2C ib         SUB AL, imm8         Subtract imm8 from AL

2D iw         SUB AX, imm16         Subtract imm16 from AX

2D id         SUB EAX, imm32         Subtract imm32 from EAX

80 /5 ib         SUB r/m8,imm8         Subtract imm8 from r/m8

81 /5 iw         SUB r/m16,imm16         Subtract imm16 from r/m16

81 /5 id         SUB r/m32,imm32         Subtract imm32 from r/m32

83 /5 ib         SUB r/m16,imm8         Subtract sign-extended imm8 from r/m16

83 /5 ib         SUB r/m32,imm8         Subtract sign-extended imm8 from r/m32

28 / r         SUB r/m8,r8         Subtract r8 from r/m8

29 / r         SUB r/m16,r16         Subtract r16 from r/m16

29 / r         SUB r/m32,r32         Subtract r32 from r/m32

2A / r         SUB r8,r/m8         Subtract r/m8 from r8

2B / r         SUB r16,r/m16         Subtract r/m16 from r16

2B / r         SUB r32,r/m32         Subtract r/m32 from r32


Description

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 does not distinguish between signed or unsigned operands. Instead, the processor evaluates the result for both data types and sets the OF and CF flags to indicate a borrow in the signed or unsigned result, respectively. The SF flag indicates the sign of the signed result.


Operands        Bytes                Clocks

reg, reg             2                    1   UV

mem, reg          2+d(0,2)         3   UV

reg, mem          2+d(0,2)         2   UV

reg, imm          2+i(1,2)         1   UV

mem, imm          2+d(0,2)+i(1,2)        3   UV*

acc, imm          1+i(1,2)         1   UV


* = not pairable if there is a displacement and immediate


Flags

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

Created with the Personal Edition of HelpNDoc: Full-featured Documentation generator