Fix internal buffer height calculation.

diff --git a/custom.cpp b/custom.cpp
index f29e9ecaabb3500975cb6a31c3b14136fc52f254..c3bfc3c2a47bd37a256e07f1f5f140507d467632 100644 (file)
--- a/custom.cpp
+++ b/custom.cpp
@@ -1565,8 +1565,9 @@ void compute_framesync(void)
        if (vidinfo->drawbuffer.extrawidth == -2 && ((new_beamcon0 & (BEAMCON0_VARVBEN | bemcon0_vsync_mask)) || currprefs.gfx_overscanmode >= OVERSCANMODE_EXTREME)) {
                vidinfo->drawbuffer.extrawidth = -1;
        }
-       int maxv = current_linear_vpos - (minfirstline > vsync_startline ? minfirstline - vsync_startline : 0);
-       vidinfo->drawbuffer.inheight = (maxv + 1) << vres2;
+       int mfl = minfirstline + 1;
+       int maxv = current_linear_vpos - (mfl > vsync_startline ? mfl - vsync_startline : 0);
+       vidinfo->drawbuffer.inheight = maxv << vres2;
        vidinfo->drawbuffer.inheight2 = vidinfo->drawbuffer.inheight;
        vidinfo->drawbuffer.inxoffset = 0;