X86 microop ISA

Register Ops

These microops typically take two sources and produce one result. Most have a version that operates on only registers and a version which operates on registers and an immediate value. Some optionally set flags according to their operation. Some of them can be predicated.

Add

Addition.

add Dest, Src1, Src2

Dest = Dest <- Src1 + Src2

Adds the contents of the Src1 and Src2 registers and puts the result in the Dest register.

addi Dest, Src1, Imm

Dest = Dest <- Src1 + Imm

Adds the contents of the Src1 register and the immediate Imm and puts the result in the Dest register.

Flags

This microop optionally sets the CF, ECF, ZF, EZF, PF, AF, SF, and OF flags.

CF and ECF	The carry out of the most significant bit.
ZF and EZF	Whether the result was zero.
PF	The parity of the result.
AF	The carry from the 4th to 5th bit positions.
SF	The sign of the result.
OF	Whether there was an overflow.

Adc

Add with carry.

adc Dest, Src1, Src2

Dest = Dest <- Src1 + Src2 + CF

Adds the contents of the Src1 and Src2 registers and the carry flag and puts the result in the Dest register.

adci Dest, Src1, Imm

Dest = Dest <- Src1 + Imm + CF

Adds the contents of the Src1 register, the immediate Imm, and the carry flag and puts the result in the Dest register.

Flags

This microop optionally sets the CF, ECF, ZF, EZF, PF, AF, SF, and OF flags.

CF and ECF	The carry out of the most significant bit.
ZF and EZF	Whether the result was zero.
PF	The parity of the result.
AF	The carry from the 4th to 5th bit positions.
SF	The sign of the result.
OF	Whether there was an overflow.

Sub

Subtraction.

sub Dest, Src1, Src2

Dest = Dest <- Src1 - Src2

Subtracts the contents of the Src2 register from the Src1 register and puts the result in the Dest register.

subi Dest, Src1, Imm

Dest = Dest <- Src1 - Imm

Subtracts the contents of the immediate Imm from the Src1 register and puts the result in the Dest register.

Flags

This microop optionally sets the CF, ECF, ZF, EZF, PF, AF, SF, and OF flags.

CF and ECF	The barrow into of the most significant bit.
ZF and EZF	Whether the result was zero.
PF	The parity of the result.
AF	The barrow from the 5th to 4th bit positions.
SF	The sign of the result.
OF	Whether there was an overflow.

Sbb

Subtract with barrow.

sbb Dest, Src1, Src2

Dest = Dest <- Src1 - Src2 - CF

Subtracts the contents of the Src2 register and the carry flag from the Src1 register and puts the result in the Dest register.

sbbi Dest, Src1, Imm

Dest = Dest <- Src1 - Imm - CF

Subtracts the immediate Imm and the carry flag from the Src1 register and puts the result in the Dest register.

Flags

This microop optionally sets the CF, ECF, ZF, EZF, PF, AF, SF, and OF flags.

CF and ECF	The barrow into of the most significant bit.
ZF and EZF	Whether the result was zero.
PF	The parity of the result.
AF	The barrow from the 5th to 4th bit positions.
SF	The sign of the result.
OF	Whether there was an overflow.

Mul1s

Signed multiply.

mul1s Src1, Src2

ProdHi:ProdLo = Src1 * Src2

Multiplies the unsigned contents of the Src1 and Src2 registers and puts the high and low portions of the product into the internal registers ProdHi and ProdLo, respectively.

mul1si Src1, Imm

ProdHi:ProdLo = Src1 * Imm

Multiplies the unsigned contents of the Src1 register and the immediate Imm and puts the high and low portions of the product into the internal registers ProdHi and ProdLo, respectively.

Flags

This microop does not set any flags.

Mul1u

Unsigned multiply.

mul1u Src1, Src2

ProdHi:ProdLo = Src1 * Src2

Multiplies the unsigned contents of the Src1 and Src2 registers and puts the high and low portions of the product into the internal registers ProdHi and ProdLo, respectively.

mul1ui Src1, Imm

ProdHi:ProdLo = Src1 * Imm

Multiplies the unsigned contents of the Src1 register and the immediate Imm and puts the high and low portions of the product into the internal registers ProdHi and ProdLo, respectively.

Flags

This microop does not set any flags.

Mulel

Unload multiply result low.

mulel Dest

Dest = Dest <- ProdLo

Moves the value of the internal ProdLo register into the Dest register.

