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(nasm.info)Section B.2.4

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B.2.4. Status Flags
-------------------

   The status flags provide some information about the result of the
arithmetic instructions. This information can be used by conditional
instructions (such a `Jcc' and `CMOVcc') as well as by some of the
other instructions (such as `ADC' and `INTO').

   There are 6 status flags:

     CF - Carry flag.

   Set if an arithmetic operation generates a carry or a borrow out of
the most-significant bit of the result; cleared otherwise. This flag
indicates an overflow condition for unsigned-integer arithmetic. It is
also used in multiple-precision arithmetic.

     PF - Parity flag.

   Set if the least-significant byte of the result contains an even
number of 1 bits; cleared otherwise.

     AF - Adjust flag.

   Set if an arithmetic operation generates a carry or a borrow out of
bit 3 of the result; cleared otherwise. This flag is used in
binary-coded decimal (BCD) arithmetic.

     ZF - Zero flag.

   Set if the result is zero; cleared otherwise.

     SF - Sign flag.

   Set equal to the most-significant bit of the result, which is the
sign bit of a signed integer. (0 indicates a positive value and 1
indicates a negative value.)

     OF - Overflow flag.

   Set if the integer result is too large a positive number or too
small a negative number (excluding the sign-bit) to fit in the
destination operand; cleared otherwise. This flag indicates an overflow
condition for signed- integer (two's complement) arithmetic.