More NES work: [Robert Bohms]

* Fixes bug in nes_apu that caused errors reading $4015
* Adds length counter status bits to $4015
* Fixes 4-screen mirroring (PPU regression)
* Fixed cham24

Also, I fixed the tab lengths in nes_apu.c

src/emu/sound/nes_apu.c

@@ -546,6 +546,10 @@ INLINE void apu_regwrite(nesapu_state *info,int address, uint8 value)
 		break;
 
 	case APU_IRQCTRL:
+		if(value & 0x80)
+			info->APU.step_mode = 5;
+		else 
+			info->APU.step_mode = 4;
 		break;
 
 	case APU_SMASK:
@@ -633,18 +637,27 @@ INLINE void apu_update(nesapu_state *info, stream_sample_t *buffer16, int sample
 /* READ VALUES FROM REGISTERS */
 INLINE uint8 apu_read(nesapu_state *info,int address)
 {
-  if (address == 0x0f) /*FIXED* Address $4015 has different behaviour*/
+	if (address == 0x15) /*FIXED* Address $4015 has different behaviour*/
   	{
 		int readval = 0;
+		if (info->APU.squ[0].vbl_length > 0)
+			readval |= 0x01;
+
+		if (info->APU.squ[1].vbl_length > 0)
+			readval |= 0x02;
+
+		if (info->APU.tri.vbl_length > 0)
+			readval |= 0x04;
+
+		if (info->APU.noi.vbl_length > 0)
+			readval |= 0x08;
+
   		if (info->APU.dpcm.enabled == TRUE)
-  			{
 			readval |= 0x10;
-  			}
 
   		if (info->APU.dpcm.irq_occurred == TRUE)
-  			{
 			readval |= 0x80;
-  			}
+
 		return readval;
 	}
 	else
@@ -753,6 +766,7 @@ static DEVICE_START( nesapu )
 	state_save_register_device_item(device, 0, info->APU.tail);
 #else
 	state_save_register_device_item(device, 0, info->APU.buf_pos);
+	state_save_register_device_item(device, 0, info->APU.step_mode);
 #endif
 }
 

src/emu/sound/nes_defs.h

@@ -168,6 +168,7 @@ typedef struct apu
 
 #endif
 
+	int step_mode;
 } apu_t;
 
 /* CONSTANTS */

src/mame/drivers/cham24.c

@@ -244,12 +244,6 @@ static const nes_interface cham24_interface_1 =
 
 static MACHINE_RESET( cham24 )
 {
-	/* switch PRG rom */
-	UINT8* dst = memory_region(machine, "maincpu");
-	UINT8* src = memory_region(machine, "user1");
-
-	memcpy(&dst[0x8000], &src[0x0f8000], 0x4000);
-	memcpy(&dst[0xc000], &src[0x0f8000], 0x4000);
 }
 
 static PALETTE_INIT( cham24 )
@@ -282,8 +276,16 @@ static VIDEO_UPDATE( cham24 )
 	return 0;
 }
 
-static DRIVER_INIT( cham24 )
+
+static MACHINE_START( cham24 )
 {
+	/* switch PRG rom */
+	UINT8* dst = memory_region(machine, "maincpu");
+	UINT8* src = memory_region(machine, "user1");
+
+	memcpy(&dst[0x8000], &src[0x0f8000], 0x4000);
+	memcpy(&dst[0xc000], &src[0x0f8000], 0x4000);
+
 	/* uses 8K swapping, all ROM!*/
 	memory_install_readwrite8_handler(cpu_get_address_space(cputag_get_cpu(machine, "ppu"), ADDRESS_SPACE_PROGRAM), 0x0000, 0x1fff, 0, 0, SMH_BANK(1), 0);
 	memory_set_bankptr(machine, 1, memory_region(machine, "gfx1"));
@@ -299,6 +301,10 @@ static DRIVER_INIT( cham24 )
 	memory_install_readwrite8_handler(cpu_get_address_space(cputag_get_cpu(machine, "ppu"), ADDRESS_SPACE_PROGRAM), 0x2000, 0x3eff, 0, 0, nt_r, nt_w);
 }
 
+static DRIVER_INIT( cham24 )
+{
+}
+
 static GFXDECODE_START( cham24 )
 	/* none, the ppu generates one */
 GFXDECODE_END
@@ -309,6 +315,7 @@ static MACHINE_DRIVER_START( cham24 )
 	MDRV_CPU_PROGRAM_MAP(cham24_map)
 
 	MDRV_MACHINE_RESET( cham24 )
+	MDRV_MACHINE_START( cham24 )
 
 	/* video hardware */
 	MDRV_SCREEN_ADD("screen", RASTER)

src/mame/video/ppu2c0x.c

@@ -19,6 +19,7 @@
 
     * Micro Machines has minor rendering glitches (needs better timing).
     * Mach Rider has minor road rendering glitches (needs better timing).
+    * Rad Racer demonstrates road glitches: it changes horizontal scrolling mid-line.
 
