docs(amiga): complete AmigaOS 3.1/3.2 developer reference — 172 files across 17 sections
Comprehensive technical documentation covering:
- Hardware: OCS/ECS/AGA custom chip registers, Copper & Blitter deep dives
- Boot sequence: cold boot through startup-sequence
- Binary format: HUNK executable spec, relocation, debug info
- Linking & ABI: .fd files, LVO tables, register calling conventions
- Exec kernel: tasks, interrupts, memory, signals, semaphores
- AmigaDOS: file I/O, FFS/OFS layout, CLI/Shell scripting
- Graphics: planar bitmaps, Copper programming, HAM/EHB modes
- Intuition: screens, windows, IDCMP, BOOPSI
- Devices: trackdisk, SCSI, serial, timer, audio, keyboard
- Libraries: utility, expansion, IFFParse, locale, ARexx
- Networking: bsdsocket API, SANA-II, TCP/IP stack comparison
- Toolchain: GCC, vasm/vlink, SAS/C, NDK, debugging
- Reverse engineering: IDA/Ghidra setup, compiler fingerprints, case studies
- CPU & MMU: 68040/060 emulation libs, PMMU, cache management
- Driver development: SANA-II, Picasso96/RTG, AHI audio
All files include breadcrumb navigation. No local paths or proprietary content.
2026-04-23 12:16:52 -04:00
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[← Home](../README.md)
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# Executable Loader & HUNK Format
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## Overview
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This section covers the complete lifecycle of an AmigaOS executable:
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1. **HUNK file format** — the binary container for all AmigaOS executables, libraries, and object files
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2. **Loader pipeline** — how `dos.library` loads and relocates an executable into memory
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3. **Object files** — how compilers produce relocatable object files for the linker
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4. **Overlays** — how programs larger than available memory use the overlay system
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## Contents
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| File | Topic |
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|---|---|
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03/04: deep enrichment of loader/exec format and linking/libraries
Sections 03 and 04 augmented to bootcamp quality with targeted
enrichment based on content analysis (not just file size).
03_loader_and_exec_format:
- overlay_system.md: full rewrite — tree architecture diagram,
HUNK_OVERLAY binary format, overlay manager runtime internals,
worked binary example, linker support, modern alternatives
- hunk_relocation.md: full rewrite — visual before/after diagram,
patching algorithm with code, RELOC32SHORT and DREL32 formats,
PC-relative impact comparison table, self-referencing relocs,
error scenarios, Python reloc scanner tool
04_linking_and_libraries:
- library_structure.md: full rewrite — ASCII memory layout diagram,
JMP table encoding (why 6 bytes), MakeLibrary internals with both
function array formats, complete library creation example with
.fd file, checksum verification, lifecycle state diagram
- shared_libraries_runtime.md: full rewrite — OpenLibrary 4-step
resolution path, ramlib disk loader internals, disk search path,
version negotiation table (v33-v47), CloseLibrary/Expunge deep
dive, memory-low sweep, common pitfalls table
- register_conventions.md: full rewrite — FPU register map,
inter-library A6 save/restore pattern, small-data model with
__saveds keyword, varargs/TagItem pattern deep dive,
stack-based wrapper explanation, disassembly identification
Updated indexes:
- 03_loader_and_exec_format/README.md
- 04_linking_and_libraries/README.md
- Root README.md (sections 03 and 04)
2026-04-23 18:30:45 -04:00
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| [hunk_format.md](hunk_format.md) | Complete HUNK binary specification — all 22 hunk type codes with wire format, memory flags, advisory bits |
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| [hunk_ext_deep_dive.md](hunk_ext_deep_dive.md) | HUNK_EXT: exports (EXT_DEF), imports (EXT_REF32), commons, linker resolution |
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| [hunk_relocation.md](hunk_relocation.md) | Relocation mechanics: visual before/after, patching algorithm, RELOC32/SHORT/DREL32, PC-relative impact |
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| [hunk_debug_info.md](hunk_debug_info.md) | HUNK_SYMBOL and HUNK_DEBUG: stabs format (SAS/C, GCC), debugger consumption, stripping |
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| [exe_load_pipeline.md](exe_load_pipeline.md) | LoadSeg → AllocMem → relocation → segment chain → CreateProc → entry point |
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| [object_file_format.md](object_file_format.md) | Compiler object files (HUNK_UNIT), multi-section layout, HUNK_LIB archives, linker operation |
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| [overlay_system.md](overlay_system.md) | HUNK_OVERLAY: tree architecture, runtime overlay manager, worked binary example, modern alternatives |
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docs(amiga): complete AmigaOS 3.1/3.2 developer reference — 172 files across 17 sections
Comprehensive technical documentation covering:
- Hardware: OCS/ECS/AGA custom chip registers, Copper & Blitter deep dives
- Boot sequence: cold boot through startup-sequence
- Binary format: HUNK executable spec, relocation, debug info
- Linking & ABI: .fd files, LVO tables, register calling conventions
- Exec kernel: tasks, interrupts, memory, signals, semaphores
- AmigaDOS: file I/O, FFS/OFS layout, CLI/Shell scripting
- Graphics: planar bitmaps, Copper programming, HAM/EHB modes
- Intuition: screens, windows, IDCMP, BOOPSI
- Devices: trackdisk, SCSI, serial, timer, audio, keyboard
- Libraries: utility, expansion, IFFParse, locale, ARexx
- Networking: bsdsocket API, SANA-II, TCP/IP stack comparison
- Toolchain: GCC, vasm/vlink, SAS/C, NDK, debugging
- Reverse engineering: IDA/Ghidra setup, compiler fingerprints, case studies
- CPU & MMU: 68040/060 emulation libs, PMMU, cache management
- Driver development: SANA-II, Picasso96/RTG, AHI audio
All files include breadcrumb navigation. No local paths or proprietary content.
2026-04-23 12:16:52 -04:00
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## Why HUNK?
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HUNK is the native AmigaOS executable format, used from AmigaOS 1.0 through 3.x. It predates ELF/COFF and has these key properties:
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- **Segmented**: separate code, data, and BSS hunks with independent memory allocation
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- **Relocatable**: all absolute references are patched at load time (no ASLR; base address changes each run)
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- **Typed memory**: each hunk can request `CHIP` or `FAST` memory independently
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- **Symbol-complete**: optional HUNK_SYMBOL and HUNK_DEBUG hunks carry debugging information
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## Key Concepts
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| Term | Meaning |
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| **Hunk** | One contiguous block in the binary (code, data, BSS, etc.) |
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| **Segment** | A loaded hunk at runtime — a `BPTR`-linked list |
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| **Segment list** | Chain of loaded hunks returned by `LoadSeg()` |
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| **BPTR** | Amiga byte pointer — 32-bit value right-shifted by 2 (`ptr >> 2`) |
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| **Relocation** | Patching absolute addresses based on actual load address |
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| **LVO** | Library Vector Offset — negative offset from library base |
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## References
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- ADCD 2.1: `Includes_and_Autodocs_3._guide/` — dos.library LoadSeg autodoc
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- NDK39: `dos/dos.h` — BPTR, segment handling macros
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- *Amiga ROM Kernel Reference Manual: Libraries* — AmigaDOS chapter
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- http://amigadev.elowar.com/read/ADCD_2.1/Libraries_Manual_guide/node0150.html
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