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https://github.com/RetroPortingToolKit/psxrecomp
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Shokunin
85a3d8d6d0
Opt-in under the render thread. Composed frames go to a ring of offscreen slots at the window's size (binds of framebuffer 0 on the composing context land on the current slot); a present thread with a second, shared context on the same window waits on the slot's fence, copies it 1:1 and swaps. The compositor's wait moves off rendering; the composing side waits only while every slot is queued or on screen. Falls back to direct swaps when the shared context or sync objects are unavailable. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
81 lines
3.3 KiB
C
81 lines
3.3 KiB
C
/* present_thread.h — opt-in present thread under the render thread
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* ([video] present_thread, docs/RENDER_THREAD.md "Present thread").
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*
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* The thread that composes frames (the render thread, or the emulation thread
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* while it holds the context at a sync point) draws each presented frame into
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* an offscreen slot instead of the window, then hands the slot over; the
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* present thread owns a second graphics context on the same window and does
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* the final copy and the swap. The swap's wait on the window compositor then
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* lands on the present thread, not on rendering.
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*
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* This core is backend-neutral: a ring of `slots` numbered slots, each FREE,
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* COMPOSING (the producer's current slot, exactly one), QUEUED or PRESENTING.
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* Queued slots are presented in submission order. The producer blocks in
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* pt_submit() only while every other slot is queued or presenting (the
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* display is the bottleneck; that wait is the swap's wait, moved).
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*
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* Fences are opaque: `ready` travels with a submitted slot to present();
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* present() returns a `done` token (e.g. a fence after its copy) that the
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* producer receives when it next takes that slot, before drawing into it.
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*
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* Producer calls (pt_current / pt_submit) may come from different threads
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* over time, but never concurrently (the context hand-off orders them). */
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#ifndef PSX_PRESENT_THREAD_H
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#define PSX_PRESENT_THREAD_H
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#include <stdint.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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#define PT_MAX_SLOTS 4
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/* Present thread: make the present context current (current != 0, return 0 on
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* failure: pt_start then fails) or release it (current == 0). */
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typedef int (*PtCtxFn)(void *user, int current);
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/* Present thread: show `slot` (wait for `ready`, copy, swap). Returns the
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* slot's done token (may be NULL). */
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typedef void *(*PtPresentFn)(void *user, int slot, void *ready);
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/* Present thread, after the last present at stop or for a token nobody will
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* collect: dispose of a done token. Optional. */
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typedef void (*PtDisposeFn)(void *user, void *token);
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typedef struct PtConfig {
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int slots; /* 2..PT_MAX_SLOTS */
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PtCtxFn ctx;
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PtPresentFn present;
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PtDisposeFn dispose; /* optional */
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void *user;
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} PtConfig;
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/* Start the thread; returns once its ctx(1) has run. 1 on success (the
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* producer's current slot is 0), 0 on failure (nothing running). */
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int pt_start(const PtConfig *cfg);
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/* Present everything queued, release the context on the present thread,
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* join. Done tokens still held are passed to dispose on the present thread
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* before it releases its context. Safe when not running. */
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void pt_stop(void);
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int pt_running(void);
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/* Producer: the slot being composed. */
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int pt_current(void);
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/* Producer: queue the current slot with `ready`, then take the next free slot
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* (blocking while none is). *next_done receives that slot's done token (NULL
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* if none); *wait_ns the time spent blocked. Returns the new current slot, or
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* -1 when not running. */
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int pt_submit(void *ready, void **next_done, uint64_t *wait_ns);
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/* Producer: wait until nothing is queued or presenting. */
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void pt_drain(void);
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typedef struct PtStats {
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uint64_t submits, presents, waits, wait_ns, present_ns, present_max_ns;
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int slots, queued_high;
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} PtStats;
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void pt_get_stats(PtStats *out);
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#ifdef __cplusplus
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}
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#endif
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#endif /* PSX_PRESENT_THREAD_H */
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