                                  _iflags instFlags)
{
    unsigned int vrex = ps->vrex, sib = 0, base = 0;
    _Operand* op = &di->ops[opNum];
    uint16_t size = 0;

    if (mod == 3) {
        /*
         * General-purpose register is handled the same way in 16/32/64 bits decoding modes.
         * NOTE!! that we have to override the size of the register, since it was set earlier as Memory and not Register!
         */
        op->type = O_REG;
        /* Start with original size which was set earlier, some registers have same size of memory and depend on it. */
        size = op->size;
        switch(type)
        {
            case OT_RFULL_M16:
            case OT_RM_FULL:
                switch (effOpSz)
                {
                    case Decode16Bits:
                        ps->usedPrefixes |= INST_PRE_OP_SIZE;
                        if (vrex & PREFIX_EX_B) {
                            ps->usedPrefixes |= INST_PRE_REX;
                            rm += EX_GPR_BASE;
                        }
                        size = 16;
                        rm += REGS16_BASE;
                    break;
                    case Decode32Bits:
                        ps->usedPrefixes |= INST_PRE_OP_SIZE;
                        if (vrex & PREFIX_EX_B) {
                            ps->usedPrefixes |= INST_PRE_REX;
                            rm += EX_GPR_BASE;
                        }
                        size = 32;
                        rm += REGS32_BASE;
                    break;
                    case Decode64Bits:
                        /* A fix for SMSW RAX which use the REX prefix. */
                        if (type == OT_RFULL_M16) ps->usedPrefixes |= INST_PRE_REX;
                        /* CALL NEAR/PUSH/POP defaults to 64 bits. --> INST_64BITS, REX isn't required, thus ignored anyways. */
                        if (instFlags & INST_PRE_REX) ps->usedPrefixes |= INST_PRE_REX;
                        /* Include REX if used for REX.B. */
                        if (vrex & PREFIX_EX_B) {
                            ps->usedPrefixes |= INST_PRE_REX;
                            rm += EX_GPR_BASE;
                        }
                        size = 64;
                        rm += REGS64_BASE;
                    break;
                }
            break;
            case OT_R32_64_M8:
            /* FALL THROUGH, decode 32 or 64 bits register. */
            case OT_R32_64_M16:
            /* FALL THROUGH, decode 32 or 64 bits register. */
            case OT_RM32_64: /* Take care specifically in MOVNTI/MOVD/CVT's instructions, making it _REG64 with REX or if they are promoted. */
                if (vrex & PREFIX_EX_B) {
                    ps->usedPrefixes |= INST_PRE_REX;
                    rm += EX_GPR_BASE;
                }
                /* Is it a promoted instruction? (only INST_64BITS is set and REX isn't required.) */
                if ((ci->dt == Decode64Bits) && ((instFlags & (INST_64BITS | INST_PRE_REX)) == INST_64BITS)) {
                    size = 64;
                    rm += REGS64_BASE;
                    break;
                }
                /* Give a chance to REX.W. Because if it was a promoted instruction we don't care about REX.W anyways. */
                if (vrex & PREFIX_EX_W) {
                    ps->usedPrefixes |= INST_PRE_REX;
                    size = 64;
                    rm += REGS64_BASE;
                } else {
                    size = 32;
                    rm += REGS32_BASE;
                }
            break;
            case OT_RM16_32: /* Used only with MOVZXD instruction to support 16 bits operand. */
                if (vrex & PREFIX_EX_B) {
                    ps->usedPrefixes |= INST_PRE_REX;
                    rm += EX_GPR_BASE;
                }
                /* Is it 16 bits operand size? */
                if (ps->decodedPrefixes & INST_PRE_OP_SIZE) {
                    ps->usedPrefixes |= INST_PRE_OP_SIZE;
                    size = 16;
                    rm += REGS16_BASE;
                } else {
                    size = 32;
                    rm += REGS32_BASE;
                }
            break;
            case OT_RM16:
                if (vrex & PREFIX_EX_B) {
                    ps->usedPrefixes |= INST_PRE_REX;
                    rm += EX_GPR_BASE;
                }
                rm += REGS16_BASE;
            break;
            case OT_RM8:
                if (ps->prefixExtType == PET_REX) {
                    ps->usedPrefixes |= INST_PRE_REX;
                    rm = operands_fix_8bit_rex_base(rm + ((vrex & PREFIX_EX_B) ? EX_GPR_BASE : 0));
                } else rm += REGS8_BASE;
            break;
            case OT_MM32:
            case OT_MM64:
                /* MMX doesn't support extended registers. */
                size = 64;
                rm += MMXREGS_BASE;
            break;

            case OT_XMM16:
            case OT_XMM32:
            case OT_XMM64:
            case OT_XMM128:
                if (vrex & PREFIX_EX_B) {
                    ps->usedPrefixes |= INST_PRE_REX;
                    rm += EX_GPR_BASE;
                }
                size = 128;
                rm += SSEREGS_BASE;
            break;

            case OT_RM32:
            case OT_R32_M8:
            case OT_R32_M16:
                if (vrex & PREFIX_EX_B) {
                    ps->usedPrefixes |= INST_PRE_REX;
                    rm += EX_GPR_BASE;
                }
                size = 32;
                rm += REGS32_BASE;
            break;

            case OT_YMM256:
                if (vrex & PREFIX_EX_B) rm += EX_GPR_BASE;
                rm += AVXREGS_BASE;
            break;
            case OT_YXMM64_256:
            case OT_YXMM128_256:
                if (vrex & PREFIX_EX_B) rm += EX_GPR_BASE;
                if (vrex & PREFIX_EX_L) {
                    size = 256;
                    rm += AVXREGS_BASE;
                } else {
                    size = 128;
                    rm += SSEREGS_BASE;
                }
            break;
            case OT_WXMM32_64:
            case OT_LXMM64_128:
                if (vrex & PREFIX_EX_B) rm += EX_GPR_BASE;
                size = 128;
                rm += SSEREGS_BASE;
            break;

            case OT_WRM32_64:
            case OT_REG32_64_M8:
            case OT_REG32_64_M16:
                if (vrex & PREFIX_EX_B) rm += EX_GPR_BASE;
                if (vrex & PREFIX_EX_W) {
                    size = 64;
                    rm += REGS64_BASE;
                } else {
                    size = 32;
                    rm += REGS32_BASE;
                }
            break;

            default: return FALSE;
        }
        op->size = size;
        op->index = (uint8_t)rm;
        return TRUE;
    }

