85 lines
3.4 KiB
Groff
85 lines
3.4 KiB
Groff
.so mnx.mac
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.TH DIS88 9
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.CD "dis88 \(en disassembler [IBM]"
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.SX "dis88\fR [\fB\(eno\fR] \fIinfile\fR [\fIoutfile\fR]"
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.FL "\(eno" "List the object code along with the assembly code"
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.EX "dis88 a.out >listing" "Disassemble \fIa.out\fR"
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.EX "dis88 \(eno a.out listing" "Ditto, but with object code"
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.PP
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\fIDis88\fR disassembles 8088 object code to the assembly language format
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used by
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.MX .
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It makes full use of
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symbol table information, supports separate
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instruction and data space, and generates synthetic labels when needed.
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It does not support 8087 mnemonics, symbolic data segment references, or
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the ESC mnemonic.
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.PP
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The program is invoked by:
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.HS
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.Cx "dis88 [\(eno] infile [outfile]"
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.HS
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The \(eno flag causes object code to be listed.
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If no outfile is given, \fIstdout\fR is used.
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.PP
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The text segment of an object file is always padded to an even address.
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In addition, if the file has split I/D space, the text segment will be padded
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to a paragraph boundary (i.e., an address divisible by 16). Due to padding, the
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disassembler may produce a few spurious, but harmless, instructions at the end
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of the text segment.
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.PP
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Because the information to which initialized data refers cannot generally
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be inferred from context, the data segment is treated literally. Byte values
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(in hexadecimal) are output, and long stretches of null data are represented by
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appropriate \fI.zerow\fR pseudo-ops.
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Disassembly of the bss segment, on the other
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hand, is quite straightforward, because uninitialized data is all zero by
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definition.
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No data is output in the bss segment, but symbolic labels are output
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as appropriate.
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.PP
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The output of operands in symbolic form is complicated somewhat by the
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existence of assembler symbolic constants and segment override opcodes. Thus,
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the program's symbol lookup routine attempts to apply a certain amount of
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intelligence when it is asked to find a symbol. If it cannot match on a symbol
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of the preferred type, it may output a symbol of some other type, depending on
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preassigned (and somewhat arbitrary) rankings within each type. Finally, if
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all else fails, it will output a string containing the address sought as a hex
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constant. For user convenience, the targets of branches are also output, in
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comments, as hexadecimal constants.
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.SS "Error Messages"
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.PP
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Various error messages may be generated as a result of problems encountered
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during the disassembly.
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They are listed below
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.HS.
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.in +3.20i
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.ta +2.75i +0.2i
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.ti -2.95i
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Cannot access input file \(en Input file cannot be opened or read
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.ti -2.95i
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Cannot open output file \(en Output file cannot be created
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.ti -2.95i
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Input file not in object format \(en Bad magic number
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.ti -2.95i
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Not an 8086/8088 object file \(en CPU ID of the file header is incorrect
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.ti -2.95i
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Reloc table overflow \(en Relocation table exceeds 1500 entries
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.ti -2.95i
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Symbol table overflow \(en Symbol table exceeds 1500 entries
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.ti -2.95i
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Lseek error \(en Input file corrupted (should never happen)
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.ti -2.95i
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Warning: no symbols \(en Symbol table is missing (use ast)
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.ti -2.95i
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Cannot reopen input file \(en Input file was removed during execution
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.in -3.20i
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.SS "Author"
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.PP
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\fIDis88\fR was written and
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copyrighted by G. M. Harding and is included here by permission. It may be
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freely redistributed provided that complete source code, with all copyright
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notices, accompanies any redistribution. This provision also applies to any
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modifications you may make. You are urged to comment such changes, giving,
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as a minimum, your name and complete address.
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