IS-DOS - "The format of the table of local symbols IS-DOS assembly language."

Category "IS-DOS - programmers" No 3


            Prokopenko SV

        Ed. Eliseev, VA


       Format the table of local

      Character IS-DOS Assembler "
________________________________________


     This article describes the format
table of local symbols generated by IS-DOS assemblers in the 
form of a temporary file *. ltb 


     Table of local symbols contains local characters names, 
digital local labels defined in the first

pass broadcast programs, and their corresponding numerical 
values. 


     The table-file is erased after broadcast.


     The table structure of local

          Character assembly.


     The entire table consists of continuously
located records of 16 bytes each.

     Each entry contains information
or about one a local symbol name
or describes one or more digital local labels (up to 8 pcs.) 
Entries local symbols, names associated with each

another in a binary tree, and the records
Digital local labels can be reached only through the 
corresponding nominal symbol-label nachinayuschuyu block of 
digital local labels. 


     The format of one record for simvolovimen following (see 
Table 1.): 


                           Table 1.

      Recording format characters names.
---------------------------------------
  Offset. length value
---------------------------------------
 0,1 (2) - a reference to the previous one

                 record
 2,3 (2) - a reference to the following

                 record

   4 (1) - number of characters in

                 name and symbol (N)

   5 (N) - signs of character (s)
 5 + N (1) - tag (*) values

                 symbol
 6 + N (2) - symbol value
 8 + N (2) - a reference to the block of digital
                 rovyh local labels

                 (If any) or the value
                 chenie Software

                 counter (for characters,

                 defined by

                 EQU). In the remaining cases
                 both cases is not defined
---------------------------------------
-------------(*) Tag (English tag - a label ztiketka) -
Part of the data item (one or more bits of the word), which 
determines its type. (Editor's note.)

-------------

     Links to the block of digital local
characters can be of 2 types:

 1. # NNFF (FF-low byte)

     # FF-sign this type of link;

     NN-digital number of local symbols
     crystals in the block (1 byte);


     In the case of this type of reference block
ts.l.s. begins immediately with the next 16
byte record and continues to the end.

 2.NNNN - offset from the beginning

     file *. ltb to block ts.l.s.


     In the case of this type of reference block
ts.l.s. begins to shift from NNNN
ts.l.s. beginning of the file, and the beginning of the block
ts.l.s. The following are 2 bytes: # FF, and then NN-digital 
number of local characters in the block. Next row followed 
ts.l.s. 


     One ts.l.s. 2 bytes. The first byte is the number ts.l.s., 
and the second - his value (offset from the beginning

Block ts.l.s.)


     Ts.l.s. written to a file in the form
16-byte records. Therefore, if their
number in the block is not a multiple of 8, then the remaining 
part of the last byte write block not used. A new block ts.l.s. 
always starts at the new 16 byte records. 

            ________________


    Once again I remind you that your suggestions and comments 
on all materials relating to the IS-DOS, we will be happy 
listen to the call 245-00-91 (from 10.00 until 16.00 on 
weekdays and ask for Software Division), on the same phone you 
can obtain prompt advice on all matters relating to the system 
IS-DOS and applications running in its environment. 

Firm "IskraSoft"
________________________________________