    /* Memory indirection decoding ahead:) */

    ps->usedPrefixes |= INST_PRE_ADDR_SIZE;
    if (lockableInstruction && (ps->decodedPrefixes & INST_PRE_LOCK)) *lockableInstruction = TRUE;

    if (effAdrSz == Decode16Bits) {
        /* Decoding according to Table 2-1. (16 bits) */
        if ((mod == 0) && (rm == 6)) {
            /* 6 is a special case - only 16 bits displacement. */
            op->type = O_DISP;
            di->dispSize = 16;
            if (!read_stream_safe_sint(ci, (int64_t*)&di->disp, sizeof(int16_t))) return FALSE;
        } else {
            /*
             * Create the O_MEM for 16 bits indirection that requires 2 registers, E.G: [BS+SI].
             * or create O_SMEM for a single register indirection, E.G: [BP].
             */
            static uint8_t MODS[] = {R_BX, R_BX, R_BP, R_BP, R_SI, R_DI, R_BP, R_BX};
            static uint8_t MODS2[] = {R_SI, R_DI, R_SI, R_DI};
            if (rm < 4) {
                op->type = O_MEM;
                di->base = MODS[rm];
                op->index = MODS2[rm];
            } else {
                op->type = O_SMEM;
                op->index = MODS[rm];
            }

            if (mod == 1) { /* 8 bits displacement + indirection */
                di->dispSize = 8;
                if (!read_stream_safe_sint(ci, (int64_t*)&di->disp, sizeof(int8_t))) return FALSE;
            } else if (mod == 2) { /* 16 bits displacement + indirection */
                di->dispSize = 16;
                if (!read_stream_safe_sint(ci, (int64_t*)&di->disp, sizeof(int16_t))) return FALSE;
            }
        }

        if ((rm == 2) || (rm == 3) || ((rm == 6) && (mod != 0))) {
            /* BP's default segment is SS, so ignore it. */
            prefixes_use_segment(INST_PRE_SS, ps, ci->dt, di);
        } else {
            /* Ignore default DS segment. */
            prefixes_use_segment(INST_PRE_DS, ps, ci->dt, di);
        }
    } else { /* Decode32Bits or Decode64Bits! */
        /* Remember that from a 32/64 bits ModR/M byte a SIB byte could follow! */
        if ((mod == 0) && (rm == 5)) {

            /* 5 is a special case - only 32 bits displacement, or RIP relative. */
            di->dispSize = 32;
            if (!read_stream_safe_sint(ci, (int64_t*)&di->disp, sizeof(int32_t))) return FALSE;

            if (ci->dt == Decode64Bits) {
                /* In 64 bits decoding mode depsite of the address size, a RIP-relative address it is. */
                op->type = O_SMEM;
                op->index = R_RIP;
                di->flags |= FLAG_RIP_RELATIVE;
            } else {
                /* Absolute address: */
                op->type = O_DISP;
            }
        } else {
            if (rm == 4) {
                /* 4 is a special case - SIB byte + disp8/32 follows! */
                /* Read SIB byte. */
                if (!read_stream_safe_uint(ci, &sib, sizeof(int8_t))) return FALSE;
                operands_extract_sib(di, opNum, ps, effAdrSz, sib, mod);
            } else {
                op->type = O_SMEM;
                if (vrex & PREFIX_EX_B) {
                    ps->usedPrefixes |= INST_PRE_REX;
                    rm += EX_GPR_BASE;
                }

                if (effAdrSz == Decode64Bits) op->index = (uint8_t)(REGS64_BASE + rm);
                else op->index = (uint8_t)(REGS32_BASE + rm);
            }

            if (mod == 1) {
                di->dispSize = 8;
                if (!read_stream_safe_sint(ci, (int64_t*)&di->disp, sizeof(int8_t))) return FALSE;
            } else if ((mod == 2) || ((sib & 7) == 5)) { /* If there is no BASE, read DISP32! */
                di->dispSize = 32;
                if (!read_stream_safe_sint(ci, (int64_t*)&di->disp, sizeof(int32_t))) return FALSE;
            }
        }

        /* Get the base register. */
        base = op->index;
        if (di->base != R_NONE) base = di->base;
        else if (di->scale >= 2) base = 0; /* If it's only an index but got scale, it's still DS. */
        /* Default for EBP/ESP is SS segment. 64 bits mode ignores DS anyway. */
        if ((base == R_EBP) || (base == R_ESP)) prefixes_use_segment(INST_PRE_SS, ps, ci->dt, di);
        else prefixes_use_segment(INST_PRE_DS, ps, ci->dt, di);
    }

    return TRUE;
}


/*
 * This function is reponsible to textually format a required operand according to its type.
 * It is vital to understand that there are other operands than what the ModR/M byte specifies.

 * Only by decoding the operands of an instruction which got a LOCK prefix, we could tell whether it may use the LOCK prefix.
 * According to Intel, LOCK prefix must precede some specific instructions AND in their memory destination operand form (which means first operand).
 * LOCK INC EAX, would generate an exception, but LOCK INC [EAX] is alright.
 * Also LOCK ADD BX, [BP] would generate an exception.

