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| author | gbc dev <gbc@localhost> | 2026-07-04 23:07:50 +0200 |
|---|---|---|
| committer | gbc dev <gbc@localhost> | 2026-07-04 23:07:50 +0200 |
| commit | f4ba890eb4b98e1a65a3d9fc8ba8f62dda66895b (patch) | |
| tree | cb1cccb2dfd0f1b59e59e8e86454849179c88cb2 /README.md | |
| parent | input: external control channel via FIFO (diff) | |
| download | sl0pboy-f4ba890eb4b98e1a65a3d9fc8ba8f62dda66895b.tar.gz sl0pboy-f4ba890eb4b98e1a65a3d9fc8ba8f62dda66895b.tar.xz sl0pboy-f4ba890eb4b98e1a65a3d9fc8ba8f62dda66895b.zip | |
speed control: frame skipping to decouple terminal draw from emulation
Emulation always runs at native rate (correct game speed); --frameskip N draws
only 1 of every N+1 frames so a slow terminal no longer bottlenecks the loop.
Adds --fps cap, --uncapped/--turbo, live [ ] and f keys, HUD readout, and an
exit summary of emulated-vs-drawn fps. Replaces the confusing --render-fps.
Diffstat (limited to 'README.md')
| -rw-r--r-- | README.md | 26 |
1 files changed, 26 insertions, 0 deletions
@@ -25,6 +25,30 @@ make Requires a truecolor-capable terminal (`COLORTERM=truecolor`) at least 160 columns wide. +### Speed & frame skipping + +The emulator always advances every Game Boy frame at the correct rate, so +games run at their intended speed. Because writing a frame to the terminal is +by far the most expensive step, drawing can be *decoupled* from emulation via +frame skipping — the machine keeps running in real time while the terminal is +refreshed less often: + +```sh +./build/gbc rom.gb --frameskip 2 # emulate 60 fps, draw every 3rd frame (20 fps) +./build/gbc rom.gb --fps 120 # run the game at 2x speed +./build/gbc rom.gb --uncapped # run as fast as possible (turbo) +``` + +| Flag | Meaning | +|-------------------|-----------------------------------------------------| +| `--frameskip N` | draw 1 of every `N+1` emulated frames (default 0) | +| `--fps N` | emulation speed cap in fps (default 59.73 native) | +| `--uncapped`/`--turbo` | run emulation as fast as possible | + +Frame skip and turbo are also adjustable live with `[` / `]` and `f`; in turbo +mode terminal redraws are additionally clamped to ~60 Hz. On exit the emulator +prints how many frames it emulated vs. actually drew. + ## Controls | Key | Button | @@ -34,6 +58,8 @@ Requires a truecolor-capable terminal (`COLORTERM=truecolor`) at least | `x` / `k` | B | | enter | Start | | space | Select | +| `f` | toggle fast-forward (turbo) | +| `[` / `]` | decrease / increase frame skip | | `q` / Ctrl-C | Quit | Since terminals don't report key-release, buttons are held for a few frames |