Add dma dirty lines mode for double buffering

2 files changed, 36 insertions, 3 deletions

diff --git a/src/profiling.c b/src/profiling.c
index 7477dca..6a4d448 100644
--- a/src/profiling.c
+++ b/src/profiling.c
@@ -86,7 +86,7 @@ static bool profile_bg_show = true;
                     2) * 60;\
             draw_filled_rect(8 * 18, 0, 239, 16, 0);\
             txt_drawf("TIME: %.6d", 8 * 18, 0, 1, frame_time >> 2);\
-            txt_drawf("MAX FPS:%.4d", 8 * 18, 8, 1, fps >> 2);\
+            txt_drawf("MAX FPS:%.4d", 8 * 18, 8, 1, (fps >> 2) + 1);\
         }\
     } while (0)
 
diff --git a/src/renderer_m0.c b/src/renderer_m0.c
index 6c509f9..5655e1d 100644
--- a/src/renderer_m0.c
+++ b/src/renderer_m0.c
@@ -673,8 +673,8 @@ flip_buffer(void) {
         dirty_tiles[j] = 0;
     }
 
-// Mode 3: Double buffering with dirty tiles, copying the dirty tiles if needed
-// after flipping buffers.
+// Mode 3: Double buffering with dirty line, copying the dirty lines if needed
+// after flipping buffers with the DMA.
 #elif FLIP_TYPE == 3
     bool should_flip = false;
     for (size_t j = 0; j < 20; ++j) {
@@ -701,6 +701,39 @@ flip_buffer(void) {
         if (dirty_tiles[j] == 0) {
             continue;
         }
+        u32 offset = j * 32 * 8;
+        dma_copy(backbuf + offset, frontbuf + offset, (30 * 8 * 4), 3);
+        dirty_tiles[j] = 0;
+    }
+
+// Mode 4: Double buffering with dirty tiles, copying the dirty tiles if needed
+// after flipping buffers.
+#elif FLIP_TYPE == 4
+    bool should_flip = false;
+    for (size_t j = 0; j < 20; ++j) {
+        if (dirty_tiles[j] == 0) {
+            continue;
+        }
+        should_flip = true;
+        break;
+    }
+    if (!should_flip) {
+        return;
+    }
+    u32 *frontbuf = backbuf;
+    if (backbuf == BUF_0) {
+        backbuf = BUF_1;
+        BG_H_SCROLL_0 = 0;
+        BG_H_SCROLL_1 = -240;
+    } else {
+        backbuf = BUF_0;
+        BG_H_SCROLL_0 = -240;
+        BG_H_SCROLL_1 = 0;
+    }
+    for (size_t j = 0; j < 20; ++j) {
+        if (dirty_tiles[j] == 0) {
+            continue;
+        }
         size_t k = 1;
         for (size_t i = 0; i < 30; ++i, k <<= 1) {
             if (dirty_tiles[j] & k) {