 * Return code:
 * TRUE - continue parsing the instruction and its operands, everything went right 'till now.
 * FALSE - not enough bytes, or invalid operands.
 */

int operands_extract(_CodeInfo* ci, _DInst* di, _InstInfo* ii,
                     _iflags instFlags, _OpType type, _OperandNumberType opNum,
                     unsigned int modrm, _PrefixState* ps, _DecodeType effOpSz,
                     _DecodeType effAdrSz, int* lockableInstruction)
{
    int ret = 0;
    unsigned int mod = 0, reg = 0, rm = 0, vexV = ps->vexV;
    unsigned int vrex = ps->vrex, typeHandled = TRUE;
    _Operand* op = &di->ops[opNum];

    /* Used to indicate the size of the MEMORY INDIRECTION only. */
    _OperandSizeType opSize = OPERAND_SIZE_NONE;

    /*
     * ModRM bits:
     * |7-6-5--------3-2-0|
     * |MOD|REG/OPCODE|RM |
     * |------------------|
     */
    mod = (modrm >> 6) & 3; /* Mode(register-indirection, disp8+reg+indirection, disp16+reg+indirection, general-purpose register) */
    reg = (modrm >> 3) & 7; /* Register(could be part of the opcode itself or general-purpose register) */
    rm = modrm & 7; /* Specifies which general-purpose register or disp+reg to use. */

    /* -- Memory Indirection Operands (that cannot be a general purpose register) -- */
    switch (type)
    {
        case OT_MEM64_128: /* Used only by CMPXCHG8/16B. */
            /* Make a specific check when the type is OT_MEM64_128 since the lockable CMPXCHG8B uses this one... */
            if (lockableInstruction && (ps->decodedPrefixes & INST_PRE_LOCK)) *lockableInstruction = TRUE;
            if (effOpSz == Decode64Bits) {
                ps->usedPrefixes |= INST_PRE_REX;
                opSize = OPERAND_SIZE128;
            } else opSize = OPERAND_SIZE64;
        break;
        case OT_MEM32: opSize = OPERAND_SIZE32; break;
        case OT_MEM32_64:
            /* Used by MOVNTI. Default size is 32bits, 64bits with REX. */
            if (effOpSz == Decode64Bits) {
                ps->usedPrefixes |= INST_PRE_REX;
                opSize = OPERAND_SIZE64;
            } else opSize = OPERAND_SIZE32;
        break;
        case OT_MEM64: opSize = OPERAND_SIZE64; break;
        case OT_MEM128: opSize = OPERAND_SIZE128; break;
        case OT_MEM16_FULL: /* The size indicates about the second item of the pair. */
            switch (effOpSz)
            {
                case Decode16Bits:
                    ps->usedPrefixes |= INST_PRE_OP_SIZE;
                    opSize = OPERAND_SIZE16;
                break;
                case Decode32Bits:
                    ps->usedPrefixes |= INST_PRE_OP_SIZE;
                    opSize = OPERAND_SIZE32;
                break;
                case Decode64Bits:
                    /* Mark usage of REX only if it was required. */
                    if ((instFlags & (INST_64BITS | INST_PRE_REX)) == (INST_64BITS | INST_PRE_REX)) ps->usedPrefixes |= INST_PRE_REX;
                    opSize = OPERAND_SIZE64;
                break;
            }
        break;
        case OT_MEM16_3264: /* The size indicates about the second item of the pair. */
            if (ci->dt == Decode64Bits) opSize = OPERAND_SIZE64;
            else opSize = OPERAND_SIZE32;
        break;
        case OT_MEM_OPT:
            /* Since the MEM is optional, only when mod != 3, then return true as if the operand was alright. */
            if (mod == 0x3) return TRUE;
        break;
        case OT_FPUM16: opSize = OPERAND_SIZE16; break;
        case OT_FPUM32: opSize = OPERAND_SIZE32; break;
        case OT_FPUM64: opSize = OPERAND_SIZE64; break;
        case OT_FPUM80: opSize = OPERAND_SIZE80; break;
        case OT_LMEM128_256:
            if (vrex & PREFIX_EX_L) opSize = OPERAND_SIZE256;
            else opSize = OPERAND_SIZE128;
        break;
        case OT_MEM: /* Size is unknown, but still handled. */ break;
        default: typeHandled = FALSE; break;
    }
    if (typeHandled) {
        /* All of the above types can't use a general-purpose register (a MOD of 3)!. */
        if (mod == 0x3) {
            if (lockableInstruction) *lockableInstruction = FALSE;
            return FALSE;
        }
        op->size = _OPSIZETOINT[opSize];
        ret = operands_extract_modrm(ci, di, type, opNum, ps, effOpSz, effAdrSz, lockableInstruction, mod, rm, instFlags);
        if ((op->type == O_REG) || (op->type == O_SMEM) || (op->type == O_MEM)) {
            di->usedRegistersMask |= _REGISTERTORCLASS[op->index];
        }
        return ret;
    }

    /* -- Memory Indirection Operands (that can be a register) -- */
    typeHandled = TRUE;
    switch (type)
    {
        case OT_RM_FULL:
            ps->usedPrefixes |= INST_PRE_OP_SIZE;
            /* PUSH/JMP/CALL are automatically promoted to 64 bits! */
            if (effOpSz == Decode32Bits) {
                opSize = OPERAND_SIZE32;
                break;
            } else if (effOpSz == Decode64Bits) {
                /* Mark usage of REX only if it was required. */
                if ((instFlags & INST_64BITS) == 0) ps->usedPrefixes |= INST_PRE_REX;
                opSize = OPERAND_SIZE64;
                break;
            }
            /* FALL THROUGH BECAUSE dt==Decoded16Bits @-<----*/
        case OT_RM16:
            /* If we got here not from OT_RM16, then the prefix was used. */
            if (type != OT_RM16) ps->usedPrefixes |= INST_PRE_OP_SIZE;
            opSize = OPERAND_SIZE16;
        break;
        case OT_RM32_64:
            /* The default size is 32, which can be 64 with a REX only. */
            if (effOpSz == Decode64Bits) {
                opSize = OPERAND_SIZE64;
                /* Mark REX prefix as used if non-promoted instruction. */
                if ((instFlags & (INST_64BITS | INST_PRE_REX)) == (INST_64BITS | INST_PRE_REX)) {
                    ps->usedPrefixes |= INST_PRE_REX;
                }
            } else opSize = OPERAND_SIZE32;
        break;
        case OT_RM16_32:
            /* Ignore REX, it's either 32 or 16 bits RM. */
            if (ps->decodedPrefixes & INST_PRE_OP_SIZE) {
                ps->usedPrefixes |= INST_PRE_OP_SIZE;
                /* Assume: We are in 64bits when we have this operand used. */
                opSize = OPERAND_SIZE16;
            } else opSize = OPERAND_SIZE32;
        break;
        case OT_WXMM32_64:
        case OT_WRM32_64:
            if (vrex & PREFIX_EX_W) opSize = OPERAND_SIZE64;
            else opSize = OPERAND_SIZE32;
        break;
        case OT_YXMM64_256:
            if (vrex & PREFIX_EX_L) opSize = OPERAND_SIZE256;
            else opSize = OPERAND_SIZE64;
        break;
        case OT_YXMM128_256:
            if (vrex & PREFIX_EX_L) opSize = OPERAND_SIZE256;
            else opSize = OPERAND_SIZE128;
        break;
        case OT_LXMM64_128:
            if (vrex & PREFIX_EX_L) opSize = OPERAND_SIZE128;
            else opSize = OPERAND_SIZE64;
        break;
        case OT_RFULL_M16:
            ps->usedPrefixes |= INST_PRE_OP_SIZE;
            opSize = OPERAND_SIZE16;
        break;

