Compatibility: 3.3+
Expects: AX    6507H
BX    Code Page (0ffffH = current code page for console)
CX    size of data to return (must be at least 5)
ES:DI address of buffer to receive the table address
                                                                  
Returns: AX    error code if CF is set to CY
ES:DI buffer is filled with 5 bytes of return information
                                                                  
Info: Returns the address of some information used in working with
double-byte character sets (DBCS).  The return information tells
which bytes are lead characters of two-byte sequences.  Such
two-byte sequences must be treated as an unbreakable unit in
DBCS-aware programs.

Upon return ES:DI points to a 5-byte structure.  The first byte
is a table identifier (07H) and the next 4 bytes are a 32-bit
address in standard address format (offset, then segment).

At that address is a variable-length table.  The first two bytes
describe the length of the table in bytes.  That is followed by a
series of byte-pairs which each describe a run of lead
characters.   The table is terminated by two bytes of 00H.   For
instance...

06,00, dc,df, f1,ff,00,00

...indicates the table is 6 bytes long and that characters dcH,
deH, dfH and deH and f1H through ffH are lead characters in DBCS
byte-pairs.

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DOS Fn 6507H: Get Double-Byte Character Set