分类： LINUX
2007-10-12 16:04:03
Usage: LAHF
Modifies flags: None
Copies bits 0-7 of the flags register into AH. This includes flags
AF, CF, PF, SF and ZF other bits are undefined.
AH := SF ZF xx AF xx PF xx CF
Clocks Size
Operands 808x 286 386 486 Bytes
none 4 2 2 3 1
Usage: LAR dest,src
Modifies flags: ZF
The high byte of the of the destination register is overwritten by
the value of the access rights byte and the low order byte is zeroed
depending on the selection in the source operand. The Zero Flag is
set if the load operation is successful.
Clocks Size
Operands 808x 286 386 486 Bytes
reg16,reg16 - 14 15 11 3
reg32,reg32 - - 15 11 3
reg16,mem16 - 16 16 11 3-7
reg32,mem32 - - 16 11 3-7
Usage: LDS dest,src
Modifies flags: None
Loads 32-bit pointer from memory source to destination register
and DS. The offset is placed in the destination register and the
segment is placed in DS. To use this instruction the word at the
lower memory address must contain the offset and the word at the
higher address must contain the segment. This simplifies the loading
of far pointers from the stack and the interrupt vector table.
Clocks Size
Operands 808x 286 386 486 Bytes
reg16,mem32 16+EA 7 7 6 2-4
reg,mem (PM) - - 22 12 5-7
Usage: LEA dest,src
Modifies flags: None
Transfers offset address of "src" to the destination register.
Clocks Size
Operands 808x 286 386 486 Bytes
reg,mem 2+EA 3 2 1 2-4
- the MOV instruction can often save clock cycles when used in
place of LEA on 8088 processors
Usage: LEAVE
Modifies flags: None
Releases the local variables created by the previous ENTER
instruction by restoring SP and BP to their condition before
the procedure stack frame was initialized.
Clocks Size
Operands 808x 286 386 486 Bytes
none - 5 4 5 1
Usage: LES dest,src
Modifies flags: None
Loads 32-bit pointer from memory source to destination register
and ES. The offset is placed in the destination register and the
segment is placed in ES. To use this instruction the word at the
lower memory address must contain the offset and the word at the
higher address must contain the segment. This simplifies the loading
of far pointers from the stack and the interrupt vector table.
Clocks Size
Operands 808x 286 386 486 Bytes
reg,mem 16+EA 7 7 6 2-4 (W88=24+EA)
reg,mem (PM) - - 22 12 5-7
Usage: LFS dest,src
Modifies flags: None
Loads 32-bit pointer from memory source to destination register
and FS. The offset is placed in the destination register and the
segment is placed in FS. To use this instruction the word at the
lower memory address must contain the offset and the word at the
higher address must contain the segment. This simplifies the loading
of far pointers from the stack and the interrupt vector table.
Clocks Size
Operands 808x 286 386 486 Bytes
reg,mem - - 7 6 5-7
reg,mem (PM) - - 22 12 5-7
Usage: LGDT src
Modifies flags: None
Loads a value from an operand into the Global Descriptor Table
(GDT) register.
Clocks Size
Operands 808x 286 386 486 Bytes
mem64 - 11 11 11 5
Usage: LIDT src
Modifies flags: None
Loads a value from an operand into the Interrupt Descriptor Table
(IDT) register.
Clocks Size
Operands 808x 286 386 486 Bytes
mem64 - 12 11 11 5
Usage: LGS dest,src
Modifies flags: None
Loads 32-bit pointer from memory source to destination register
and GS. The offset is placed in the destination register and the
segment is placed in GS. To use this instruction the word at the
lower memory address must contain the offset and the word at the
higher address must contain the segment. This simplifies the loading
of far pointers from the stack and the interrupt vector table.
Clocks Size
Operands 808x 286 386 486 Bytes
reg,mem - - 7 6 5-7
reg,mem (PM) - - 22 12 5-7
Usage: LLDT src
Modifies flags: None
Loads a value from an operand into the Local Descriptor Table
Register (LDTR).
Clocks Size
Operands 808x 286 386 486 Bytes
reg16 - 17 20 11 3
mem16 - 19 24 11 5
Usage: LMSW src
Modifies flags: None
Loads the Machine Status Word (MSW) from data found at "src"
Clocks Size
Operands 808x 286 386 486 Bytes
reg16 - 3 10 13 3
mem16 - 6 13 13 5
Usage: LOCK
LOCK: (386+ prefix)
Modifies flags: None
This instruction is a prefix that causes the CPU assert bus lock
signal during the execution of the next instruction. Used to
avoid two processors from updating the same data location. The
286 always asserts lock during an XCHG with memory operands. This
should only be used to lock the bus prior to XCHG, MOV, IN and
OUT instructions.
