|
Bit
|
Label
|
EFLAGS Flag Description
|
|
0
|
CF |
Carry Flag: Set by arithmetic instructions which generate either a carry or
borrow. Set when an operation generates a carry to or a borrow from
a destination operand.
|
|
2
|
PF |
Parity flag: Set by most CPU instructions if the least significant (aka the
low-order bits) of the destination operand contain an even number of 1's.
|
|
4
|
AF |
Auxiliary Carry Flag: Set if there is a carry or borrow involving bit 4 of
EAX. Set when a CPU instruction generates a carry to or a borrow from
the low-order 4 bits of an operand. This flag is used for binary coded decimal
(BCD) arithmetic.
|
|
6
|
ZF |
Zero Flag: Set by most instructions if the result an operation is binary zero.
|
|
7
|
SF |
Sign Flag: Most operations set this bit the same as the most significant
bit (aka high-order bit) of the result. 0 is positive, 1 is negative.
|
|
8
|
TF |
Trap Flag: (sometimes named a Trace Flag.) Permits single stepping of
programs. After executing a single instruction, the processor generates an internal
exception 1. When Trap Flag is set by a program, the processor generates a single-step
interrupt after each instruction. A debugging program can use this feature to execute
a program one instruction at a time.
|
|
9
|
IF |
Interrupt Enable Flag: when set, the processor recognizes external interrupts
on the INTR pin. When set, interrupts are recognized and acted on as they are received.
The bit can be cleared to turn off interrupt processing temporarily.
|
|
10
|
DF |
Direction Flag: Set and cleared using the STD and CLD instructions. It is
used in string processing. When set to 1, string operations process down from high
addresses to low addresses. If cleared, string operations process up from low addresses
to high addresses.
|
|
11
|
OF |
Overflow Flag: Most arithmetic instructions set this bit, indicating that
the result was too large to fit in the destination. When set, it indicates that
the result of an operation is too large or too small to fit in the destination operand.
|
|
12-13
|
IOPL |
Input/Output privilege level flags: Used in protected mode to generate
four levels of security.
|
|
14
|
NT |
Nested Task Flag: Used in protected mode. When set, it indicates that one
system task has invoked another via a CALL Instruction, rather than a JMP.
|
|
16
|
RF |
Resume Flag: Used by the debug registers DR6 and DR7. It enables you to turn
off certain exceptions while debugging code.
|
|
17
|
VM |
Virtual 8086 Mode flag: Permits 80386 to behave like a high speed 8086.
|
