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include vmm.inc
 
mov     ah, SegOffset    ; offset in Client_Reg_Struc to segment reg
mov     al, OffOffset    ; offset in Client_Reg_Struc to offset reg
VMMcall Map_Flat
 
cmp     eax, -1         ; -1 if error
je      error
mov     [LinAddr], eax  ; ring-0 linear address
 
The Map_Flat service converts a segment:offset or selector:offset pair into
a linear address. This service works only for the current virtual machine.
It determines whether the value passed to it is a V86 segment or a
protected-mode selector by the execution mode of the current virtual
machine.
 
Parameter  Description
────────────────────────────────────────────────────────────────────────────
 
SegOffset  Specifies the offset in bytes from the start of the
           Client_Reg_Struc structure to the segment register that contains
           the segment address or selector to convert.
 
OffOffset  Specifies the offset in bytes from the start of the
           Client_Reg_Struc structure to the register that contains the
           address offset to convert. If this parameter is -1, this service
           uses 0 as the address offset to convert.
 
Return Value
 
The EAX register contains the ring-0 linear address that corresponds to the
specified V86 or protected-mode address. The EAX register contains -1 if if
the specified selector is invalid.
 
Comments
 
Before converting an address, Map_Flat checks the current execution mode
and, for protected-mode applications, the segment granularity (16- or 32-bit
offsets). If the virtual machine is running a 32-bit protected mode
application, it uses 32-bit address offsets. For V86 and 16-bit
protected-mode applications, it uses 16-bit address offsets and ignores the
high word if the OffOffset parameter specifies a 32-bit register.
 
Example
 
The following example converts the address Client_DS:Client_DX and returns
the linear address in EAX:
 
mov     ax, (Client_DS SHL 8) + Client_DX
VMMcall Map_Flat
 
Uses
 
EAX, Flags
 
See Also
 
Client_Ptr_Flat
 
 
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