Add getblockat function

map.h

@@ -16,6 +16,7 @@
 
   The STORAGE map format is binary and consists of the following values:
     - 76, 77 (for "LM", magic number)
+    - one byte recording the map environment
     - ASCII map name
     - 10 (separator)
     - ASCII comment
@@ -95,6 +96,8 @@ struct
   uint8_t blocks[LCR_SETTING_MAP_MAX_SIZE * 4];
   uint32_t startPos;
 
+  uint8_t environment;
+
   // TODO: name, desc? possibly as a single '\n' separated string?
 } LCR_currentMap;
 
@@ -132,6 +135,32 @@ uint32_t LCR_mapBlockGetCoordNumber(const uint8_t block[4])
     ((((uint32_t) block[3]) & 0x3) << 16);
 }
 
+uint8_t *LCR_getMapBlockAtCoordNumber(uint32_t coord)
+{
+  // binary search the block:
+
+  uint16_t a = 0, b = LCR_currentMap.blockCount - 1;
+
+  while (b >= a)
+  {
+    uint16_t mid = (a + b) / 2;
+
+    uint8_t *block = LCR_currentMap.blocks + mid * 4;
+
+    uint32_t coord2 =
+      LCR_mapBlockGetCoordNumber(block);
+
+    if (coord2 == coord)
+      return block;
+    else if (coord2 > coord)
+      b = mid - 1;
+    else
+      a = mid + 1;
+  }
+
+  return 0;
+}
+
 /**
   Adds given block to current map, including possibly deleting a block by
   adding LCR_BLOCK_NONE. The function handles sorting the block to the right
@@ -213,6 +242,10 @@ uint8_t LCR_mapLoad(const uint8_t *map)
 
   map++;
 
+  LCR_currentMap.environment = *map;
+
+  map++;
+
   while (*map != LCR_MAP_TERMINATOR)
   {
     if (!_LCR_mapAddBlock(map))