Assembler:Commands:SUB

command sub destination, source

Subtracts the source from the destination.

Subtracts the second operand (source operand) from the first operand (destination operand) and stores the result in the destination operand. The destination operand can be a register or a memory location; the source operand can be an immediate, register, or memory location. (However, two memory operands cannot be used in one instruction.) When an immediate value is used as an operand, it is sign-extended to the length of the destination operand format.

The SUB instruction performs integer subtraction. It evaluates the result for both signed and unsigned integer operands and sets the OF and CF flags to indicate an overflow in the signed or unsigned result, respectively. The SF flag indicates the sign of the signed result.

The OF, SF, ZF, AF, PF, and CF flags are set according to the result.

destination = destination - source

Command Parameters

Parameter	Description
destination	The destination operand
source	The source operand

Examples

sub al,1

sub ax,1

sub eax,1

sub rax,-1

sub [eax],0x9

sub [rax],1

sub [rax],rsi

sub eax,[rax]

sub rax,[rax]

sub [SomeSymbol],1

sub [SomeSymbol],eax

See also

• Assembler
• Auto Assembler
• Assembler Commands

External links

• wikipedia.org/wiki/X86_instruction_listings
• wikibooks.org/wiki/X86_Assembly/Other_Instructions
• asmpedia.org
• x86.renejeschke.de/html/file_module_x86_id_308.html