From 00dedfabc90465b6183e6fee4287d3d494921aa6 Mon Sep 17 00:00:00 2001
From: 0kmg <9137159+0kmg@users.noreply.github.com>
Date: Wed, 23 Mar 2022 10:16:49 -0800
Subject: [PATCH] bus/nes: Simplifications using bit utility functions. (#9444)

* bus/nes: Simplifications using bit utility functions.
* Corrected UNL-KOF97 board's address decoding.
* Cleaned up Gouder board further and added missing mirroring bit. Fixes BG graphics.
---
 src/devices/bus/nes/act53.cpp       |   2 +-
 src/devices/bus/nes/batlab.cpp      |   2 +-
 src/devices/bus/nes/bootleg.cpp     |  18 ++---
 src/devices/bus/nes/camerica.cpp    |   2 +-
 src/devices/bus/nes/discrete.cpp    |   2 +-
 src/devices/bus/nes/irem.cpp        |   2 +-
 src/devices/bus/nes/jaleco.cpp      |   4 +-
 src/devices/bus/nes/kaiser.cpp      |  33 +++++----
 src/devices/bus/nes/mmc1.cpp        |  25 +++----
 src/devices/bus/nes/mmc1_clones.cpp |   4 +-
 src/devices/bus/nes/mmc3_clones.cpp | 102 +++++++++++++---------------
 src/devices/bus/nes/multigame.cpp   |   8 +--
 src/devices/bus/nes/namcot.cpp      |   8 +--
 src/devices/bus/nes/nes_slot.cpp    |  10 +--
 src/devices/bus/nes/ntdec.cpp       |   2 +-
 src/devices/bus/nes/nxrom.cpp       |   6 +-
 src/devices/bus/nes/pirate.cpp      |  74 +++++---------------
 src/devices/bus/nes/sachen.cpp      |   2 +-
 src/devices/bus/nes/sealie.cpp      |   4 +-
 src/devices/bus/nes/somari.cpp      |   6 +-
 src/devices/bus/nes/taito.cpp       |  12 ++--
 src/devices/bus/nes/txc.cpp         |   2 +-
 src/devices/bus/nes/vrc_clones.cpp  |   2 +-
 23 files changed, 140 insertions(+), 192 deletions(-)

diff --git a/src/devices/bus/nes/act53.cpp b/src/devices/bus/nes/act53.cpp
index 51e2d75a7e1..2c0dee10afc 100644
--- a/src/devices/bus/nes/act53.cpp
+++ b/src/devices/bus/nes/act53.cpp
@@ -155,7 +155,7 @@ void nes_action53_device::write_l(offs_t offset, u8 data)
 	LOG_MMC(("action 53 write_l, offset: %04x, data: %02x\n", offset, data));
 	offset += 0x100;
 	if (offset >= 0x1000)
-		m_sel = BIT(data, 0) | (BIT(data, 7) << 1);
+		m_sel = bitswap<2>(data, 7, 0);
 }
 
 
diff --git a/src/devices/bus/nes/batlab.cpp b/src/devices/bus/nes/batlab.cpp
index 7f11696134d..820082033ef 100644
--- a/src/devices/bus/nes/batlab.cpp
+++ b/src/devices/bus/nes/batlab.cpp
@@ -237,7 +237,7 @@ void nes_batmap_srrx_device::write_h(offs_t offset, u8 data)
 				set_irq_line(CLEAR_LINE);
 			break;
 		case 0x4000:
-			m_dpcm_addr = (m_dpcm_addr << 1 | data >> 7);
+			m_dpcm_addr = m_dpcm_addr << 1 | data >> 7;
 			break;
 		case 0x5000:
 			m_dpcm_ctrl = data;
diff --git a/src/devices/bus/nes/bootleg.cpp b/src/devices/bus/nes/bootleg.cpp
index fdbdf497dd0..ea482a93052 100644
--- a/src/devices/bus/nes/bootleg.cpp
+++ b/src/devices/bus/nes/bootleg.cpp
@@ -967,7 +967,7 @@ void nes_btl_cj_device::write_h(offs_t offset, u8 data)
 	}
 	else
 	{
-		offset = (offset >> 13) & 0x03;
+		offset = BIT(offset, 13, 2);
 		if (offset != 3)
 			prg8_x(offset, data & 0x0f);
 	}
@@ -1335,7 +1335,7 @@ void nes_n32_4in1_device::write_h(offs_t offset, u8 data)
 			prg8_ef(3);
 		}
 
-		chr8((data >> 1) & 0x03, CHRROM);
+		chr8(BIT(data, 1, 2), CHRROM);
 		set_nt_mirroring(BIT(data, 2) ? PPU_MIRROR_HORZ : PPU_MIRROR_VERT);
 	}
 }
@@ -1482,7 +1482,7 @@ void nes_l001_device::write_h(offs_t offset, u8 data)
 	{
 		case 0x0000:
 		case 0x2000:
-			chr1_x((offset >> 11) & 0x07, data, CHRROM);
+			chr1_x(BIT(offset, 11, 3), data, CHRROM);
 			break;
 		case 0x0400:
 			m_irq_count = (m_irq_count & 0xff00) | data;
@@ -1492,11 +1492,11 @@ void nes_l001_device::write_h(offs_t offset, u8 data)
 			set_irq_line(CLEAR_LINE);
 			break;
 		case 0x4000:
-			set_nt_page((offset >> 11) & 0x03, CIRAM, data & 1, 1);
+			set_nt_page(BIT(offset, 11, 2), CIRAM, data & 1, 1);
 			break;
 		case 0x6000:
 			if (offset < 0x7800)
-				prg8_x((offset >> 11) & 0x03, data & 0x1f);
+				prg8_x(BIT(offset, 11, 2), data & 0x1f);
 			break;
 	}
 }
@@ -1613,7 +1613,7 @@ void nes_palthena_device::write_m(offs_t offset, u8 data)
 u8 nes_palthena_device::read_h(offs_t offset)
 {
 //  LOG_MMC(("palthena read_h, offset: %04x\n", offset));
-	u8 page = (offset >> 8);
+	u8 page = offset >> 8;
 	if ((page >= 0x40 && page < 0x52) || page == 0x5f)
 		return m_prgram[offset & 0x1fff];
 	else if (page == 0x02)
@@ -1625,7 +1625,7 @@ u8 nes_palthena_device::read_h(offs_t offset)
 void nes_palthena_device::write_h(offs_t offset, u8 data)
 {
 	LOG_MMC(("palthena write_h, offset: %04x, data: %02x\n", offset, data));
-	u8 page = (offset >> 8);
+	u8 page = offset >> 8;
 	if ((page >= 0x40 && page < 0x52) || page == 0x5f)
 		m_prgram[offset & 0x1fff] = data;
 	else if (page == 0x02)
@@ -2048,7 +2048,7 @@ void nes_ac08_device::write_h(offs_t offset, uint8_t data)
 	LOG_MMC(("AC-08 write_h, offset: %04x, data: %02x\n", offset, data));
 