 ******************************************************************************/
 
@@ -380,7 +381,6 @@ static void draw_background( const device_config *device, UINT8 *line_priority )
 
 	const pen_t *color_table;
 	const pen_t *paldata;
-	// const UINT8 *sd;
 
 	int tilecount = 0;
 
@@ -447,19 +447,16 @@ static void draw_background( const device_config *device, UINT8 *line_priority )
 
 		if (start_x < VISIBLE_SCREEN_WIDTH)
 		{
-			UINT8 plane1, plane2;	// use extended size so I can shift!
+			UINT8 plane1, plane2;
 			paldata = &color_table[4 * (((color_byte >> color_bits) & 0x03))];
-			// start = scroll_y_fine * line_modulo;
 
 			// need to read 0x0000 or 0x1000 + 16*nametable data
 			address = ((this_ppu->tile_page) ? 0x1000 : 0) + (page2 * 16);
 			// plus something that accounts for y
-			// address -= (scanline % 8);
 			address += scroll_y_fine;
 
 			plane1 = memory_read_byte(device->space[0], (address & 0x1fff));
 			plane2 = memory_read_byte(device->space[0], (address + 8) & 0x1fff);
-			// plane2 = plane2 << 1;
 
 			/* render the pixel */
 			for (i = 0; i < 8; i++)
@@ -618,30 +615,23 @@ static void draw_sprites( const device_config *device, UINT8 *line_priority )
 		plane1 = memory_read_byte(device->space[0], (index1 + sprite_line) & 0x1fff);
 		plane2 = memory_read_byte(device->space[0], (index1 + sprite_line + 8) & 0x1fff);
 
-//      sd = gfx_element_get_data(device->machine->gfx[gfx_bank], index1 % total_elements) + start;
-//      if (size > 8)
-//          gfx_element_get_data(device->machine->gfx[gfx_bank], (index1 + 1) % total_elements);
-
 		if (pri)
 		{
 			/* draw the low-priority sprites */
 			for (pixel = 0; pixel < 8; pixel++)
 			{
-//              UINT8 pixelData = flipx ? sd[7-pixel] : sd[pixel];
 				UINT8 pixelData;
 				if (flipx)
 				{
 					pixelData = (plane1 & 1) + ((plane2 & 1) << 1);
 					plane1 = plane1 >> 1;
 					plane2 = plane2 >> 1;
-					// sd[7 - pixel]
 				}
 				else
 				{
 					pixelData = ((plane1 >> 7) & 1) | (((plane2 >> 7) & 1) << 1);
 					plane1 = plane1 << 1;
 					plane2 = plane2 << 1;
-					// sd[pixel];
 				}
 
 				/* is this pixel non-transparent? */
@@ -1037,11 +1027,11 @@ READ8_HANDLER( ppu2c0x_palette_read )
 {
 	ppu2c0x_chip *this_ppu = get_token(space->cpu);
 	{
-		// it's a palette
-		// ERROR: doesn't currently handle monochrome!
 		if (this_ppu->regs[PPU_CONTROL1] & PPU_CONTROL1_DISPLAY_MONO)
 			return (this_ppu->palette_ram[offset & 0x1f] & 0x30);
-		else return (this_ppu->palette_ram[offset & 0x1f] & 0x3f);
+
+		else 
+			return (this_ppu->palette_ram[offset & 0x1f] & 0x3f);
 	}
 }
 
@@ -1242,9 +1232,6 @@ WRITE8_DEVICE_HANDLER( ppu2c0x_w )
 				{
 					/* store the data */
 					memory_write_byte(device->space[0], tempAddr, data);
-
-					/* mark the char dirty */
-					// gfx_element_mark_dirty(device->machine->gfx[intf->gfx_layout_number], tempAddr >> 4);
 				}
 
 				else
@@ -1273,28 +1260,14 @@ void ppu2c0x_spriteram_dma( const address_space *space, const device_config *dev
 	int i;
 	int address = page << 8;
 
-//  logerror("sprite DMA: %d (scanline: %d)\n", page, this_ppu->scanline);
 	for (i = 0; i < SPRITERAM_SIZE; i++)
 	{
 		UINT8 spriteData = memory_read_byte(space, address + i);
 		memory_write_byte(space, 0x2004, spriteData);
-//      ppu2c0x_w(device, PPU_SPRITE_DATA, spriteData);
 	}
 
 	// should last 513 CPU cycles.
 	cpu_adjust_icount(space->cpu, -513);
-
-	// ????TODO : need to account for PPU rendering - this is roughly 4.5 scanlines eaten up.
-	// Because the DMA is only useful during vblank, this may not be strictly necessary since
-	// the scanline timers should catch us up before drawing actually happens.
-#if 0
-{
-	scanline_callback(device);
-	scanline_callback(device);
-	scanline_callback(device);
-	scanline_callback(device);
-}
-#endif
 }
 
 /*************************************