Add getblockat function

TODO.txt

@@ -23,6 +23,10 @@
   - possibility to turn off textures completely
   - how to map textures to blocks?
     - figured out nice procedural mapping in Blender :)
+  - PROBABLY LIKE THIS:
+    - background textures: 128x128 with image-specific 256 color palette,
+      pixel access shouldn't be as time critical here
+    - other textures 64x64 with direct 565 values stored
 - Rendering: two pass: 1st pass renders the scaled down background (possibly not
   rendering floor, can be just pure green for "grass") to prevent overflows,
   second pass renders the tracks (or the nearest part of it).

main.c

@@ -9,5 +9,13 @@ int main(void)
 
   LCR_debugPrintCurrentMap();
 
+
+  uint8_t *b = LCR_getMapBlockAtCoordNumber(0);
+
+  if (!b)
+    printf("NO!\n");
+  else
+    printf("%d\n",(b - LCR_currentMap.blocks) / 4);
+
   return 0;
 }

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))