 	if (offset == 1)
-		m_latch = (data >> 1) & 0x0f;
+		m_latch = BIT(data, 1, 4);
 	else
 		m_latch = data & 0x0f;  // apparently there also is a Castlevania FDS conversion using same board with different banking lines
 }
@@ -2148,7 +2148,7 @@ void nes_yung08_device::write_45(offs_t offset, u8 data)
 	switch (offset & 0x51ff)
 	{
 		case 0x4022:
-			prg8_cd(data & 1 ? 3 : 4 + ((data & 0x07) >> 1));
+			prg8_cd(data & 1 ? 3 : 4 + BIT(data, 1, 2));
 			break;
 		case 0x4122:
 			m_irq_latch = data & 0x35;
diff --git a/src/devices/bus/nes/camerica.cpp b/src/devices/bus/nes/camerica.cpp
index 5870b2911ab..863467f2e09 100644
--- a/src/devices/bus/nes/camerica.cpp
+++ b/src/devices/bus/nes/camerica.cpp
@@ -180,7 +180,7 @@ void nes_bf9096_device::write_h(offs_t offset, uint8_t data)
 
 	if (offset < 0x4000)
 	{
-		m_bank_base = ((data >> 3) & 3) << 2;
+		m_bank_base = (data & 0x18) >> 1;
 		prg16_89ab(m_bank_base | m_latch);
 		prg16_cdef(m_bank_base | 3);
 	}
diff --git a/src/devices/bus/nes/discrete.cpp b/src/devices/bus/nes/discrete.cpp
index 6cdaa63d3ba..7b415794167 100644
--- a/src/devices/bus/nes/discrete.cpp
+++ b/src/devices/bus/nes/discrete.cpp
@@ -156,7 +156,7 @@ void nes_74x139x74_device::write_m(offs_t offset, uint8_t data)
 {
 	LOG_MMC(("74x139x74 write_m, offset: %04x, data: %02x\n", offset, data));
 
-	chr8(((data & 0x02) >> 1) | ((data & 0x01) << 1), CHRROM);
+	chr8(bitswap<2>(data, 0, 1), CHRROM);
 }
 
 /*-------------------------------------------------
diff --git a/src/devices/bus/nes/irem.cpp b/src/devices/bus/nes/irem.cpp
index 0d6f7bd6f63..266266c1ff0 100644
--- a/src/devices/bus/nes/irem.cpp
+++ b/src/devices/bus/nes/irem.cpp
@@ -174,7 +174,7 @@ void nes_lrog017_device::write_h(offs_t offset, uint8_t data)
 	data = account_bus_conflict(offset, data);
 
 	prg32(data);
-	chr2_0((data >> 4), CHRROM);
+	chr2_0(data >> 4, CHRROM);
 }
 
 /*-------------------------------------------------
diff --git a/src/devices/bus/nes/jaleco.cpp b/src/devices/bus/nes/jaleco.cpp
index fbddd8415e0..71d5210ac8a 100644
--- a/src/devices/bus/nes/jaleco.cpp
+++ b/src/devices/bus/nes/jaleco.cpp
@@ -280,8 +280,8 @@ void nes_jf13_device::write_m(offs_t offset, uint8_t data)
 
 	if (offset < 0x1000)
 	{
-		prg32((data >> 4) & 0x03);
-		chr8(((data >> 4) & 0x04) | (data & 0x03), CHRROM);
+		prg32(BIT(data, 4, 2));
+		chr8(bitswap<3>(data, 6, 1, 0), CHRROM);
 	}
 	else
 	{
diff --git a/src/devices/bus/nes/kaiser.cpp b/src/devices/bus/nes/kaiser.cpp
index b27adc61af3..644597dbd12 100644
--- a/src/devices/bus/nes/kaiser.cpp
+++ b/src/devices/bus/nes/kaiser.cpp
@@ -681,12 +681,15 @@ void nes_ks7017_device::write_l(offs_t offset, uint8_t data)
 	LOG_MMC(("ks7017 write_l, offset: %04x, data: %02x\n", offset, data));
 
 	offset += 0x100;
-
-	if (offset >= 0xa00 && offset < 0xb00)
-		m_latch = ((offset >> 2) & 0x03) | ((offset >> 4) & 0x04);
-
-	if (offset >= 0x1100 && offset < 0x1200)
-		prg16_89ab(m_latch);
+	switch (offset & 0x1f00)
+	{
+		case 0x0a00:
+			m_latch = bitswap<3>(offset, 6, 3, 2);
+			break;
+		case 0x1100:
+			prg16_89ab(m_latch);
+			break;
+	}
 }
 
 void nes_ks7017_device::write_ex(offs_t offset, uint8_t data)
@@ -746,7 +749,7 @@ void nes_ks7021a_device::write_h(offs_t offset, u8 data)
 	switch (offset & 0x7000)
 	{
 		case 0x0000:
-			prg16_89ab((data >> 1) & 0x07);
+			prg16_89ab(BIT(data, 1, 3));
 			break;
 		case 0x1000:
 			set_nt_mirroring(BIT(data, 0) ? PPU_MIRROR_HORZ : PPU_MIRROR_VERT);
@@ -778,7 +781,7 @@ void nes_ks7021a_device::write_h(offs_t offset, u8 data)
 u8 nes_ks7010_device::read_m(offs_t offset)
 {
 //  LOG_MMC(("ks7010 read_m, offset: %04x, data: %02x\n", offset, data));
-	return m_prg[m_latch * 0x2000 + offset];
+	return m_prg[(m_latch * 0x2000 + offset) & (m_prg_size - 1)];
 }
 
 u8 nes_ks7010_device::read_h(offs_t offset)
@@ -786,7 +789,7 @@ u8 nes_ks7010_device::read_h(offs_t offset)
 //  LOG_MMC(("ks7010 read_h, offset: %04x, data: %02x\n", offset, data));
 	if ((offset >= 0x4ab6 && offset <= 0x4ad6) || offset == 0x6be2 || offset == 0x6be3 || offset == 0x6e32 || offset == 0x7ffc) // HACK! FIXME
 	{
-		m_latch = (offset >> 2) & 0x0f;
+		m_latch = BIT(offset, 2, 4);
 		chr8(m_latch, CHRROM);
 	}
 