Flags

This microop does not set any flags.

Muleh

Unload multiply result high.

muleh Dest

Dest = Dest <- ProdHi

Moves the value of the internal ProdHi register into the Dest register.

Flags

This microop optionally sets the CF, ECF, and OF flags.

CF and ECF	Whether ProdHi is non-zero
OF	Whether ProdHi is non-zero.

Div1

First stage of division.

div1 Src1, Src2

Quotient * Src2 + Remainder = Src1 Divisor = Src2

Begins a division operation where the contents of SrcReg1 is the high part of the dividend and the contents of SrcReg2 is the divisor. The remainder from this partial division is put in the internal register Remainder. The quotient is put in the internal register Quotient. The divisor is put in the internal register Divisor.

div1i Src1, Imm:

Quotient * Imm + Remainder = Src1 Divisor = Imm

Begins a division operation where the contents of SrcReg1 is the high part of the dividend and the immediate Imm is the divisor. The remainder from this partial division is put in the internal register Remainder. The quotient is put in the internal register Quotient. The divisor is put in the internal register Divisor.

Flags

This microop does not set any flags.

Div2

Second and later stages of division.

div2 Dest, Src1, Src2

Quotient * Divisor + Remainder = original Remainder with bits shifted in from Src1

Dest = Dest <- Src2 - number of bits shifted in above

Performs subsequent steps of division following a div1 instruction. The contents of the register Src1 is the low portion of the dividend. The contents of the register Src2 denote the number of bits in Src1 that have not yet been used before this step in the division. Dest is set to the number of bits in Src1 that have not been used after this step. The internal registers Quotient, Divisor, and Remainder are updated by this instruction.

If there are no remaining bits in Src1, this instruction does nothing except optionally compute flags.

div2i Dest, Src1, Imm

Quotient * Divisor + Remainder = original Remainder with bits shifted in from Src1

Dest = Dest <- Imm - number of bits shifted in above

Performs subsequent steps of division following a div1 instruction. The contents of the register Src1 is the low portion of the dividend. The immediate Imm denotes the number of bits in Src1 that have not yet been used before this step in the division. Dest is set to the number of bits in Src1 that have not been used after this step. The internal registers Quotient, Divisor, and Remainder are updated by this instruction.

If there are no remaining bits in Src1, this instruction does nothing except optionally compute flags.

Flags

This microop optionally sets the EZF flag.

EZF	Whether there are any remaining bits in Src1 after this step.

Divq

Unload division quotient.

divq Dest

Dest = Dest <- Quotient

Moves the value of the internal Quotient register into the Dest register.

Flags

This microop does not set any flags.

Divr

Unload division remainder.

divr Dest

Dest = Dest <- Remainder

Moves the value of the internal Remainder register into the Dest register.

Flags

This microop does not set any flags.

Or

Logical or.

or Dest, Src1, Src2

Dest = Dest <- Src1 | Src2

Computes the bitwise or of the contents of the Src1 and Src2 registers and puts the result in the Dest register.

ori Dest, Src1, Imm

Dest = Dest <- Src1 | Imm

Computes the bitwise or of the contents of the Src1 register and the immediate Imm and puts the result in the Dest register.

Flags

This microop optionally sets the CF, ECF, ZF, EZF, PF, AF, SF, and OF flags. There is nothing that prevents computing a value for the AF flag, but it's value will be meaningless.

CF and ECF	Cleared
ZF and EZF	Whether the result was zero.
PF	The parity of the result.
AF	Undefined
SF	The sign of the result.
OF	Cleared

And

Logical And

and Dest, Src1, Src2

Dest = Dest <- Src1 & Src2

Computes the bitwise and of the contents of the Src1 and Src2 registers and puts the result in the Dest register.

andi Dest, Src1, Imm

Dest = Dest <- Src1 & Imm

Computes the bitwise and of the contents of the Src1 register and the immediate Imm and puts the result in the Dest register.

Flags

This microop optionally sets the CF, ECF, ZF, EZF, PF, AF, SF, and OF flags. There is nothing that prevents computing a value for the AF flag, but it's value will be meaningless.

CF and ECF	Cleared
ZF and EZF	Whether the result was zero.
PF	The parity of the result.
AF	Undefined
SF	The sign of the result.
OF	Cleared

Xor

Logical exclusive or.

xor Dest, Src1, Src2

Dest = Dest <- Src1 | Src2

Computes the bitwise xor of the contents of the Src1 and Src2 registers and puts the result in the Dest register.

xori Dest, Src1, Imm

Dest = Dest <- Src1 | Imm

Computes the bitwise xor of the contents of the Src1 register and the immediate Imm and puts the result in the Dest register.

