Free Serialization on Shared Memory

Releases a shared memory block serialization that was
previously obtained with Int 31H Fn 0D02H.

Call With:

   AX     = 0D03H
   SI:DI  = shared memory block handle
   DX     = option flags
           Bit    Significance
           0      0 = release exclusive serialization
                  1 = release shared serialization
           1      0 = don't free pending serialization
                  1 = free pending serialization (see Note)
           2-15   reserved, must be zero

Returns:

   if function successful
   Carry flag= clear

   if function unsuccessful
   Carry flag= set
   AX     = error code
           8002H   invalid state (client does not own a
                   successful serialization of the specified
                   type)
           8023H   invalid handle

Notes:

o  For each client, the DPMI host maintains four different
   local (virtual machine) serialization counts (exclusive,
   shared, pending shared, and pending exclusive) for each
   shared memory block, as well as a global serialization
   count.  The global serialization count is only updated
   when the sum of a virtual machine's exclusive and shared
   serialization counts goes from 0 to 1 (serialize) or 1 to
   0 (free).
o  A client's interrupt handler can call this function with
   bit 1 of DX set to cancel a serialization request that
   has suspended the main thread of execution of the same
   client.  In such cases, the original serialization
   request will return with the Carry flag set and AX =
   8005H.