Minor fixes with addressing modes and ldy instr

snes-core/src/cpu/cycles.rs

@@ -96,7 +96,7 @@ fn common_conditions(cpu_registers: &Registers, addressing_mode: AddressingMode,
             },
             // Add 1 byte if <index> = 0 (16-bit index registers)
             Condition::IndexIs16Bit => {
-                if cpu_registers.is_16bit_index() {
+                if addressing_mode == AddressingMode::Immediate && cpu_registers.is_16bit_index() {
                     bytes += 1; cycles += 1;
                 }
             },

snes-core/src/cpu/instructions/lda.rs

@@ -4,7 +4,7 @@ use crate::cpu::{bus::Bus, registers::Registers};
 use crate::utils::addressing::AddressingMode;
 
 use super::read_write_common::{read_8bit_from_address, read_16bit_from_address};
-use super::{CPUInstruction, bit_common};
+use super::CPUInstruction;
 use super::decoder_common;
 
 static INSTR_NAME: &str = "LDA";
@@ -41,12 +41,11 @@ pub struct LDA8 {
 impl CPUInstruction for LDA8 {
     fn execute(&self, registers: &mut Registers, bus: &mut Bus) {
         let value = read_8bit_from_address(registers, bus, self.addressing_mode);
+        registers.set_low_a(value);
         registers.set_flags(&[
             Flags::Negative(value >> 7 == 1),
             Flags::Zero(value == 0),
         ]);
-        registers.set_low_a(value);
-        bit_common::do_bit(registers, registers.a as u8, value, self.addressing_mode);
         let (bytes, cycles) = cycles::increment_cycles_lda(registers, self.addressing_mode);
         registers.increment_pc(bytes); registers.cycles += cycles;
     }

snes-core/src/cpu/instructions/ldx.rs

@@ -4,7 +4,7 @@ use crate::cpu::{bus::Bus, registers::Registers};
 use crate::utils::addressing::AddressingMode;
 
 use super::read_write_common::{read_8bit_from_address, read_16bit_from_address};
-use super::{CPUInstruction, bit_common};
+use super::CPUInstruction;
 use super::decoder_common;
 
 static INSTR_NAME: &str = "LDX";
@@ -41,12 +41,11 @@ pub struct LDX8 {
 impl CPUInstruction for LDX8 {
     fn execute(&self, registers: &mut Registers, bus: &mut Bus) {
         let value = read_8bit_from_address(registers, bus, self.addressing_mode);
+        registers.set_low_x(value);
         registers.set_flags(&[
             Flags::Negative(value >> 7 == 1),
             Flags::Zero(value == 0),
         ]);
-        registers.set_low_x(value);
-        bit_common::do_bit(registers, registers.x as u8, value, self.addressing_mode);
         let (bytes, cycles) = cycles::increment_cycles_ld_index(registers, self.addressing_mode);
         registers.increment_pc(bytes); registers.cycles += cycles;
     }

snes-core/src/cpu/instructions/ldy.rs

@@ -4,7 +4,7 @@ use crate::cpu::{bus::Bus, registers::Registers};
 use crate::utils::addressing::AddressingMode;
 
 use super::read_write_common::{read_8bit_from_address, read_16bit_from_address};
-use super::{CPUInstruction, bit_common};
+use super::CPUInstruction;
 use super::decoder_common;
 
 static INSTR_NAME: &str = "LDY";
@@ -41,12 +41,11 @@ pub struct LDY8 {
 impl CPUInstruction for LDY8 {
     fn execute(&self, registers: &mut Registers, bus: &mut Bus) {
         let value = read_8bit_from_address(registers, bus, self.addressing_mode);
+        registers.set_low_y(value);
         registers.set_flags(&[
             Flags::Negative(value >> 7 == 1),
             Flags::Zero(value == 0),
         ]);
-        registers.set_low_y(value);
-        bit_common::do_bit(registers, registers.y as u8, value, self.addressing_mode);
         let (bytes, cycles) = cycles::increment_cycles_ld_index(registers, self.addressing_mode);
         registers.increment_pc(bytes); registers.cycles += cycles;
     }

snes-core/src/cpu/instructions/mapper.rs

@@ -178,8 +178,8 @@ pub fn map_opcode_to_instruction(opcode: u8) -> Box<dyn CPUInstruction> {
         0xA0 => Box::new(LDY{addressing_mode: A::Immediate}),
         0xAC => Box::new(LDY{addressing_mode: A::Absolute}),
         0xA4 => Box::new(LDY{addressing_mode: A::DirectPage}),
-        0xB4 => Box::new(LDY{addressing_mode: A::AbsoluteIndexed(I::Y)}),
+        0xBC => Box::new(LDY{addressing_mode: A::AbsoluteIndexed(I::X)}),
-        0xBC => Box::new(LDY{addressing_mode: A::DirectPageIndexed(I::Y)}),
+        0xB4 => Box::new(LDY{addressing_mode: A::DirectPageIndexed(I::X)}),
         // LSR
         0x4A => Box::new(LSR{addressing_mode: A::Accumulator}),
         0x4E => Box::new(LSR{addressing_mode: A::Absolute}),

snes-core/src/rom/special_ram_cart.rs

@@ -7,7 +7,7 @@ pub struct SpecialRAMCart {
 impl SpecialRAMCart {
     pub fn new() -> Self {
         Self {
-            data: vec![0x00; 0x1000000],
+            data: vec![0x00; 0x100000000],
         }
     }
 }

snes-core/src/utils/addressing.rs

@@ -21,7 +21,12 @@ pub fn immediate(pc_addr: u32) -> u32 {
 
 /// OPCODE addr
 pub fn absolute(bus: &mut Bus, pc_addr: u32, dbr: u8) -> u32 {
-    let addr = (bus.read(pc_addr + 1) as u32) | ((bus.read(pc_addr + 2) as u32) << 8);
+    let pbr = pc_addr & 0xFF0000;
+    let bus_addr_1 = pbr | ((pc_addr as u16).wrapping_add(1) as u32);
+    let bus_addr_2 = pbr | ((pc_addr as u16).wrapping_add(2) as u32);
+    let addr =
+        (bus.read(bus_addr_1) as u32) |
+        ((bus.read(bus_addr_2) as u32) << 8);
     ((dbr as u32) << 16) | addr
 }
 
@@ -49,7 +54,9 @@ pub fn absolute_indirect_long(bus: &mut Bus, pc_addr: u32, dbr: u8) -> u32 {
 
 /// OPCODE dp
 pub fn direct_page(bus: &mut Bus, pc_addr: u32, direct_page_register: u16) -> u32 {
-    (bus.read(pc_addr + 1) as u16).wrapping_add(direct_page_register) as u32
+    let pbr = pc_addr & 0xFF0000;
+    let bus_addr = pbr | ((pc_addr as u16).wrapping_add(1) as u32);
+    (bus.read(bus_addr) as u16).wrapping_add(direct_page_register) as u32
 }
 
 /// OPCODE (dp)
@@ -142,7 +149,7 @@ impl Display for IndexRegister {
     }
 }
 
-#[derive(Copy, Clone)]
+#[derive(Copy, Clone, PartialEq)]
 pub enum AddressingMode {
     Accumulator,
     Immediate,