lib/net/conversion/position.hpp: Add library

Unit tests tbd

src/lib/net/conversion/position.hpp

@@ -0,0 +1,68 @@
+// Copyright 2022, FOSS-VG Developers and Contributers
+//
+// Author(s):
+//   BodgeMaster, Shwoomple
+//
+// This program is free software: you can redistribute it and/or modify it
+// under the terms of the GNU Affero General Public License as published
+// by the Free Software Foundation, version 3.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied
+// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+// See the GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// version 3 along with this program.
+// If not, see https://www.gnu.org/licenses/agpl-3.0.en.html
+
+#include <cstdint>
+#include <vector>
+
+#include "../../error.hpp"
+
+namespace Position {
+    struct Location {
+        // 26 bit integer
+        int32_t x;
+        // 12 bit integer
+        int16_t y;
+        // 26 bit integer
+        int32_t z;
+    }
+
+    Location fromPosition(uint64_t position) {
+        Location location;
+
+        location.x = (int32_t) ((0xFFFFFFC000000000 & position) >> 38);
+        if (location.x >= 0x02000000) {
+            location.x -= 0x04000000;
+        }
+
+        location.y = (int16_t) ((0x0000000000000FFF & position));
+        if (location.y >= 0x0800) {
+            location.y -= 0x1000;
+        }
+
+        location.z = (int32_t) ((0x0000003FFFFFF000 & position) >> 12);
+        if (location.z >= 0x02000000) {
+            location.z -= 0x04000000;
+        }
+    }
+
+    ErrorOr<Location> fromPosition(std::vector data, uint64_t initialPosition=0) {
+        if (inititalPosition >= data.size()) {
+            return ErrorOr<Location>(true, ErrorCodes::OUT_OF_BOUNDS);
+        }
+        if (initialPosition+7 >= data.size()) {
+            return ErrorOr<Location>(true, ErrorCodes::OVERRUN);
+        }
+
+        uint64_t deserialized = 0;
+        for (uint8_t i=0; i<8; i++) {
+            deserialized += (uint64_t) data[initialPosition+i] << i*8;
+        }
+
+        return ErrorOr<Location>(fromPosition(deserialized));
+    }
+}