        case OT_RM8:
        case OT_R32_M8:
        case OT_R32_64_M8:
        case OT_REG32_64_M8:
            opSize = OPERAND_SIZE8;
        break;

        case OT_XMM16:
        case OT_R32_M16:
        case OT_R32_64_M16:
        case OT_REG32_64_M16:
            opSize = OPERAND_SIZE16;
        break;

        case OT_RM32:
        case OT_MM32:
        case OT_XMM32:
            opSize = OPERAND_SIZE32;
        break;

        case OT_MM64:
        case OT_XMM64:
            opSize = OPERAND_SIZE64;
        break;

        case OT_XMM128: opSize = OPERAND_SIZE128; break;
        case OT_YMM256: opSize = OPERAND_SIZE256; break;
        default: typeHandled = FALSE; break;
    }
    if (typeHandled) {
        /* Fill size of memory dereference for operand. */
        op->size = _OPSIZETOINT[opSize];
        ret = operands_extract_modrm(ci, di, type, opNum, ps, effOpSz, effAdrSz, lockableInstruction, mod, rm, instFlags);
        if ((op->type == O_REG) || (op->type == O_SMEM) || (op->type == O_MEM)) {
            di->usedRegistersMask |= _REGISTERTORCLASS[op->index];
        }
        return ret;
    }

    /* Simple operand type (no ModRM byte). */
    switch (type)
    {
        case OT_IMM8:
            operands_set_ts(op, O_IMM, 8);
            if (!read_stream_safe_uint(ci, &di->imm.byte, sizeof(int8_t))) return FALSE;
        break;
        case OT_IMM_FULL: /* 16, 32 or 64, depends on prefixes. */
            if (effOpSz == Decode16Bits) {
                ps->usedPrefixes |= INST_PRE_OP_SIZE;
                /* FALL THROUGH */
        case OT_IMM16: /* Force 16 bits imm. */
            operands_set_ts(op, O_IMM, 16);
            if (!read_stream_safe_uint(ci, &di->imm.word, sizeof(int16_t))) return FALSE;
        break;
            /*
             * Extension: MOV imm64, requires REX.
             * Make sure it needs the REX.
             * REX must be present because op size function takes it into consideration.
             */
            } else if ((effOpSz == Decode64Bits) &&
                        ((instFlags & (INST_64BITS | INST_PRE_REX)) == (INST_64BITS | INST_PRE_REX))) {
                ps->usedPrefixes |= INST_PRE_REX;

                operands_set_ts(op, O_IMM, 64);
                if (!read_stream_safe_uint(ci, &di->imm.qword, sizeof(int64_t))) return FALSE;
                break;
            } else ps->usedPrefixes |= INST_PRE_OP_SIZE;
            /* FALL THROUGH BECAUSE dt==Decoded32Bits @-<----*/
        case OT_IMM32:
            op->type = O_IMM;
            if (ci->dt == Decode64Bits) {
                /* Imm32 is sign extended to 64 bits! */
                op->size = 64;
                di->flags |= FLAG_IMM_SIGNED;
                if (!read_stream_safe_sint(ci, &di->imm.sqword, sizeof(int32_t))) return FALSE;
            } else {
                op->size = 32;
                if (!read_stream_safe_uint(ci, &di->imm.dword, sizeof(int32_t))) return FALSE;
            }
        break;
        case OT_SEIMM8: /* Sign extended immediate. */
            /*
             * PUSH SEIMM8 can be prefixed by operand size:
             * Input stream: 66, 6a, 55
             * 64bits DT: push small 55
             * 32bits DT: push small 55
             * 16bits DT: push large 55
             * small/large indicates the size of the eSP pointer advancement.
             * Check the instFlags (ii->flags) if it can be operand-size-prefixed and if the prefix exists.
             */
            op->type = O_IMM;
            if ((instFlags & INST_PRE_OP_SIZE) && (ps->decodedPrefixes & INST_PRE_OP_SIZE)) {
                ps->usedPrefixes |= INST_PRE_OP_SIZE;
                switch (ci->dt)
                {
                    case Decode16Bits: op->size = 32; break;
                    case Decode32Bits:
                    case Decode64Bits:
                        op->size = 16;
                    break;
                }
            } else op->size = 8;
            di->flags |= FLAG_IMM_SIGNED;
            if (!read_stream_safe_sint(ci, &di->imm.sqword, sizeof(int8_t))) return FALSE;
        break;
        case OT_IMM16_1:
            operands_set_ts(op, O_IMM1, 16);
            if (!read_stream_safe_uint(ci, &di->imm.ex.i1, sizeof(int16_t))) return FALSE;
        break;
        case OT_IMM8_1:
            operands_set_ts(op, O_IMM1, 8);
            if (!read_stream_safe_uint(ci, &di->imm.ex.i1, sizeof(int8_t))) return FALSE;
        break;
        case OT_IMM8_2:
            operands_set_ts(op, O_IMM2, 8);
            if (!read_stream_safe_uint(ci, &di->imm.ex.i2, sizeof(int8_t))) return FALSE;
        break;
        case OT_REG8:
            operands_set_ts(op, O_REG, 8);
            if (ps->prefixExtType) {
                /*
                 * If REX prefix is valid then we will have to use low bytes.
                 * This is a PASSIVE behaviour changer of REX prefix, it affects operands even if its value is 0x40 !
                 */
                ps->usedPrefixes |= INST_PRE_REX;
                op->index = (uint8_t)operands_fix_8bit_rex_base(reg + ((vrex & PREFIX_EX_R) ? EX_GPR_BASE : 0));
            } else op->index = (uint8_t)(REGS8_BASE + reg);
        break;
        case OT_REG16:
            operands_set_tsi(op, O_REG, 16, REGS16_BASE + reg);
        break;
        case OT_REG_FULL:
            switch (effOpSz)
            {
                case Decode16Bits:
                    ps->usedPrefixes |= INST_PRE_OP_SIZE;
                    if (vrex & PREFIX_EX_R) {
                        ps->usedPrefixes |= INST_PRE_REX;
                        reg += EX_GPR_BASE;
                    }
                    operands_set_tsi(op, O_REG, 16, REGS16_BASE + reg);
                break;
                case Decode32Bits:
                    if (vrex & PREFIX_EX_R) {
                        ps->usedPrefixes |= INST_PRE_REX;
                        reg += EX_GPR_BASE;
                    } else ps->usedPrefixes |= INST_PRE_OP_SIZE;
                    operands_set_tsi(op, O_REG, 32, REGS32_BASE + reg);
                break;
                case Decode64Bits: /* rex must be presented. */
                    ps->usedPrefixes |= INST_PRE_REX;
                    operands_set_tsi(op, O_REG, 64, REGS64_BASE + reg + ((vrex & PREFIX_EX_R) ? EX_GPR_BASE : 0));
                break;
            }
        break;
        case OT_REG32:
            if (vrex & PREFIX_EX_R) {
                ps->usedPrefixes |= INST_PRE_REX;
                reg += EX_GPR_BASE;
            }
            operands_set_tsi(op, O_REG, 32, REGS32_BASE + reg);
        break;
        case OT_REG32_64: /* Handle CVT's, MOVxX and MOVNTI instructions which could be extended to 64 bits registers with REX. */
            if (vrex & PREFIX_EX_R) {
                ps->usedPrefixes |= INST_PRE_REX;
                reg += EX_GPR_BASE;
            }