@@ -932,20 +935,20 @@ void nes_ks7030_device::write_h(offs_t offset, u8 data)
 uint8_t nes_ks7031_device::read_m(offs_t offset)
 {
 //  LOG_MMC(("ks7031 read_m, offset: %04x\n", offset));
-	return m_prg[(m_reg[(offset >> 11) & 3] * 0x0800) + (offset & 0x7ff)];
+	return m_prg[(m_reg[BIT(offset, 11, 2)] * 0x0800) + (offset & 0x7ff)];
 }
 
 uint8_t nes_ks7031_device::read_h(offs_t offset)
 {
 	// here the first 32K are accessed, but in 16x2K blocks loaded in reverse order
-	int accessed_2k = (offset >> 11) & 0x0f;
+	int accessed_2k = BIT(offset, 11, 4);
 	return m_prg[((0x0f - accessed_2k) * 0x0800) + (offset & 0x7ff)];
 }
 
 void nes_ks7031_device::write_h(offs_t offset, uint8_t data)
 {
 	LOG_MMC(("ks7031 write_h, offset: %04x, data: %02x\n", offset, data));
-	m_reg[(offset >> 11) & 3] = data & 0x3f;
+	m_reg[BIT(offset, 11, 2)] = data & 0x3f;
 }
 
 /*-------------------------------------------------
@@ -1045,14 +1048,14 @@ void nes_ks7037_device::write_h(offs_t offset, uint8_t data)
 u8 nes_ks7057_device::read_m(offs_t offset)
 {
 //  LOG_MMC(("ks7057 read_m, offset: %04x\n", offset));
-	return m_prg[0x800 * m_reg[((offset >> 11) & 0x03) + 4] + (offset & 0x7ff)];
+	return m_prg[0x800 * m_reg[BIT(offset, 11, 2) + 4] + (offset & 0x7ff)];
 }
 
 u8 nes_ks7057_device::read_h(offs_t offset)
 {
 //  LOG_MMC(("ks7057 read_h, offset: %04x\n", offset));
 	if (offset < 0x2000)
-		return m_prg[0x800 * m_reg[(offset >> 11) & 0x03] + (offset & 0x7ff)];
+		return m_prg[0x800 * m_reg[BIT(offset, 11, 2)] + (offset & 0x7ff)];
 
 	return hi_access_rom(offset);
 }
@@ -1065,7 +1068,7 @@ void nes_ks7057_device::write_h(offs_t offset, u8 data)
 		set_nt_mirroring(BIT(data, 0) ? PPU_MIRROR_VERT : PPU_MIRROR_HORZ);
 	else if (offset >= 0x3000 && offset < 0x6004)
 	{
-		u8 reg = (((offset >> 11) & 0x0e) | BIT(offset, 1)) - 6;
+		u8 reg = bitswap<4>(offset, 14, 13, 12, 1) - 6;
 		if (BIT(offset, 0))
 			m_reg[reg] = (m_reg[reg] & 0x0f) | ((data & 0x03) << 4);
 		else
diff --git a/src/devices/bus/nes/mmc1.cpp b/src/devices/bus/nes/mmc1.cpp
index f8362ba1960..0cc0a8720e4 100644
--- a/src/devices/bus/nes/mmc1.cpp
+++ b/src/devices/bus/nes/mmc1.cpp
@@ -120,7 +120,7 @@ void nes_sxrom_device::set_prg(int prg_base, int prg_mask)
 {
 	u8 bank = prg_base | (m_reg[3] & prg_mask);
 
-	switch ((m_reg[0] >> 2) & 3)
+	switch (BIT(m_reg[0], 2, 2))
 	{
 		case 0:
 		case 1:
@@ -235,7 +235,6 @@ void nes_sxrom_device::write_h(offs_t offset, uint8_t data)
 	if (data & 0x80)
 	{
 		m_count = 0;
-		m_latch = 0;
 
 		// Set reg at 0x8000 to size 16k and lower half swap - needed for Robocop 3, Dynowars
 		m_reg[0] |= 0x0c;
@@ -243,25 +242,21 @@ void nes_sxrom_device::write_h(offs_t offset, uint8_t data)
 		return;
 	}
 
-	if (m_count < 5)
-	{
-		if (m_count == 0) m_latch = 0;
-		m_latch >>= 1;
-		m_latch |= (data & 0x01) ? 0x10 : 0x00;
-		m_count++;
-	}
+	m_latch >>= 1;
+	m_latch |= (data & 1) << 4;
+	m_count = (m_count + 1) % 5;
 
-	if (m_count == 5)
+	if (!m_count)
 	{
-		m_reg[(offset & 0x6000) >> 13] = m_latch;
-		update_regs((offset & 0x6000) >> 13);
-		m_count = 0;
+		int reg = BIT(offset, 13, 2);
+		m_reg[reg] = m_latch;
+		update_regs(reg);
 	}
 }
 
 void nes_sxrom_device::write_m(offs_t offset, uint8_t data)
 {
-	uint8_t bank = (m_reg[1] >> 2) & 3;
+	uint8_t bank = BIT(m_reg[1], 2, 2);
 	LOG_MMC(("sxrom write_m, offset: %04x, data: %02x\n", offset, data));
 
 	if (!BIT(m_reg[3], 4) || m_mmc1_type == mmc1_type::MMC1A)  // WRAM enabled
@@ -275,7 +270,7 @@ void nes_sxrom_device::write_m(offs_t offset, uint8_t data)
 
 uint8_t nes_sxrom_device::read_m(offs_t offset)
 {
-	uint8_t bank = (m_reg[1] >> 2) & 3;
+	uint8_t bank = BIT(m_reg[1], 2, 2);
 	LOG_MMC(("sxrom read_m, offset: %04x\n", offset));
 
