From e48e63d68419576bb2d9ca9b73d164d904f727dc Mon Sep 17 00:00:00 2001
From: Aaron Giles <aaron@aarongiles.com>
Date: Thu, 5 Apr 2012 19:19:38 +0000
Subject: [PATCH] Add logic to ensure that shared pointers are checked to be of
 the right width. The primary upshot is that if you declare
 AM_SHARE("paletteram") in an 8-bit memory map, then only
 m_generic_paletteram_8 will be populated, and m_generic_paletteram_16 will be
 NULL. But it applies to all required_/optional_shared_ptrs declared, so make
 sure they are of the right type.

The required_/optional_shared_ptr mechanism should be used to replace
AM_BASE_MEMBER and AM_SIZE_MEMBER, which are technically dangerous and
illegal in C++ but work today through some trickery.
---
 src/emu/device.c | 10 ++++++++--
 src/emu/device.h | 14 ++++++++------
 2 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/src/emu/device.c b/src/emu/device.c
index cccec2644b7..86a9d0190c3 100644
--- a/src/emu/device.c
+++ b/src/emu/device.c
@@ -859,12 +859,18 @@ device_t::finder_base::~finder_base()
 //  find_memory - find memory
 //-------------------------------------------------
 
-void *device_t::finder_base::find_memory(size_t &size)
+void *device_t::finder_base::find_memory(UINT8 width, size_t &bytes, bool required)
 {
 	memory_share *share = m_base.machine().memory().shared(m_base, m_tag);
 	if (share == NULL)
 		return NULL;
-	size = share->bytes();
+	if (share->width() != width)
+	{
+		if (required)
+			mame_printf_warning("Shared ptr '%s' found but is width %d, not %d as requested\n", m_tag, share->width(), width);
+		return NULL;
+	}
+	bytes = share->bytes();
 	return share->ptr();
 }
 
diff --git a/src/emu/device.h b/src/emu/device.h
index 0e96b9572e3..df101d93911 100644
--- a/src/emu/device.h
+++ b/src/emu/device.h
@@ -303,7 +303,7 @@ protected:
 
 	protected:
 		// static helpers
-		void *find_memory(size_t &size);
+		void *find_memory(UINT8 width, size_t &bytes, bool required);
 
 		// internal state
 		finder_base *m_next;
@@ -367,11 +367,12 @@ protected:
 	{
 	public:
 		// construction/destruction
-		shared_ptr_finder(device_t &base, const char *tag)
+		shared_ptr_finder(device_t &base, const char *tag, UINT8 width = 0)
 			: finder_base(base, tag),
 			  m_target(0),
 			  m_bytes(0),
-			  m_allocated(false) { }
+			  m_allocated(false),
+			  m_width((width != 0) ? width : sizeof(_PointerType) * 8) { }
 		
 		virtual ~shared_ptr_finder() { if (m_allocated) global_free(m_target); }
 
@@ -404,13 +405,14 @@ protected:
 		}
 
 		// finder
-		virtual void findit() { m_target = reinterpret_cast<_PointerType *>(find_memory(m_bytes)); }
+		virtual void findit() { m_target = reinterpret_cast<_PointerType *>(find_memory(m_width, m_bytes, _Required)); }
 
 	protected:
 		// internal state
 		_PointerType *m_target;
 		size_t m_bytes;
 		bool m_allocated;
+		UINT8 m_width;
 	};
 	
 	// optional device finder
@@ -418,7 +420,7 @@ protected:
 	class optional_shared_ptr : public shared_ptr_finder<_PointerType, false>
 	{
 	public:
-		optional_shared_ptr(device_t &base, const char *tag) : shared_ptr_finder<_PointerType, false>(base, tag) { }
+		optional_shared_ptr(device_t &base, const char *tag, UINT8 width = 0) : shared_ptr_finder<_PointerType, false>(base, tag, width) { }
 	};
 
 	// required devices are similar but throw an error if they are not found
@@ -426,7 +428,7 @@ protected:
 	class required_shared_ptr : public shared_ptr_finder<_PointerType, true>
 	{
 	public:
-		required_shared_ptr(device_t &base, const char *tag) : shared_ptr_finder<_PointerType, true>(base, tag) { }
+		required_shared_ptr(device_t &base, const char *tag, UINT8 width = 0) : shared_ptr_finder<_PointerType, true>(base, tag, width) { }
 	};
 
 	// internal helpers