63 lines
2.3 KiB
C++
63 lines
2.3 KiB
C++
/*
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* VizionStreamer - Shared Memory Writer Interface
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* Copyright (c) 2025 Maik Jurischka
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*
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* Licensed under CC BY-NC-SA 4.0
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* https://creativecommons.org/licenses/by-nc-sa/4.0/
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*/
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#pragma once
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#include <string>
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#include <cstdint>
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#include <atomic>
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// Shared memory header structure for lock-free synchronization
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struct SharedMemoryHeader {
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uint32_t magic; // Magic number for validation (0x56495A4E = "VIZN")
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uint32_t width; // Frame width in pixels
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uint32_t height; // Frame height in pixels
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uint32_t format; // Format enum (matches VX_IMAGE_FORMAT)
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uint32_t data_size; // Actual frame data size in bytes
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uint64_t timestamp_ns; // Timestamp in nanoseconds
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uint32_t frame_sequence; // Monotonic frame counter
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std::atomic<uint32_t> write_sequence; // Lock-free synchronization counter
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char format_str[16]; // Format string ("YUY2", "MJPG", etc.)
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uint8_t reserved[72]; // Reserved for future expansion (padding to 128 bytes)
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};
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static_assert(sizeof(SharedMemoryHeader) == 128, "SharedMemoryHeader must be exactly 128 bytes");
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class SharedMemoryWriter {
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public:
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explicit SharedMemoryWriter(std::string name);
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~SharedMemoryWriter();
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// Initialize shared memory region with given buffer size
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bool create(size_t frame_buffer_size);
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// Write frame to shared memory with lock-free protocol
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bool writeFrame(const uint8_t* data, size_t size,
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int width, int height,
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const std::string& format,
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uint64_t timestamp_ns = 0);
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// Cleanup shared memory
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void destroy();
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// Status queries
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bool isCreated() const { return shm_fd_ >= 0; }
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std::string getName() const { return shm_name_; }
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size_t getBufferSize() const { return buffer_size_; }
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uint32_t getFrameCount() const { return frame_counter_; }
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private:
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SharedMemoryHeader* getHeader();
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std::string shm_name_; // Shared memory object name
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int shm_fd_; // File descriptor from shm_open
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void* shm_ptr_; // Mapped memory pointer
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size_t buffer_size_; // Total size (header + frame data)
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uint32_t frame_counter_; // Frame sequence counter
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};
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