Clocks Size
Operands 808x 286 386 486 Bytes
none 2 0 0 1 1
Usage: LODS src
LODSB
LODSW
LODSD (386+)
Modifies flags: None
Transfers string element addressed by DS:SI (even if an operand is
supplied) to the accumulator. SI is incremented based on the size
of the operand or based on the instruction used. If the Direction
Flag is set SI is decremented, if the Direction Flag is clear SI
is incremented. Use with REP prefixes.
Clocks Size
Operands 808x 286 386 486 Bytes
src 12/16 5 5 5 1
Usage: LOOP label
Modifies flags: None
Decrements CX by 1 and transfers control to "label" if CX is not
Zero. The "label" operand must be within -128 or 127 bytes of the
instruction following the loop instruction
Clocks Size
Operands 808x 286 386 486 Bytes
label: jump 18 8+m 11+m 6 2
no jump 5 4 ? 2
Usage: LOOPE label
LOOPZ label
Modifies flags: None
Decrements CX by 1 (without modifying the flags) and transfers
control to "label" if CX != 0 and the Zero Flag is set. The
"label" operand must be within -128 or 127 bytes of the instruction
following the loop instruction.
Clocks Size
Operands 808x 286 386 486 Bytes
label: jump 18 8+m 11+m 9 2
no jump 5 4 ? 6
Usage: LOOPNZ label
LOOPNE label
Modifies flags: None
Decrements CX by 1 (without modifying the flags) and transfers
control to "label" if CX != 0 and the Zero Flag is clear. The
"label" operand must be within -128 or 127 bytes of the instruction
following the loop instruction.
Clocks Size
Operands 808x 286 386 486 Bytes
label: jump 19 8+m 11+m 9 2
no jump 5 4 ? 6
Usage: LSL dest,src
Modifies flags: ZF
Loads the segment limit of a selector into the destination register
if the selector is valid and visible at the current privilege level.
If loading is successful the Zero Flag is set, otherwise it is
cleared.
Clocks Size
Operands 808x 286 386 486 Bytes
reg16,reg16 - 14 20/25 10 3
reg32,reg32 - - 20/25 10 3
reg16,mem16 - 16 21/26 10 5
reg32,mem32 - - 21/26 10 5
- 386 times are listed "byte granular" / "page granular"
Usage: LSS dest,src
Modifies flags: None
Loads 32-bit pointer from memory source to destination register
and SS. The offset is placed in the destination register and the
segment is placed in SS. To use this instruction the word at the
lower memory address must contain the offset and the word at the
higher address must contain the segment. This simplifies the loading
of far pointers from the stack and the interrupt vector table.
Clocks Size
Operands 808x 286 386 486 Bytes
reg,mem - - 7 6 5-7
reg,mem (PM) - - 22 12 5-7
Usage: LTR src
Modifies flags: None
Loads the current task register with the value specified in "src".
Clocks Size
Operands 808x 286 386 486 Bytes
reg16 - 17 23 20 3
mem16 - 19 27 20 5
Usage: MOV dest,src
Modifies flags: None
Copies byte or word from the source operand to the destination
operand. If the destination is SS interrupts are disabled except
on early buggy 808x CPUs. Some CPUs disable interrupts if the
destination is any of the segment registers
Clocks Size
Operands 808x 286 386 486 Bytes
reg,reg 2 2 2 1 2
mem,reg 9+EA 3 2 1 2-4 (W88=13+EA)
reg,mem 8+EA 5 4 1 2-4 (W88=12+EA)
mem,immed 10+EA 3 2 1 3-6 (W88=14+EA)
reg,immed 4 2 2 1 2-3
mem,accum 10 3 2 1 3 (W88=14)
accum,mem 10 5 4 1 3 (W88=14)
segreg,reg16 2 2 2 3 2
segreg,mem16 8+EA 5 5 9 2-4 (W88=12+EA)
reg16,segreg 2 2 2 3 2
mem16,segreg 9+EA 3 2 3 2-4 (W88=13+EA)
reg32,CR0/CR2/CR3 - - 6 4
CR0,reg32 - - 10 16
CR2,reg32 - - 4 4 3
CR3,reg32 - - 5 4 3
reg32,DR0/DR1/DR2/DR3 - 22 10 3
reg32,DR6/DR7 - - 22 10 3
DR0/DR1/DR2/DR3,reg32 - 22 11 3
DR6/DR7,reg32 - - 16 11 3
reg32,TR6/TR7 - - 12 4 3
TR6/TR7,reg32 - - 12 4 3
reg32,TR3 3
TR3,reg32 6
- when the 386 special registers are used all operands are 32 bits
Usage: MOVS dest,src
MOVSB
MOVSW
MOVSD (386+)
Modifies flags: None
Copies data from addressed by DS:SI (even if operands are given) to
the location ES:DI destination and updates SI and DI based on the
size of the operand or instruction used. SI and DI are incremented
when the Direction Flag is cleared and decremented when the Direction
Flag is Set. Use with REP prefixes.
