Dis88 disassembles 8088 object code to the assembly language for-
mat used by It makes full use of symbol table information, sup-
ports separate instruction and data space, and generates synthet-
ic labels when needed. It does not support 8087 mnemonics, sym-
bolic data segment references, or the ESC mnemonic. The program
is invoked by: The -o flag causes object code to be listed. If
no outfile is given, stdout is used. The text segment of an ob-
ject file is always padded to an even address. In addition, if
the file has split I/D space, the text segment will be padded to
a paragraph boundary (i.e., an address divisible by 16). Due to
padding, the disassembler may produce a few spurious, but harm-
less, instructions at the end of the text segment. Because the
information to which initialized data refers cannot generally be
inferred from context, the data segment is treated literally.
Byte values (in hexadecimal) are output, and long stretches of
null data are represented by appropriate .zerow pseudo-ops. Dis-
assembly of the bss segment, on the other hand, is quite
straightforward, because uninitialized data is all zero by defi-
nition. No data is output in the bss segment, but symbolic la-
bels are output as appropriate. The output of operands in sym-
bolic form is complicated somewhat by the existence of assembler
symbolic constants and segment override opcodes. Thus, the pro-
gram's symbol lookup routine attempts to apply a certain amount
of intelligence when it is asked to find a symbol. If it cannot
match on a symbol of the preferred type, it may output a symbol
of some other type, depending on preassigned (and somewhat arbi-
trary) rankings within each type. Finally, if all else fails, it
will output a string containing the address sought as a hex con-
stant. For user convenience, the targets of branches are also
output, in comments, as hexadecimal constants. Various error
messages may be generated as a result of problems encountered
during the disassembly. They are listed below
Cannot access input file - Input file cannot be opened or
read
Cannot open output file - Output file cannot be created
Input file not in object format-Bad magic number
Not an 8086/8088 object file -CPU ID of the file header is in-
correct
Reloc table overflow - Relocation table exceeds 1500 en-
tries
Symbol table overflow - Symbol table exceeds 1500 entries
Lseek error - Input file corrupted (should nev-
er happen)
Warning: no symbols - Symbol table is missing (use ast)
Cannot reopen input file - Input file was removed during ex-
ecution
Dis88 was written and copyrighted by G. M. Harding and is in-
cluded here by permission. It may be freely redistributed provid-
ed that complete source code, with all copyright notices, accom-
panies any redistribution. This provision also applies to any
modifications you may make. You are urged to comment such
changes, giving, as a minimum, your name and complete address.
