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INSTRUCTION SET DESCRIPTIONS
C-22
JCXZ Jump if CX Zero:
JCXZ
disp8
Transfers control to the target location
if CX is 0. Useful at the beginning of a
loop to bypass the loop if CX has a
zero value, i.e., to execute the loop
zero times.
Instruction Operands:
JCXZ short-label
if
(CX) = 0
then
(IP) ← (IP) + disp8 (sign-ext to 16 bits)
AF –
CF –
DF –
IF –
OF –
PF –
SF –
TF –
ZF –
JE
JZ
Jump on Equal:
Jump on Zero:
JE
disp8
JZ
disp8
Transfers control to the target location
if the condition tested (ZF = 1) is true.
Instruction Operands:
JE short-label
JZ short-label
if
(ZF) = 1
then
(IP) ← (IP) + disp8 (sign-ext to 16 bits)
AF –
CF –
DF –
IF –
OF –
PF –
SF –
TF –
ZF –
JG
JNLE
Jump on Greater Than:
Jump on Not Less Than or Equal:
JG
disp8
JNLE
disp8
Transfers control to the target location
if the condition tested (SF = OF) and
(ZF=0) is true.
Instruction Operands:
JG short-label
JNLE short-label
if
((SF) = (OF)) and ((ZF) = 0)
then
(IP) ← (IP) + disp8 (sign-ext to 16 bits)
AF –
CF –
DF –
IF –
OF –
PF –
SF –
TF –
ZF –
JGE
JNL
Jump on Greater Than or Equal:
Jump on Not Less Than:
JGE
disp8
JNL
disp8
Transfers control to the target location
if the condition tested (SF=OF) is true.
Instruction Operands:
JGE short-label
JNL short-label
if
(SF) = (OF)
then
(IP) ← (IP) + disp8 (sign-ext to 16 bits)
AF –
CF –
DF –
IF –
OF –
PF –
SF –
TF –
ZF –
Table C-4. Instruction Set (Continued)
Name Description Operation
Flags
Affected
NOTE: The three symbols used in the Flags Affected column are defined as follows:
– the contents of the flag remain unchanged after the instruction is executed
? the contents of the flag is undefined after the instruction is executed
the flag is updated after the instruction is executed