Flags

This microop optionally sets the CF, ECF, ZF, EZF, PF, AF, SF, and OF flags. There is nothing that prevents computing a value for the AF flag, but it's value will be meaningless.

CF and ECF	Cleared
ZF and EZF	Whether the result was zero.
PF	The parity of the result.
AF	Undefined
SF	The sign of the result.
OF	Cleared

Sll

Logical left shift.

sll Dest, Src1, Src2

Dest = Dest <- Src1 << Src2

Shifts the contents of the Src1 register to the left by the value in the Src2 register and writes the result into the Dest register. The shift amount is truncated to either 5 or 6 bits, depending on the operand size.

slli Dest, Src1, Imm

Dest = Dest <- Src1 << Imm

Shifts the contents of the Src1 register to the left by the value in the immediate Imm and writes the result into the Dest register. The shift amount is truncated to either 5 or 6 bits, depending on the operand size.

Flags

This microop optionally sets the CF, ECF, and OF flags. If the shift amount is zero, no flags are modified.

CF and ECF	The last bit shifted out of the result.
OF	The exclusive or of the what this instruction would set the CF flag to (if requested) and the most significant bit of the result

Srl

Logical right shift.

srl Dest, Src1, Src2

Dest = Dest <- Src1 >>(logical) Src2

Shifts the contents of the Src1 register to the right by the value in the Src2 register and writes the result into the Dest register. Bits which are shifted in sign extend the result. The shift amount is truncated to either 5 or 6 bits, depending on the operand size.

srli Dest, Src1, Imm

Dest = Dest <- Src1 >>(logical) Imm

Shifts the contents of the Src1 register to the right by the value in the immediate Imm and writes the result into the Dest register. Bits which are shifted in sign extend the result. The shift amount is truncated to either 5 or 6 bits, depending on the operand size.

Flags

This microop optionally sets the CF, ECF, and OF flags. If the shift amount is zero, no flags are modified.

CF and ECF	The last bit shifted out of the result.
OF	The most significant bit of the original value to shift

Sra

Arithmetic right shift.

sra Dest, Src1, Src2

Dest = Dest <- Src1 >>(arithmetic) Src2

Shifts the contents of the Src1 register to the right by the value in the Src2 register and writes the result into the Dest register. Bits which are shifted in zero extend the result. The shift amount is truncated to either 5 or 6 bits, depending on the operand size.

srai Dest, Src1, Imm

Dest = Dest <- Src1 >>(arithmetic) Imm

Shifts the contents of the Src1 register to the right by the value in the immediate Imm and writes the result into the Dest register. Bits which are shifted in zero extend the result. The shift amount is truncated to either 5 or 6 bits, depending on the operand size.

Flags

This microop optionally sets the CF, ECF, and OF flags. If the shift amount is zero, no flags are modified.

CF and ECF	The last bit shifted out of the result.
OF	Cleared

Ror

Rotate right.

ror Dest, Src1, Src2

Rotates the contents of the Src1 register to the right by the value in the Src2 register and writes the result into the Dest register. The rotate amount is truncated to either 5 or 6 bits, depending on the operand size.

rori Dest, Src1, Imm

Rotates the contents of the Src1 register to the right by the value in the immediate Imm and writes the result into the Dest register. The rotate amount is truncated to either 5 or 6 bits, depending on the operand size.

Flags

This microop optionally sets the CF, ECF, and OF flags. If the rotate amount is zero, no flags are modified.

CF and ECF	The most significant bit of the result.
OF	The exclusive or of the two most significant bits of the original value.

Rcr

Rotate right through carry.

rcr Dest, Src1, Src2

Rotates the contents of the Src1 register through the carry flag and to the right by the value in the Src2 register and writes the result into the Dest register. The rotate amount is truncated to either 5 or 6 bits, depending on the operand size.

rcri Dest, Src1, Imm

Rotates the contents of the Src1 register through the carry flag and to the right by the value in the immediate Imm and writes the result into the Dest register. The rotate amount is truncated to either 5 or 6 bits, depending on the operand size.

Flags

This microop optionally sets the CF, ECF, and OF flags. If the rotate amount is zero, no flags are modified.

