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03/04: deep enrichment of loader/exec format and linking/libraries

Browse source 
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)
This commit is contained in:
Ilia Sharin 2026-04-23 18:30:45 -04:00
parent 99a6d53f57
commit 7df1f11f15
8 changed files with 1556 additions and 360 deletions
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25
04_linking_and_libraries/README.md
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@ -10,12 +10,16 @@ This section documents how AmigaOS shared libraries work at the binary level —
| File | Topic |
|---|---|
| [library_structure.md](library_structure.md) | Library node, LVO table, OpenLibrary mechanics |
| [fd_files.md](fd_files.md) | Function Definition files — the library ABI source |
| [lvo_table.md](lvo_table.md) | JMP table layout and reconstruction |
| [compiler_stubs.md](compiler_stubs.md) | How SAS/C, GCC, VBCC call libraries |
| [setfunction.md](setfunction.md) | Runtime function patching with SetFunction |
| [startup_code.md](startup_code.md) | c.o / gcrt0.S — startup and exit sequences |
| [library_structure.md](library_structure.md) | Library memory layout, JMP table encoding, MakeLibrary construction, complete library creation example |
| [shared_libraries_runtime.md](shared_libraries_runtime.md) | OpenLibrary resolution path, ramlib disk loader, version negotiation, expunge mechanics |
| [register_conventions.md](register_conventions.md) | Register ABI: integer, FPU, varargs/TagItem, small-data model, __saveds, inter-library calls |
| [fd_files.md](fd_files.md) | Function Definition files — the library ABI source of truth, LVO calculation |
| [lvo_table.md](lvo_table.md) | JMP table layout, complete exec.library LVO table, IDA reconstruction script |
| [compiler_stubs.md](compiler_stubs.md) | How SAS/C, GCC, VBCC call libraries — compiler signature identification |
| [inline_stubs.md](inline_stubs.md) | Compiler inline stubs: pragma (SAS/C), inline asm (GCC), __reg (VBCC), stub generation tools |
| [link_libraries.md](link_libraries.md) | Static linking: amiga.lib, sc.lib, libnix, auto.lib, WBStartup glue, stack cookie |
| [startup_code.md](startup_code.md) | c.o / gcrt0.S: entry contract, CLI vs WB detection, argument parsing, WBStartup message |
| [setfunction.md](setfunction.md) | Runtime function patching: canonical pattern, chaining, removal, RE detection heuristics |
## The Library ABI Model
@ -23,10 +27,13 @@ Every AmigaOS shared library exposes its functions through a **negative-offset J
```
Library base: LIB+0 → Library node (struct Library)
LIB-6 → JMP _funcN (last function)
LIB-12 → JMP _funcN-1
LIB-6 → JMP _Open (mandatory)
LIB-12 → JMP _Close (mandatory)
LIB-18 → JMP _Expunge (mandatory)
LIB-24 → JMP _Reserved (mandatory)
LIB-30 → JMP _func1 (first user function)
LIB-36 → JMP _func2
...
LIB-6 → JMP _func1 (first user function)
```
A C call like `OpenLibrary("graphics.library", 0)` compiles to: