Replace kProducerStateBit with kFirstClientBitMask.

kProducerStateBit covers the MSB of the buffer/fence state.
kFirstClientBitMask covers the LSB of the buffer/fence state.
This change replaces the kProducerStateBit with kFirstClientBitMask, and
update the kConsumerStateBit to be the inverse of kFirstClientBitMask.

Test: AHardwareBufferTest BufferHubBuffer_test BufferHubMetadata_test
buffer_hub-test buffer_hub_binder_service-test buffer_hub_queue-test
buffer_hub_queue_producer-test buffer_node-test dvr_api-test
dvr_buffer_queue-test dvr_display-test libgui_test libdvrcommon_test
pdx_tests GraphicBuffer_test
Bug: 118718713
Change-Id: I647f36ee3fb2eb5dc996b781ed0ff71f7f72c112
diff --git a/libs/vr/libbufferhub/buffer_hub-test.cpp b/libs/vr/libbufferhub/buffer_hub-test.cpp
index db624de..18b97db 100644
--- a/libs/vr/libbufferhub/buffer_hub-test.cpp
+++ b/libs/vr/libbufferhub/buffer_hub-test.cpp
@@ -29,8 +29,8 @@
 using android::dvr::BufferHubDefs::IsBufferPosted;
 using android::dvr::BufferHubDefs::IsBufferReleased;
 using android::dvr::BufferHubDefs::kConsumerStateMask;
+using android::dvr::BufferHubDefs::kFirstClientBitMask;
 using android::dvr::BufferHubDefs::kMetadataHeaderSize;
-using android::dvr::BufferHubDefs::kProducerStateBit;
 using android::pdx::LocalChannelHandle;
 using android::pdx::LocalHandle;
 using android::pdx::Status;
@@ -62,14 +62,14 @@
   ASSERT_TRUE(c2.get() != nullptr);
 
   // Producer state mask is unique, i.e. 1.
-  EXPECT_EQ(p->client_state_mask(), kProducerStateBit);
+  EXPECT_EQ(p->client_state_mask(), kFirstClientBitMask);
   // Consumer state mask cannot have producer bit on.
-  EXPECT_EQ(c->client_state_mask() & kProducerStateBit, 0U);
+  EXPECT_EQ(c->client_state_mask() & kFirstClientBitMask, 0U);
   // Consumer state mask must be a single, i.e. power of 2.
   EXPECT_NE(c->client_state_mask(), 0U);
   EXPECT_EQ(c->client_state_mask() & (c->client_state_mask() - 1), 0U);
   // Consumer state mask cannot have producer bit on.
-  EXPECT_EQ(c2->client_state_mask() & kProducerStateBit, 0U);
+  EXPECT_EQ(c2->client_state_mask() & kFirstClientBitMask, 0U);
   // Consumer state mask must be a single, i.e. power of 2.
   EXPECT_NE(c2->client_state_mask(), 0U);
   EXPECT_EQ(c2->client_state_mask() & (c2->client_state_mask() - 1), 0U);
@@ -190,7 +190,7 @@
     EXPECT_EQ(client_state_masks & cs[i]->client_state_mask(), 0U);
     client_state_masks |= cs[i]->client_state_mask();
   }
-  EXPECT_EQ(client_state_masks, kProducerStateBit | kConsumerStateMask);
+  EXPECT_EQ(client_state_masks, kFirstClientBitMask | kConsumerStateMask);
 
   // The 64th creation will fail with out-of-memory error.
   auto state = p->CreateConsumer();
@@ -205,7 +205,7 @@
     // The released state mask will be reused.
     EXPECT_EQ(client_state_masks & cs[i]->client_state_mask(), 0U);
     client_state_masks |= cs[i]->client_state_mask();
-    EXPECT_EQ(client_state_masks, kProducerStateBit | kConsumerStateMask);
+    EXPECT_EQ(client_state_masks, kFirstClientBitMask | kConsumerStateMask);
   }
 }
 
@@ -891,6 +891,7 @@
   int b1_id = b1->id();
   EXPECT_TRUE(b1->IsValid());
   EXPECT_EQ(b1->user_metadata_size(), kUserMetadataSize);
+  EXPECT_NE(b1->client_state_mask(), 0ULL);
 
   auto status_or_handle = b1->Duplicate();
   EXPECT_TRUE(status_or_handle);
@@ -908,6 +909,7 @@
   ASSERT_TRUE(b2 != nullptr);
   EXPECT_TRUE(b2->IsValid());
   EXPECT_EQ(b2->user_metadata_size(), kUserMetadataSize);
+  EXPECT_NE(b2->client_state_mask(), 0ULL);
 
   int b2_id = b2->id();
 
@@ -916,10 +918,6 @@
   EXPECT_EQ(b1_id, b2_id);
   // We use client_state_mask() to tell those two instances apart.
   EXPECT_NE(b1->client_state_mask(), b2->client_state_mask());
-  EXPECT_NE(b1->client_state_mask(), 0ULL);
-  EXPECT_NE(b2->client_state_mask(), 0ULL);
-  EXPECT_NE(b1->client_state_mask(), kProducerStateBit);
-  EXPECT_NE(b2->client_state_mask(), kProducerStateBit);
 