CF and ECF	The last bit shifted out of the result.
OF	The exclusive or of the CF flag before the rotate and the most significant bit of the original value.

Rol

Rotate left.

rol Dest, Src1, Src2

Rotates the contents of the Src1 register to the left by the value in the Src2 register and writes the result into the Dest register. The rotate amount is truncated to either 5 or 6 bits, depending on the operand size.

roli Dest, Src1, Imm

Rotates the contents of the Src1 register to the left by the value in the immediate Imm and writes the result into the Dest register. The rotate amount is truncated to either 5 or 6 bits, depending on the operand size.

Flags

This microop optionally sets the CF, ECF, and OF flags. If the rotate amount is zero, no flags are modified.

CF and ECF	The least significant bit of the result.
OF	The exclusive or of the most and least significant bits of the result.

Rcl

Rotate left through carry.

rcl Dest, Src1, Src2

Rotates the contents of the Src1 register through the carry flag and to the left by the value in the Src2 register and writes the result into the Dest register. The rotate amount is truncated to either 5 or 6 bits, depending on the operand size.

rcli Dest, Src1, Imm

Rotates the contents of the Src1 register through the carry flag and to the left by the value in the immediate Imm and writes the result into the Dest register. The rotate amount is truncated to either 5 or 6 bits, depending on the operand size.

Flags

This microop optionally sets the CF, ECF, and OF flags. If the rotate amount is zero, no flags are modified.

CF and ECF	The last bit rotated out of the result.
OF	The exclusive or of CF before the rotate and most significant bit of the result.

Mov

Move.

mov Dest, Src1, Src2

Dest = Src1 <- Src2

Merge the contents of the Src2 register into the contents of Src1 and put the result into the Dest register.

movi Dest, Src1, Imm

Dest = Src1 <- Imm

Merge the contents of the immediate Imm into the contents of Src1 and put the results into the Dest register.

Flags

This microop does not set any flags. It is optionally predicated.

Sext

Sign extend.

sext Dest, Src1, Imm

Dest = Dest <- sign_extend(Src1, Imm)

Sign extend the value in the Src1 register starting at the bit position in the immediate Imm, and put the result in the Dest register.

Flags

This microop does not set any flags.

Zext

Zero extend.

zext Dest, Src1, Imm

Dest = Dest <- zero_extend(Src1, Imm)

Zero extend the value in the Src1 register starting at the bit position in the immediate Imm, and put the result in the Dest register.

Flags

This microop does not set any flags.

Ruflag

Read user flag.

ruflag Dest, Imm

Reads the user level flag stored in the bit position specified by the immediate Imm and stores it in the register Dest.

The mapping between values of Imm and user level flags is show in the following table.

0	CF (carry flag)
2	PF (parity flag)
3	ECF (emulation carry flag)
4	AF (auxiliary carry flag)
5	EZF (emulation zero flag)
6	ZF (zero flag)
7	SF (sign flag)
10	DF (direction flag)
11	OF (overflow flag)

Flags

The EZF flag is always set. In the future this may become optional.

EZF	Set if the value of the flag read was zero.

Ruflags

Read all user flags.

ruflags Dest

Dest = user flags

Store the user level flags into the Dest register.

Flags

This microop does not set any flags.

Wruflags

Write all user flags.

wruflags Src1, Src2

user flags = Src1 ^ Src2

Set the user level flags to the exclusive or of the Src1 and Src2 registers.

wruflagsi Src1, Imm

user flags = Src1 ^ Imm

Set the user level flags to the exclusive or of the Src1 register and the immediate Imm.

Flags

See above.

Rdip

Read the instruction pointer.

rdip Dest

Dest = rIP

Set the Dest register to the current value of rIP.

Flags

This microop does not set any flags.

Wrip

Write the instruction pointer.

wrip Src1, Src2

rIP = Src1 + Src2

Set the rIP to the sum of the Src1 and Src2 registers. This causes a macroop branch at the end of the current macroop.

wripi Src1, Imm

micropc = Src1 + Imm

Set the rIP to the sum of the Src1 register and immediate Imm. This causes a macroop branch at the end of the current macroop.

Flags

This microop does not set any flags. It is optionally predicated.

Chks

Check selector.

Not yet implemented.

Load/Store Ops

Ld

Load.

ld Data, Seg, Sib, Disp

Loads the integer register Data from memory.