Clocks Size
Operands 808x 286 386 486 Bytes
dest,src 18 5 7 7 1 (W88=26)
Usage: MOVSX dest,src
Modifies flags: None
Copies the value of the source operand to the destination register
with the sign extended.
Clocks Size
Operands 808x 286 386 486 Bytes
reg,reg - - 3 3 3
reg,mem - - 6 3 3-7
Usage: MOVZX dest,src
Modifies flags: None
Copies the value of the source operand to the destination register
with the zeroes extended.
Clocks Size
Operands 808x 286 386 486 Bytes
reg,reg - - 3 3 3
reg,mem - - 6 3 3-7
Usage: MUL src
Modifies flags: CF OF (AF,PF,SF,ZF undefined)
Unsigned multiply of the accumulator by the source. If "src" is
a byte value, then AL is used as the other multiplicand and the
result is placed in AX. If "src" is a word value, then AX is
multiplied by "src" and DX:AX receives the result. If "src" is
a double word value, then EAX is multiplied by "src" and EDX:EAX
receives the result. The 386+ uses an early out algorithm which
makes multiplying any size value in EAX as fast as in the 8 or 16
bit registers.
Clocks Size
Operands 808x 286 386 486 Bytes
reg8 70-77 13 9-14 13-18 2
reg16 118-113 21 9-22 13-26 2
reg32 - - 9-38 13-42 2-4
mem8 (76-83)+EA 16 12-17 13-18 2-4
mem16 (124-139)+EA 24 12-25 13-26 2-4
mem32 - - 12-21 13-42 2-4
Usage: NEG dest
Modifies flags: AF CF OF PF SF ZF
Subtracts the destination from 0 and saves the 2s complement of
"dest" back into "dest".
Clocks Size
Operands 808x 286 386 486 Bytes
reg 3 2 2 1 2
mem 16+EA 7 6 3 2-4 (W88=24+EA)
Usage: NOP
Modifies flags: None
This is a do nothing instruction. It results in occupation of both
space and time and is most useful for patching code segments.
(This is the original XCHG AL,AL instruction)
Clocks Size
Operands 808x 286 386 486 Bytes
none 3 3 3 1 1
Usage: NOT dest
Modifies flags: None
Inverts the bits of the "dest" operand forming the 1s complement.
Clocks Size
Operands 808x 286 386 486 Bytes
reg 3 2 2 1 2
mem 16+EA 7 6 3 2-4 (W88=24+EA)
Usage: OR dest,src
Modifies flags: CF OF PF SF ZF (AF undefined)
Logical inclusive OR of the two operands returning the result in
the destination. Any bit set in either operand will be set in the
destination.
Clocks Size
Operands 808x 286 386 486 Bytes
reg,reg 3 2 2 1 2
mem,reg 16+EA 7 7 3 2-4 (W88=24+EA)
reg,mem 9+EA 7 6 2 2-4 (W88=13+EA)
reg,immed 4 3 2 1 3-4
mem8,immed8 17+EA 7 7 3 3-6
mem16,immed16 25+EA 7 7 3 3-6
accum,immed 4 3 2 1 2-3
Usage: OUT port,accum
Modifies flags: None
Transfers byte in AL,word in AX or dword in EAX to the specified
hardware port address. If the port number is in the range of 0-255
it can be specified as an immediate. If greater than 255 then the
port number must be specified in DX. Since the PC only decodes 10
bits of the port address, values over 1023 can only be decoded by
third party vendor equipment and also map to the port range 0-1023.
Clocks Size
Operands 808x 286 386 486 Bytes
immed8,accum 10/14 3 10 16 2
immed8,accum (PM) - - 4/24 11/31/29 2
DX,accum 8/12 3 11 16 1
DX,accum (PM) - - 5/25 10/30/29 1
- 386+ protected mode timings depend on privilege levels.
first number is the timing when: CPL ≤ IOPL
second number is the timing when: CPL > IOPL
third number is the timing when: virtual mode on 486 processor
Usage: OUTS port,src
OUTSB
OUTSW
OUTSD (386+)
Modifies flags: None
Transfers a byte, word or doubleword from "src" to the hardware
port specified in DX. For instructions with no operands the "src"
is located at DS:SI and SI is incremented or decremented by the
size of the operand or the size dictated by the instruction format.
When the Direction Flag is set SI is decremented, when clear, SI is
incremented. If the port number is in the range of 0-255 it can
be specified as an immediate. If greater than 255 then the port
number must be specified in DX. Since the PC only decodes 10 bits
of the port address, values over 1023 can only be decoded by third
party vendor equipment and also map to the port range 0-1023.