   // Both buffer instances should be in gained state.
   EXPECT_TRUE(IsBufferGained(b1->buffer_state()));
diff --git a/libs/vr/libbufferhub/consumer_buffer.cpp b/libs/vr/libbufferhub/consumer_buffer.cpp
index 83d6951..8e630ec 100644
--- a/libs/vr/libbufferhub/consumer_buffer.cpp
+++ b/libs/vr/libbufferhub/consumer_buffer.cpp
@@ -59,7 +59,8 @@
 
   uint64_t fence_state = fence_state_->load(std::memory_order_acquire);
   // If there is an acquire fence from producer, we need to return it.
-  if (fence_state & BufferHubDefs::kProducerStateBit) {
+  // The producer state bit mask is kFirstClientBitMask for now.
+  if (fence_state & BufferHubDefs::kFirstClientBitMask) {
     *out_fence = shared_acquire_fence_.Duplicate();
   }
 
diff --git a/libs/vr/libbufferhub/include/private/dvr/buffer_hub_defs.h b/libs/vr/libbufferhub/include/private/dvr/buffer_hub_defs.h
index 80a00be..650da97 100644
--- a/libs/vr/libbufferhub/include/private/dvr/buffer_hub_defs.h
+++ b/libs/vr/libbufferhub/include/private/dvr/buffer_hub_defs.h
@@ -26,14 +26,14 @@
 // MSB           LSB
 //  |             |
 //  v             v
-// [P|C62|...|C1|C0]
-// Gain'ed state:     [0|..|0|0] -> Exclusively Writable.
-// Post'ed state:     [1|..|0|0]
-// Acquired'ed state: [1|..|X|X] -> At least one bit is set in lower 63 bits
-// Released'ed state: [0|..|X|X] -> At least one bit is set in lower 63 bits
+// [C62|...|C1|C0|P]
+// Gain'ed state:     [..|0|0|0] -> Exclusively Writable.
+// Post'ed state:     [..|0|0|1]
+// Acquired'ed state: [..|X|X|1] -> At least one bit is set in higher 63 bits
+// Released'ed state: [..|X|X|0] -> At least one bit is set in higher 63 bits
 static constexpr int kMaxNumberOfClients = 64;
-static constexpr uint64_t kProducerStateBit = 1ULL << 63;
-static constexpr uint64_t kConsumerStateMask = (1ULL << 63) - 1;
+static constexpr uint64_t kFirstClientBitMask = 1ULL;
+static constexpr uint64_t kConsumerStateMask = ~kFirstClientBitMask;
 
 static inline void ModifyBufferState(std::atomic<uint64_t>* buffer_state,
                                      uint64_t clear_mask, uint64_t set_mask) {
@@ -49,15 +49,15 @@
 
 static inline bool IsBufferPosted(uint64_t state,
                                   uint64_t consumer_bit = kConsumerStateMask) {
-  return (state & kProducerStateBit) && !(state & consumer_bit);
+  return (state & kFirstClientBitMask) && !(state & consumer_bit);
 }
 
 static inline bool IsBufferAcquired(uint64_t state) {
-  return (state & kProducerStateBit) && (state & kConsumerStateMask);
+  return (state & kFirstClientBitMask) && (state & kConsumerStateMask);
 }
 
 static inline bool IsBufferReleased(uint64_t state) {
-  return !(state & kProducerStateBit) && (state & kConsumerStateMask);
+  return !(state & kFirstClientBitMask) && (state & kConsumerStateMask);
 }
 
 static inline uint64_t FindNextAvailableClientStateMask(uint64_t bits) {
@@ -65,7 +65,7 @@
 }
 
 static inline uint64_t FindFirstClearedBit() {
-  return FindNextAvailableClientStateMask(kProducerStateBit);
+  return FindNextAvailableClientStateMask(kFirstClientBitMask);
 }
 
 struct __attribute__((packed, aligned(8))) MetadataHeader {
@@ -123,7 +123,7 @@
 
   // State mask of the buffer client. Each BufferHubBuffer client backed by the
   // same buffer channel has uniqued state bit among its siblings. For a
-  // producer buffer the bit must be kProducerStateBit; for a consumer the bit
+  // producer buffer the bit must be kFirstClientBitMask; for a consumer the bit
   // must be one of the kConsumerStateMask.
   uint64_t client_state_mask() const { return client_state_mask_; }
   uint64_t metadata_size() const { return metadata_size_; }
diff --git a/libs/vr/libbufferhub/producer_buffer.cpp b/libs/vr/libbufferhub/producer_buffer.cpp
index 10517c5..f36e169 100644
--- a/libs/vr/libbufferhub/producer_buffer.cpp
+++ b/libs/vr/libbufferhub/producer_buffer.cpp
@@ -102,8 +102,9 @@
     return error;
 
   // Set the producer bit atomically to transit into posted state.
+  // The producer state bit mask is kFirstClientBitMask for now.
   BufferHubDefs::ModifyBufferState(buffer_state_, 0ULL,
-                                   BufferHubDefs::kProducerStateBit);
+                                   BufferHubDefs::kFirstClientBitMask);
   return 0;
 }