P96CTS -- P96 driver Conformance Test Suite

Validates the rendering primitives of P96 RTG card drivers as well as the graphics.library accelerated rendering routines.

Each testcase renders a scene and compares it pixel by pixel against a committed reference in golden/. The references are captured from a working implementation rather than drawn by hand: golden/clut comes from AGA chipset modes, so a driver is checked against what the Amiga's own graphics hardware produces for the same primitives.

Runs are non-interactive and the exit code reflects the result, so the suite works as an automated check -- including under an emulator with no display.

This is a different tool from iComp's P96Tests, which is an interactive visual suite by the P96 maintainer and covers far more of the driver surface. Use that one to look at a driver; use this one to gate a change.

Running

Capture the reference from P96's software rasteriser, then compare a board against it:

p96cts CAPTURE
p96cts MONITOR=Z3660 MODE=640x400x8 DIFF

Output looks like:

p96cts 0.1 (19.7.2026)
testing Z3660:640x400  8bit, 640x400x8, scene 320x200, comparing against golden/clut
PASS lines-solid        0 pixels differ
PASS lines-pattern      0 pixels differ
FAIL lines-complement   4 of 64000 pixels differ
       at 247, 72 golden  89, got 166

Reference images live in golden/<pixel format>/, a run's own images in output/<monitor>/, and DIFF additionally writes <test>.diff.png marking the differing pixels in red. All images are 8-bit palette PNGs, which compress these flat synthetic scenes to a few hundred bytes and can be viewed anywhere, so the references are committed rather than regenerated.

Arguments

Argument	Meaning
TEST/M	Testcases to run; all of them by default
CAPTURE/S	Write the reference instead of comparing against it
MONITOR/K	Render on a screen of this monitor; omit to use the software rasteriser
MODE/K	Screen mode as WxHxD (default: the scene size)
SCENE/K	Region rendered and compared, as WxH (default 320x200)
GOLDEN/K	Reference directory (default golden/<format>)
DIR/K	Output directory (default output/<monitor>)
THRESHOLD/K/N	Tolerate up to this many differing pixels
DIFF/S	Write a diff image on mismatch
LIST/S	Dump the display database and exit

MODE and SCENE are separate because a board need not offer a mode as small as the scene. The smallest Z3660 mode is 640x400, so a 320x200 scene is drawn into the corner of a larger screen and only that corner is compared, which keeps reference images small and comparable across boards with different mode lists.

Building

The default include path is where the amiga-gcc toolchain ships the P96 headers, so a containerised build takes no arguments:

make docker-build

With a toolchain that does not bundle them, point at an unpacked P96Develop.lha:

make CC=/path/to/bin/m68k-amigaos-gcc \
     P96INC=/path/to/Picasso96Develop/Include

Images are read and written with zlib and libpng, which are committed under third_party/ already built for this target, so nothing needs fetching or cross-building first. They rarely need rebuilding, but when they do, the same container runs their build script:

make docker-thirdparty

The archives are reproducible, so a rebuild can be checked byte for byte against the committed ones. third_party/README.md has the upstream versions, checksums, and why both are built -noixemul.

Adding testcases

A test group is one translation unit exporting a P96TestGroup; see drawline.c. Add the file to OBJS in the Makefile and the group to GROUPS in p96cts.c.

A testcase renders a complete scene, clearing it first, and must keep all drawing inside the bitmap: the RastPort has no Layer, so graphics.library does not clip it and drawing outside corrupts memory.

Scenes should be built so that a wrong driver cannot pass by accident. Drawing solid lines in one pen, for instance, cannot detect a pixel written twice -- it takes a mode like COMPLEMENT, where writing twice is not the same as writing once, and a figure whose lines actually cross.

Status

Only 8-bit palette (clut) is supported so far: results are read back with ReadPixelArray8, which yields pen values. Deeper formats need p96ReadPixelArray and a wider comparison path.

Licence

0BSD, the same terms iComp chose for P96Tests, so testcases can move freely between the two and either can be absorbed into a driver tree regardless of its own licence. See LICENSE.