Clocks Size
Operands 808x 286 386 486 Bytes
port,src - 5 14 17 1
port,src (PM) - - 8/28 10/32/30 1
- 386+ protected mode timings depend on privilege levels.
first number is the timing when: CPL ≤ IOPL
second number is the timing when: CPL > IOPL
third number is the timing when: virtual mode on 486 processor
Usage: POP dest
Modifies flags: None
Transfers word at the current stack top (SS:SP) to the destination
then increments SP by two to point to the new stack top. CS is not
a valid destination.
Clocks Size
Operands 808x 286 386 486 Bytes
reg16 8 5 4 4 1
reg32 4 - - 4 1
segreg 8 5 7 3 1
mem16 17+EA 5 5 6 2-4
mem32 5 - - 6 2-4
Usage: POPA
POPAD (386+)
Modifies flags: None
Pops the top 8 words off the stack into the 8 general purpose 16/32
bit registers. Registers are popped in the following order: (E)DI,
(E)SI, (E)BP, (E)SP, (E)DX, (E)CX and (E)AX. The (E)SP value popped
from the stack is actually discarded.
Clocks Size
Operands 808x 286 386 486 Bytes
none - 19 24 9 1
Usage: POPF
POPFD (386+)
Modifies flags: all flags
Pops word/doubleword from stack into the Flags Register and then
increments SP by 2 (for POPF) or 4 (for POPFD).
Clocks Size
Operands 808x 286 386 486 Bytes
none 8/12 5 5 9 1 (W88=12)
none (PM) - - 5 6 1
Usage: PUSH src
PUSH immed (80188+ only)
Modifies flags: None
Decrements SP by the size of the operand (two or four, byte values
are sign extended) and transfers one word from source to the stack
top (SS:SP).
Clocks Size
Operands 808x 286 386 486 Bytes
reg16 11/15 3 2 1 1
reg32 - - 2 1 1
mem16 16+EA 5 5 4 2-4 (W88=24+EA)
mem32 - - 5 4 2-4
segreg 10/14 3 2 3 1
immed - 3 2 1 2-3
Usage: PUSHA
PUSHAD (386+)
Modifies flags: None
Pushes all general purpose registers onto the stack in the following
order: (E)AX, (E)CX, (E)DX, (E)BX, (E)SP, (E)BP, (E)SI, (E)DI. The
value of SP is the value before the actual push of SP.
Clocks Size
Operands 808x 286 386 486 Bytes
none - 19 24 11 1
Usage: PUSHF
PUSHFD (386+)
Modifies flags: None
Transfers the Flags Register onto the stack. PUSHF saves a 16 bit
value while PUSHFD saves a 32 bit value.
Clocks Size
Operands 808x 286 386 486 Bytes
none 10/14 3 4 4 1
none (PM) - - 4 3 1
Usage: RCL dest,count
Modifies flags: CF OF
+-+ +---------------+
+-+|C|<+--+|7 <---------- 0|<-+
| +-+ +---------------+ |
+-----------------------------+
Rotates the bits in the destination to the left "count" times with
all data pushed out the left side re-entering on the right. The
Carry Flag holds the last bit rotated out.
Clocks Size
Operands 808x 286 386 486 Bytes
reg,1 2 2 9 3 2
mem,1 15+EA 7 10 4 2-4 (W88=23+EA)
reg,CL 8+4n 5+n 9 8-30 2
mem,CL 20+EA+4n 8+n 10 9-31 2-4 (W88=28+EA+4n)
reg,immed8 - 5+n 9 8-30 3
mem,immed8 - 8+n 10 9-31 3-5
Usage: RCR dest,count
Modifies flags: CF OF
+---------------+ +-+
+->|7 +---------> 0|+--->|C|+-+
| +---------------+ +-+ |
+-----------------------------+
Rotates the bits in the destination to the right "count" times with
all data pushed out the right side re-entering on the left. The
Carry Flag holds the last bit rotated out.
Clocks Size
Operands 808x 286 386 486 Bytes
reg,1 2 2 9 3 2
mem,1 15+EA 7 10 4 2-4 (W88=23+EA)
reg,CL 8+4n 5+n 9 8-30 2
mem,CL 20+EA+4n 8+n 10 9-31 2-4 (W88=28+EA+4n)
reg,immed8 - 5+n 9 8-30 3
mem,immed8 - 8+n 10 9-31 3-5
Usage: REP
Modifies flags: None
Repeats execution of string instructions while CX != 0. After
each string operation, CX is decremented and the Zero Flag is
tested. The combination of a repeat prefix and a segment override
on CPU's before the 386 may result in errors if an interrupt occurs
before CX=0. The following code shows code that is susceptible to
this and how to avoid it:
again: rep movs byte ptr ES:[DI],ES:[SI] ; vulnerable instr.
jcxz next ; continue if REP successful
loop again ; interrupt goofed count
next:
Clocks Size
Operands 808x 286 386 486 Bytes
none 2 2 2 1
Usage: REPE
REPZ
Modifies flags: None
Repeats execution of string instructions while CX != 0 and the Zero
Flag is set. CX is decremented and the Zero Flag tested after
each string operation. The combination of a repeat prefix and a
segment override on processors other than the 386 may result in
errors if an interrupt occurs before CX=0.
