iPod Nano 2G port (Rockbox plugin)

[colemancda]

Adds ports/iPod: a Rockbox plugin port of Junkbot for the iPod Nano 2G, compiled as Embedded Swift for armv4t-none-none-eabi (the Nano's FPU-less ARM940T) and linked into junkbot.rock by Rockbox's own build system. Modeled on celeste-swift's iPod port.

Architecture

• C owns the process (plugin/junkbot.c): the plugin loop, click-wheel input, scrolled world blit, level intro / win-lose / status text (Rockbox's own font, so no font asset), and the HOLD pause menu.
• Swift owns the game (source/Plugin.swift): the GameEngine, current level, a click-wheel aiming cursor, and the scrolled viewport, exposed as @_cdecl entry points. source/Renderer.swift rasterizes the engine's RenderCommand list into an RGB565 canvas (adapted from ports/3DS).
• Shim (plugin/rockbox_shim.c): TLSF allocator over the plugin buffer, non-atomic __atomic_* (single-threaded plugin on a core with no atomic instructions), mem* helpers, stack protector, entropy, and the libm gaps (floor/ceil/round).

Assets load from the filesystem

Unlike every other port, neither sprites nor levels are compiled in — both live in /.rockbox/junkbot/ and load into the audio buffer at startup:

• sprites.bin (~5.6 MB RGB555 pixel data); only the small per-sprite offset table is compiled in.
• levels.bin (~1.1 MB, all 121 campaign levels). The generated level data every other port embeds is ~1.6 MB of code — over 3× a plugin's entire 512 KB PLUGIN_RAM (the first device link overflowed by 1.3 MB). tools/LevelPack (a host tool importing JunkbotCore natively) serializes embeddedLevels into a binary catalog and round-trip-verifies the blob through the device decoder at build time; the codec is one file compiled into both the tool and the plugin so the field order can't drift. Final plugin: 167 KB text.

Controls

Input	Action
scroll wheel / LEFT / RIGHT	move cursor by one stud
MENU / PLAY	move cursor up / down one brick
SELECT	grab / drop
HOLD	pause menu

Building

cd ports/iPod
make toolchain   # once: arm-elf-eabi-gcc into the rbdev Docker volume
make rock        # libjunkbot.a (host swiftc) + assets + Rockbox in-tree build
make install IPOD=/Volumes/<ipod>

Verified

• make swift: armv4t Embedded Swift object passes the undefined-symbol audit and archives cleanly (swift-6.3.2-RELEASE).
• make assets: LevelPack round-trips all 121 levels through the device decoder with zero field mismatches.
• make sim: the C host compiles and links junkbot.rock against the pinned Rockbox tree's UI simulator with no warnings.
• make rock: device build links at 167 KB text / 221 KB total, inside the 512 KB PLUGIN_RAM.
• Installed to a real Nano 2G (make install) for on-hardware testing.

Audio is not started yet (rb_audio_sfx is a no-op); the README documents the phased plan.