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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)
51 lines
2.7 KiB
Markdown
51 lines
2.7 KiB
Markdown
[← Home](../README.md)
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# Linking & Library Integration
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## Overview
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This section documents how AmigaOS shared libraries work at the binary level — how compilers produce library call stubs, how the linker wires them up, and how to reconstruct this mechanism during reverse engineering.
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## Contents
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| File | Topic |
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|---|---|
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| [library_structure.md](library_structure.md) | Library memory layout, JMP table encoding, MakeLibrary construction, complete library creation example |
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| [shared_libraries_runtime.md](shared_libraries_runtime.md) | OpenLibrary resolution path, ramlib disk loader, version negotiation, expunge mechanics |
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| [register_conventions.md](register_conventions.md) | Register ABI: integer, FPU, varargs/TagItem, small-data model, __saveds, inter-library calls |
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| [fd_files.md](fd_files.md) | Function Definition files — the library ABI source of truth, LVO calculation |
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| [lvo_table.md](lvo_table.md) | JMP table layout, complete exec.library LVO table, IDA reconstruction script |
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| [compiler_stubs.md](compiler_stubs.md) | How SAS/C, GCC, VBCC call libraries — compiler signature identification |
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| [inline_stubs.md](inline_stubs.md) | Compiler inline stubs: pragma (SAS/C), inline asm (GCC), __reg (VBCC), stub generation tools |
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| [link_libraries.md](link_libraries.md) | Static linking: amiga.lib, sc.lib, libnix, auto.lib, WBStartup glue, stack cookie |
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| [startup_code.md](startup_code.md) | c.o / gcrt0.S: entry contract, CLI vs WB detection, argument parsing, WBStartup message |
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| [setfunction.md](setfunction.md) | Runtime function patching: canonical pattern, chaining, removal, RE detection heuristics |
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## The Library ABI Model
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Every AmigaOS shared library exposes its functions through a **negative-offset JMP table** relative to the library base pointer:
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```
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Library base: LIB+0 → Library node (struct Library)
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LIB-6 → JMP _Open (mandatory)
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LIB-12 → JMP _Close (mandatory)
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LIB-18 → JMP _Expunge (mandatory)
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LIB-24 → JMP _Reserved (mandatory)
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LIB-30 → JMP _func1 (first user function)
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LIB-36 → JMP _func2
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...
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```
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A C call like `OpenLibrary("graphics.library", 0)` compiles to:
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```asm
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MOVE.L 4.W, A6 ; A6 = SysBase (exec)
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JSR -552(A6) ; LVO for OpenLibrary = -552
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```
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The negative offset (`-552`) is the **Library Vector Offset (LVO)** — a fixed ABI value defined in the library's `.fd` file and `proto/` include.
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## References
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- NDK39: `fd/` directory, `proto/` includes, `inline/` inline stubs
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- ADCD 2.1: Library writing guide, ROM Kernel Manual
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- http://amigadev.elowar.com/read/ADCD_2.1/Libraries_Manual_guide/node0000.html
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