Clocks Size
Operands 808x 286 386 486 Bytes
none 2 2 2 1
Usage: REPNE
REPNZ
Modifies flags: None
Repeats execution of string instructions while CX != 0 and the Zero
Flag is clear. CX is decremented and the Zero Flag tested after
each string operation. The combination of a repeat prefix and a
segment override on processors other than the 386 may result in
errors if an interrupt occurs before CX=0.
Clocks Size
Operands 808x 286 386 486 Bytes
none 2 2 2 1
Usage: RET nBytes
RETF nBytes
RETN nBytes
Modifies flags: None
Transfers control from a procedure back to the instruction address
saved on the stack. "n bytes" is an optional number of bytes to
release. Far returns pop the IP followed by the CS, while near
returns pop only the IP register.
Clocks Size
Operands 808x 286 386 486 Bytes
retn 16/20 11+m 10+m 5 1
retn immed 20/24 11+m 10+m 5 3
retf 26/34 15+m 18+m 13 1
retf (PM, same priv.) - 32+m 18 1
retf (PM, lesser priv.) - 68 33 1
retf immed 25/33 15+m 18+m 14 3
retf immed (PM, same priv.) 32+m 17 1
retf immed (PM, lesser priv.) 68 33 1
Usage: ROL dest,count
Modifies flags: CF OF
+-+ +---------------+
|C|<++-+|7 <---------- 0|<-+
+-+ | +---------------+ |
+---------------------+
Rotates the bits in the destination to the left "count" times with
all data pushed out the left side re-entering on the right. The
Carry Flag will contain the value of the last bit rotated out.
Clocks Size
Operands 808x 286 386 486 Bytes
reg,1 2 2 3 3 2
mem,1 15+EA 7 7 4 2-4 (W88=23+EA)
reg,CL 8+4n 5+n 3 3 2
mem,CL 20+EA+4n 8+n 7 4 2-4 (W88=28+EA+4n)
reg,immed8 - 5+n 3 2 3
mem,immed8 - 8+n 7 4 3-5
Usage: ROR dest,count
Modifies flags: CF OF
+---------------+ +-+
+->|7 +---------> 0|+-+->|C|
| +---------------+ | +-+
+---------------------+
Rotates the bits in the destination to the right "count" times with
all data pushed out the right side re-entering on the left. The
Carry Flag will contain the value of the last bit rotated out.
Clocks Size
Operands 808x 286 386 486 Bytes
reg,1 2 2 3 3 2
mem,1 15+EA 7 7 4 2-4 (W88=23+EA)
reg,CL 8+4n 5+n 3 3 2
mem,CL 20+EA+4n 8+n 7 4 2-4 (W88=28+EA+4n)
reg,immed8 - 5+n 3 2 3
mem,immed8 - 8+n 7 4 3-5
Usage: SAHF
Modifies flags: AF CF PF SF ZF
Transfers bits 0-7 of AH into the Flags Register. This includes
AF, CF, PF, SF and ZF.
Clocks Size
Operands 808x 286 386 486 Bytes
none 4 2 3 2 1
Usage: SAL dest,count
SHL dest,count
Modifies flags: CF OF PF SF ZF (AF undefined)
+-+ +---------------+ +-+
|C|<---+|7 <---------- 0|<---+|0|
+-+ +---------------+ +-+
Shifts the destination left by "count" bits with zeroes shifted
in on right. The Carry Flag contains the last bit shifted out.
Clocks Size
Operands 808x 286 386 486 Bytes
reg,1 2 2 3 3 2
mem,1 15+EA 7 7 4 2-4 (W88=23+EA)
reg,CL 8+4n 5+n 3 3 2
mem,CL 20+EA+4n 8+n 7 4 2-4 (W88=28+EA+4n)
reg,immed8 - 5+n 3 2 3
mem,immed8 - 8+n 7 4 3-5
Usage: SAR dest,count
Modifies flags: CF OF PF SF ZF (AF undefined)
+---------------+ +-+
+-+|7 ----------> 0|---+>|C|
| +---------------+ +-+
+---^
Shifts the destination right by "count" bits with the current sign
bit replicated in the leftmost bit. The Carry Flag contains the
last bit shifted out.