Ldf

Load floating point.

ldf Data, Seg, Sib, Disp

Loads the floating point register Data from memory.

Ldm

Load multimedia.

ldm Data, Seg, Sib, Disp

Load the multimedia register Data from memory. This is not implemented and may never be.

Ldst

Load with store check.

Ldst Data, Seg, Sib, Disp

Load the integer register Data from memory while also checking if a store to that location would succeed. This is not implemented currently.

Ldstl

Load with store check, locked.

Ldst Data, Seg, Sib, Disp

Load the integer register Data from memory while also checking if a store to that location would succeed, and also provide the semantics of the "LOCK" instruction prefix. This is not implemented currently.

St

Store.

st Data, Seg, Sib, Disp

Stores the integer register Data to memory.

Stf

Store floating point.

stf Data, Seg, Sib, Disp

Stores the floating point register Data to memory.

Stm

Store multimedia.

stm Data, Seg, Sib, Disp

Store the multimedia register Data to memory. This is not implemented and may never be.

Stupd

Store with base update.

Stupd Data, Seg, Sib, Disp

Store the integer register Data to memory and update the base register.

Lea

Load effective address.

lea Data, Seg, Sib, Disp

Calculates the address for this combination of parameters and stores it in Data.

Cda

Check data address.

cda Seg, Sib, Disp

Check whether the data address is valid. This is not implemented currently.

Cdaf

CDA with cache line flush.

cdaf Seg, Sib, Disp

Check whether the data address is valid, and flush cache lines This is not implemented currently.

Cia

Check instruction address.

cia Seg, Sib, Disp

Check whether the instruction address is valid. This is not implemented currently.

Tia

TLB invalidate address

tia Seg, Sib, Disp

Invalidate the tlb entry which corresponds to this address. This is not implemented currently.

Load immediate Op

Limm

limm Dest, Imm

Stores the 64 bit immediate Imm into the integer register Dest.

Floating Point Ops

Movfp

movfp Dest, Src

Dest = Src

Move the contents of the floating point register Src into the floating point register Dest.

This instruction is predicated.

Xorfp

xorfp Dest, Src1, Src2

Dest = Src1 ^ Src2

Compute the bitwise exclusive or of the floating point registers Src1 and Src2 and put the result in the floating point register Dest.

Sqrtfp

sqrtfp Dest, Src

Dest = sqrt(Src)

Compute the square root of the floating point register Src and put the result in floating point register Dest.

Addfp

addfp Dest, Src1, Src2

Dest = Src1 + Src2

Compute the sum of the floating point registers Src1 and Src2 and put the result in the floating point register Dest.

Subfp

subfp Dest, Src1, Src2

Dest = Src1 - Src2

Compute the difference of the floating point registers Src1 and Src2 and put the result in the floating point register Dest.

Mulfp

mulfp Dest, Src1, Src2

Dest = Src1 * Src2

Compute the product of the floating point registers Src1 and Src2 and put the result in the floating point register Dest.

Divfp

divfp Dest, Src1, Src2

Dest = Src1 / Src2

Divide Src1 by Src2 and put the result in the floating point register Dest.

Compfp

compfp Src1, Src2

Compare floating point registers Src1 and Src2.

Cvtf_i2d

cvtf_i2d Dest, Src

Convert integer register Src into a double floating point value and store the result in the lower part of Dest.

Cvtf_i2d_hi

cvtf_i2d_hi Dest, Src

Convert integer register Src into a double floating point value and store the result in the upper part of Dest.

Cvtf_d2i

cvtf_d2i Dest, Src

Convert floating point register Src into an integer value and store the result in the integer register Dest.

Special Ops

Fault

Generate a fault.

fault fault_code

Uses the C++ code fault_code to allocate a Fault object to return.

Lddha

Set the default handler for a fault. This is not implemented currently.

Ldaha

Set the alternate handler for a fault This is not implemented currently.

Sequencing Ops

These microops are used for control flow withing microcode

Br

Microcode branch. This is never considered the last microop of a sequence. If it appears at the end of a macroop, it is assumed that it branches to microcode in the ROM.

br target

micropc = target

Set the micropc to the 16 bit immediate target.

Flags

This microop does not set any flags. It is optionally predicated.

Eret

Return from emulation. This instruction is always considered the last microop in a sequence. When executing from the ROM, it is the only way to return to normal instruction decoding.

eret

Return from emulation.

Flags

This microop does not set any flags. It is optionally predicated.