CALL - Procedure Call
Usage: CALL destination
Modifies Flags: None
Pushes Instruction Pointer (and Code Segment for far calls) onto stack and loads Instruction Pointer with the address of proc-name. Code continues with execution at CS:IP.
| Clocks | |||
|---|---|---|---|
| operands | 286 | 386 | 486 |
| rel16 (near, IP relative) | 7 | 7+m | 3 |
| rel32 (near, IP relative) | 7+m | 3 | |
| reg16 (near, register indirect) | 7 | 7+m | 5 |
| reg32 (near, register indirect) | 7+m | 5 | |
| mem16 (near, memory indirect) | 11 | 10+m | 5 |
| mem32 (near, memory indirect) | 10+m | 5 | |
| ptr16:16 (far, full ptr supplied) | 13 | 17+m | 18 |
| ptr16:32 (far, full ptr supplied) | 17+m | 18 | |
| ptr16:16 (far, ptr supplied, prot. mode) | 26 | 34+m | 20 |
| ptr16:32 (far, ptr supplied, prot. mode) | 34+m | 20 | |
| m16:16 (far, indirect) | 16 | 22+m | 17 |
| m16:32 (far, indirect) | 22+m | 17 | |
| m16:16 (far, indirect, prot. mode) | 29 | 38+m | 20 |
| m16:32 (far, indirect, prot. mode) | 38+m | 20 | |
| ptr16:16 (task, via TSS or task gate) | 177 | TS | 37+TS |
| m16:16 (task, via TSS or task gate) | 180/185 | 5+TS | 37+TS |
| m16:32 (task) | TS | 37+TS | |
| m16:32 (task) | 5+TS | 37+TS | |
| ptr16:16 (gate, same privilege) | 41 | 52+m | 35 |
| ptr16:32 (gate, same privilege) | 52+m | 35 | |
| m16:16 (gate, same privilege) | 44 | 56+m | 35 |
| m16:32 (gate, same privilege) | 56+m | 35 | |
| ptr16:16 (gate, more priv, no parm) | 82 | 86+m | 69 |
| ptr16:32 (gate, more priv, no parm) | 86+m | 69 | |
| m16:16 (gate, more priv, no parm) | 83 | 90+m | 69 |
| m16:32 (gate, more priv, no parm) | 90+m | 69 | |
| ptr16:16 (gate, more priv, x parms) | 86+4x | 94+4x+m | 77+4x |
| ptr16:32 (gate, more priv, x parms) | 94+4x+m | 77+4x | |
| m16:16 (gate, more priv, x parms) | 90+4x | 98+4x+m | 77+4x |
| m16:32 (gate, more priv, x parms) | 98+4x+m | 77+4x | |
CBW - Convert Byte to Word
Usage: CBW
Modifies Flags: None
Converts byte in AL to word Value in AX by extending sign of AL throughout register AH.
| Clocks | ||||
|---|---|---|---|---|
| operands | 286 | 386 | 486 | Size Bytes |
| none | 2 | 3 | 3 | 1 |
CDQ - Convert Double to Quad (386+)
Usage: CDQ
Modifies Flags: None
Converts signed DWORD in EAX to a signed quad word in EDX:EAX by extending the high order bit of EAX throughout EDX
| Clocks | ||||
|---|---|---|---|---|
| operands | 286 | 386 | 486 | Size Bytes |
| none | 2 | 3 | 1 | |
CLC - Clear Carry
Usage: CLC
Modifies Flags: CF
Clears the Carry Flag.
| Clocks | ||||
|---|---|---|---|---|
| operands | 286 | 386 | 486 | Size Bytes |
| none | 2 | 2 | 2 | 1 |
CLD - Clear Direction Flag
Usage: CLD
Modifies Flags: DF
Clears the Direction Flag causing string instructions to increment the SI and DI index registers.
| Clocks | ||||
|---|---|---|---|---|
| operands | 286 | 386 | 486 | Size Bytes |
| none | 2 | 2 | 2 | 1 |
CLI - Clear Interrupt Flag (disable)
Usage: CLI
Modifies Flags: IF
Disables the maskable hardware interrupts by clearing the Interrupt flag. NMI's and software interrupts are not inhibited.
| Clocks | ||||
|---|---|---|---|---|
| operands | 286 | 386 | 486 | Size Bytes |
| none | 2 | 3 | 5 | 1 |
CLTS - Clear Task Switched Flag (286+ privileged)
Usage: CLTS
Modifies Flags: None
Clears the Task Switched Flag in the Machine Status Register. This is a privileged operation and is generally used only by operating system code.
| Clocks | ||||
|---|---|---|---|---|
| operands | 286 | 386 | 486 | Size Bytes |
| none | 2 | 5 | 7 | 2 |
CMC - Complement Carry Flag
Usage: CMC
Modifies Flags: CF
Toggles (inverts) the Carry Flag
| Clocks | ||||
|---|---|---|---|---|
| operands | 286 | 386 | 486 | Size Bytes |
| none | 2 | 2 | 2 | 1 |
CMP - Compare
Usage: CMP dest,src
Modifies Flags: AF CF OF PF SF ZF
Subtracts source from destination and updates the flags but does not save result. Flags can subsequently be checked for conditions.
| Clocks | ||||
|---|---|---|---|---|
| operands | 286 | 386 | 486 | Size Bytes |
| reg,reg | 2 | 2 | 1 | 2 |
| mem,reg | 7 | 5 | 2 | 2-4 |
| reg,mem | 6 | 6 | 2 | 2-4 |
| reg,immed | 3 | 2 | 1 | 3-4 |
| mem,immed | 6 | 5 | 2 | 3-6 |
| accum,immed | 3 | 2 | 1 | 2-3 |
CMPS - Compare String (Byte, Word or Doubleword)
Usage: CMPS dest,src
CMPSB
CMPSW
CMPSD (386+)
Modifies Flags: AF CF OF PF SF ZF
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.
| Clocks | ||||
|---|---|---|---|---|
| operands | 286 | 386 | 486 | Size Bytes |
| dest,src | 8 | 10 | 8 | 1 |
CMPXCHG - Compare and Exchange (486+)
Usage: CMPXCHG dest,src
Modifies Flags: AF CF OF PF SF ZF
Compares the accumulator (8-32 bits) with "dest". If equal the "dest" is loaded with "src", otherwise the accumulator is loaded with "dest".
| Clocks | ||||
|---|---|---|---|---|
| operands | 286 | 386 | 486 | Size Bytes |
| reg,reg | 6 | 2 | ||
| mem,reg | 7 | 2 | ||
| add 3 clocks if the "mem,reg" comparison fails | ||||
CWD - Convert Word to Doubleword
Usage: CWD
Modifies Flags: None
Extends sign of word in register AX throughout register DX forming a doubleword quantity in DX:AX.
| Clocks | ||||
|---|---|---|---|---|
| operands | 286 | 386 | 486 | Size Bytes |
| none | 2 | 2 | 3 | 1 |
CWDE - Convert Word to Extended Doubleword (386+)
Usage: CWDE
Modifies Flags: None
Converts a signed word in AX to a signed doubleword in EAX by extending the sign bit of AX throughout EAX.
| Clocks | ||||
|---|---|---|---|---|
| operands | 286 | 386 | 486 | Size Bytes |
| none | 3 | 3 | 1 | |
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