CTR-DS

A fork of CTR Native that adds a second screen, a 64-bit build, and a set of graphics and frame-rate options.

CTR Native is itself a native port of Crash Team Racing (PS1, 1999) built on the CTR-ModSDK decompilation. This fork does not change what the game is; it changes where it can run and what it can be told to do.

What this fork adds

A companion screen. On a dual-screen handheld the HUD, the live map and a settings panel move to the bottom display, leaving the top one entirely to the game. The map draws driver portraits rather than coloured dots, because there is room for them.

A 64-bit build. The original targets 32-bit only. CTR_FORCE_32BIT=OFF builds LP64, which is what lets it run on a device with no 32-bit runtime at all — a modern phone, for instance. Pointers no longer fit the 32-bit fields the PSX structures use, so they are resolved through a region registry instead.

Frame caps above 30. The game was written for a 30fps frame and a 60Hz VBlank, and a great deal of it counts one or the other. Anything that does now reads a clock that advances at the retail rate whatever the cap is, so a 120fps race does not play at four times speed.

Internal resolution up to 8x. Geometry is drawn into a target of 240 × scale lines and presented to the panel. Past roughly 3x on a handheld this is supersampling rather than detail.

Widescreen, an HD replacement path for the 2D HUD art, CHD disc images, on-screen touch controls, and a launcher for picking a disc and settings without editing a file.

Devices this has run on

device	notes
AYN Thor	dual-screen handheld; the companion display is the reason this fork exists
OnePlus 15	64-bit only, so it needs the LP64 build; single screen
Linux desktop	both 32- and 64-bit, used for most debugging

Building

The upstream README.md covers prerequisites and the standard build. Two things are specific to this fork.

64-bit desktop

cmake -S . -B build64 -DCTR_FORCE_32BIT=OFF -DCMAKE_BUILD_TYPE=RelWithDebInfo
cmake --build build64 -j$(nproc)

Put ctr-u.bin (or ctr-u.chd) in build64/assets/ and run build64/ctr_native from that directory.

Android

cd android && ./gradlew assembleDebug
adb install -r app/build/outputs/apk/debug/app-debug.apk

The debug variant compiles the native side with -O2 (see app/build.gradle). Without that the Android plugin passes no -O flag at all, and a recompiled PS1 game runs roughly three to four times slower — enough to miss a 120fps cap that it otherwise holds comfortably.

Settings

ctrds.cfg lives beside the disc image — on Android at /sdcard/Android/data/com.ctrnative/files/assets/. The launcher writes it, the in-game panel writes it, and lines it does not recognise are preserved.

key	values	meaning
target_fps	30, 60, 90, 120, …	frame cap; VBlanks are emitted at this rate
internal_scale	1–8	render target is 240 × scale lines
aspect_mode	0, 1	0 is retail 4:3, 1 follows the display
fxaa, crt	0, 1	post-processing
touch_controls	0, 1, 2	off, on, automatic
swap_face_buttons	0, 1	swap cross and circle
online*	—	built but there is no public server to reach

Not offered in the launcher, but read if present:

key	meaning
hd_art	use replacement HUD art from assets/hd/
hd_dump, hd_log	author the replacements: dump icons out of VRAM, report indices
skip_av	disc has no intro video or XA audio (also auto-detected)
prim_reject	oversize primitive cull; 2 reports what it drops
perf	write per-frame bucket timings next to the config
widescreen	derived from the aspect; override only if you know why

Diagnostics

The frame line, on by default, is the fastest way to see what the game is doing:

FPS: 120.0 of 120 reachable (cap 120, 1 vblanks per flip, race, 6x) audio 60.0/s disc 0/0

reachable is the cap the current cadence allows — menus deliberately flip every cap/30 VBlanks, so 30 is the correct answer there and a lower number is not a fault. audio should read 60/s at any cap; it is the rate the sound is consumed at, and it made a doubled-speed bug visible that the ear had already caught.

A watchdog aborts the process if no VBlank is emitted for twelve seconds while the window is in front. That is deliberate: a frozen process tells you nothing, while an abort produces a tombstone with a native backtrace for every thread. CTRDS_WATCHDOG=0 disables it.

Setting perf=1 writes perf/frame_times.csv with a column per timing bucket.

Known issues

• Small flat lavender quads appear on some level geometry, and a rectangle in the lower-left of the main screen. Present on both 32- and 64-bit builds, at both 4:3 and widescreen, with the HD art path and the oversize-primitive cull both disabled — so none of those is the cause. Not yet found.
• The dual-screen path presents at the frame cap in menus while the game logic advances at 30, so the same frame is presented repeatedly. Wasted GPU rather than a speed fault.
• Online is implemented but has no server to connect to.

Licence

Same as upstream; see LICENSE.