add checksumrect utilities

[netwatch.git] / video / checksumrect.c

diff --git a/video/checksumrect.c b/video/checksumrect.c
new file mode 100644 (file)
index 0000000..f96c033
--- /dev/null
+++ b/video/checksumrect.c
@@ -0,0 +1,26 @@
+#include <stdint.h>
+#include <fb.h>
+
+uint32_t checksum_rect_generic32(int x, int y, int width, int height) {
+
+       /* Generic checksum_rect function for video modes with 32-bit pixels
+        * (i.e. fb->curmode.bytestride = 4).
+        */
+
+        int scanline = fb->curmode.xres * 4;
+        uint32_t * lineaddr;
+        int i, j;
+
+        uint32_t sum = 0;
+
+        for (i = 0; i < height; i++) {
+                lineaddr = (uint32_t *)(fb->fbaddr + (i + y) * scanline);
+
+                for (j = 0; j < width; j++) {
+                        sum += lineaddr[j + x];
+                }
+        }
+
+        return sum;
+}
+