(svn r14191) -Codechange: unify the code to skip sprite payload (i.e. not the header).

-Fix: sprite payload skipping wouldn't skip enough bytes in a very small subset of compressed sprites.

3 files changed, 32 insertions, 35 deletions

diff --git a/src/newgrf.cpp b/src/newgrf.cpp
index 1ef2fe87c..b49605b22 100644
--- a/src/newgrf.cpp
+++ b/src/newgrf.cpp
@@ -5935,23 +5935,7 @@ void LoadNewGRFFile(GRFConfig *config, uint file_index, GrfLoadingStage stage)
 			}
 
 			FioSkipBytes(7);
-			num -= 8;
-
-			if (type & 2) {
-				FioSkipBytes(num);
-			} else {
-				while (num > 0) {
-					int8 i = FioReadByte();
-					if (i >= 0) {
-						num -= i;
-						FioSkipBytes(i);
-					} else {
-						i = -(i >> 3);
-						num -= i;
-						FioReadByte();
-					}
-				}
-			}
+			SkipSpriteData(type, num - 8);
 		}
 
 		if (_skip_sprites > 0) _skip_sprites--;
diff --git a/src/sprite.h b/src/sprite.h
index b996280d8..26bdb0595 100644
--- a/src/sprite.h
+++ b/src/sprite.h
@@ -56,5 +56,6 @@ struct DrawBuildingsTileStruct {
 /** Iterate through all DrawTileSeqStructs in DrawTileSprites. */
 #define foreach_draw_tile_seq(idx, list) for (idx = list; ((byte) idx->delta_x) != 0x80; idx++)
 
+void SkipSpriteData(byte type, uint16 num);
 
 #endif /* SPRITE_H */
diff --git a/src/spritecache.cpp b/src/spritecache.cpp
index 296744ab5..ae331e3ed 100644
--- a/src/spritecache.cpp
+++ b/src/spritecache.cpp
@@ -72,31 +72,20 @@ static int _compact_cache_counter;
 
 static void CompactSpriteCache();
 
-static bool ReadSpriteHeaderSkipData()
+/**
+ * Skip the given amount of sprite graphics data.
+ * @param type the type of sprite (compressed etc)
+ * @param num the amount of sprites to skip
+ */
+void SkipSpriteData(byte type, uint16 num)
 {
-	uint16 num = FioReadWord();
-	byte type;
-
-	if (num == 0) return false;
-
-	type = FioReadByte();
-	if (type == 0xFF) {
-		FioSkipBytes(num);
-		/* Some NewGRF files have "empty" pseudo-sprites which are 1
-		 * byte long. Catch these so the sprites won't be displayed. */
-		return num != 1;
-	}
-
-	FioSkipBytes(7);
-	num -= 8;
-	if (num == 0) return true;
-
 	if (type & 2) {
 		FioSkipBytes(num);
 	} else {
 		while (num > 0) {
 			int8 i = FioReadByte();
 			if (i >= 0) {
+				i = (i == 0) ? 0x80 : i;
 				num -= i;
 				FioSkipBytes(i);
 			} else {
@@ -106,6 +95,29 @@ static bool ReadSpriteHeaderSkipData()
 			}
 		}
 	}
+}
+
+/**
+ * Read the sprite header data and then skip the real payload.
+ * @return true if the sprite is a pseudo sprite.
+ */
+static bool ReadSpriteHeaderSkipData()
+{
+	uint16 num = FioReadWord();
+	byte type;
+
+	if (num == 0) return false;
+
+	type = FioReadByte();
+	if (type == 0xFF) {
+		FioSkipBytes(num);
+		/* Some NewGRF files have "empty" pseudo-sprites which are 1
+		 * byte long. Catch these so the sprites won't be displayed. */
+		return num != 1;
+	}
+
+	FioSkipBytes(7);
+	SkipSpriteData(type, num - 8);
 
 	return true;
 }