 	if (!BIT(m_reg[3], 4) || m_mmc1_type == mmc1_type::MMC1A)  // WRAM enabled
diff --git a/src/devices/bus/nes/mmc1_clones.cpp b/src/devices/bus/nes/mmc1_clones.cpp
index 2694384d2de..0d36caa9270 100644
--- a/src/devices/bus/nes/mmc1_clones.cpp
+++ b/src/devices/bus/nes/mmc1_clones.cpp
@@ -183,7 +183,7 @@ void nes_txc_22110_device::pcb_reset()
 void nes_ninjaryu_device::write_h(offs_t offset, u8 data)
 {
 	LOG_MMC(("unl_ninjaryu write_h, offset: %04x, data: %02x\n", offset, data));
-	u8 reg = (offset >> 13) & 0x03;
+	u8 reg = BIT(offset, 13, 2);
 	m_reg[reg] = data;
 	update_regs(reg);
 }
@@ -399,7 +399,7 @@ u8 nes_srpg5in1_device::read_m(offs_t offset)
 void nes_txc_22110_device::update_banks()    // used by menu and Space Shadow
 {
 	u8 outer = (m_mode & 0x02) << 1;
-	prg16_89ab(outer | (m_latch0 & 0x30) >> 4);
+	prg16_89ab(outer | BIT(m_latch0, 4, 2));
 	prg16_cdef(outer | 3);
 	chr8(m_latch0 & 0x0f, CHRROM);
 }
diff --git a/src/devices/bus/nes/mmc3_clones.cpp b/src/devices/bus/nes/mmc3_clones.cpp
index 78ce73639ba..aac3ec7ec5c 100644
--- a/src/devices/bus/nes/mmc3_clones.cpp
+++ b/src/devices/bus/nes/mmc3_clones.cpp
@@ -1119,15 +1119,15 @@ void nes_smd133_device::pcb_reset()
 
  iNES: mapper 250
 
- In MESS: Supported.
+ In MAME: Supported.
 
  -------------------------------------------------*/
 
-void nes_nitra_device::write_h(offs_t offset, uint8_t data)
+void nes_nitra_device::write_h(offs_t offset, u8 data)
 {
 	LOG_MMC(("nitra write_h, offset: %04x, data: %02x\n", offset, data));
 
-	txrom_write((offset & 0x6000) | ((offset & 0x400) >> 10), offset & 0xff);
+	txrom_write((offset & 0x6000) | BIT(offset, 10), offset);
 }
 
 /*-------------------------------------------------
@@ -1180,12 +1180,11 @@ void nes_bmw8544_device::write_m(offs_t offset, u8 data)
 
  -------------------------------------------------*/
 
-void nes_fs6_device::write_h(offs_t offset, uint8_t data)
+void nes_fs6_device::write_h(offs_t offset, u8 data)
 {
 	LOG_MMC(("fs6 write_h, offset: %04x, data: %02x\n", offset, data));
 
-	offset = (BIT(offset, 0) << 1) | BIT(offset, 1) | (offset & ~0x03);
-	txrom_write(offset, data);
+	txrom_write(bitswap<2>(offset, 0, 1) | (offset & ~0x03), data);
 }
 
 /*-------------------------------------------------
@@ -1199,15 +1198,15 @@ void nes_fs6_device::write_h(offs_t offset, uint8_t data)
 
  iNES: mapper 196
 
- In MESS: Supported.
+ In MAME: Supported.
 
  -------------------------------------------------*/
 
-void nes_sbros11_device::write_h(offs_t offset, uint8_t data)
+void nes_sbros11_device::write_h(offs_t offset, u8 data)
 {
 	LOG_MMC(("smb11 write_h, offset: %04x, data: %02x\n", offset, data));
 
-	txrom_write((offset & 0x6000) | ((offset & 0x04) >> 2), data);
+	txrom_write((offset & 0x6000) | BIT(offset, 2), data);
 }
 
 /*-------------------------------------------------
@@ -1219,30 +1218,30 @@ void nes_sbros11_device::write_h(offs_t offset, uint8_t data)
  This is very similar to mapper 196, but with additional
  data bit swap.
 
- In MESS: Supported.
+ In MAME: Supported.
 
  -------------------------------------------------*/
 
 void nes_malisb_device::prg_cb(int start, int bank)
 {
-	bank = (bank & 3) | ((bank & 8) >> 1) | ((bank & 4) << 1);
+	bank = bitswap<4>(bank, 2, 3, 1, 0);
 	prg8_x(start, bank);
 }
 
 void nes_malisb_device::chr_cb(int start, int bank, int source)
 {
-	bank = (bank & 0xdd) | ((bank & 0x20) >> 4) | ((bank & 2) << 4);
+	bank = bitswap<8>(bank, 7, 6, 1, 4, 3, 2, 5, 0);
 	chr1_x(start, bank, source);
 }
 
-void nes_malisb_device::write_h(offs_t offset, uint8_t data)
+void nes_malisb_device::write_h(offs_t offset, u8 data)
 {
 	LOG_MMC(("malisb write_h, offset: %04x, data: %02x\n", offset, data));
 
 	if (offset > 0x4000)
-		txrom_write((offset & 0xfffe) | ((offset & 0x04) >> 2) | ((offset & 0x08) >> 3), data);
+		txrom_write((offset & 0xfffe) | BIT(offset, 2) | BIT(offset, 3), data);
 	else
-		txrom_write((offset & 0xfffe) | ((offset & 0x08) >> 3), data);
+		txrom_write((offset & 0xfffe) | BIT(offset, 3), data);
 }
 
 /*-------------------------------------------------
@@ -1797,35 +1796,23 @@ void nes_txc_tw_device::prg_cb(int start, int bank)
 
  Board UNL-KOF97
 
- Games: King of Fighters 97 (Rex Soft)
+ Games: King of Fighters 97 (Rex Soft), Boogerman II
 
  MMC3 clone
 
- In MESS: Not working
+ In MAME: Supported.
 
