added page flipping/scrolling VBE calls

[dosrtxon] / src / dos / main.c

diff --git a/src/dos/main.c b/src/dos/main.c
index 0b3747e..c25ea6d 100644 (file)
--- a/src/dos/main.c
+++ b/src/dos/main.c
@@ -3,6 +3,7 @@
 #include <math.h>
 #include <string.h>
 #include <limits.h>
+#include <assert.h>
 #include <conio.h>
 #include "demo.h"
 #include "keyb.h"
@@ -45,11 +46,15 @@ int main(int argc, char **argv)
                return 1;
        }
 
-       if(!(vmem_front = set_video_mode(fb_width, fb_height, fb_bpp))) {
+       if(!(vmem_back = set_video_mode(fb_width, fb_height, fb_bpp))) {
                return 1;
        }
-       /* TODO implement multiple video memory pages for flipping */
-       vmem_back = vmem_front;
+       if(!(vmem_front = page_flip(FLIP_NOW))) {
+               /* page flipping not supported */
+               vmem_front = vmem_back;
+       } else {
+               assert(vmem_back != vmem_front);
+       }
 
        if(demo_init(argc, argv) == -1) {
                set_text_mode();
@@ -95,18 +100,30 @@ void demo_quit(void)
 
 void swap_buffers(void *pixels)
 {
-       /* TODO implement page flipping */
        if(pixels) {
+               /* just memcpy to the front buffer */
                if(opt.vsync) {
                        wait_vsync();
                }
                drawFps(pixels);
                memcpy(vmem_front, pixels, fbsize);
+
        } else {
-               drawFps(vmem_back);
+               /* attempt page flipping */
+               void *next;
 
-               if(opt.vsync) {
-                       wait_vsync();
+               drawFps(vmem_back);
+               if((next = page_flip(opt.vsync ? FLIP_VBLANK_WAIT : FLIP_NOW))) {
+                       assert(next == vmem_back);
+                       vmem_back = vmem_front;
+                       vmem_front = next;
+               } else {
+                       /* failed to page flip, assume we drew in the front buffer then
+                        * and just wait for vsync if necessary
+                        */
+                       if(opt.vsync) {
+                               wait_vsync();
+                       }
                }
        }
 }