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A1200 / AGA games

examples/ironwraith is a complete eight-bitplane AGA demo. The existing ACE and vAmiga AGA implementations support its 256-entry RGB24 palette, FMODE=3 fetches, attached sprites and blitter objects; this work needed no additional emulator or ACE patches. The A1200 profile remains experimental and real hardware validation is still outstanding.

Project setup

In agk.toml:

profile = "a1200"
test_profiles = ["a1200"]
[cmake]
M68K_CPU = "68020"
ACE_USE_AGA_FEATURES = true

In art/art.toml:

[art]
chipset = "aga"
depth = 8

art/palette.txt now accepts indices 0–255 and 0xRRGGBB colors. PNG input keeps all eight bits of each channel. Text art also uses RGB24 when AGA is selected; write six digits for clarity. The generated palette functions accept ULONG *:

artPaletteApply((ULONG *)port->pPalette);

Per-bitmap palettes, sprite palettes, previews, nearest-color mapping, art-export and Retro Diffusion palette input all honor the selected chipset. The default remains OCS RGB12, with the original UWORD * palette API and output. art-clean fade colors retain their existing RGB12 syntax.

Create both an AGA view and an explicitly AGA first viewport:

view = viewCreate(0, TAG_VIEW_USES_AGA, 1,
                    TAG_VIEW_GLOBAL_PALETTE, 1, TAG_DONE);
port = vPortCreate(0, TAG_VPORT_VIEW, view, TAG_VPORT_USES_AGA, 1,
                     TAG_VPORT_BPP, 8, TAG_VPORT_FMODE, 3, TAG_DONE);

FMODE 3 selects 64-bit bitplane fetches while retaining 16-pixel sprite fetches. At width 320 the interleaved plane stride is 40 bytes, divisible by eight. The raw simple-buffer copper list needs 6 + 2 * depth commands: 22 at eight planes, or 38 including the sprite manager's 16 pointer commands. Keep those offsets separate. AGA palettes are stored as ULONGs by ACE despite its viewport field being declared as a UWORD pointer.

BPLCON0's eight-plane encoding is 0x0210; palette banks and low component nibbles are selected through BPLCON3. ACE writes both halves when loading the palette. The original hardware notes are preserved in AGA.guide.

Palette and display tests

The A1200 harness preserves RGB24 output. Use the new exact assertion:

screenshot arena
expect-rgb arena 0 0 0x080E18
expect-rgb arena 160 130 0x123456 near 2

The last value is illustrative: use an observed, intended asset color at that coordinate. Existing expect-color ... 0xRGB assertions remain nibble checks. expect-rgb checks every bit and reports the actual six-digit value on failure. Its optional near radius has the same square neighborhood semantics as expect-color. Goldens for AGA projects should be recorded on AGA.

Run identical scenarios twice with the snapshot cache and once with --fresh; the screenshots, state log and audio must agree. Palette correctness alone does not prove DMA timing. Inspect moving sprites, busy boss scenes and result screens, and keep the performance checks enabled.

tools/selftest a500-aros now skips examples whose declared test targets do not include that profile, so adding an AGA-only example does not break the free A500 CI sweep. Without arguments, selftest still tests every project's declared profiles, including the A1200 demo (which needs a user-provided ROM).