pokey update: eliminate clipping & add volume attenuation. also make centipede & millipede the same volume

src/burn/drv/pre90s/d_atetris.cpp

@@ -327,7 +327,7 @@ static INT32 CommonInit(INT32 boot)
 		SN76496SetRoute(1, 0.50, BURN_SND_ROUTE_BOTH);
 		SN76496SetRoute(2, 0.50, BURN_SND_ROUTE_BOTH);
 	} else {
-		PokeyInit(0, 2, 6, 0);
+		PokeyInit(0, 2, 1.00, 0);
 	}
 
 	GenericTilesInit();

src/burn/drv/pre90s/d_millipede.cpp

@@ -726,7 +726,7 @@ static INT32 DrvInit()
 	M6502SetReadOpHandler(millipede_read);
 	M6502Close();
 
-	PokeyInit(12096000/8, 2, 6, 0);
+	PokeyInit(12096000/8, 2, 1.00, 0);
 
 	init_penmask();
 
@@ -777,7 +777,7 @@ static INT32 DrvInitcentiped()
 	M6502SetReadOpHandler(centipede_read);
 	M6502Close();
 
-	PokeyInit(12096000/8, 2, 6, 0);
+	PokeyInit(12096000/8, 2, 2.40, 0);
 
 	init_penmask();
 

src/burn/snd/pokey.cpp

@@ -56,6 +56,8 @@
  * I use 15/11 = 1.3636, so this is a little lower.
  */
 #define POKEY_DEFAULT_GAIN (32767/11/4)
+static double pokey_mastervol = 1.0;
+static INT32 nLeftSample = 0, nRightSample = 0;
 
 #define VERBOSE 		0
 #define VERBOSE_SOUND	0
@@ -326,9 +328,12 @@ static UINT8 *rand17;
 		pokey[chip].samplepos_fract &= 0x000000ff;						\
 	}																	\
 	/* store sum of output signals into the buffer */					\
-	*buffer++ += (sum > 65535) ? 0x7fff : sum - 0x8000;					\
-	*buffer++ += (sum > 65535) ? 0x7fff : sum - 0x8000;					\
-	length--
+	nLeftSample  = buffer[0] + (sum * pokey_mastervol);                 \
+	nRightSample = buffer[1] + (sum * pokey_mastervol);                 \
+	buffer[0] = BURN_SND_CLIP(nLeftSample);                             \
+	buffer[1] = BURN_SND_CLIP(nRightSample);                            \
+	buffer++; buffer++;                                                 \
+	length--;
 
 #if HEAVY_MACRO_USAGE
 
@@ -570,14 +575,15 @@ static void rand_init(UINT8 *rng, int size, int left, int right, int add)
 	}
 }
 
-int PokeyInit(int clock, int num, int vol, int addtostream)
+int PokeyInit(int clock, int num, double vol, int addtostream)
 {
 	int chip, sample_rate;
 
 	memset(&intf, 0, sizeof(intf));
 	sample_rate = nBurnSoundRate;
 	intf.num = num;
-	intf.mixing_level[0] = vol;
+	//intf.mixing_level[0] = vol;
+	pokey_mastervol = vol;
 	intf.baseclock = (clock) ? clock : FREQ_17_EXACT;
 	intf.addtostream = addtostream;
 

src/burn/snd/pokey.h

@@ -98,7 +98,7 @@ struct POKEYinterface {
 };
 
 
-int PokeyInit (int clock, int num, int vol, int addtostream);
+int PokeyInit (int clock, int num, double vol, int addtostream);
 void PokeyExit (void);
 
 void pokey_update(int num, INT16 *buffer, int length);