  -------------------------------------------------*/
 
-inline uint8_t kof97_unscramble( uint8_t data )
-{
-	return ((data >> 1) & 0x01) | ((data >> 4) & 0x02) | ((data << 2) & 0x04) | ((data >> 0) & 0xd8) | ((data << 3) & 0x20);
-}
-
-void nes_kof97_device::write_h(offs_t offset, uint8_t data)
+void nes_kof97_device::write_h(offs_t offset, u8 data)
 {
 	LOG_MMC(("kof97 write_h, offset: %04x, data: %02x\n", offset, data));
 
-	// Addresses 0x9000, 0xa000, 0xd000 & 0xf000 behaves differently than MMC3
-	if (offset == 0x1000)
-		txrom_write(0x0001, kof97_unscramble(data));
-	else if (offset == 0x2000)
-		txrom_write(0x0000, kof97_unscramble(data));
-	else if (offset == 0x5000)
-		txrom_write(0x4001, kof97_unscramble(data));
-	else if (offset == 0x7000)
-		txrom_write(0x6001, kof97_unscramble(data));
-	// Other addresses behaves like MMC3, up to unscrambling data
-	else
-		txrom_write(offset, kof97_unscramble(data));
+	// unscramble address and data
+	offset = (offset & 0x6000) | BIT(offset, 12);
+	data = bitswap<8>(data, 7, 6, 2, 4, 3, 0, 5, 1);
+
+	txrom_write(offset, data);
 }
 
 /*-------------------------------------------------
@@ -1866,7 +1853,7 @@ void nes_kof96_device::write_l(offs_t offset, u8 data)
 			set_prg(m_prg_base, m_prg_mask);
 		else
 		{
-			u8 bank = (data >> 1) & 0x0f;
+			u8 bank = BIT(data, 1, 4);
 			u8 mode = BIT(data, 5);
 			prg16_89ab(bank & ~mode);
 			prg16_cdef(bank | mode);
@@ -1972,13 +1959,13 @@ void nes_cocoma_device::write_h(offs_t offset, u8 data)
 
  iNES: mapper 208
 
- In MESS: Preliminary Support.
+ In MAME: Preliminary Support.
 
  -------------------------------------------------*/
 
-void nes_gouder_device::write_l(offs_t offset, uint8_t data)
+void nes_gouder_device::write_l(offs_t offset, u8 data)
 {
-	static const uint8_t conv_table[256] =
+	static constexpr u8 conv_table[256] =
 	{
 		0x59,0x59,0x59,0x59,0x59,0x59,0x59,0x59,0x59,0x49,0x19,0x09,0x59,0x49,0x19,0x09,
 		0x59,0x59,0x59,0x59,0x59,0x59,0x59,0x59,0x51,0x41,0x11,0x01,0x51,0x41,0x11,0x01,
@@ -2000,22 +1987,31 @@ void nes_gouder_device::write_l(offs_t offset, uint8_t data)
 
 	LOG_MMC(("gouder write_l, offset: %04x, data: %02x\n", offset, data));
 
-	if (!(offset < 0x1700))
-		m_reg[offset & 0x03] = data ^ conv_table[m_reg[4]];
-	else if (!(offset < 0xf00))
-		m_reg[4] = data;
-	else if (!(offset < 0x700))
-		prg32(((data >> 3) & 0x02) | (data & 0x01));
+	offset += 0x100;
+	switch (offset & 0x1800)
+	{
+		case 0x0800:
+			prg32(bitswap<2>(data, 4, 0));
+			set_nt_mirroring(BIT(data, 5) ? PPU_MIRROR_HORZ : PPU_MIRROR_VERT);
+			break;
+		case 0x1000:
+			m_reg[4] = data;
+			break;
+		case 0x1800:
+			m_reg[offset & 0x03] = data ^ conv_table[m_reg[4]];
+			break;
+	}
 }
 
-uint8_t nes_gouder_device::read_l(offs_t offset)
+u8 nes_gouder_device::read_l(offs_t offset)
 {
 	LOG_MMC(("gouder read_l, offset: %04x\n", offset));
 
-	if (!(offset < 0x1700))
+	offset += 0x100;
+	if (offset >= 0x1800)
 		return m_reg[offset & 0x03];
 
-	return 0x00;
+	return get_open_bus();
 }
 
 // writes to 0x8000-0xffff are like MMC3 but no PRG bankswitch (beacuse it is handled by low writes)
@@ -2066,7 +2062,7 @@ void nes_sa9602b_device::write_h(offs_t offset, uint8_t data)
 			break;
 		case 0x0001:
 			if ((m_reg & 7) < 6)
-				m_prg_chip = (data & 0xc0) >> 6;
+				m_prg_chip = BIT(data, 6, 2);
 			set_prg(0, m_prg_mask);
 			break;
 	}
@@ -2151,7 +2147,7 @@ void nes_a9746_device::update_banks(uint8_t value)
 		case 0x08: case 0x0a: case 0x0c: case 0x0e:
 		case 0x10: case 0x12: case 0x14: case 0x16:
 		case 0x18: case 0x1a: case 0x1c: case 0x1e:
-			m_reg[2] = (value << 4);
+			m_reg[2] = value << 4;
 			break;
 		case 0x09: chr1_0(m_reg[2] | (value >> 1), m_chr_source); break;
 		case 0x0b: chr1_1(m_reg[2] | (value >> 1) | 1, m_chr_source);  break;
@@ -2509,7 +2505,7 @@ void nes_bmc_5in1_device::write_m(offs_t offset, u8 data)
 	if ((m_wram_protect & 0xc0) == 0x80)
 	{
 		if (!(offset & 0x03))
-			prg32((data >> 1) & 0x03);
+			prg32(BIT(data, 1, 2));
 	}
 }
 
@@ -2814,7 +2810,7 @@ void nes_bmc_hik4_device::write_m(offs_t offset, u8 data)
 			set_prg(m_prg_base, m_prg_mask);
 		}
 		else                // Master Fighter III only
-			prg32((data & 0x30) >> 4);
+			prg32(BIT(data, 4, 2));
 
 		m_chr_base = (data & 0xc0) << 1;
 		set_chr(m_chr_source, m_chr_base, m_chr_mask);
@@ -3399,7 +3395,7 @@ void nes_bmc_810305c_device::write_h(offs_t offset, u8 data)
 
 	if (BIT(offset, 7))    // outer register
 	{
-		m_outer = (offset >> 13) & 0x03;
+		m_outer = BIT(offset, 13, 2);
 
 		m_prg_base = m_outer << 5;
 		m_prg_mask = 0x1f >> (m_outer == 2);
diff --git a/src/devices/bus/nes/multigame.cpp b/src/devices/bus/nes/multigame.cpp
index bf7cf7e8dfd..1a140f6175a 100644
--- a/src/devices/bus/nes/multigame.cpp
+++ b/src/devices/bus/nes/multigame.cpp
@@ -1327,7 +1327,7 @@ void nes_caltron6in1_device::write_h(offs_t offset, u8 data)
 void nes_caltron9in1_device::write_h(offs_t offset, u8 data)
 {
 	LOG_MMC(("caltron9in1 write_h, offset: %04x, data: %02x\n", offset, data));
-	int nibble = (offset >> 12) & 0x07;
+	int nibble = BIT(offset, 12, 3);
 	m_latch[std::min(nibble, 2)] = offset & 0x7f;
 
