Instruction Set SBB
SBB -- Integer Subtraction with Borrow
SBB -- Integer Subtraction with Borrow
Opcode Instruction Clocks Description
1C ib SBB AL,imm8 2 Subtract with borrow immediate byte
from AL
1D iw SBB AX,imm16 2 Subtract with borrow immediate word
from AX
1D id SBB EAX,imm32 2 Subtract with borrow immediate
dword from EAX
80 /3 ib SBB r/m8,imm8 2/7 Subtract with borrow immediate byte
from r/m byte
81 /3 iw SBB r/m16,imm16 2/7 Subtract with borrow immediate word
from r/m word
81 /3 id SBB r/m32,imm32 2/7 Subtract with borrow immediate
dword from r/m dword
83 /3 ib SBB r/m16,imm8 2/7 Subtract with borrow sign-extended
immediate byte from r/m word
83 /3 ib SBB r/m32,imm8 2/7 Subtract with borrow sign-extended
immediate byte from r/m dword
18 /r SBB r/m8,r8 2/6 Subtract with borrow byte register
from r/m byte
19 /r SBB r/m16,r16 2/6 Subtract with borrow word register
from r/m word
19 /r SBB r/m32,r32 2/6 Subtract with borrow dword register
from r/m dword
1A /r SBB r8,r/m8 2/7 Subtract with borrow byte register
from r/m byte
1B /r SBB r16,r/m16 2/7 Subtract with borrow word register
from r/m word
1B /r SBB r32,r/m32 2/7 Subtract with borrow dword register
from r/m dword
Operation
IF SRC is a byte and DEST is a word or dword
THEN DEST = DEST - (SignExtend(SRC) + CF)
ELSE DEST = DEST - (SRC + CF);
Description
SBB adds the second operand (DEST) to the carry flag (CF) and
subtracts the result from the first operand (SRC). The result of the
subtraction is assigned to the first operand (DEST), and the flags are
set accordingly.
When an immediate byte value is subtracted from a word operand, the
immediate value is first sign-extended.
Flags Affected
OF, SF, ZF, AF, PF, and CF as described in Appendix C
Protected Mode Exceptions
#GP(0) if the result is in a nonwritable segment; #GP(0) for an illegal
memory operand effective address in the CS, DS, ES, FS, or GS
segments; #SS(0) for an illegal address in the SS segment; #PF(fault-code)
for a page fault
Real Address Mode Exceptions
Interrupt 13 if any part of the operand would lie outside of the effective
address space from 0 to 0FFFFH
Virtual 8086 Mode Exceptions
Same exceptions as in Real Address Mode; #PF(fault-code) for a page
fault