Clocks Size
Operands 808x 286 386 486 Bytes
reg,1 2 2 3 3 2
mem,1 15+EA 7 7 4 2-4 (W88=23+EA)
reg,CL 8+4n 5+n 3 3 2
mem,CL 20+EA+4n 8+n 7 4 2-4 (W88=28+EA+4n)
reg,immed8 - 5+n 3 2 3
mem,immed8 - 8+n 7 4 3-5
Usage: SBB dest,src
Modifies flags: AF CF OF PF SF ZF
Subtracts the source from the destination, and subtracts 1 extra if
the Carry Flag is set. Results are returned in "dest".
Clocks Size
Operands 808x 286 386 486 Bytes
reg,reg 3 2 2 1 2
mem,reg 16+EA 7 6 3 2-4 (W88=24+EA)
reg,mem 9+EA 7 7 2 2-4 (W88=13+EA)
reg,immed 4 3 2 1 3-4
mem,immed 17+EA 7 7 3 3-6 (W88=25+EA)
accum,immed 4 3 2 1 2-3
Usage: SCAS string
SCASB
SCASW
SCASD (386+)
Modifies flags: AF CF OF PF SF ZF
Compares value at ES:DI (even if operand is specified) from the
accumulator and sets the flags similar to a subtraction. DI is
incremented/decremented based on the instruction format (or
operand size) and the state of the Direction Flag. Use with REP
prefixes.
Clocks Size
Operands 808x 286 386 486 Bytes
string 15 7 7 6 1 (W88=19)
Usage: SETAE dest
SETNB dest
(unsigned, 386+)
Modifies flags: none
Sets the byte in the operand to 1 if the Carry Flag is clear
otherwise sets the operand to 0.
Clocks Size
Operands 808x 286 386 486 Bytes
reg8 - - 4 3 3
mem8 - - 5 4 3
Usage: SETB dest
SETNAE dest
(unsigned, 386+)
Modifies flags: none
Sets the byte in the operand to 1 if the Carry Flag is set
otherwise sets the operand to 0.
Clocks Size
Operands 808x 286 386 486 Bytes
reg8 - - 4 3 3
mem8 - - 5 4 3
Usage: SETBE dest
SETNA dest
(unsigned, 386+)
Modifies flags: none
Sets the byte in the operand to 1 if the Carry Flag or the Zero
Flag is set, otherwise sets the operand to 0.
Clocks Size
Operands 808x 286 386 486 Bytes
reg8 - - 4 3 3
mem8 - - 5 4 3
Usage: SETE dest
SETZ dest
Modifies flags: none
Sets the byte in the operand to 1 if the Zero Flag is set,
otherwise sets the operand to 0.
Clocks Size
Operands 808x 286 386 486 Bytes
reg8 - - 4 3 3
mem8 - - 5 4 3
Usage: SETNE dest
SETNZ dest
Modifies flags: none
Sets the byte in the operand to 1 if the Zero Flag is clear,
otherwise sets the operand to 0.
Clocks Size
Operands 808x 286 386 486 Bytes
reg8 - - 4 3 3
mem8 - - 5 4 3
Usage: SETL dest
SETNGE dest
(signed, 386+)
Modifies flags: none
Sets the byte in the operand to 1 if the Sign Flag is not equal
to the Overflow Flag, otherwise sets the operand to 0.
Clocks Size
Operands 808x 286 386 486 Bytes
reg8 - - 4 3 3
mem8 - - 5 4 3
Usage: SETGE dest
SETNL dest
(signed, 386+)
Modifies flags: none
Sets the byte in the operand to 1 if the Sign Flag equals the
Overflow Flag, otherwise sets the operand to 0.
Clocks Size
Operands 808x 286 386 486 Bytes
reg8 - - 4 3 3
mem8 - - 5 4 3
Usage: SETLE dest
SETNG dest
(signed, 386+)
Modifies flags: none
Sets the byte in the operand to 1 if the Zero Flag is set or the
Sign Flag is not equal to the Overflow Flag, otherwise sets the
operand to 0.
Clocks Size
Operands 808x 286 386 486 Bytes
reg8 - - 4 3 3
mem8 - - 5 4 3
Usage: SETG dest
SETNLE dest
(signed, 386+)
Modifies flags: none
Sets the byte in the operand to 1 if the Zero Flag is clear or the
Sign Flag equals to the Overflow Flag, otherwise sets the operand
to 0.
Clocks Size
Operands 808x 286 386 486 Bytes
reg8 - - 4 3 3
mem8 - - 5 4 3
Usage: SETS dest
Modifies flags: none
Sets the byte in the operand to 1 if the Sign Flag is set, otherwise
sets the operand to 0.
Clocks Size
Operands 808x 286 386 486 Bytes
reg8 - - 4 3 3
mem8 - - 5 4 3
Usage: SETNS dest
Modifies flags: none
Sets the byte in the operand to 1 if the Sign Flag is clear,
otherwise sets the operand to 0.
