decoupled frame rate from movement rate

animations/amphibian.c

@@ -146,5 +146,5 @@ static uint8_t amphibian_getChunk(unsigned char const nBitPlane,
 
 void amphibian()
 {
-	bitmap_scroll(48, 38, 2, 400, 75, amphibian_getChunk);
+	bitmap_scroll(48, 38, 2, 400, 75, 1, 1, amphibian_getChunk);
 }

animations/bitmapscroller.c

@@ -176,18 +176,24 @@ static void bitmap_recalculateVector(bitmap_t const *const pBitmap,
  * @param nWidth Width of the bitmap.
  * @param nHeight Height of bitmap.
  * @param nBitPlanes Amount of bit planes.
- * @param nFrameCount How many frames shall be shown.
- * @param nFrameTick Duration of a displayed frame in milliseconds.
+ * @param nTickCount How many ticks the animation will last.
+ * @param nTick Time quantum in milliseconds.
+ * @param nFrameTickDivider Amount of ticks between frame changes.
+ * @param nMovementTickDiver Amount of ticks between movement changes.
  * @param fpGetChunk Function that returns an eight-by-one chunk of a bitmap.
  */
 void bitmap_scroll(unsigned char const nWidth,
                    unsigned char const nHeight,
                    unsigned char const nBitPlanes,
-                   unsigned int const nFrameCount,
-                   unsigned int const nFrameTick,
+                   unsigned int const nTickCount,
+                   unsigned int const nTick,
+                   unsigned char const nFrameTickDivider,
+                   unsigned char const nMovementTickDivider,
                    bitmap_getChunk_t fpGetChunk)
 {
 	assert((nBitPlanes > 0) && (nBitPlanes <= 8));
+	assert(nFrameTickDivider > 0);
+	assert(nFrameTickDivider > 0);
 
 	bitmap_t bitmap;
 
@@ -206,18 +212,25 @@ void bitmap_scroll(unsigned char const nWidth,
 	bitmap.nChunkCount = (((bitmap.nViewportWidth - 1) / 8) + 1);
 
 	// initial starting point
+	bitmap.nFrame = 0;
 	unsigned char x = bitmap.nXDomain > 0 ? random8() % bitmap.nXDomain : 0;
 	unsigned char y = bitmap.nYDomain > 0 ? random8() % bitmap.nYDomain : 0;
 	signed char dx = 0;
 	signed char dy = 0;
 
-	for (bitmap.nFrame = 0; bitmap.nFrame < nFrameCount; ++bitmap.nFrame)
+	for (unsigned int i = 0; i < nTickCount; ++i)
 	{
 		bitmap_drawViewport(&bitmap, x, y);
+		if ((i % nFrameTickDivider) == 0)
+		{
+			++bitmap.nFrame;
+		}
+		if ((i % nMovementTickDivider) == 0)
+		{
 			bitmap_recalculateVector(&bitmap, x, y, &dx, &dy);
 			x += bitmap.nWidth > bitmap.nViewportWidth ? dx : 0;
 			y += bitmap.nHeight > bitmap.nViewportHeight ? dy : 0;
-
-		wait(nFrameTick);
+		}
+		wait(nTick);
 	}
 }

animations/bitmapscroller.h

@@ -26,8 +26,10 @@ typedef uint8_t (*bitmap_getChunk_t)(unsigned char const nBitPlane,
 void bitmap_scroll(unsigned char const nWidth,
                    unsigned char const nHeight,
                    unsigned char const nBitPlanes,
-                   unsigned int const nFrameCount,
-                   unsigned int const nFrameTick,
+                   unsigned int const nTickCount,
+                   unsigned int const nTick,
+                   unsigned char const nFrameTickDivider,
+                   unsigned char const nMovementTickDivider,
                    bitmap_getChunk_t fpGetChunk);
 
 #endif /* BITMAP_SCROLLER_H_ */

animations/fairydust.c

@@ -204,6 +204,6 @@ static uint8_t fairydust_getChunk(unsigned char const nBitPlane,
 
 void fairydust()
 {
-	// width 72, height 30+x, 2 bitplanes (4 colors), 600 frames à 50ms (20 fps)
-	bitmap_scroll(72, nMargin + 30 + nMargin, 2, 600, 50, fairydust_getChunk);
+	bitmap_scroll(72, nMargin + 30 + nMargin, 2, 2400, 12, 1, 4,
+			fairydust_getChunk);
 }

animations/laborlogo.c

@@ -70,5 +70,5 @@ static uint8_t laborlogo_getChunk(unsigned char const nBitPlane,
 
 void laborlogo()
 {
-	bitmap_scroll(48, 48, 2, 400, 75, laborlogo_getChunk);
+	bitmap_scroll(48, 48, 2, 400, 75, 1, 1, laborlogo_getChunk);
 }

animations/outofspec.c

@@ -125,6 +125,5 @@ static uint8_t logo_OutOfSpec_getChunk(unsigned char const nBitPlane,
 
 void logo_OutOfSpec()
 {
-	// width 64, height 50, 2 bitplanes (4 colors), 600 frames à 50ms (20 fps)
-	bitmap_scroll(64, 50, 2, 600, 50, logo_OutOfSpec_getChunk);
+	bitmap_scroll(64, 50, 2, 600, 50, 1, 1, logo_OutOfSpec_getChunk);
 }