From 1f73dc5d5e5bb49ff9a4648b424efe50b69e239c Mon Sep 17 00:00:00 2001
From: MihailRis <mexaruc@gmail.com>
Date: Tue, 9 Dec 2025 01:20:41 +0300
Subject: [PATCH] feat: pre-read region chunks offsets table

---
 src/world/files/RegionsLayer.cpp | 20 ++++++++++++++++----
 src/world/files/WorldRegions.hpp |  1 +
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/src/world/files/RegionsLayer.cpp b/src/world/files/RegionsLayer.cpp
index 2da2bd011..04821d463 100644
--- a/src/world/files/RegionsLayer.cpp
+++ b/src/world/files/RegionsLayer.cpp
@@ -50,6 +50,20 @@ regfile::regfile(io::path filename) : file(filename), filename(filename) {
             " is not supported in " + filename.string()
         );
     }
+
+    size_t file_size = file.length();
+    size_t table_offset = file_size - REGION_CHUNKS_COUNT * 4;
+
+    file.seekg(table_offset);
+    file.read(
+        reinterpret_cast<char*>(offsets.data()),
+        sizeof(uint32_t) * REGION_CHUNKS_COUNT
+    );
+    if (dataio::is_big_endian()) {
+        for (size_t i = 0; i < offsets.size(); i++) {
+            offsets[i] = dataio::le2h(i);
+        }
+    }
 }
 
 std::unique_ptr<ubyte[]> regfile::read(
@@ -58,14 +72,12 @@ std::unique_ptr<ubyte[]> regfile::read(
     size_t file_size = file.length();
     size_t table_offset = file_size - REGION_CHUNKS_COUNT * 4;
 
-    uint32_t buff32;
-    file.seekg(table_offset + index * 4);
-    file.read(reinterpret_cast<char*>(&buff32), 4);
-    uint32_t offset = dataio::le2h(buff32);
+    uint32_t offset = offsets.at(index);
     if (offset == 0) {
         return nullptr;
     }
 
+    uint32_t buff32;
     file.seekg(offset);
     file.read(reinterpret_cast<char*>(&buff32), 4);
     size = dataio::le2h(buff32);
diff --git a/src/world/files/WorldRegions.hpp b/src/world/files/WorldRegions.hpp
index 3b4a63fa6..e3bf2774a 100644
--- a/src/world/files/WorldRegions.hpp
+++ b/src/world/files/WorldRegions.hpp
@@ -55,6 +55,7 @@ struct regfile {
     io::path filename;
     int version;
     bool inUse = false;
+    std::array<uint32_t, REGION_CHUNKS_COUNT> offsets;
 
     regfile(io::path filename);
     regfile(const regfile&) = delete;