 	if (BIT(m_latch[1], 1))
@@ -2205,7 +2205,7 @@ u8 nes_bmc_tf2740_device::read_m(offs_t offset)
 void nes_bmc_tj03_device::write_h(offs_t offset, u8 data)
 {
 	LOG_MMC(("bmc_tj03 write_h, offset: %04x, data: %02x\n", offset, data));
-	u8 bank = (offset >> 8) & 0x03;
+	u8 bank = BIT(offset, 8, 2);
 	prg32(bank);
 	chr8(bank, CHRROM);
 	set_nt_mirroring(BIT(offset, 9) ? PPU_MIRROR_HORZ : PPU_MIRROR_VERT);
@@ -2316,7 +2316,7 @@ void nes_bmc_g146_device::write_h(offs_t offset, u8 data)
 void nes_bmc_2751_device::write_h(offs_t offset, u8 data)
 {
 	LOG_MMC(("bmc_2751 write_h, offset: %04x, data: %02x\n", offset, data));
-	u8 bank = (offset >> 4) & 0x07;
+	u8 bank = BIT(offset, 4, 3);
 	u8 mode = BIT(offset, 7);
 	prg16_89ab(bank & ~mode);
 	prg16_cdef(bank | mode);
@@ -2345,7 +2345,7 @@ void nes_bmc_8157_device::write_h(offs_t offset, u8 data)
 {
 	LOG_MMC(("bmc_8157 write_h, offset: %04x, data: %02x\n", offset, data));
 
-	u8 bank = (offset >> 2) & 0x1f;
+	u8 bank = BIT(offset, 2, 5);
 	prg16_89ab(bank);
 	if (BIT(offset, 9))
 		bank |= 0x07;
diff --git a/src/devices/bus/nes/namcot.cpp b/src/devices/bus/nes/namcot.cpp
index 4bb1d6ce235..cb8f0bd5b9a 100644
--- a/src/devices/bus/nes/namcot.cpp
+++ b/src/devices/bus/nes/namcot.cpp
@@ -448,7 +448,7 @@ uint8_t nes_namcot340_device::n340_loread(offs_t offset)
 			set_irq_line(CLEAR_LINE); // FIXME: unreachable
 			[[fallthrough]];
 		case 0x1800:
-			return (m_irq_count >> 8) & 0xff;
+			return m_irq_count >> 8;
 			set_irq_line(CLEAR_LINE); // FIXME: unreachable
 			[[fallthrough]];
 		default:
@@ -656,7 +656,6 @@ void nes_namcot163_device::set_mirror(uint8_t page, uint8_t data)
 
 void nes_namcot163_device::write_h(offs_t offset, uint8_t data)
 {
-	int page;
 	LOG_MMC(("namcot163 write_h, offset: %04x, data: %02x\n", offset, data));
 
 	switch (offset & 0x7800)
@@ -666,14 +665,13 @@ void nes_namcot163_device::write_h(offs_t offset, uint8_t data)
 		case 0x2000: case 0x2800:
 		case 0x3000: case 0x3800:
 			m_chr_bank = data;
-			chr1_x(offset / 0x800, m_chr_bank, CHRROM);
+			chr1_x(offset >> 11, m_chr_bank, CHRROM);
 			break;
 		case 0x4000:
 		case 0x4800:
 		case 0x5000:
 		case 0x5800:
-			page = (offset & 0x1800) >> 11;
-			set_mirror(page, data);
+			set_mirror(BIT(offset, 11, 2), data);
 			break;
 		case 0x6000:
 			m_namco163snd->disable_w((data & 0x40) ? ASSERT_LINE : CLEAR_LINE);
diff --git a/src/devices/bus/nes/nes_slot.cpp b/src/devices/bus/nes/nes_slot.cpp
index 3d14ed3ad0d..07f6c5b4f90 100644
--- a/src/devices/bus/nes/nes_slot.cpp
+++ b/src/devices/bus/nes/nes_slot.cpp
@@ -493,7 +493,7 @@ void device_nes_cart_interface::reset_cpu()
 // the memory banks)
 uint8_t device_nes_cart_interface::hi_access_rom(uint32_t offset)
 {
-	int bank = (offset & 0x6000) >> 13;
+	int bank = BIT(offset, 13, 2);
 	return m_prg[m_prg_bank[bank] * 0x2000 + (offset & 0x1fff)];
 }
 
@@ -518,7 +518,7 @@ uint8_t device_nes_cart_interface::account_bus_conflict(uint32_t offset, uint8_t
 
 void device_nes_cart_interface::chr_w(offs_t offset, uint8_t data)
 {
-	int bank = offset >> 10;
+	int bank = BIT(offset, 10, 3);
 
 	if (m_chr_src[bank] == CHRRAM)
 		m_chr_access[bank][offset & 0x3ff] = data;
@@ -526,14 +526,14 @@ void device_nes_cart_interface::chr_w(offs_t offset, uint8_t data)
 
 uint8_t device_nes_cart_interface::chr_r(offs_t offset)
 {
-	int bank = offset >> 10;
+	int bank = BIT(offset, 10, 3);
 	return m_chr_access[bank][offset & 0x3ff];
 }
 
 
 void device_nes_cart_interface::nt_w(offs_t offset, uint8_t data)
 {
-	int page = (offset & 0xc00) >> 10;
+	int page = BIT(offset, 10, 2);
 
 	if (!m_nt_writable[page])
 		return;
@@ -543,7 +543,7 @@ void device_nes_cart_interface::nt_w(offs_t offset, uint8_t data)
 
 uint8_t device_nes_cart_interface::nt_r(offs_t offset)
 {
-	int page = (offset & 0xc00) >> 10;
+	int page = BIT(offset, 10, 2);
 	return m_nt_access[page][offset & 0x3ff];
 }
 
diff --git a/src/devices/bus/nes/ntdec.cpp b/src/devices/bus/nes/ntdec.cpp
index d4554d9e4bd..ba59a1e4924 100644
--- a/src/devices/bus/nes/ntdec.cpp
+++ b/src/devices/bus/nes/ntdec.cpp
@@ -207,6 +207,6 @@ void nes_ntdec_fh_device::write_m(offs_t offset, u8 data)
 void nes_ntdec_n715021_device::write_h(offs_t offset, u8 data)
 {
 	LOG_MMC(("ntdec_n715021 write_h, offset: %04x, data: %02x\n", offset, data));
-	prg16_89ab((offset >> 2) & 0x03);
+	prg16_89ab(BIT(offset, 2, 2));
 	chr8(offset & 0x03, CHRROM);
 }
diff --git a/src/devices/bus/nes/nxrom.cpp b/src/devices/bus/nes/nxrom.cpp
index 352b7534250..1b25cf864f6 100644
--- a/src/devices/bus/nes/nxrom.cpp
+++ b/src/devices/bus/nes/nxrom.cpp
@@ -411,8 +411,6 @@ void nes_cnrom_device::write_h(offs_t offset, uint8_t data)
 