            /* Is it a promoted instruction? (only INST_64BITS is set and REX isn't required.) */
            if ((ci->dt == Decode64Bits) && ((instFlags & (INST_64BITS | INST_PRE_REX)) == INST_64BITS)) {
                operands_set_tsi(op, O_REG, 64, REGS64_BASE + reg);
                break;
            }
            /* Give a chance to REX.W. Because if it was a promoted instruction we don't care about REX.W anyways. */
            if (vrex & PREFIX_EX_W) {
                ps->usedPrefixes |= INST_PRE_REX;
                operands_set_tsi(op, O_REG, 64, REGS64_BASE + reg);
            } else operands_set_tsi(op, O_REG, 32, REGS32_BASE + reg);
        break;
        case OT_FREG32_64_RM: /* Force decoding mode. Used for MOV CR(n)/DR(n) which defaults to 64 bits operand size in 64 bits. */
            if (vrex & PREFIX_EX_B) {
                ps->usedPrefixes |= INST_PRE_REX;
                rm += EX_GPR_BASE;
            }

            if (ci->dt == Decode64Bits) operands_set_tsi(op, O_REG, 64, REGS64_BASE + rm);
            else operands_set_tsi(op, O_REG, 32, REGS32_BASE + rm);
        break;
        case OT_MM: /* MMX register */
            operands_set_tsi(op, O_REG, 64, MMXREGS_BASE + reg);
        break;
        case OT_MM_RM: /* MMX register, this time from the RM field */
            operands_set_tsi(op, O_REG, 64, MMXREGS_BASE + rm);
        break;
        case OT_REGXMM0: /* Implicit XMM0 operand. */
            reg = 0;
            vrex = 0;
        /* FALL THROUGH */
        case OT_XMM: /* SSE register */
            if (vrex & PREFIX_EX_R) {
                ps->usedPrefixes |= INST_PRE_REX;
                reg += EX_GPR_BASE;
            }
            operands_set_tsi(op, O_REG, 128, SSEREGS_BASE + reg);
        break;
        case OT_XMM_RM: /* SSE register, this time from the RM field */
            if (vrex & PREFIX_EX_B) {
                ps->usedPrefixes |= INST_PRE_REX;
                rm += EX_GPR_BASE;
            }
            operands_set_tsi(op, O_REG, 128, SSEREGS_BASE + rm);
        break;
        case OT_CREG:
            /*
             * Don't parse if the reg exceeds the bounds of the array.
             * Most of the CR's are not implemented, so if there's no matching string, the operand is invalid.
             */
            if (vrex & PREFIX_EX_R) {
                ps->usedPrefixes |= INST_PRE_REX;
                reg += EX_GPR_BASE;
            } else if ((ci->dt == Decode32Bits) && (ps->decodedPrefixes & INST_PRE_LOCK)) {
                /*
                 * NOTE: In 32 bits decoding mode,
                 * if the lock prefix is set before MOV CR(n) it will become the 4th bit of the REG field like REX.R in 64 bits.
                 */
                reg += EX_GPR_BASE;
                ps->usedPrefixes |= INST_PRE_LOCK;
            }
            /* Ignore some registers which do not exist. */
            if ((reg >= CREGS_MAX) || (reg == 1) || ((reg >= 5) && (reg <= 7))) return FALSE;

            op->type = O_REG;
            if (ci->dt == Decode64Bits) op->size = 64;
            else op->size = 32;
            op->index = (uint8_t)(CREGS_BASE + reg);
        break;
        case OT_DREG:
            /*
             * In 64 bits there are 16 debug registers.
             * but accessing any of dr8-15 which aren't implemented will cause an #ud.
             */
            if ((reg == 4) || (reg == 5) || (vrex & PREFIX_EX_R)) return FALSE;