Clocks Size
Operands 808x 286 386 486 Bytes
reg8 - - 4 3 3
mem8 - - 5 4 3
Usage: SETC dest
Modifies flags: none
Sets the byte in the operand to 1 if the Carry Flag is set,
otherwise sets the operand to 0.
Clocks Size
Operands 808x 286 386 486 Bytes
reg8 - - 4 3 3
mem8 - - 5 4 3
Usage: SETNC dest
Modifies flags: none
Sets the byte in the operand to 1 if the Carry Flag is clear,
otherwise sets the operand to 0.
Clocks Size
Operands 808x 286 386 486 Bytes
reg8 - - 4 3 3
mem8 - - 5 4 3
Usage: SETO dest
Modifies flags: none
Sets the byte in the operand to 1 if the Overflow Flag is set,
otherwise sets the operand to 0.
Clocks Size
Operands 808x 286 386 486 Bytes
reg8 - - 4 3 3
mem8 - - 5 4 3
Usage: SETNO dest
Modifies flags: none
Sets the byte in the operand to 1 if the Overflow Flag is clear,
otherwise sets the operand to 0.
Clocks Size
Operands 808x 286 386 486 Bytes
reg8 - - 4 3 3
mem8 - - 5 4 3
Usage: SETP dest
SETPE dest
Modifies flags: none
Sets the byte in the operand to 1 if the Parity Flag is set,
otherwise sets the operand to 0.
Clocks Size
Operands 808x 286 386 486 Bytes
reg8 - - 4 3 3
mem8 - - 5 4 3
Usage: SETNP dest
SETPO dest
Modifies flags: none
Sets the byte in the operand to 1 if the Parity Flag is clear,
otherwise sets the operand to 0.
Clocks Size
Operands 808x 286 386 486 Bytes
reg8 - - 4 3 3
mem8 - - 5 4 3
Usage: SGDT dest
Modifies flags: none
Stores the Global Descriptor Table (GDT) Register into the
specified operand.
Clocks Size
Operands 808x 286 386 486 Bytes
mem64 - 11 9 10 5
Usage: SIDT dest
Modifies flags: none
Stores the Interrupt Descriptor Table (IDT) Register into the
specified operand.
Clocks Size
Operands 808x 286 386 486 Bytes
mem64 - 12 9 10 5
See: SAL
Usage: SHR dest,count
Modifies flags: CF OF PF SF ZF (AF undefined)
+-+ +---------------+ +-+
|0|---+>|7 ----------> 0|---+>|C|
+-+ +---------------+ +-+
Shifts the destination right by "count" bits with zeroes shifted
in on the left. The Carry Flag contains the last bit shifted out.
Clocks Size
Operands 808x 286 386 486 Bytes
reg,1 2 2 3 2
mem,1 15+EA 7 7 2-4 (W88=23+EA)
reg,CL 8+4n 5+n 3 2
mem,CL 20+EA+4n 8+n 7 2-4 (W88=28+EA+4n)
reg,immed8 - 5+n 3 3
mem,immed8 - 8+n 7 3-5
Usage: SHLD dest,src,count
SHRD dest,src,count
Modifies flags: CF PF SF ZF (OF,AF undefined)
SHLD shifts "dest" to the left "count" times and the bit positions
opened are filled with the most significant bits of "src". SHRD
shifts "dest" to the right "count" times and the bit positions
opened are filled with the least significant bits of the second
operand. Only the 5 lower bits of "count" are used.
Clocks Size
Operands 808x 286 386 486 Bytes
reg16,reg16,immed8 - - 3 2 4
reg32,reg32,immed8 - - 3 2 4
mem16,reg16,immed8 - - 7 3 6
mem32,reg32,immed8 - - 7 3 6
reg16,reg16,CL - - 3 3 3
reg32,reg32,CL - - 3 3 3
mem16,reg16,CL - - 7 4 5
mem32,reg32,CL - - 7 4 5
Usage: SLDT dest
Modifies flags: none
Stores the Local Descriptor Table (LDT) Register into the
specified operand.
Clocks Size
Operands 808x 286 386 486 Bytes
reg16 - 2 2 2 3
mem16 - 2 2 3 5
Usage: SMSW dest
Modifies flags: none
Store Machine Status Word (MSW) into "dest".
Clocks Size
Operands 808x 286 386 486 Bytes
reg16 - 2 10 2 3
mem16 - 3 3 3 5
Usage: STC
Modifies flags: CF
Sets the Carry Flag to 1.
Clocks Size
Operands 808x 286 386 486 Bytes
none 2 2 2 2 1
Usage: STD
Modifies flags: DF
Sets the Direction Flag to 1 causing string instructions to
auto-decrement SI and DI instead of auto-increment.
