mirror of
https://github.com/alfishe/amiga-bootcamp.git
synced 2026-06-13 00:26:28 +00:00
4593ff135a
New comprehensive article on Amiga executable crunchers covering: - Architecture: how crunched files remain valid HUNK executables - Major crunchers: PowerPacker, Imploder, Shrinkler, ByteKiller, Titanics, CrunchMania, PackFire, XPK framework - PP20 format: efficiency table, decrunch info, decrunch colours - Shrinkler internals: 1536-context adaptive probability model, range coder, parity context flag, stack-based context table, actual 68000 decompressor source from GitHub - LZ77/LZSS vs context-modelling+range-coding algorithms - Relocation handling: 3 strategies (compressed relocs, delta table, merged single-hunk) - Memory layout diagrams: before/during/after decompression - Detection: magic signatures table, fake header warning, Python scanner script - Tools: xfdmaster modular architecture, Ancient C++ library, debugger-based extraction (last resort) - FPGA/emulation impact: timing, self-modifying code, cache Based on web research: verified PP20 format spec, Shrinkler source (askeksa/Shrinkler), Ancient library (temisu/ancient), xfdmaster slave module architecture. Updated indexes: 03/README.md, root README.md
52 lines
2.9 KiB
Markdown
52 lines
2.9 KiB
Markdown
[← Home](../README.md)
|
|
|
|
# Executable Loader & HUNK Format
|
|
|
|
## Overview
|
|
|
|
This section covers the complete lifecycle of an AmigaOS executable:
|
|
|
|
1. **HUNK file format** — the binary container for all AmigaOS executables, libraries, and object files
|
|
2. **Loader pipeline** — how `dos.library` loads and relocates an executable into memory
|
|
3. **Object files** — how compilers produce relocatable object files for the linker
|
|
4. **Overlays** — how programs larger than available memory use the overlay system
|
|
|
|
## Contents
|
|
|
|
| File | Topic |
|
|
|---|---|
|
|
| [hunk_format.md](hunk_format.md) | Complete HUNK binary specification — all 22 hunk type codes with wire format, memory flags, advisory bits |
|
|
| [hunk_ext_deep_dive.md](hunk_ext_deep_dive.md) | HUNK_EXT: exports (EXT_DEF), imports (EXT_REF32), commons, linker resolution |
|
|
| [hunk_relocation.md](hunk_relocation.md) | Relocation mechanics: visual before/after, patching algorithm, RELOC32/SHORT/DREL32, PC-relative impact |
|
|
| [hunk_debug_info.md](hunk_debug_info.md) | HUNK_SYMBOL and HUNK_DEBUG: stabs format (SAS/C, GCC), debugger consumption, stripping |
|
|
| [exe_load_pipeline.md](exe_load_pipeline.md) | LoadSeg → AllocMem → relocation → segment chain → CreateProc → entry point |
|
|
| [object_file_format.md](object_file_format.md) | Compiler object files (HUNK_UNIT), multi-section layout, HUNK_LIB archives, linker operation |
|
|
| [overlay_system.md](overlay_system.md) | HUNK_OVERLAY: tree architecture, runtime overlay manager, worked binary example, modern alternatives |
|
|
| [**exe_crunchers.md**](exe_crunchers.md) | **Executable packers: PowerPacker/Imploder/Shrinkler, decrunch stubs, compression algorithms, detection** |
|
|
|
|
## Why HUNK?
|
|
|
|
HUNK is the native AmigaOS executable format, used from AmigaOS 1.0 through 3.x. It predates ELF/COFF and has these key properties:
|
|
|
|
- **Segmented**: separate code, data, and BSS hunks with independent memory allocation
|
|
- **Relocatable**: all absolute references are patched at load time (no ASLR; base address changes each run)
|
|
- **Typed memory**: each hunk can request `CHIP` or `FAST` memory independently
|
|
- **Symbol-complete**: optional HUNK_SYMBOL and HUNK_DEBUG hunks carry debugging information
|
|
|
|
## Key Concepts
|
|
|
|
| Term | Meaning |
|
|
|---|---|
|
|
| **Hunk** | One contiguous block in the binary (code, data, BSS, etc.) |
|
|
| **Segment** | A loaded hunk at runtime — a `BPTR`-linked list |
|
|
| **Segment list** | Chain of loaded hunks returned by `LoadSeg()` |
|
|
| **BPTR** | Amiga byte pointer — 32-bit value right-shifted by 2 (`ptr >> 2`) |
|
|
| **Relocation** | Patching absolute addresses based on actual load address |
|
|
| **LVO** | Library Vector Offset — negative offset from library base |
|
|
|
|
## References
|
|
|
|
- ADCD 2.1: `Includes_and_Autodocs_3._guide/` — dos.library LoadSeg autodoc
|
|
- NDK39: `dos/dos.h` — BPTR, segment handling macros
|
|
- *Amiga ROM Kernel Reference Manual: Libraries* — AmigaDOS chapter
|
|
- http://amigadev.elowar.com/read/ADCD_2.1/Libraries_Manual_guide/node0150.html
|