386+

Examples:

SBB SBB SBB SBB SBB SBB BX,DI AX,0FFFFH ;Uses single-byte opcode AL,42H ;Uses single-byte opcode BP,17H WORD [BX+SI+Inset],5 WORD [ES:BX],0B800H

Notes:

SBB performs a subtraction with borrow, where the source is subtracted from the destination, and then the Carry flag is subtracted from the result The result then replaces the destination If the result is negative, the Carry flag is set To subtract without taking the Carry flag into account (ie, without borrowing), use the SUB instruction r8 = AL AH BL BH CL CH DL DH sr = CS DS SS ES FS GS m8 = 8-bit memory data m32 = 32-bit memory data i16 = 16-bit immediate data d8 = 8-bit signed displacement d32 = 32-bit unsigned displacement r16 = AX BX CX DX BP SP SI DI r32 = EAX EBX ECX EDX EBP ESP ESI EDI m16 = 16-bit memory data i8 = 8-bit immediate data i32 = 32-bit immediate data d16 = 16-bit signed displacement

SHL Shift Left Flags affected:

O D I T S Z A P C F F F F F F F F F * * * * * * OF: Overflow flag TF: Trap flag AF: Aux carry DF: Direction flag SF: Sign flag PF: Parity flag IF: Interrupt flag ZF: Zero flag CF: Carry flag

Legal forms:

SHL SHL SHL SHL SHL SHL SHL SHL SHL SHL SHL SHL SHL SHL SHL SHL SHL SHL r8,1 m8,1 r16,1 m16,1 r32,1 m32,1 r8,CL m8,CL r16,CL m16,CL r32,CL m32,CL r8,i8 m8,i8 r16,i8 m16,i8 r32,i8 m32,i8

Examples:

Notes:

SHL shifts the bits within the destination operand to the left, where left is toward the most significant bit (MSB) The number of bit positions shifted may be specified either as an 8-bit immediate value, or by the value in CLnot CX or ECX (The 8086 and 8088 are limited to the immediate value 1) Note that while CL may accept a value up to 255, it is meaningless to shift by any value larger than 16-or 32 in 32-bit mode-even though the shifts are actually performed on the 8086 and 8088 (The 286 and later limit the number of shift operations performed to the native word size except when running in Virtual 86 mode) The leftmost bit of the operand is shifted into the Carry flag; the rightmost bit is cleared to 0 The Auxiliary carry flag (AF) becomes undefined after this instruction OF is modified only by the shift-by-one forms of SHL; after shift-by-CL forms, OF becomes undefined SHL is a synonym for SAL (Shift Arithmetic Left) Except for the direction the shift operation takes, SHL is identical to SHR r8 = AL AH BL BH CL CH DL DH sr = CS DS SS ES FS GS m8 = 8-bit memory data m32 = 32-bit memory data r16 = AX BX CX DX BP SP SI DI r32 = EAX EBX ECX EDX EBP ESP ESI EDI m16 = 16-bit memory data i8 = 8-bit immediate data

SHR Shift Right Flags affected:

O D I T S Z A P C F F F F F F F F F * * * * * * OF: Overflow flag TF: Trap flag AF: Aux carry DF: Direction flag SF: Sign flag PF: Parity flag IF: Interrupt flag ZF: Zero flag CF: Carry flag

Legal forms:

SHR SHR SHR SHR SHR SHR SHR SHR SHR SHR SHR SHR SHR SHR SHR SHR SHR SHR r8,1 m8,1 r16,1 m16,1 r32,1 m32,1 r8,CL m8,CL r16,CL m16,CL r32,CL m32,CL r8,i8 m8,i8 r16,i8 m16,i8 r32,i8 m32,i8

Examples:

Notes:

SHR shifts the bits within the destination operand to the right, where right is toward the least-significant bit (LSB) The number of bit positions shifted may be specified either as an 8-bit immediate value, or by the value in CL not CX or ECX (The 8086 and 8088 are limited to the immediate value 1) Note that while CL may accept a value up to 255, it is meaningless to shift by any value larger than 16 or 32 in 32-bit mode even though the shifts are actually performed on the 8086 and 8088 (The 286 and later limit the number of shift operations performed to the native word size except when running in Virtual 86 mode) The rightmost bit of the operand is shifted into the Carry flag; the leftmost bit is cleared to 0 The Auxiliary carry flag (AF) becomes undefined after this instruction OF is modified only by the shift-by-one forms of SHL; after shift-by-CL forms, OF becomes undefined SHR is a synonym for SAR (Shift Arithmetic Right) Except for the direction the shift operation takes, SHR is identical to SHL r8 = AL AH BL BH CL CH DL DH sr = CS DS SS ES FS GS m8 = 8-bit memory data m32 = 32-bit memory data r16 = AX BX CX DX BP SP SI DI r32 = EAX EBX ECX EDX EBP ESP ESI EDI m16 = 16-bit memory data i8 = 8-bit immediate data