 uint8_t nes_cnrom_device::chr_r(offs_t offset)
 {
-	int bank = offset >> 10;
-
 	// a few CNROM boards contained copy protection schemes through
 	// suitably configured diodes, so that subsequent CHR reads can
 	// give actual VROM content or open bus values.
@@ -420,7 +418,7 @@ uint8_t nes_cnrom_device::chr_r(offs_t offset)
 	if (m_chr_open_bus)
 		return get_open_bus();
 
-	return m_chr_access[bank][offset & 0x3ff];
+	return device_nes_cart_interface::chr_r(offset);
 }
 
 
@@ -466,7 +464,7 @@ void nes_gxrom_device::write_h(offs_t offset, uint8_t data)
 	// this pcb is subject to bus conflict
 	data = account_bus_conflict(offset, data);
 
-	prg32((data & 0xf0) >> 4);
+	prg32(data >> 4);
 	chr8(data & 0x0f, CHRROM);
 }
 
diff --git a/src/devices/bus/nes/pirate.cpp b/src/devices/bus/nes/pirate.cpp
index e846f164c7a..32db966505c 100644
--- a/src/devices/bus/nes/pirate.cpp
+++ b/src/devices/bus/nes/pirate.cpp
@@ -285,17 +285,17 @@ void nes_eh8813a_device::pcb_reset()
 
  iNES: mapper 144
 
- In MESS: Supported.
+ In MAME: Supported.
 
  -------------------------------------------------*/
 
-void nes_agci_device::write_h(offs_t offset, uint8_t data)
+void nes_agci_device::write_h(offs_t offset, u8 data)
 {
 	LOG_MMC(("agci write_h, offset: %04x, data: %02x\n", offset, data));
 
 	// this pcb is subject to bus conflict
-	uint8_t temp = account_bus_conflict(offset, 0xff);
-	data = (data & temp) | (temp & 1);
+	// bit 0 is always determined by the ROM value at the offset due to a resistor on the board
+	data = account_bus_conflict(offset, data | 1);
 
 	chr8(data >> 4, CHRROM);
 	prg32(data);
@@ -479,70 +479,28 @@ void nes_magseries_device::write_h(offs_t offset, u8 data)
 
  iNES: mapper 156
 
- In MESS: Supported.
+ In MAME: Supported.
 
  Notes: Metal Force and Buzz & Waldog only use the first 4
  regs and no mirroring. Janggun ui Adeul uses all features
 
  -------------------------------------------------*/
 
-void nes_daou306_device::write_h(offs_t offset, uint8_t data)
+void nes_daou306_device::write_h(offs_t offset, u8 data)
 {
 	LOG_MMC(("daou306 write_h, offset: %04x, data: %02x\n", offset, data));
-	int reg = BIT(offset, 2) ? 8 : 0;
 
-	switch (offset)
+	if (offset >= 0x4000 && offset < 0x4010)
 	{
-		case 0x4000:
-		case 0x4004:
-			m_reg[reg + 0] = data;
-			chr1_0(m_reg[0] | (m_reg[8] << 8), CHRROM);
-			break;
-		case 0x4001:
-		case 0x4005:
-			m_reg[reg + 1] = data;
-			chr1_1(m_reg[1] | (m_reg[9] << 8), CHRROM);
-			break;
-		case 0x4002:
-		case 0x4006:
-			m_reg[reg + 2] = data;
-			chr1_2(m_reg[2] | (m_reg[10] << 8), CHRROM);
-			break;
-		case 0x4003:
-		case 0x4007:
-			m_reg[reg + 3] = data;
-			chr1_3(m_reg[3] | (m_reg[11] << 8), CHRROM);
-			break;
-		case 0x4008:
-		case 0x400c:
-			m_reg[reg + 4] = data;
-			chr1_4(m_reg[4] | (m_reg[12] << 8), CHRROM);
-			break;
-		case 0x4009:
-		case 0x400d:
-			m_reg[reg + 5] = data;
-			chr1_5(m_reg[5] | (m_reg[13] << 8), CHRROM);
-			break;
-		case 0x400a:
-		case 0x400e:
-			m_reg[reg + 6] = data;
-			chr1_6(m_reg[6] | (m_reg[14] << 8), CHRROM);
-			break;
-		case 0x400b:
-		case 0x400f:
-			m_reg[reg + 7] = data;
-			chr1_7(m_reg[7] | (m_reg[15] << 8), CHRROM);
-			break;
-		case 0x4010:
-			prg16_89ab(data);
-			break;
-		case 0x4014:
-			if (data & 1)
-				set_nt_mirroring(PPU_MIRROR_HORZ);
-			else
-				set_nt_mirroring(PPU_MIRROR_VERT);
-			break;
+		int reg = bitswap<4>(offset, 2, 3, 1, 0);
+		m_reg[reg] = data;
+		reg &= 0x07;
+		chr1_x(reg, m_reg[reg] | (m_reg[reg | 8] << 8), CHRROM);
 	}
+	else if (offset == 0x4010)
+		prg16_89ab(data);
+	else if (offset == 0x4014)
+		set_nt_mirroring(data & 1 ? PPU_MIRROR_HORZ : PPU_MIRROR_VERT);
 }
 
