From 71f78fa89cd29843fb7e186f9744d8a2c4adc5f2 Mon Sep 17 00:00:00 2001
From: Joshua Ashton <joshua@froggi.es>
Date: Thu, 13 Aug 2020 15:54:57 +0100
Subject: [PATCH] Support > 4 bitsPerBlock

---
 src/DedicatedServer.cpp | 14 ++++++--------
 src/data/IDMapper.h     |  2 +-
 src/world/Chunk.cpp     | 13 +++++--------
 src/world/Chunk.h       | 13 +++++--------
 4 files changed, 17 insertions(+), 25 deletions(-)

diff --git a/src/DedicatedServer.cpp b/src/DedicatedServer.cpp
index d55dcbd..015e142 100644
--- a/src/DedicatedServer.cpp
+++ b/src/DedicatedServer.cpp
@@ -217,11 +217,7 @@ namespace Feather
 
         for (int i = 0; i < Chunk::NUM_SECTIONS; i++)
         {
-            ChunkSection sect = chunk->sections[i];
-
-            // Don't support bitsPerBlock != 4 yet!
-            if (i == 4)
-                continue;
+            const ChunkSection& sect = chunk->sections[i];
 
             Log::Trace("Chunk: Got Section {} with local palette size {}", i, sect.localPalette.Size());
 
@@ -230,7 +226,7 @@ namespace Feather
             // Block Count: fudge
             sections.Write<int16_t>(1024);
             
-            const size_t bitsPerBlock = 4;
+            const uint8_t bitsPerBlock = sect.bitsPerBlock;
             sections.Write<uint8_t>(bitsPerBlock);
 
             const size_t dataLength = (16 * 16 * 16) * bitsPerBlock / 64;
@@ -240,12 +236,14 @@ namespace Feather
                 // Palette
                 sections.WriteVarInt(sect.localPalette.Size());
 
-                for (int j = 0; j < sect.localPalette.Size(); j++)
+                for (size_t j = 0; j < sect.localPalette.Size(); j++)
                     sections.WriteVarInt(sect.localPalette.ByID(j));
             }
 
             sections.WriteVarInt(dataLength);
-            sections.WriteData(sect.blockStates, dataLength * sizeof(int64_t));
+            // Can't just copy because endian-ness!
+            for (size_t i = 0; i < dataLength; i++)
+                sections.Write<uint64_t>(sect.blockStates[i]);
         }
 
         Log::Trace("Section bits: {:#b}", sectionsBits);
diff --git a/src/data/IDMapper.h b/src/data/IDMapper.h
index 3103578..93db410 100644
--- a/src/data/IDMapper.h
+++ b/src/data/IDMapper.h
@@ -46,7 +46,7 @@ namespace Feather
 			return m_IDtoValue.at(id);
 		}
 
-		inline int Size() const
+		inline size_t Size() const
 		{
 			return m_IDtoValue.size();
 		}
diff --git a/src/world/Chunk.cpp b/src/world/Chunk.cpp
index b546f42..35bf153 100644
--- a/src/world/Chunk.cpp
+++ b/src/world/Chunk.cpp
@@ -49,7 +49,7 @@ namespace Feather
 
 			ListTag<CompoundTag> palette = sectData.GetList<CompoundTag>("Palette");
 
-			for (int i = 0; i < palette.GetLength(); i++)
+			for (size_t i = 0; i < palette.GetLength(); i++)
 			{
 				CompoundTag state = palette[i];
 				const char* name = state.Get<StringTag>("Name").GetValue();
@@ -82,15 +82,12 @@ namespace Feather
 				continue;
 			}
 
-			int len = blockStates.GetLength();
-			if (len != ChunkSection::NUM_LONGS) {
-				Log::Warn("Section {} has {} longs, expected {}", y, len, ChunkSection::NUM_LONGS);
-			}
+			assert(blockStates.GetLength() < ChunkSection::MaximumLongCount);
 
-			for (int i = 0; i < blockStates.GetLength() && i < ChunkSection::NUM_LONGS; i++)
-			{
+			for (size_t i = 0; i < blockStates.GetLength(); i++)
 				section->blockStates[i] = blockStates[i];
-			}
+
+			section->bitsPerBlock = (blockStates.GetLength() * 64) / (16 * 16 * 16);
 
 			n++;
 		}
diff --git a/src/world/Chunk.h b/src/world/Chunk.h
index 0c0efc8..4928e6e 100644
--- a/src/world/Chunk.h
+++ b/src/world/Chunk.h
@@ -12,20 +12,17 @@
 namespace Feather
 {
 	// 16x16x16 sections of a chunk
-	class ChunkSection
+	struct ChunkSection
 	{
-	public:
-		// 4 bits per block
-		// 16^3 = 4096 blocks total
-		// 4096 * 4 = 16384 bits = 256x int64
-		// 16 blocks per int64
-		static constexpr int NUM_LONGS = 256;
+		static constexpr size_t MaximumLongCount = (16 * 16 * 16) * 14 / 64;
 
-		int64_t blockStates[NUM_LONGS];
+		std::array<uint64_t, MaximumLongCount> blockStates;
 
 		// TODO: this should eventually be Palette<BlockState>
 		// Palette of local indexs to indexs in the global palette
 		IDMapper<int> localPalette;
+
+		uint8_t bitsPerBlock;
 	};
 
 	// Chunk: 16x256x16 world chunk