Decrease by 1 (dec)

dec{bwl}		r/m[8|16|32]

Operation

r/m[8|16|32] - 1 -> r/m[8|16|32]

Description

Subtracts 1 from the operand. Does not change the carry flag. To change the carry flag, use the sub instruction with an immediate value of 1.

Example

Subtract 1 from the 8-bit contents of the effective address (addressed by the ESI register plus an offset of 1):

decb 1(%esi)

Subtract 1 from the 16-bit contents of the BX register:

decw %bx

Subtract 1 from the 32-bit contents of the effective address (addressed by the EDI register plus an offset of 4):

decl 4(%edi)