 /*-------------------------------------------------
@@ -607,7 +565,7 @@ void nes_edu2k_device::write_h(offs_t offset, uint8_t data)
 	LOG_MMC(("edu2k write_h, offset: %04x, data: %02x\n", offset, data));
 
 	prg32(data & 0x1f);
-	m_latch = (data & 0xc0) >> 6;
+	m_latch = BIT(data, 6, 2);
 }
 
 void nes_edu2k_device::write_m(offs_t offset, uint8_t data)
diff --git a/src/devices/bus/nes/sachen.cpp b/src/devices/bus/nes/sachen.cpp
index 52c67838cf1..9b0ad2b7a32 100644
--- a/src/devices/bus/nes/sachen.cpp
+++ b/src/devices/bus/nes/sachen.cpp
@@ -467,7 +467,7 @@ void nes_sachen_tcu01_device::write_l(offs_t offset, uint8_t data)
 
 	if ((offset & 0x103) == 0x002)
 	{
-		prg32(((data >> 6) & 0x02) | ((data >> 2) & 0x01));
+		prg32(bitswap<2>(data, 7, 2));
 		chr8(data >> 3, CHRROM);
 	}
 }
diff --git a/src/devices/bus/nes/sealie.cpp b/src/devices/bus/nes/sealie.cpp
index 8ebad9191a7..e06a1ad73f0 100644
--- a/src/devices/bus/nes/sealie.cpp
+++ b/src/devices/bus/nes/sealie.cpp
@@ -132,7 +132,7 @@ void nes_cufrom_device::write_h(offs_t offset, u8 data)
 {
 	LOG_MMC(("cufrom write_h, offset: %04x, data: %02x\n", offset, data));
 
-	prg16_89ab((data >> 2) & 0x07);
+	prg16_89ab(BIT(data, 2, 3));
 	chr8(data & 0x03, CHRRAM);
 }
 
@@ -186,7 +186,7 @@ void nes_unrom512_device::write_h(offs_t offset, u8 data)
 	if (m_pcb_ctrl_mirror)
 		set_nt_mirroring(BIT(data, 7) ? PPU_MIRROR_HIGH : PPU_MIRROR_LOW);
 	prg16_89ab(data & 0x1f);
-	chr8((data >> 5) & 0x03, CHRRAM);
+	chr8(BIT(data, 5, 2), CHRRAM);
 }
 
 /*-------------------------------------------------
diff --git a/src/devices/bus/nes/somari.cpp b/src/devices/bus/nes/somari.cpp
index adf8b1b1330..fcbf5a35126 100644
--- a/src/devices/bus/nes/somari.cpp
+++ b/src/devices/bus/nes/somari.cpp
@@ -148,7 +148,7 @@ void nes_somari_device::mmc1_w(offs_t offset, u8 data)
 		m_mmc1_count = (m_mmc1_count + 1) % 5;
 		if (!m_mmc1_count)
 		{
-			m_mmc1_reg[(offset & 0x6000) >> 13] = m_mmc1_latch;
+			m_mmc1_reg[BIT(offset, 13, 2)] = m_mmc1_latch;
 			update_all_banks();
 		}
 	}
@@ -196,7 +196,7 @@ void nes_somari_device::update_prg()
 			set_prg(m_prg_base, m_prg_mask);
 			break;
 		case SOMARI_MMC1_MODE:
-			switch ((m_mmc1_reg[0] >> 2) & 3)
+			switch (BIT(m_mmc1_reg[0], 2, 2))
 			{
 				case 0:
 				case 1:
@@ -233,7 +233,7 @@ void nes_somari_device::update_chr()
 				chr4_4(m_mmc1_reg[2] & 0x1f, CHRROM);
 			}
 			else
-				chr8((m_mmc1_reg[1] & 0x1f) >> 1, CHRROM);
+				chr8(BIT(m_mmc1_reg[1], 1, 4), CHRROM);
 			break;
 	}
 }
diff --git a/src/devices/bus/nes/taito.cpp b/src/devices/bus/nes/taito.cpp
index 28c37b6109c..8c806672a7d 100644
--- a/src/devices/bus/nes/taito.cpp
+++ b/src/devices/bus/nes/taito.cpp
@@ -298,19 +298,19 @@ void nes_x1_005_device::write_m(offs_t offset, uint8_t data)
 	switch (offset)
 	{
 		case 0x1ef0:
-			chr2_0((data & 0x7f) >> 1, CHRROM);
+			chr2_0(BIT(data, 1, 6), CHRROM);
 			if (m_x1_005_alt_mirroring)
 			{
-				set_nt_page(0, CIRAM, (data & 0x80) ? 1 : 0, 1);
-				set_nt_page(1, CIRAM, (data & 0x80) ? 1 : 0, 1);
+				set_nt_page(0, CIRAM, BIT(data, 7), 1);
+				set_nt_page(1, CIRAM, BIT(data, 7), 1);
 			}
 			break;
 		case 0x1ef1:
-			chr2_2((data & 0x7f) >> 1, CHRROM);
+			chr2_2(BIT(data, 1, 6), CHRROM);
 			if (m_x1_005_alt_mirroring)
 			{
-				set_nt_page(2, CIRAM, (data & 0x80) ? 1 : 0, 1);
-				set_nt_page(3, CIRAM, (data & 0x80) ? 1 : 0, 1);
+				set_nt_page(2, CIRAM, BIT(data, 7), 1);
+				set_nt_page(3, CIRAM, BIT(data, 7), 1);
 			}
 			break;
 		case 0x1ef2:
diff --git a/src/devices/bus/nes/txc.cpp b/src/devices/bus/nes/txc.cpp
index 4149c6262a3..605e431fe53 100644
--- a/src/devices/bus/nes/txc.cpp
+++ b/src/devices/bus/nes/txc.cpp
@@ -185,7 +185,7 @@ void nes_txc_dumarc_device::write_h(offs_t offset, uint8_t data)
 	LOG_MMC(("TXC Du Ma Racing write_h, offset: %04x, data: %02x\n", offset, data));
 
 	prg32(m_reg[2] >> 2);
-	chr8((((data ^ m_reg[2]) >> 3) & 0x02) | (((data ^ m_reg[2]) >> 5) & 0x01), CHRROM);
+	chr8(bitswap<2>(data ^ m_reg[2], 4, 5), CHRROM);
 }
 
 /*-------------------------------------------------
diff --git a/src/devices/bus/nes/vrc_clones.cpp b/src/devices/bus/nes/vrc_clones.cpp
index a8c709313f1..93be86cc3f7 100644
--- a/src/devices/bus/nes/vrc_clones.cpp
+++ b/src/devices/bus/nes/vrc_clones.cpp
@@ -400,7 +400,7 @@ void nes_cityfight_device::write_h(offs_t offset, u8 data)
 		case 0x0800:
 			break;  // PRG banking at $8000 ignored
 		case 0x1000:
-			prg32((data >> 2) & 0x03);
+			prg32(BIT(data, 2, 2));
 			if (!(offset & 3))  // $9000 is also VRC4 mirroring
 				nes_konami_vrc4_device::write_h(offset, data);
 			break;