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45 lines
1.7 KiB
Markdown
45 lines
1.7 KiB
Markdown
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[← 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 node, LVO table, OpenLibrary mechanics |
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| [fd_files.md](fd_files.md) | Function Definition files — the library ABI source |
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| [lvo_table.md](lvo_table.md) | JMP table layout and reconstruction |
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| [compiler_stubs.md](compiler_stubs.md) | How SAS/C, GCC, VBCC call libraries |
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| [setfunction.md](setfunction.md) | Runtime function patching with SetFunction |
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| [startup_code.md](startup_code.md) | c.o / gcrt0.S — startup and exit sequences |
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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 _funcN (last function)
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LIB-12 → JMP _funcN-1
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...
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LIB-6 → JMP _func1 (first user function)
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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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