Find a string -- reverse

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DOS pseudo functions: Find a string -- reverse

Syntax:

 DOSMS(AX-value, BX-value, CX-value, DX-value) EXCP=statement-label  

Entry:

   AX = "@FFFB@"
                                                                                                                          .
    Upon execution of the DOSMS function, the AX register acts as
    a "countdown" field. If the number of occurrences of the
    search string is found, the value in this register is 0. A
    non-0 value means that a beginning-of-file was encountered
    before the specified number of occurrences were found.
                                                                                                                         .        BX = file handle
   CX = number of occurrences to find (in hex)
   DX = the search string

Discussion:
This pseudo function searches an entire file for a specified string in reverse record order (physical order).
If the string is found anywhere within the file, the file pointer is positioned at the physical record where the string was found.
The search starts at current position in the file.