video/pc_vga_cirrus: fix pitch offset

Author: angelosa

src/devices/bus/pci/clgd5446.cpp

@@ -23,7 +23,7 @@ Assume Rev. B
 #define LOGWARN(...)            LOGMASKED(LOG_WARN, __VA_ARGS__)
 #define LOGTODO(...)            LOGMASKED(LOG_TODO, __VA_ARGS__)
 
-DEFINE_DEVICE_TYPE(GD5446_PCI, cirrus_gd5446_pci_device, "clgd5446_pci", "Cirrus Logic GD-5446 card")
+DEFINE_DEVICE_TYPE(GD5446_PCI, cirrus_gd5446_pci_device, "clgd5446_pci", "Cirrus Logic GD5446 card")
 
 cirrus_gd5446_pci_device::cirrus_gd5446_pci_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
 	: pci_card_device(mconfig, GD5446_PCI, tag, owner, clock)

src/devices/video/pc_vga.h

@@ -125,6 +125,8 @@ class vga_device : public device_t
 	virtual void gc_map(address_map &map);
 	virtual void attribute_map(address_map &map);
 
+	// NOTE: do not use the subclassed result when determining pitch in SVGA modes.
+	// dw & word mode should apply to normal VGA modes only.
 	virtual uint16_t offset();
 	virtual uint32_t start_addr();
 	virtual uint8_t vga_latch_write(int offs, uint8_t data);

src/devices/video/pc_vga_cirrus.cpp

@@ -220,6 +220,7 @@ void cirrus_gd5428_vga_device::crtc_map(address_map &map)
 			cirrus_define_video_mode();
 		})
 	);
+//	map(0x25, 0x25) PSR Part Status (r/o, "factory testing and internal tracking only")
 	map(0x27, 0x27).lr8(
 		NAME([this] (offs_t offset) {
 			LOGMASKED(LOG_REG, "CR27: Read ID\n");
@@ -841,13 +842,10 @@ void cirrus_gd5428_vga_device::cirrus_define_video_mode()
 
 uint16_t cirrus_gd5428_vga_device::offset()
 {
-	uint16_t off = vga_device::offset();
-
 	// TODO: check true enable condition
 	if (svga.rgb8_en || svga.rgb15_en || svga.rgb16_en || svga.rgb24_en || svga.rgb32_en)
-		off <<= 2;
-//  popmessage("Offset: %04x  %s %s ** -- actual: %04x",vga.crtc.offset,vga.crtc.dw?"DW":"--",vga.crtc.word_mode?"BYTE":"WORD",off);
-	return off;
+		return vga.crtc.offset << 3;
+	return svga_device::offset();
 }
 
 void cirrus_gd5428_vga_device::start_bitblt()
@@ -1164,7 +1162,6 @@ uint8_t cirrus_gd5428_vga_device::mem_r(offs_t offset)
 
 	// Is the display address adjusted automatically when not using Chain-4 addressing?
 	// The GD542x BIOS doesn't do it, but Virtual Pool expects it.
-
 	if(!(vga.sequencer.data[4] & 0x8))
 		addr <<= 2;
 

src/devices/video/pc_vga_oak.cpp

@@ -357,12 +357,9 @@ void oak_oti111_vga_device::ramdac_mmio_map(address_map &map)
 
 uint16_t oak_oti111_vga_device::offset()
 {
-	uint16_t off = svga_device::offset();
-
 	if (m_oak_gfx_mode)
 		return vga.crtc.offset << 4;
-	else
-		return off;
+	return svga_device::offset();
 }
 
 u8 oak_oti111_vga_device::mem_r(offs_t offset)

src/devices/video/pc_vga_s3.cpp

@@ -94,7 +94,6 @@ u16 s3vision864_vga_device::line_compare_mask()
 
 uint16_t s3vision864_vga_device::offset()
 {
-	//popmessage("Offset: %04x  %s %s %s",vga.crtc.offset,vga.crtc.dw?"DW":"--",vga.crtc.word_mode?"BYTE":"WORD",(s3.memory_config & 0x08)?"31":"--");
 	if(s3.memory_config & 0x08)
 		return vga.crtc.offset << 3;
 	return vga_device::offset();

src/devices/video/pc_vga_trident.cpp

@@ -812,12 +812,10 @@ uint32_t trident_vga_device::screen_update(screen_device &screen, bitmap_rgb32 &
 
 uint16_t trident_vga_device::offset()
 {
-	uint16_t off = svga_device::offset();
-
+	// don't know if this is right, but Eggs Playing Chicken switches off doubleword mode, but expects the same offset length
 	if (svga.rgb8_en || svga.rgb15_en || svga.rgb16_en || svga.rgb32_en)
-		return vga.crtc.offset << 3;  // don't know if this is right, but Eggs Playing Chicken switches off doubleword mode, but expects the same offset length
-	else
-		return off;
+		return vga.crtc.offset << 3;
+	return svga_device::offset();
 }
 
 int trident_vga_device::calculate_clock()