            op->type = O_REG;
            if (ci->dt == Decode64Bits) op->size = 64;
            else op->size = 32;
            op->index = (uint8_t)(DREGS_BASE + reg);
        break;
        case OT_SREG: /* Works with REG16 only! */
            /* If lockableInstruction pointer is non-null we know it's the first operand. */
            if (lockableInstruction && (reg == 1)) return FALSE; /* Can't MOV CS, <REG>. */
            /*Don't parse if the reg exceeds the bounds of the array. */
            if (reg <= SEG_REGS_MAX - 1) operands_set_tsi(op, O_REG, 16, SREGS_BASE + reg);
            else return FALSE;
        break;
        case OT_SEG:
            op->type = O_REG;
            /* Size of reg is always 16, it's up to caller to zero extend it to operand size. */
            op->size = 16;
            ps->usedPrefixes |= INST_PRE_OP_SIZE;
            /*
             * Extract the SEG from ii->flags this time!!!
             * Check whether an operand size prefix is used.
             */
            switch (instFlags & INST_PRE_SEGOVRD_MASK)
            {
                case INST_PRE_ES: op->index = R_ES; break;
                case INST_PRE_CS: op->index = R_CS; break;
                case INST_PRE_SS: op->index = R_SS; break;
                case INST_PRE_DS: op->index = R_DS; break;
                case INST_PRE_FS: op->index = R_FS; break;
                case INST_PRE_GS: op->index = R_GS; break;
            }
        break;
        case OT_ACC8:
            operands_set_tsi(op, O_REG, 8, R_AL);
        break;
        case OT_ACC16:
            operands_set_tsi(op, O_REG, 16, R_AX);
        break;
        case OT_ACC_FULL_NOT64: /* No REX.W support for IN/OUT. */
            vrex &= ~PREFIX_EX_W;
        case OT_ACC_FULL:
            if (effOpSz == Decode16Bits) {
                ps->usedPrefixes |= INST_PRE_OP_SIZE;
                operands_set_tsi(op, O_REG, 16, R_AX);
            } else if (effOpSz == Decode32Bits) {
                ps->usedPrefixes |= INST_PRE_OP_SIZE;
                operands_set_tsi(op, O_REG, 32, R_EAX);
            } else { /* Decode64Bits */
                /* Only non-promoted instructions need REX in order to decode in 64 bits. */
                /* MEM-OFFSET MOV's are NOT automatically promoted to 64 bits. */
                if (~instFlags & INST_64BITS) {
                    ps->usedPrefixes |= INST_PRE_REX;
                }
                operands_set_tsi(op, O_REG, 64, R_RAX);
            }
        break;
        case OT_PTR16_FULL:
            /* ptr16:full - full is size of operand size to read, therefore Operand Size Prefix affects this. So we need to handle it. */
            if (effOpSz == Decode16Bits) {
                ps->usedPrefixes |= INST_PRE_OP_SIZE;
                ci->codeLen -= sizeof(int16_t)*2;
                if (ci->codeLen < 0) return FALSE;

                operands_set_ts(op, O_PTR, 16);
                di->imm.ptr.off = RUSHORT(ci->code); /* Read offset first. */
                di->imm.ptr.seg = RUSHORT((ci->code + sizeof(int16_t))); /* And read segment. */

                ci->code += sizeof(int16_t)*2;
            } else { /* Decode32Bits, for Decode64Bits this instruction is invalid. */
                ps->usedPrefixes |= INST_PRE_OP_SIZE;
                ci->codeLen -= sizeof(int32_t) + sizeof(int16_t);
                if (ci->codeLen < 0) return FALSE;

                operands_set_ts(op, O_PTR, 32);
                di->imm.ptr.off = RULONG(ci->code); /* Read 32bits offset this time. */
                di->imm.ptr.seg = RUSHORT((ci->code + sizeof(int32_t))); /* And read segment, 16 bits. */
                
                ci->code += sizeof(int32_t) + sizeof(int16_t);
            }
        break;
        case OT_RELCB:
        case OT_RELC_FULL:

            if (type == OT_RELCB) {
                operands_set_ts(op, O_PC, 8);
                if (!read_stream_safe_sint(ci, &di->imm.sqword, sizeof(int8_t))) return FALSE;
            } else { /* OT_RELC_FULL */

                /* Yep, operand size prefix affects relc also.  */
                ps->usedPrefixes |= INST_PRE_OP_SIZE;
                if (effOpSz == Decode16Bits) {
                    operands_set_ts(op, O_PC, 16);
                    if (!read_stream_safe_sint(ci, &di->imm.sqword, sizeof(int16_t))) return FALSE;
                } else { /* Decode32Bits or Decode64Bits = for now they are the same */
                    operands_set_ts(op, O_PC, 32);
                    if (!read_stream_safe_sint(ci, &di->imm.sqword, sizeof(int32_t))) return FALSE;
                }
            }

            /* Support for hint, see if there's a segment override. */
            if ((ii->opcodeId >= I_JO) && (ii->opcodeId <= I_JG)) {
                if (ps->decodedPrefixes & INST_PRE_CS) {
                    ps->usedPrefixes |= INST_PRE_CS;
                    di->flags |= FLAG_HINT_NOT_TAKEN;
                } else if (ps->decodedPrefixes & INST_PRE_DS) {
                    ps->usedPrefixes |= INST_PRE_DS;
                    di->flags |= FLAG_HINT_TAKEN;
                }
            }
        break;
        case OT_MOFFS8:
            op->size = 8;
            /* FALL THROUGH, size won't be changed. */
        case OT_MOFFS_FULL:
            op->type = O_DISP;
            if (op->size == 0) {
                /* Calculate size of operand (same as ACC size). */
                switch (effOpSz)
                {
                    case Decode16Bits: op->size = 16; break;
                    case Decode32Bits: op->size = 32; break;
                    case Decode64Bits: op->size = 64; break;
                }
            }

            prefixes_use_segment(INST_PRE_DS, ps, ci->dt, di);

