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<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN"><HTML><HEAD><TITLE>80386 Programmer's Reference Manual -- Opcode LSL</TITLE></HEAD><BODY><B>up:</B> <A HREF="c17.htm">Chapter 17 -- 80386 Instruction Set</A><BR><B>prev:</B><A HREF="LOOP.htm"> LOOP/LOOPcond Loop Control with CX Counter</A><BR><B>next:</B><A HREF="LTR.htm"> LTR Load Task Register</A><P><HR><P><H1>LSL -- Load Segment Limit</H1><PRE>Opcode Instruction Clocks Description0F 03 /r LSL r16,r/m16 pm=20/21 Load: r16 := segment limit, selector r/m16 (byte granular)0F 03 /r LSL r32,r/m32 pm=20/21 Load: r32 := segment limit, selector r/m32 (byte granular)0F 03 /r LSL r16,r/m16 pm=25/26 Load: r16 := segment limit, selector r/m16 (page granular)0F 03 /r LSL r32,r/m32 pm=25/26 Load: r32 := segment limit, selector r/m32 (page granular)</PRE><H2>Description</H2>The LSL instruction loads a register with an unscrambled segment limit,and sets ZF to 1, provided that the source selector is visible at the CPLweakened by RPL, and that the descriptor is a type accepted by LSL.Otherwise, ZF is cleared to 0, and the destination register is unchanged.The segment limit is loaded as a byte granular value. If the descriptorhas a page granular segment limit, LSL will translate it to a byte limitbefore loading it in the destination register (shift left 12 the 20-bit"raw" limit from descriptor, then OR with 00000FFFH).<P>The 32-bit forms of this instruction store the 32-bit byte granular limitin the 16-bit destination register.<P>Code and data segment descriptors are valid for LSL.<P>The valid special segment and gate descriptor types for LSL are givenin the following table:<PRE>Type Name Valid/Invalid 0 Invalid Invalid 1 Available 80286 TSS Valid 2 LDT Valid 3 Busy 80286 TSS Valid 4 80286 call gate Invalid 5 80286/80386 task gate Invalid 6 80286 trap gate Invalid 7 80286 interrupt gate Invalid 8 Invalid Valid 9 Available 80386 TSS Valid A Invalid Invalid B Busy 80386 TSS Valid C 80386 call gate Invalid D Invalid Invalid E 80386 trap gate Invalid F 80386 interrupt gate Invalid</PRE><H2>Flags Affected</H2>ZF as described above<H2>Protected Mode Exceptions</H2>#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<H2>Real Address Mode Exceptions</H2>Interrupt 6; LSL is not recognized in Real Address Mode<H2>Virtual 8086 Mode Exceptions</H2>Same exceptions as in Real Address Mode<P><HR><P><B>up:</B> <A HREF="c17.htm">Chapter 17 -- 80386 Instruction Set</A><BR><B>prev:</B><A HREF="LOOP.htm"> LOOP/LOOPcond Loop Control with CX Counter</A><BR><B>next:</B><A HREF="LTR.htm"> LTR Load Task Register</A></BODY>⌨️ 快捷键说明
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