Clocks Size
Operands 808x 286 386 486 Bytes
none 2 2 2 2 1
Usage: STI
Modifies flags: IF
Sets the Interrupt Flag to 1, which enables recognition of all
hardware interrupts. If an interrupt is generated by a hardware
device, an End of Interrupt (EOI) must also be issued to enable
other hardware interrupts of the same or lower priority.
Clocks Size
Operands 808x 286 386 486 Bytes
none 2 2 2 5 1
Usage: STOS dest
STOSB
STOSW
STOSD
Modifies flags: None
Stores value in accumulator to location at ES:(E)DI (even if operand
is given). (E)DI is incremented/decremented based on the size of
the operand (or instruction format) and the state of the Direction
Flag. Use with REP prefixes.
Clocks Size
Operands 808x 286 386 486 Bytes
dest 11 3 4 5 1 (W88=15)
Usage: STR dest
Modifies flags: None
Stores the current Task Register to the specified operand.
Clocks Size
Operands 808x 286 386 486 Bytes
reg16 - 2 2 2 3
mem16 - 3 2 3 5
Usage: SUB dest,src
Modifies flags: AF CF OF PF SF ZF
The source is subtracted from the destination and the result is
stored in the destination.
Clocks Size
Operands 808x 286 386 486 Bytes
reg,reg 3 2 2 1 2
mem,reg 16+EA 7 6 3 2-4 (W88=24+EA)
reg,mem 9+EA 7 7 2 2-4 (W88=13+EA)
reg,immed 4 3 2 1 3-4
mem,immed 17+EA 7 7 3 3-6 (W88=25+EA)
accum,immed 4 3 2 1 2-3
Usage: TEST dest,src
Modifies flags: CF OF PF SF ZF (AF undefined)
Performs a logical AND of the two operands updating the flags
register without saving the result.
Clocks Size
Operands 808x 286 386 486 Bytes
reg,reg 3 2 1 1 2
reg,mem 9+EA 6 5 1 2-4 (W88=13+EA)
mem,reg 9+EA 6 5 2 2-4 (W88=13+EA)
reg,immed 5 3 2 1 3-4
mem,immed 11+EA 6 5 2 3-6
accum,immed 4 3 2 1 2-3
Usage: VERR src
Modifies flags: ZF
Verifies the specified segment selector is valid and is readable
at the current privilege level. If the segment is readable,
the Zero Flag is set, otherwise it is cleared.
Clocks Size
Operands 808x 286 386 486 Bytes
reg16 - 14 10 11 3
mem16 - 16 11 11 5
Usage: VERW src
Modifies flags: ZF
Verifies the specified segment selector is valid and is ratable
at the current privilege level. If the segment is writable,
the Zero Flag is set, otherwise it is cleared.
Clocks Size
Operands 808x 286 386 486 Bytes
reg16 - 14 15 11 3
mem16 - 16 16 11 5
Usage: WAIT
FWAIT
Modifies flags: None
CPU enters wait state until the coprocessor signals it has finished
its operation. This instruction is used to prevent the CPU from
accessing memory that may be temporarily in use by the coprocessor.
WAIT and FWAIT are identical.
Clocks Size
Operands 808x 286 386 486 Bytes
none 4 3 6+ 1-3 1
Usage: WBINVD
Modifies flags: None
Flushes internal cache, then signals the external cache to write
back current data followed by a signal to flush the external cache.
Clocks Size
Operands 808x 286 386 486 Bytes
none - - - 5 2
Usage: XCHG dest,src
Modifies flags: None
Exchanges contents of source and destination.
Clocks Size
Operands 808x 286 386 486 Bytes
reg,reg 4 3 3 3 2
mem,reg 17+EA 5 5 5 2-4 (W88=25+EA)
reg,mem 17+EA 5 5 3 2-4 (W88=25+EA)
accum,reg 3 3 3 3 1
reg,accum 3 3 3 3 1
Usage: XLAT translation-table
XLATB (masm 5.x)
Modifies flags: None
Replaces the byte in AL with byte from a user table addressed by
BX. The original value of AL is the index into the translate table.
The best way to discripe this is MOV AL,[BX+AL]
Clocks Size
Operands 808x 286 386 486 Bytes
table offset 11 5 5 4 1
Usage: XOR dest,src
Modifies flags: CF OF PF SF ZF (AF undefined)
Performs a bitwise exclusive OR of the operands and returns
the result in the destination.
Clocks Size
Operands 808x 286 386 486 Bytes
reg,reg 3 2 2 1 2
mem,reg 16+EA 7 6 3 2-4 (W88=24+EA)
reg,mem 9+EA 7 7 2 2-4 (W88=13+EA)
reg,immed 4 3 2 1 3-4
mem,immed 17+EA 7 7 3 3-6 (W88=25+EA)
accum,immed 4 3 2 1 2-3
