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Ilia Sharin 21751c0025 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 12:17:35 -04:00

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Library System — OpenLibrary Lifecycle

Overview

The AmigaOS library system provides versioned, shared code via a standardised interface. Libraries are identified by name, opened with a version check, and reference-counted for safe unloading.

Library Node

Every library is an NT_LIBRARY node on SysBase->LibList:

struct Library {
    struct Node  lib_Node;       /* ln_Name = "dos.library" */
    UBYTE        lib_Flags;      /* LIBF_SUMUSED | LIBF_DELEXP */
    UBYTE        lib_Pad;
    UWORD        lib_NegSize;    /* size of JMP table in bytes */
    UWORD        lib_PosSize;    /* size of library base struct */
    UWORD        lib_Version;    /* major version */
    UWORD        lib_Revision;   /* minor revision */
    APTR         lib_IdString;   /* "dos.library 40.1 (16.7.93)" */
    ULONG        lib_Sum;        /* JMP table checksum */
    UWORD        lib_OpenCnt;    /* reference count */
};

OpenLibrary / CloseLibrary

/* Open — get a reference: */
struct DosLibrary *DOSBase =
    (struct DosLibrary *)OpenLibrary("dos.library", 40);

/* Use the library ... */

/* Close — release reference: */
CloseLibrary((struct Library *)DOSBase);

Internally:

exec scans LibList for ln_Name == "dos.library"
If not found, searches resident list and LIBS: path
If found on disk: LoadSeg + call InitLib
Check lib_Version >= requested_version
Call library's Open() vector → lib_OpenCnt++
Return library base

Library Flags

Flag	Value	Meaning
`LIBF_SUMUSED`	0x01	Checksum is maintained
`LIBF_CHANGED`	0x02	Checksum needs recalculation
`LIBF_DELEXP`	0x04	Expunge deferred (opened while expunge pending)

Version Numbering Convention

lib_Version.lib_Revision:

40.1 = OS 3.1 release
40.x = OS 3.1 (various revisions)
44.x = OS 3.2

Increment rules:

lib_Revision — minor bugfix, compatible
lib_Version — API change or major update (requestors check this)

Finding a Library Without Opening

/* Read-only peek — no open count increment */
Forbid();
struct Library *lib = FindName(&SysBase->LibList, "graphics.library");
Permit();
if (lib) printf("Found v%d\n", lib->lib_Version);

Caution

Using FindName without Forbid() is a race condition — the library could be expunged between finding it and using it.

References

NDK39: exec/libraries.h
ADCD 2.1: OpenLibrary, CloseLibrary, FindName
04_linking_and_libraries/shared_libraries_runtime.md — expunge lifecycle

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