📄 80x86-code.htm
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<pre><font color="#008080"> none 2 2 3 5 1
</font></pre>
<pre><font color="#008080">CLTS - Clear Task Switched Flag (286+ privileged)</font></pre>
<pre><font color="#008080"> Usage: CLTS
Modifies flags: None</font></pre>
<pre><font color="#008080"> Clears the Task Switched Flag in the Machine Status Register. This
is a privileged operation and is generally used only by operating
system code.</font></pre>
<pre><font color="#008080"> Clocks Size
Operands 808x 286 386 486 Bytes</font></pre>
<pre><font color="#008080"> none - 2 5 7 2
</font></pre>
<pre><font color="#008080">CMC - Complement Carry Flag</font></pre>
<pre><font color="#008080"> Usage: CMC
Modifies flags: CF</font></pre>
<pre><font color="#008080"> Toggles (inverts) the Carry Flag</font></pre>
<pre><font color="#008080"> Clocks Size
Operands 808x 286 386 486 Bytes</font></pre>
<pre><font color="#008080"> none 2 2 2 2 1
CMP - Compare</font></pre>
<pre><font color="#008080"> Usage: CMP dest,src
Modifies flags: AF CF OF PF SF ZF</font></pre>
<pre><font color="#008080"> Subtracts source from destination and updates the flags but does
not save result. Flags can subsequently be checked for conditions.</font></pre>
<pre><font color="#008080"> Clocks Size
Operands 808x 286 386 486 Bytes</font></pre>
<pre><font color="#008080"> reg,reg 3 2 2 1 2
mem,reg 9+EA 7 5 2 2-4 (W88=13+EA)
reg,mem 9+EA 6 6 2 2-4 (W88=13+EA)
reg,immed 4 3 2 1 3-4
mem,immed 10+EA 6 5 2 3-6 (W88=14+EA)
accum,immed 4 3 2 1 2-3
</font></pre>
<pre><font color="#008080">CMPS - Compare String (Byte, Word or Doubleword)</font></pre>
<pre><font color="#008080"> Usage: CMPS dest,src
CMPSB
CMPSW
CMPSD (386+)
Modifies flags: AF CF OF PF SF ZF</font></pre>
<pre><font color="#008080"> Subtracts destination value from source without saving results.
Updates flags based on the subtraction and the index registers
(E)SI and (E)DI are incremented or decremented depending on the
state of the Direction Flag. CMPSB inc/decrements the index
registers by 1, CMPSW inc/decrements by 2, while CMPSD increments
or decrements by 4. The REP prefixes can be used to process
entire data items.</font></pre>
<pre><font color="#008080"> Clocks Size
Operands 808x 286 386 486 Bytes</font></pre>
<pre><font color="#008080"> dest,src 22 8 10 8 1 (W88=30)
</font></pre>
<pre><font color="#008080">CMPXCHG - Compare and Exchange</font></pre>
<pre><font color="#008080"> Usage: CMPXCHG dest,src (486+)
Modifies flags: AF CF OF PF SF ZF</font></pre>
<pre><font color="#008080"> Compares the accumulator (8-32 bits) with "dest". If equal the
"dest" is loaded with "src", otherwise the accumulator is loaded
with "dest".</font></pre>
<pre><font color="#008080"> Clocks Size
Operands 808x 286 386 486 Bytes</font></pre>
<pre><font color="#008080"> reg,reg - - - 6 2
mem,reg - - - 7 2</font></pre>
<pre><font color="#008080"> - add 3 clocks if the "mem,reg" comparison fails
</font></pre>
<pre><font color="#008080">CWD - Convert Word to Doubleword</font></pre>
<pre><font color="#008080"> Usage: CWD
Modifies flags: None</font></pre>
<pre><font color="#008080"> Extends sign of word in register AX throughout register DX forming
a doubleword quantity in DX:AX.</font></pre>
<pre><font color="#008080"> Clocks Size
Operands 808x 286 386 486 Bytes</font></pre>
<pre><font color="#008080"> none 5 2 2 3 1
CWDE - Convert Word to Extended Doubleword (386+)</font></pre>
<pre><font color="#008080"> Usage: CWDE
Modifies flags: None</font></pre>
<pre><font color="#008080"> Converts a signed word in AX to a signed doubleword in EAX by
extending the sign bit of AX throughout EAX.</font></pre>
<pre><font color="#008080"> Clocks Size
Operands 808x 286 386 486 Bytes</font></pre>
<pre><font color="#008080"> none - - 3 3 1
</font></pre>
<pre><font color="#008080">DAA - Decimal Adjust for Addition</font></pre>
<pre><font color="#008080"> Usage: DAA
Modifies flags: AF CF PF SF ZF (OF undefined)</font></pre>
<pre><font color="#008080"> Corrects result (in AL) of a previous BCD addition operation.
Contents of AL are changed to a pair of packed decimal digits.</font></pre>
<pre><font color="#008080"> Clocks Size
Operands 808x 286 386 486 Bytes</font></pre>
<pre><font color="#008080"> none 4 3 4 2 1
</font></pre>
<pre><font color="#008080">DAS - Decimal Adjust for Subtraction</font></pre>
<pre><font color="#008080"> Usage: DAS
Modifies flags: AF CF PF SF ZF (OF undefined)</font></pre>
<pre><font color="#008080"> Corrects result (in AL) of a previous BCD subtraction operation.
Contents of AL are changed to a pair of packed decimal digits.</font></pre>
<pre><font color="#008080"> Clocks Size
Operands 808x 286 386 486 Bytes</font></pre>
<pre><font color="#008080"> none 4 3 4 2 1
</font></pre>
<pre><font color="#008080">DEC - Decrement</font></pre>
<pre><font color="#008080"> Usage: DEC dest
Modifies flags: AF OF PF SF ZF</font></pre>
<pre><font color="#008080"> Unsigned binary subtraction of one from the destination.</font></pre>
<pre><font color="#008080"> Clocks Size
Operands 808x 286 386 486 Bytes</font></pre>
<pre><font color="#008080"> reg8 3 2 2 1 2
mem 15+EA 7 6 3 2-4
reg16/32 3 2 2 1 1
</font></pre>
<pre><font color="#008080">DIV - Divide</font></pre>
<pre><font color="#008080"> Usage: DIV src
Modifies flags: (AF,CF,OF,PF,SF,ZF undefined)</font></pre>
<pre><font color="#008080"> Unsigned binary division of accumulator by source. If the source
divisor is a byte value then AX is divided by "src" and the quotient
is placed in AL and the remainder in AH. If source operand is a word
value, then DX:AX is divided by "src" and the quotient is stored in AX
and the remainder in DX.</font></pre>
<pre><font color="#008080"> Clocks Size
Operands 808x 286 386 486 Bytes</font></pre>
<pre><font color="#008080"> reg8 80-90 14 14 16 2
reg16 144-162 22 22 24 2
reg32 - - 38 40 2
mem8 (86-96)+EA 17 17 16 2-4
mem16 (150-168)+EA 25 25 24 2-4 (W88=158-176+EA)
mem32 - - 41 40 2-4
ENTER - Make Stack Frame (80188+)</font></pre>
<pre><font color="#008080"> Usage: ENTER locals,level
Modifies flags: None</font></pre>
<pre><font color="#008080"> Modifies stack for entry to procedure for high level language.
Operand "locals" specifies the amount of storage to be allocated
on the stack. "Level" specifies the nesting level of the routine.
Paired with the LEAVE instruction, this is an efficient method of
entry and exit to procedures.</font></pre>
<pre><font color="#008080"> Clocks Size
Operands 808x 286 386 486 Bytes</font></pre>
<pre><font color="#008080"> immed16,0 - 11 10 14 4
immed16,1 - 15 12 17 4
immed16,immed8 - 12+4(n-1) 15+4(n-1) 17+3n 4
</font></pre>
<pre><font color="#008080">ESC - Escape</font></pre>
<pre><font color="#008080"> Usage: ESC immed,src
Modifies flags: None</font></pre>
<pre><font color="#008080"> Provides access to the data bus for other resident processors.
The CPU treats it as a NOP but places memory operand on bus.</font></pre>
<pre><font color="#008080"> Clocks Size
Operands 808x 286 386 486 Bytes</font></pre>
<pre><font color="#008080"> immed,reg 2 9-20 ? 2
immed,mem 2 9-20 ? 2-4
</font></pre>
<pre><font color="#008080">HLT - Halt CPU</font></pre>
<pre><font color="#008080"> Usage: HLT
Modifies flags: None</font></pre>
<pre><font color="#008080"> Halts CPU until RESET line is activated, NMI or maskable interrupt
received. The CPU becomes dormant but retains the current CS:IP
for later restart.</font></pre>
<pre><font color="#008080"> Clocks Size
Operands 808x 286 386 486 Bytes</font></pre>
<pre><font color="#008080"> none 2 2 5 4 1
</font></pre>
<pre><font color="#008080">IDIV - Signed Integer Division</font></pre>
<pre><font color="#008080"> Usage: IDIV src
Modifies flags: (AF,CF,OF,PF,SF,ZF undefined)</font></pre>
<pre><font color="#008080"> Signed binary division of accumulator by source. If source is a
byte value, AX is divided by "src" and the quotient is stored in
AL and the remainder in AH. If source is a word value, DX:AX is
divided by "src", and the quotient is stored in AL and the
remainder in DX.
Clocks Size
Operands 808x 286 386 486 Bytes</font></pre>
<pre><font color="#008080"> reg8 101-112 17 19 19 2
reg16 165-184 25 27 27 2
reg32 - - 43 43 2
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