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https://github.com/4gray/iptvnator.git
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4gray
59e08fd2d6
Port the embedded mpv frame-copy pipeline to Windows with WGL rendering and named shared memory. Includes packaging validation, platform gates, tests, and architecture documentation.
104 lines
3.5 KiB
C++
104 lines
3.5 KiB
C++
/*
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* Shared-memory frame ring for the frame-copy embedded MPV helper.
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*
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* Same triple-buffer seqlock protocol as spikes/mpv-frame-copy (validated
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* there on M1 Pro up to 4K60), plus a `generation` field: every viewport
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* resize creates a fresh shm segment named `<base>-g<generation>` and the
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* reader re-attaches when the helper announces the new generation.
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*
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* Must compile as C11 (reader addon) and C++17 (helper) on POSIX; on
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* Windows both consumers build as C++ (MSVC's C mode lacks <stdatomic.h>).
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* POSIX builds use node-gyp's GNU dialects; frame_shm_now_ns() relies on
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* clock_gettime there, which strict -std=c11 (__STRICT_ANSI__) would hide.
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*/
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#pragma once
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#include <stdint.h>
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#if defined(_WIN32)
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#ifndef WIN32_LEAN_AND_MEAN
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#define WIN32_LEAN_AND_MEAN
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#endif
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#ifndef NOMINMAX
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#define NOMINMAX
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#endif
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#include <windows.h>
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#include <stdio.h>
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#include <string.h>
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#else
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#include <time.h>
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#endif
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#ifdef __cplusplus
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#include <atomic>
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typedef std::atomic<uint64_t> frame_shm_atomic_u64;
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#else
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#include <stdatomic.h>
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typedef _Atomic uint64_t frame_shm_atomic_u64;
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#endif
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/* Monotonic clock for produce_time_ns/heartbeat_ns. Producer (helper) and
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* consumer (reader addon) MUST use this same clock so age math stays valid.
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* POSIX: CLOCK_MONOTONIC (macOS 10.12+, Linux). Windows: QPC, scaled to ns
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* without overflow by splitting whole seconds from the remainder. */
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static inline uint64_t frame_shm_now_ns(void) {
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#if defined(_WIN32)
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/* C++11 function-local initialization is synchronized, so the helper's
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* render/event threads cannot race while caching the boot-stable QPF. */
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static const uint64_t frequency = []() -> uint64_t {
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LARGE_INTEGER value;
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if (QueryPerformanceFrequency(&value) != TRUE ||
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value.QuadPart <= 0) {
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return 1;
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}
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return (uint64_t)value.QuadPart;
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}();
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LARGE_INTEGER counter;
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QueryPerformanceCounter(&counter);
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const uint64_t ticks = (uint64_t)counter.QuadPart;
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return (ticks / frequency) * 1000000000ull +
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(ticks % frequency) * 1000000000ull / frequency;
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#else
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struct timespec ts;
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clock_gettime(CLOCK_MONOTONIC, &ts);
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return (uint64_t)ts.tv_sec * 1000000000ull + (uint64_t)ts.tv_nsec;
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#endif
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}
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#if defined(_WIN32)
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/* The stdio protocol carries POSIX-style names ("/impv-...-gN") on every
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* platform so the TypeScript layer stays platform-agnostic; on Windows the
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* helper (create) and reader (open) both derive the actual file-mapping
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* object name from it: session-local namespace, slashes stripped. */
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static inline void frame_shm_windows_name(const char* posix_name, char* out,
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size_t out_size) {
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while (*posix_name == '/') posix_name++;
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snprintf(out, out_size, "Local\\%s", posix_name);
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}
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#endif
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#define FRAME_SHM_MAGIC 0x564d5046u /* 'FPMV' */
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#define FRAME_SHM_VERSION 1u
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#define FRAME_SHM_RING_SLOTS 3u
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#define FRAME_SHM_DATA_ALIGN 4096u
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typedef struct {
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frame_shm_atomic_u64 seq; /* 0 while the slot is being (re)written */
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uint64_t produce_time_ns; /* frame_shm_now_ns() after copy completes */
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} FrameShmSlot;
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typedef struct {
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uint32_t magic; /* written last during init; readers gate on it */
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uint32_t version;
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uint32_t width;
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uint32_t height;
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uint32_t stride; /* bytes per row, tightly packed BGRA */
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uint32_t generation;
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uint64_t frame_bytes;
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uint64_t data_offset;
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frame_shm_atomic_u64 latest_seq; /* newest complete frame, 0 = none */
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frame_shm_atomic_u64 heartbeat_ns;
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FrameShmSlot slots[FRAME_SHM_RING_SLOTS];
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} FrameShmHeader;
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