ioport_array_finder: [Alex Jackson]

Clean build probably needed since this touches a core header file.

ioport_array_finder is a new device finder template for finding,
unsurprisingly, an array of ioports. It is mainly intended to
help handle multiplexed ioports without runtime tagmap lookups
in a more elegant way than was previously possible.

It is similar in principle to shared_ptr_array_finder; however,
rather than passing a single tag that gets automatically decorated
with numeric suffixes, you need to pass an array of tags (this is so
ioports can continue to have human-meaningful tags rather than the
tags being forced by how the hardware multiplexing happens to work).

Because C++ doesn't have array literals, and because most driver
state class constructors are defined in header files, the semantics
are a little different from other device finders (and possibly
awkward/suboptimal, this is the best I could think of). You have to
declare the array of tags as a static class member and define it
somewhere in a source file (defining it near the function that
actually reads the multiplexed ports seems like the most logical
place to me).

Updated bladestl.c to use ioport_array_finder; will wait for Micko to
pass judgement on the semantics before updating more drivers.

src/emu/devfind.h

@@ -240,6 +240,48 @@ public:
 };
 
 
+// ======================> ioport_array_finder
+
+// ioport array finder template
+template<int _Count, bool _Required>
+class ioport_array_finder
+{
+	typedef ioport_finder<_Required> ioport_finder_type;
+
+public:
+	// construction/destruction
+	ioport_array_finder(device_t &base, const char * const *tags)
+	{
+		for (int index = 0; index < _Count; index++)
+			m_array[index].reset(global_alloc(ioport_finder_type(base, tags[index])));
+	}
+
+	// array accessors
+	const ioport_finder_type &operator[](int index) const { assert(index < _Count); return *m_array[index]; }
+	ioport_finder_type &operator[](int index) { assert(index < _Count); return *m_array[index]; }
+
+protected:
+	// internal state
+	auto_pointer<ioport_finder_type> m_array[_Count];
+};
+
+// optional ioport array finder
+template<int _Count>
+class optional_ioport_array: public ioport_array_finder<_Count, false>
+{
+public:
+	optional_ioport_array(device_t &base, const char * const *tags) : ioport_array_finder<_Count, false>(base, tags) { }
+};
+
+// required ioport array finder
+template<int _Count>
+class required_ioport_array: public ioport_array_finder<_Count, true>
+{
+public:
+	required_ioport_array(device_t &base, const char * const *tags) : ioport_array_finder<_Count, true>(base, tags) { }
+};
+
+
 // ======================> shared_ptr_finder
 
 // shared pointer finder template

src/mame/drivers/bladestl.c

@@ -50,14 +50,13 @@ TIMER_DEVICE_CALLBACK_MEMBER(bladestl_state::bladestl_scanline)
  *  Memory handlers
  *
  *************************************/
+const char * const bladestl_state::trackball_tags[] =
+	{ "TRACKBALL_P1_1", "TRACKBALL_P1_2", "TRACKBALL_P2_1", "TRACKBALL_P2_2" };
 
 READ8_MEMBER(bladestl_state::trackball_r)
 {
-	static const char *const port[] = { "TRACKBALL_P1_1", "TRACKBALL_P1_2", "TRACKBALL_P2_1", "TRACKBALL_P2_2" };
-	int curr, delta;
-
-	curr = ioport(port[offset])->read();
-	delta = (curr - m_last_track[offset]) & 0xff;
+	int curr = m_trackball[offset]->read();
+	int delta = (curr - m_last_track[offset]) & 0xff;
 	m_last_track[offset] = curr;
 
 	return (delta & 0x80) | (curr >> 1);

src/mame/includes/bladestl.h

@@ -10,6 +10,7 @@
 
 class bladestl_state : public driver_device
 {
+	static const char * const trackball_tags[];
 public:
 	bladestl_state(const machine_config &mconfig, device_type type, const char *tag)
 		: driver_device(mconfig, type, tag),
@@ -20,6 +21,7 @@ public:
 		m_k007420(*this, "k007420"),
 		m_upd7759(*this, "upd"),
 		m_gfxdecode(*this, "gfxdecode"),
+		m_trackball(*this, trackball_tags),
 		m_rombank(*this, "rombank") { }
 
 	required_device<cpu_device> m_maincpu;
@@ -28,6 +30,7 @@ public:
 	required_device<k007420_device> m_k007420;
 	required_device<upd7759_device> m_upd7759;
 	required_device<gfxdecode_device> m_gfxdecode;
+	required_ioport_array<4> m_trackball;
 
 	/* memory pointers */
 	required_memory_bank m_rombank;