1 #ifndef ANDROID_DVR_SHARED_BUFFERS_H_ 2 #define ANDROID_DVR_SHARED_BUFFERS_H_ 3 4 #include <dvr/dvr_config.h> 5 #include <dvr/dvr_pose.h> 6 #include <dvr/dvr_vsync.h> 7 #include <libbroadcastring/broadcast_ring.h> 8 9 // This header is shared by VrCore and Android and must be kept in sync. 10 namespace android { 11 namespace dvr { 12 13 // Increment when the layout for the buffers change. 14 enum : uint32_t { kSharedBufferLayoutVersion = 2 }; 15 16 // Note: These buffers will be mapped from various system processes as well 17 // as VrCore and the application processes in a r/w manner. 18 // 19 // Therefore it is possible for the application to mess with the contents of 20 // these buffers. 21 // 22 // While using them, assume garbage memory: Your logic must not crash or lead 23 // to execution of unsafe code as a function of the contents of these buffers. 24 25 // Sanity check for basic type sizes. 26 static_assert(sizeof(DvrPoseAsync) == 128, "Unexpected size for DvrPoseAsync"); 27 static_assert(sizeof(DvrPose) == 112, "Unexpected size for DvrPose"); 28 static_assert(sizeof(DvrVsync) == 32, "Unexpected size for DvrVsync"); 29 static_assert(sizeof(DvrConfig) == 16, "Unexpected size for DvrConfig"); 30 31 // A helper class that provides compile time sized traits for the BroadcastRing. 32 template <class DvrType, size_t StaticCount> 33 class DvrRingBufferTraits { 34 public: 35 using Record = DvrType; 36 static constexpr bool kUseStaticRecordSize = false; 37 static constexpr uint32_t kStaticRecordCount = StaticCount; 38 static constexpr int kMaxReservedRecords = 1; 39 static constexpr int kMinAvailableRecords = 1; 40 }; 41 42 // Traits classes. 43 using DvrPoseTraits = DvrRingBufferTraits<DvrPose, 0>; 44 using DvrVsyncTraits = DvrRingBufferTraits<DvrVsync, 2>; 45 using DvrConfigTraits = DvrRingBufferTraits<DvrConfig, 2>; 46 47 // The broadcast ring classes that will expose the data. 48 using DvrPoseRing = BroadcastRing<DvrPose, DvrPoseTraits>; 49 using DvrVsyncRing = BroadcastRing<DvrVsync, DvrVsyncTraits>; 50 using DvrConfigRing = BroadcastRing<DvrConfig, DvrConfigTraits>; 51 52 // This is a shared memory buffer for passing pose data estimated at vsyncs. 53 // 54 // This will be primarily used for late latching and EDS where we bind this 55 // buffer in a shader and extract the right vsync-predicted pose. 56 struct __attribute__((packed, aligned(16))) DvrVsyncPoseBuffer { 57 enum : int { 58 // The number vsync predicted poses to keep in the ring buffer. 59 // Must be a power of 2. 60 kSize = 8, 61 kIndexMask = kSize - 1, 62 63 // The number of vsyncs (from the current vsync) we predict in vsync buffer. 64 // The other poses are left alone. 65 kMinFutureCount = 4 66 }; 67 68 // The vsync predicted poses. 69 // The pose for the vsync n is: 70 // vsync_poses[n % kSize] 71 // 72 // This buffer is unsynchronized: It is possible to get torn reads as the 73 // sensor service updates the predictions as new sensor measurements come 74 // in. In particular, it is possible to get the position and an updated 75 // orientation while reading. 76 DvrPoseAsync vsync_poses[kSize]; 77 78 // The latest sensor pose for GPU usage. 79 DvrPose current_pose; 80 81 // Current vsync_count (where sensord is writing poses from). 82 uint32_t vsync_count; 83 84 // For 16 byte alignment. 85 uint8_t padding[12]; 86 }; 87 88 static_assert(sizeof(DvrVsyncPoseBuffer) == 1152, 89 "Unexpected size for DvrVsyncPoseBuffer"); 90 91 // The keys for the dvr global buffers. 92 enum DvrGlobalBuffers : int32_t { 93 kVsyncPoseBuffer = 1, 94 kVsyncBuffer = 2, 95 kSensorPoseBuffer = 3, 96 kVrFlingerConfigBufferKey = 4 97 }; 98 99 } // namespace dvr 100 } // namespace android 101 102 #endif // ANDROID_DVR_SHARED_BUFFERS_H_ 103
