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https://github.com/maksasj/diasm
simple x86 16-bit real mode instruction subset disassembler
https://github.com/maksasj/diasm
asm disassembler dos dosbox tasm
Last synced: about 6 hours ago
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simple x86 16-bit real mode instruction subset disassembler
- Host: GitHub
- URL: https://github.com/maksasj/diasm
- Owner: Maksasj
- License: mit
- Created: 2023-12-13T14:16:45.000Z (11 months ago)
- Default Branch: master
- Last Pushed: 2024-06-03T14:39:16.000Z (6 months ago)
- Last Synced: 2024-06-03T17:03:26.145Z (6 months ago)
- Topics: asm, disassembler, dos, dosbox, tasm
- Language: Assembly
- Homepage:
- Size: 45.9 KB
- Stars: 2
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE.md
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README
# diasm
diasm - simple x86 16-bit real mode instruction subset disassembler, for **MS-DOS** operating system
### Overview
diasm is a simple x86 16-bit real mode instruction subset disassembler, for **MS-DOS** operating system. Written in assembly with **tasm** compiler, basically proof of concept of writing disassembler in assembly.
### Supported instructions
- **mov** *all 6 scenarios*
- **out** *2 scenarios*
- **not** *4 scenarios*
- **rcr** *4 scenarios*
- **xlat** *1 scenarios*
### Implementation
Actually most interesting aspect of this program is code itself, for example
```c++
process_not:
@PRINT_STR(offset not_str)
mov w_val, al
@MASK_VALUE(w_val, 00000001b)
@RETRIEVE_NEXT_BYTE
mov rm_val, al
@MASK_VALUE(rm_val, 00000111b)
mov mod_val, al
@MASK_VALUE(mod_val, 11000000b)
shr mod_val, 3
@JMP_EQL(mod_val, 00000000b, not_scenario_mod_00)
@JMP_EQL(mod_val, 00001000b, not_scenario_mod_01)
@JMP_EQL(mod_val, 00010000b, not_scenario_mod_10)
@JMP_EQL(mod_val, 00011000b, not_scenario_mod_11)
not_scenario_mod_00:
call process_mod_xxx_rm_scenario_00
jmp not_continue
// process scenarios 01 - 11, same as 00
not_continue:
@PRINT_STR(offset endl_str)
jmp inst_loop
```
Note that for an **assembly** code is pretty readable, now it is very easy to even add support for new instructions.
Main benefit comes from **@JMP_EQL()**, **@MASK_VALUE()** and other macros. **Tasm** itself does not support such macros, these macros are resolved by my own preprocessor [link](https://github.com/AlexShukel/am08x24arc/tree/main/src/preprocessor).
Probably no one will build this project, so I will not include or release this preprocessor, if you really need it, just open an issue in this repository.
> Sadly this time diasm is a asm framework ?
Cool looking widgets
### Build
1. **Build manually**
First of all requirements:
- Dosbox (an x86 emulator with Dos)
- tasm (Should be installed in Dosbox)
- tlink (Should be installed in Dosbox)
## License
**diasm** is free and open source thing. All code in this repository is licensed under
- MIT License ([LICENSE.md](https://github.com/Maksasj/diasm/blob/master/LICENSE.md) or https://opensource.org/license/mit/)