Frame buffer management fixes

core/vb.c

@@ -312,6 +312,7 @@ struct VB {
             int      frame;    /* FRMCYC counter */
             int32_t  halfword; /* Current output halfword offset */
             int      step;     /* Processing phase */
+            uint8_t  toggle;   /* Switch frame buffers next frame */
             uint32_t until;    /* Clocks until interrupt condition */
         } xp;
 
@@ -326,6 +327,7 @@ struct VB {
         uint16_t spt[4];     /* Object control */
 
         /* Rendering shadow memory */
+        uint8_t  buffer;            /* Output buffer */
         uint16_t halfwords[384*28]; /* Output timing by 1x8 halfword */
         Pixels   output[2];         /* Output images, row-major */
         Pixels   shadow;            /* Drawing shadow image, column-major */
@@ -632,7 +634,7 @@ VBAPI void vbGetPixels(VB *sim, void *left, int leftStrideX, int leftStrideY,
             continue;
 
         /* Transfer pixels to the destination */
-        src = sim->vip.output[sim->vip.dp.buffer ^ 1][i];
+        src = sim->vip.output[sim->vip.buffer][i];
         for (y = 0; y < 224; y++, dest += yStride)
         for (x = offset = 0; x < 384; x++, offset += xStride)
             dest[offset] = *src++;