            /*
             * Just a pointer to a BYTE, WORD, DWORD, QWORD. Works only with ACC8/16/32/64 respectively. 
             * MOV [0x1234], AL ; MOV AX, [0x1234] ; MOV EAX, [0x1234], note that R/E/AX will be chosen by OT_ACC_FULL.
             */
            if (effAdrSz == Decode16Bits) {
                ps->usedPrefixes |= INST_PRE_ADDR_SIZE;

                di->dispSize = 16;
                if (!read_stream_safe_uint(ci, &di->disp, sizeof(int16_t))) return FALSE;
            } else if (effAdrSz == Decode32Bits) {
                ps->usedPrefixes |= INST_PRE_ADDR_SIZE;

                di->dispSize = 32;
                if (!read_stream_safe_uint(ci, &di->disp, sizeof(int32_t))) return FALSE;
            } else { /* Decode64Bits */
                di->dispSize = 64;
                if (!read_stream_safe_uint(ci, &di->disp, sizeof(int64_t))) return FALSE;
            }
        break;
        case OT_CONST1:
            operands_set_ts(op, O_IMM, 8);
            di->imm.byte = 1;
        break;
        case OT_REGCL:
            operands_set_tsi(op, O_REG, 8, R_CL);
        break;

        case OT_FPU_SI:
            /* Low 3 bits specify the REG, similar to the MODR/M byte reg. */
            operands_set_tsi(op, O_REG, 32, FPUREGS_BASE + (*(ci->code-1) & 7));
        break;
        case OT_FPU_SSI:
            operands_set_tsi(op, O_REG, 32, R_ST0);
            operands_set_tsi(op + 1, O_REG, 32, FPUREGS_BASE + (*(ci->code-1) & 7));
        break;
        case OT_FPU_SIS:
            operands_set_tsi(op, O_REG, 32, FPUREGS_BASE + (*(ci->code-1) & 7));
            operands_set_tsi(op + 1, O_REG, 32, R_ST0);
        break;

        /*
         * Special treatment for Instructions-Block:
         * INC/DEC (only 16/32 bits) /PUSH/POP/XCHG instructions, which get their REG from their own binary code.

         * Notice these instructions are 1 or 2 byte long,
         * code points after the byte which represents the instruction itself,
         * thus, even if the instructions are 2 bytes long it will read its last byte which contains the REG info.
         */
        case OT_IB_RB:
            /* Low 3 bits specify the REG, similar to the MODR/M byte reg. */
            operands_set_ts(op, O_REG, 8);
            reg = *(ci->code-1) & 7;
            if (vrex & PREFIX_EX_B) {
                ps->usedPrefixes |= INST_PRE_REX;
                op->index = (uint8_t)operands_fix_8bit_rex_base(reg + EX_GPR_BASE);
            } else if (ps->prefixExtType == PET_REX) {
                ps->usedPrefixes |= INST_PRE_REX;
                op->index = (uint8_t)operands_fix_8bit_rex_base(reg);
            } else op->index = (uint8_t)(REGS8_BASE + reg);
        break;
        case OT_IB_R_FULL:
            reg = *(ci->code-1) & 7;
            switch (effOpSz)
            {
                case Decode16Bits:
                    ps->usedPrefixes |= INST_PRE_OP_SIZE;
                    if (vrex & PREFIX_EX_B) {
                        ps->usedPrefixes |= INST_PRE_REX;
                        reg += EX_GPR_BASE;
                    }
                    operands_set_tsi(op, O_REG, 16, REGS16_BASE + reg);
                break;
                case Decode32Bits:
                    if (vrex & PREFIX_EX_B) {
                        ps->usedPrefixes |= INST_PRE_REX;
                        reg += EX_GPR_BASE;
                    } else ps->usedPrefixes |= INST_PRE_OP_SIZE;
                    operands_set_tsi(op, O_REG, 32, REGS32_BASE + reg);
                break;
                case Decode64Bits:
                    /*
                     * Automatically promoted instruction can drop REX prefix if not required.
                     * PUSH/POP defaults to 64 bits. --> INST_64BITS
                     * MOV imm64 / BSWAP requires REX.W to be 64 bits --> INST_64BITS | INST_PRE_REX
                     */
                    if ((instFlags & INST_64BITS) && ((instFlags & INST_PRE_REX) == 0)) {
                        if (vrex & PREFIX_EX_B) {
                            ps->usedPrefixes |= INST_PRE_REX;
                            reg += EX_GPR_BASE;
                        }
                    } else {
                        ps->usedPrefixes |= INST_PRE_REX;
                        reg += (vrex & PREFIX_EX_B) ? EX_GPR_BASE : 0;
                    }
                    operands_set_tsi(op, O_REG, 64, REGS64_BASE + reg);
                break;
            }
        break;

        /*
         * Special treatment for repeatable instructions.

         * We want the following output:
         * If there's only the REP/NZ prefix, we won't output anything (All operands are implicit).
         * If there's an operand size prefix, we will change the suffix letter of the mnemonic, which specifies the size of operand to the required one.
         * If there's a segment override prefix, we will output the segment and the used index register (EDI/ESI).
         * If there's an address size prefix, we will output the (segment if needed and) the used and inverted index register (DI/SI).

         * Example:
         * :: Decoding in 16 bits mode! ::
         * AD ~ LODSW
         * 66 AD ~ LODSD
         * F3 AC ~ REP LODSB
         * F3 66 AD ~ REP LODSD
         * F3 3E AC ~ REP LODS BYTE DS:[SI]
         * F3 67 AD ~ REP LODS WORD [ESI]

         * The basic form of a repeatable instruction has its operands hidden and has a suffix letter
         * which implies on the size of operation being done.
         * Therefore, we cannot change the mnemonic here when we encounter another prefix and its not the decoder's responsibility to do so.
         * That's why the caller is responsible to add the suffix letter if no other prefixes are used.
         * And all we are doing here is formatting the operand correctly.
         */
        case OT_REGI_ESI:
            ps->usedPrefixes |= INST_PRE_ADDR_SIZE;

            op->type = O_SMEM;

            /* This might be a 16, 32 or 64 bits instruction, depends on the decoding mode. */
            if (instFlags & INST_16BITS) {
                ps->usedPrefixes |= INST_PRE_OP_SIZE;

                if (effOpSz == Decode16Bits) op->size = 16;
                else if ((effOpSz == Decode64Bits) && (instFlags & INST_64BITS)) {
                    ps->usedPrefixes |= INST_PRE_REX;
                    op->size = 64;
                } else op->size = 32;
            } else op->size = 8;

