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Code Mnemonic Description
1C ib SBB AL, imm8 Subtract with borrow imm8 from AL
1D iw SBB AX, imm16 Subtract with borrow imm16 from AX
1D id SBB EAX, imm32 Subtract with borrow imm32 from EAX
80 /3 ib SBB r/m8, imm8 Subtract with borrow imm8 from r/m8
81 /3 iw SBB r/m16, imm16 Subtract with borrow imm16 from r/m16
81 /3 id SBB r/m32, imm32 Subtract with borrow imm32 from r/m32
83 /3 ib SBB r/m16, imm8 Subtract with borrow sign-extended imm8 from r/m16
83 /3 ib SBB r/m32, imm8 Subtract with borrow sign-extended imm8 from r/m32
18 / r SBB r/m8, r8 Subtract with borrow r8 from r/m8
19 / r SBB r/m16, r16 Subtract with borrow r16 from r/m16
19 / r SBB r/m32, r32 Subtract with borrow r32 from r/m32
1A / r SBB r8, r/m8 Subtract with borrow r/m8 from r8
1B / r SBB r16, r/m16 Subtract with borrow r/m16 from r16
1B / r SBB r32, r/m32 Subtract with borrow r/m32 from r32

Description
Adds the source operand (second operand) and the carry (CF) flag, and subtracts the result from the destination operand (first operand). The result of the subtraction is stored in the destination operand. The destination operand can be a register or a memory location; the source operand can be an immediate, a register, or a memory location. (However, two memory operands cannot be used in one instruction.) The state of the CF flag represents a borrow from a previous subtraction.

When an immediate value is used as an operand, it is sign-extended to the length of the destination operand format.

The SBB 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.

The SBB instruction is usually executed as part of a multibyte or multiword subtraction in which a SUB instruction is followed by a SBB instruction.
Operands Bytes Clocks
reg, reg 2 1 PU
mem, reg 2 + d(0, 2) 3 PU
reg, mem 2 + d(0, 2) 2 PU
reg, imm 2 + i(1, 2) 1 PU
mem, imm 2 + d(0, 2) + i(1, 2) 3 PU ( not pairable if there is a displacement and immediate)
acc, imm 1 + i(1, 2) 1 PU

Flags
ID unaffected DF unaffected
VIP unaffected IF unaffected
VIF unaffected TF unaffected
AC unaffected SF sets according to the result
VM unaffected ZF sets according to the result
RF unaffected AF sets according to the result
NT unaffected PF sets according to the result
IOPL unaffected CF sets according to the result
OF sets according to the result