From 9bbca338d476ea6ce73dce3f07fc5e3c8b0d00b0 Mon Sep 17 00:00:00 2001
From: Roberto Zandona <robertoz@mamedev.org>
Date: Sat, 14 Mar 2009 11:39:17 +0000
Subject: [PATCH] 00230: On the emulated game when the waves are near the
 border of the screen you can see them on the other side. This is wrong.

---
 src/mame/video/m57.c | 29 ++++++++++++++++++++++++++---
 1 file changed, 26 insertions(+), 3 deletions(-)

diff --git a/src/mame/video/m57.c b/src/mame/video/m57.c
index e24f3e7be24..4e1deec3a15 100644
--- a/src/mame/video/m57.c
+++ b/src/mame/video/m57.c
@@ -174,11 +174,34 @@ WRITE8_HANDLER( m57_flipscreen_w )
 
 static void draw_background(running_machine *machine, bitmap_t *bitmap, const rectangle *cliprect)
 {
-	int y;
+	int y,x;
+
+	for (y = 0; y < 128; y++)
+		tilemap_set_scrollx(bg_tilemap, y, (y < 64) ? 0 : m57_scroll[64]);
 
-	for (y = 0; y < 256; y++)
-		tilemap_set_scrollx(bg_tilemap, y, (y < 64) ? 0 : (y < 128) ? m57_scroll[64] : m57_scroll[y]);
 	tilemap_draw(bitmap, cliprect, bg_tilemap, 0, 0);
+
+	for (y = 128; y <= cliprect->max_y; y++)
+	{
+		if (m57_scroll[y] < 128)
+		{
+			for (x = cliprect->min_x; x <= cliprect->max_x; x++)
+			{
+				if ((x + m57_scroll[y]) <= cliprect->max_x)
+					*BITMAP_ADDR16(bitmap, y, x) = *BITMAP_ADDR16(bitmap, y, x + m57_scroll[y]);
+				else
+					*BITMAP_ADDR16(bitmap, y, x) = *BITMAP_ADDR16(bitmap, y, cliprect->max_x);
+			}
+		} else {
+			for (x = cliprect->max_x; x >= cliprect->min_x; x--)
+			{
+				if ((x + m57_scroll[y] - 256) >= cliprect->min_x)
+					*BITMAP_ADDR16(bitmap, y, x) = *BITMAP_ADDR16(bitmap, y, x + m57_scroll[y] - 256);
+				else
+					*BITMAP_ADDR16(bitmap, y, x) = *BITMAP_ADDR16(bitmap, y, cliprect->min_x);
+			}
+		}
+	}
 }
 
 /*************************************