Command: dis88 - disassembler [IBM]
Syntax: dis88 [-o] infile [outfile]
Flags: -o List the object code along with the assembly code
Examples: dis88 a.out >listing # Disassemble a.out
dis88 -o a.out listing # Ditto, but with object code
Dis88 disassembles 8088 object code to the assembly language format
used by MINIX. It makes full use of symbol table information, supports
separate instruction and data space, and generates synthetic labels when
needed. It does not support 8087 mnemonics, symbolic data segment
references, or the ESC mnemonic.
The program is invoked by:
dis88 [-o] infile [outfile]
The -o flag causes object code to be listed. If no outfile is given,
stdout is used.
The text segment of an object 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
harmless, 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.
Disassembly of the bss segment, on the other hand, is quite
straightforward, because uninitialized data is all zero by definition.
No data is output in the bss segment, but symbolic labels are output as
appropriate.
The output of operands in symbolic form is complicated somewhat by
the existence of assembler symbolic constants and segment override
opcodes. Thus, the program'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 arbitrary)
rankings within each type. Finally, if all else fails, it will output a
string containing the address sought as a hex constant. For user
convenience, the targets of branches are also output, in comments, as
hexadecimal constants.
Error Messages
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
incorrect
Reloc table overflow - Relocation table exceeds 1500
entries
Symbol table overflow - Symbol table exceeds 1500 entries
Lseek error - Input file corrupted (should never
happen)
Warning: no symbols - Symbol table is missing (use ast)
Cannot reopen input file - Input file was removed during
execution
Author
Dis88 was written and copyrighted by G. M. Harding and is included
here by permission. It may be freely redistributed provided that
complete source code, with all copyright notices, accompanies 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.
