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include v86mmgr.inc
 
VxDcall V86MMGR_Allocate_Buffer
 
The V86MMGR_Allocate_Buffer service allocates a portion of the current
virtual machine's  translation buffer and optionally copies data from the
protected-mode pointer in FS:ESI registers into the allocated buffer.
 
Parameter  Description
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EBX        Specifies the current virtual machine handle. The current virtual
           machine must be in protected mode.
 
EBP        Points to a Client_Reg_Struc structure containing the register
           values of the current virtual machine.
 
ECX        Specifies the number of bytes to allocate.
 
FS:ESI     Specifies a pointer to the extended memory to copy. If the carry
           flag is set, the service copies the source buffer into a V86
           buffer; otherwise, it copies the source buffer into V86 memory.
 
Return Value
 
The carry flag is clear if the service is successful. The ECX register
contains the actual number of bytes allocated ( less than or equal to the
original ECX parameter). The high word of the EDI register contains the V86
segment for the translation buffer and the low word of the EDI register
contains the offset of the allocated buffer.
 
If the carry flag is set, the service could not allocate buffer.
 
Comments
 
This service maps fewer bytes than the value specified in the ECX parameter
if the length of the buffer would extend past the FS segment limit.
Therefore, a virtual device needs to preserve the value returned in ECX from
this service to use when deallocating the buffer using the
V86MMGR_Free_Buffer service.
 
The buffers are maintained as a stack. Therefore, the last buffer allocated
must be the first buffer freed.
 
Uses
 
ECX, EDI, Flags
 
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