vatrog-vm-vgpu-streamer/src/stream/include/stream.h

#ifndef VGPU_STREAM_ENGINE_H
#define VGPU_STREAM_ENGINE_H

/* stream.h — OS-agnostic streaming protocol over the shared contract.
 * Declares the neutral region-view handle (resolved contract pointers) and the
 * seqlock publish / control-reconcile API. No platform headers: the engine
 * operates purely on the contract; a platform layer (e.g. src/stream/win32/)
 * builds the region and hands its pointers in as a vgpu_region_view. */

#include <stdint.h>
#include "vgpu_stream.h"   /* contract: producer/control types, slot geometry */

/* Neutral view of the live contract: the three resolved blocks the engine
 * publishes into / reconciles against. The platform region owns the backing
 * memory; this is a borrowed view (no ownership). */
typedef struct {
    vgpu_producer_t* producer;
    vgpu_control_t*  control;
    uint8_t*         ring;
} vgpu_region_view;

/* Resolved view of the control block after a clean generation read. */
typedef struct {
    uint32_t gen;            /* even generation that was read (for ctrl_ack) */
    uint32_t desired_state;  /* VGPU_CMD_* */
    uint32_t target_fps;
    uint32_t draw_cursor;
    uint32_t full_frame_req;
    uint32_t consumer_tick;
    uint32_t attached;
} vgpu_control_view;

/* Seqlock-publish a tight BGRA frame into the next ring slot.
 * Clamps by SLOT_STRIDE (rejects frames that do not fit). Writes desc[],
 * bumps frame_id, release-stores latest. Returns 0 on publish, 1 if dropped
 * (frame too large for a slot). */
int vgpu_publish_frame(const vgpu_region_view* rv, const uint8_t* tight_bgra,
                       uint32_t width, uint32_t height, uint64_t timestamp_ns);

/* Read control block under its generation seqlock (bounded retry). Returns 1
 * on a clean read (view filled), 0 if the writer kept it busy past the limit. */
int vgpu_control_read(const vgpu_region_view* rv, vgpu_control_view* out);

/* Echo the applied generation back to the host. */
void vgpu_publish_ctrl_ack(const vgpu_region_view* rv, uint32_t gen);

/* Status / lifecycle helpers (cold line). */
void vgpu_set_status(const vgpu_region_view* rv, uint32_t status);
void vgpu_set_backend(const vgpu_region_view* rv, uint32_t backend);
void vgpu_set_error(const vgpu_region_view* rv, uint32_t error_code);
void vgpu_set_applied_fps(const vgpu_region_view* rv, uint32_t fps);
void vgpu_bump_run_epoch(const vgpu_region_view* rv);
void vgpu_tick_heartbeat(const vgpu_region_view* rv);
void vgpu_publish_full_frame_ack(const vgpu_region_view* rv, uint32_t req);

/* Publish the on-screen cursor position (host-RO). Position is sensor data and is
 * reported independent of control.draw_cursor (host may draw its own overlay even when the
 * producer does not composite the cursor). x,y are screen coords (signed; multi-monitor may
 * be negative); visible!=0 when the cursor is shown. Packs x|y into one 8-aligned 64-bit
 * field (single atomic store) and bumps cursor_seq last. */
void vgpu_publish_cursor(const vgpu_region_view* rv, int32_t x, int32_t y, uint32_t visible);

#endif /* VGPU_STREAM_ENGINE_H */