            /*
             * Clear segment in case OT_REGI_EDI was parsed earlier,
             * DS can be overridden and therefore has precedence.
             */
            di->segment = 0;
            prefixes_use_segment(INST_PRE_DS, ps, ci->dt, di);

            if (effAdrSz == Decode16Bits) op->index = R_SI;
            else if (effAdrSz == Decode32Bits) op->index = R_ESI;
            else op->index = R_RSI;
        break;
        case OT_REGI_EDI:
            ps->usedPrefixes |= INST_PRE_ADDR_SIZE;

            op->type = O_SMEM;

            /* This might be a 16 or 32 bits instruction, depends on the decoding mode. */
            if (instFlags & INST_16BITS) {
                ps->usedPrefixes |= INST_PRE_OP_SIZE;

                if (effOpSz == Decode16Bits) op->size = 16;
                else if ((effOpSz == Decode64Bits) && (instFlags & INST_64BITS)) {
                    ps->usedPrefixes |= INST_PRE_REX;
                    op->size = 64;
                } else op->size = 32;
            } else op->size = 8;

            /* Note: The [rDI] operand can't be prefixed by a segment override, therefore we don't set usedPrefixes. */
            if ((opNum == ONT_1) && (ci->dt != Decode64Bits)) di->segment = R_ES | SEGMENT_DEFAULT; /* No ES in 64 bits mode. */

            if (effAdrSz == Decode16Bits) op->index = R_DI;
            else if (effAdrSz == Decode32Bits) op->index = R_EDI;
            else op->index = R_RDI;
        break;

        /* Used for In/Out instructions varying forms. */
        case OT_REGDX:
            /* Simple single IN/OUT instruction. */
            operands_set_tsi(op, O_REG, 16, R_DX);
        break;

        /* Used for INVLPGA instruction. */
        case OT_REGECX:
            operands_set_tsi(op, O_REG, 32, R_ECX);
        break;
        case OT_REGI_EBXAL:
            /* XLAT BYTE [rBX + AL] */
            ps->usedPrefixes |= INST_PRE_ADDR_SIZE;

            prefixes_use_segment(INST_PRE_DS, ps, ci->dt, di);

            /* Size of deref is always 8 for xlat. */
            operands_set_tsi(op, O_MEM, 8, R_AL);

            if (effAdrSz == Decode16Bits) di->base = R_BX;
            else if (effAdrSz == Decode32Bits) di->base = R_EBX;
            else {
                ps->usedPrefixes |= INST_PRE_REX;
                di->base = R_RBX;
            }
        break;
        case OT_REGI_EAX:
            /*
             * Implicit rAX as memory indirection operand. Used by AMD's SVM instructions.
             * Since this is a memory indirection, the default address size in 64bits decoding mode is 64.
             */

            if (effAdrSz == Decode64Bits) operands_set_tsi(op, O_SMEM, 64, R_RAX);
            else if (effAdrSz == Decode32Bits) {
                ps->usedPrefixes |= INST_PRE_ADDR_SIZE;
                operands_set_tsi(op, O_SMEM, 32, R_EAX);
            } else {
                ps->usedPrefixes |= INST_PRE_ADDR_SIZE;
                operands_set_tsi(op, O_SMEM, 16, R_AX);
            }
        break;
        case OT_VXMM:
            operands_set_tsi(op, O_REG, 128, SSEREGS_BASE + vexV);
        break;
        case OT_XMM_IMM:
            ci->codeLen -= sizeof(int8_t);
            if (ci->codeLen < 0) return FALSE;

            if (ci->dt == Decode32Bits) reg = (*ci->code >> 4) & 0x7;
            else reg = (*ci->code >> 4) & 0xf;
            operands_set_tsi(op, O_REG, 128, SSEREGS_BASE + reg);

            ci->code += sizeof(int8_t);
        break;
        case OT_YXMM:
            if (vrex & PREFIX_EX_R) reg += EX_GPR_BASE;
            if (ps->vrex & PREFIX_EX_L) operands_set_tsi(op, O_REG, 256, AVXREGS_BASE + reg);
            else operands_set_tsi(op, O_REG, 128, SSEREGS_BASE + reg);
        break;
        case OT_YXMM_IMM:
            ci->codeLen -= sizeof(int8_t);
            if (ci->codeLen < 0) return FALSE;

            if (ci->dt == Decode32Bits) reg = (*ci->code >> 4) & 0x7;
            else reg = (*ci->code >> 4) & 0xf;

            if (ps->vrex & PREFIX_EX_L) operands_set_tsi(op, O_REG, 256, AVXREGS_BASE + reg);
            else operands_set_tsi(op, O_REG, 128, SSEREGS_BASE + reg);

            ci->code += sizeof(int8_t);
        break;
        case OT_YMM:
            if (vrex & PREFIX_EX_R) reg += EX_GPR_BASE;
            operands_set_tsi(op, O_REG, 256, AVXREGS_BASE + reg);
        break;
        case OT_VYMM:
            operands_set_tsi(op, O_REG, 256, AVXREGS_BASE + vexV);
        break;
        case OT_VYXMM:
            if (ps->vrex & PREFIX_EX_L) operands_set_tsi(op, O_REG, 256, AVXREGS_BASE + vexV);
            else operands_set_tsi(op, O_REG, 128, SSEREGS_BASE + vexV); 
        break;
        case OT_WREG32_64:
            if (vrex & PREFIX_EX_R) reg += EX_GPR_BASE;
            if (ps->vrex & PREFIX_EX_W) operands_set_tsi(op, O_REG, 64, REGS64_BASE + reg);
            else operands_set_tsi(op, O_REG, 32, REGS32_BASE + reg);
        break;
        default: return FALSE;
    }

    if ((op->type == O_REG) || (op->type == O_SMEM) || (op->type == O_MEM)) {
        di->usedRegistersMask |= _REGISTERTORCLASS[op->index];
    }

    return TRUE;
}