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<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN"><HTML><HEAD><TITLE>80386 Programmer's Reference Manual -- Opcode SBB</TITLE></HEAD><BODY><B>up:</B> <A HREF="c17.htm">Chapter 17 -- 80386 Instruction Set</A><BR><B>prev:</B><A HREF="SAL.htm"> SAL/SAR/SHL/SHR Shift Instructions</A><BR><B>next:</B><A HREF="SCAS.htm"> SCAS/SCASB/SCASW/SCASD Compare String Data</A><P><HR><P><H1>SBB -- Integer Subtraction with Borrow</H1><PRE>Opcode Instruction Clocks Description1C ib SBB AL,imm8 2 Subtract with borrow immediate byte from AL1D iw SBB AX,imm16 2 Subtract with borrow immediate word from AX1D id SBB EAX,imm32 2 Subtract with borrow immediate dword from EAX80 /3 ib SBB r/m8,imm8 2/7 Subtract with borrow immediate byte from r/m byte81 /3 iw SBB r/m16,imm16 2/7 Subtract with borrow immediate word from r/m word81 /3 id SBB r/m32,imm32 2/7 Subtract with borrow immediate dword from r/m dword83 /3 ib SBB r/m16,imm8 2/7 Subtract with borrow sign-extended immediate byte from r/m word83 /3 ib SBB r/m32,imm8 2/7 Subtract with borrow sign-extended immediate byte from r/m dword18 /r SBB r/m8,r8 2/6 Subtract with borrow byte register from r/m byte19 /r SBB r/m16,r16 2/6 Subtract with borrow word register from r/m word19 /r SBB r/m32,r32 2/6 Subtract with borrow dword register from r/m dword1A /r SBB r8,r/m8 2/7 Subtract with borrow byte register from r/m byte1B /r SBB r16,r/m16 2/7 Subtract with borrow word register from r/m word1B /r SBB r32,r/m32 2/7 Subtract with borrow dword register from r/m dword</PRE><H2>Operation</H2><PRE>IF SRC is a byte and DEST is a word or dwordTHEN DEST := DEST - (SignExtend(SRC) + CF)ELSE DEST := DEST - (SRC + CF);</PRE><H2>Description</H2>SBB adds the second operand (DEST) to the carry flag (CF) andsubtracts the result from the first operand (SRC). The result of thesubtraction is assigned to the first operand (DEST), and the flags areset accordingly.<P>When an immediate byte value is subtracted from a word operand, theimmediate value is first sign-extended.<H2>Flags Affected</H2>OF, SF, ZF, AF, PF, and CF as described in <A HREF="appc.htm">Appendix C</A><H2>Protected Mode Exceptions</H2>#GP(0) if the result is in a nonwritable segment; #GP(0) for an illegalmemory operand effective address in the CS, DS, ES, FS, or GSsegments; #SS(0) for an illegal address in the SS segment; #PF(fault-code)for a page fault<H2>Real Address Mode Exceptions</H2>Interrupt 13 if any part of the operand would lie outside of the effectiveaddress space from 0 to 0FFFFH<H2>Virtual 8086 Mode Exceptions</H2>Same exceptions as in Real Address Mode; #PF(fault-code) for a pagefault<P><HR><P><B>up:</B> <A HREF="c17.htm">Chapter 17 -- 80386 Instruction Set</A><BR><B>prev:</B><A HREF="SAL.htm"> SAL/SAR/SHL/SHR Shift Instructions</A><BR><B>next:</B><A HREF="SCAS.htm"> SCAS/SCASB/SCASW/SCASD Compare String Data</A></BODY>⌨️ 快捷键说明
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