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====== Int 31H, AH=00H, AL=0CH ======

===== Version =====

0.9

===== Brief =====

Set Descriptor

===== Input =====

  AX = 000CH
  BX = selector
  ES:(E)DI = selector:offset of 8-byte buffer containing descriptor

===== Return =====

  if function successful
  Carry flag = clear
  
  if function unsuccessful
  Carry flag = set
  AX = error code
  8021H	invalid value (access rights/type byte invalid)
  8022H	invalid selector
  8025H	invalid linear address (descriptor references a linear address range outside that allowed for DPMI clients)

===== Notes =====

Copies the contents of an 8-byte buffer into the LDT descriptor for the specified selector.

32-bit programs must use ES:EDI to point to the buffer. 16-bit programs should use ES:DI.

The descriptor's access rights/type byte (byte 5) follows the same format and restrictions as the access rights/type parameter (in CL) for the Set Descriptor Access Rights function (Int 31H Function 0009H). On 80386 (or later) machines, the descriptor's extended access rights/type byte (byte 6) follows the same format and restrictions as the extended access rights/type parameter (in CH) for the same function, except the low-order 4 bits (marked "reserved") are used to set the upper 4 bits of the descriptor's limit.

If the descriptor's present bit is not set, then the only error checking is that the client's CPL must be equal to the descriptor's DPL field and the "must be 1" bit in the descriptor's byte 5 must be set.

A DPMI 1.0 host will reload any segment register which contains a selector specified in register BX. It is suggested that DPMI 0.9 hosts also implement this.

Refer to the rules for descriptor usage in Appendix D.
    
===== See also =====

   

===== Note =====

Text based on [[http://www.delorie.com/djgpp/doc/dpmi/]]

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