From 94322a95f8cf294a61d78b9ab54e4d75badf3fb2 Mon Sep 17 00:00:00 2001
From: Olivier Galibert <galibert@pobox.com>
Date: Sat, 24 Feb 2018 21:09:24 +0100
Subject: [PATCH] cave graphics fix (nw)

---
 src/mame/drivers/cave.cpp | 20 ++++++++++++++++++--
 src/mame/includes/cave.h  |  1 +
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/src/mame/drivers/cave.cpp b/src/mame/drivers/cave.cpp
index b8f3a0e0536..3df9d155d4f 100644
--- a/src/mame/drivers/cave.cpp
+++ b/src/mame/drivers/cave.cpp
@@ -2947,6 +2947,22 @@ void cave_state::unpack_sprites(int chip)
 }
 
 
+/* 4 bits -> 8 bits. Even and odd pixels are not swapped */
+void cave_state::ddp_unpack_sprites(int chip)
+{
+	const uint32_t len    =   m_spriteregion[chip]->bytes();
+	uint8_t *rgn          =   m_spriteregion[chip]->base();
+	uint8_t *src          =   rgn + len / 2 - 1;
+	uint8_t *dst          =   rgn + len - 1;
+
+	while(dst > src)
+	{
+		uint8_t data = *src--;
+		*dst-- = data & 0xf;     *dst-- = data >> 4;
+	}
+}
+
+
 /* 2 pages of 4 bits -> 8 bits */
 void cave_state::esprade_unpack_sprites(int chip)
 {
@@ -5155,7 +5171,7 @@ DRIVER_INIT_MEMBER(cave_state,ddonpach)
 {
 	init_cave();
 
-	unpack_sprites(0);
+	ddp_unpack_sprites(0);
 	m_spritetype[0] = 1;    // "different" sprites (no zooming?)
 	m_time_vblank_irq = 90;
 }
@@ -5164,7 +5180,7 @@ DRIVER_INIT_MEMBER(cave_state,donpachi)
 {
 	init_cave();
 
-	unpack_sprites(0);
+	ddp_unpack_sprites(0);
 	m_spritetype[0] = 1;    // "different" sprites (no zooming?)
 	m_time_vblank_irq = 90;
 }
diff --git a/src/mame/includes/cave.h b/src/mame/includes/cave.h
index 55925834755..629e67ea3e7 100644
--- a/src/mame/includes/cave.h
+++ b/src/mame/includes/cave.h
@@ -258,6 +258,7 @@ public:
 	DECLARE_WRITE_LINE_MEMBER(sound_irq_gen);
 	void update_irq_state();
 	void unpack_sprites(int chip);
+	void ddp_unpack_sprites(int chip);
 	void esprade_unpack_sprites(int chip);
 	void sailormn_unpack_tiles(int chip);