Fix issues when displaying the background tiles

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

@@ -24,7 +24,7 @@ impl CPUInstruction for BRL {
     }
 
     fn mnemonic(&self, registers: &Registers, bus: &Bus, opcode: u8) -> String {
-        decoder_common::mnemonic_absolute(opcode, INSTR_NAME, registers, bus)
+        decoder_common::mnemonic_absolute_16bit(opcode, INSTR_NAME, registers, bus)
     }
 }
 

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

@@ -10,7 +10,10 @@ pub fn mnemonic_arithmetic(is_16bit: bool, opcode: u8, instr_name: &str, address
             true =>  mnemonic_16bit_immediate(opcode, instr_name, registers, bus),
             false => mnemonic_8bit_immediate(opcode, instr_name, registers, bus),
         },
-        A::Absolute => mnemonic_absolute(opcode, instr_name, registers, bus),
+        A::Absolute => match is_16bit {
+            true => mnemonic_absolute_16bit(opcode, instr_name, registers, bus),
+            false => mnemonic_absolute_8bit(opcode, instr_name, registers, bus),
+        },
         A::AbsoluteLong => mnemonic_absolute_long(opcode, instr_name, registers, bus),
         A::DirectPage => mnemonic_direct_page(opcode, instr_name, registers, bus),
         A::DirectPageIndirect => mnemonic_direct_page_indirect(opcode, instr_name, registers, bus),
@@ -38,14 +41,21 @@ pub fn mnemonic_8bit_immediate(opcode: u8, instr_name: &str, registers: &Registe
 pub fn mnemonic_16bit_immediate(opcode: u8, instr_name: &str, registers: &Registers, bus: &Bus) -> String {
     let next_byte = bus.read_external(registers.get_pc_address() + 1);
     let next_second_byte = bus.read_external(registers.get_pc_address() + 2);
-    let word = (next_byte as u16) | ((next_byte as u16) << 8);
+    let word = (next_byte as u16) | ((next_second_byte as u16) << 8);
     format!("{:02X} {:02X} {:02X} __ | {} #${:04X}", opcode, next_byte, next_second_byte, instr_name, word)
 }
 
-pub fn mnemonic_absolute(opcode: u8, instr_name: &str, registers: &Registers, bus: &Bus) -> String {
+pub fn mnemonic_absolute_8bit(opcode: u8, instr_name: &str, registers: &Registers, bus: &Bus) -> String {
     let next_byte = bus.read_external(registers.get_pc_address() + 1);
     let next_second_byte = bus.read_external(registers.get_pc_address() + 2);
-    let word = (next_byte as u16) | ((next_byte as u16) << 8);
+    let word = (next_byte as u16) | ((next_second_byte as u16) << 8);
+    format!("{:02X} {:02X} {:02X} __ | {} ${:04X}", opcode, next_byte, next_second_byte, instr_name, word)
+}
+
+pub fn mnemonic_absolute_16bit(opcode: u8, instr_name: &str, registers: &Registers, bus: &Bus) -> String {
+    let next_byte = bus.read_external(registers.get_pc_address() + 1);
+    let next_second_byte = bus.read_external(registers.get_pc_address() + 2);
+    let word = (next_byte as u16) | ((next_second_byte as u16) << 8);
     format!("{:02X} {:02X} {:02X} __ | {} ${:04X}", opcode, next_byte, next_second_byte, instr_name, word)
 }
 

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

@@ -19,7 +19,7 @@ impl CPUInstruction for PEA {
     }
 
     fn mnemonic(&self, registers: &Registers, bus: &Bus, opcode: u8) -> String {
-        decoder_common::mnemonic_absolute(opcode, INSTR_NAME, registers, bus)
+        decoder_common::mnemonic_absolute_16bit(opcode, INSTR_NAME, registers, bus)
     }
 }
 

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

@@ -24,7 +24,7 @@ impl CPUInstruction for PER {
     }
 
     fn mnemonic(&self, registers: &Registers, bus: &Bus, opcode: u8) -> String {
-        decoder_common::mnemonic_absolute(opcode, INSTR_NAME, registers, bus)
+        decoder_common::mnemonic_absolute_16bit(opcode, INSTR_NAME, registers, bus)
     }
 }
 

snes-core/src/cpu/internal_registers.rs

@@ -57,9 +57,11 @@ impl InternalRegisters {
     }
 
     fn read_vblank_nmi_mut(&self, ppu_registers: &mut PPURegisters) -> u8 {
-        let byte = self._read(RDNMI);
+        let result = self.read_vblank_nmi(ppu_registers);
+        if result == 0x80 {
+            println!("nmi set");
+        }
         // When register is read, bit 7 is cleared
-        let result = (byte & 0x7F) | ((ppu_registers.vblank_nmi as u8) << 7);
         ppu_registers.vblank_nmi = false;
         result
     }

snes-core/src/rom/lo_rom.rs

@@ -27,7 +27,7 @@ impl ROM for LoROM {
         let address = LoROM::adjust_address(address);
         match self.data.get(address as usize) {
             Some(byte) => *byte,
-            None => 0xFF,
+            None => 0x00,
         }
     }
 

snes-frontend/src/emu_state/debug_options.rs

@@ -103,6 +103,7 @@ pub struct PPUDebugControlOptions {
     pub show_registers: bool,
     pub show_vram: bool,
     pub vram_inputs: VramInputs,
+    pub vram_inputs_result: VramInputs,
     pub backgrounds: [BgDebug; 4],
 }
 
@@ -113,6 +114,7 @@ impl PPUDebugControlOptions {
             show_registers: true,
             show_vram: true,
             vram_inputs: VramInputs::new(),
+            vram_inputs_result: VramInputs::new(),
             backgrounds: [
                 BgDebug::new(PPUBg::Bg1),
                 BgDebug::new(PPUBg::Bg2),

snes-frontend/src/emu_ui/debug/ppu.rs

@@ -164,13 +164,15 @@ fn build_vram_window(ctx: &egui::Context, ppu_debug_options: &mut PPUDebugContro
             if ui.button("Search").clicked() {
                 sanitize_input(&mut ppu_debug_options.vram_inputs.address_start, false);
                 sanitize_input(&mut ppu_debug_options.vram_inputs.address_end, false);
+                ppu_debug_options.vram_inputs_result.address_start = ppu_debug_options.vram_inputs.address_start.to_string();
+                ppu_debug_options.vram_inputs_result.address_end = ppu_debug_options.vram_inputs.address_end.to_string();
             }
 
             ui.separator();
 
             egui::ScrollArea::both().show(ui, |ui| {
-                let address_start = u16::from_str_radix(&ppu_debug_options.vram_inputs.address_start, 16).unwrap();
+                let address_start = u16::from_str_radix(&ppu_debug_options.vram_inputs_result.address_start, 16).unwrap();
-                let address_end = u16::from_str_radix(&ppu_debug_options.vram_inputs.address_end, 16).unwrap();
+                let address_end = u16::from_str_radix(&ppu_debug_options.vram_inputs_result.address_end, 16).unwrap();
                 let mut header = String::from("     | ");
                 for page in 0x00..=0x0F {
                     header = format!("{}  {:02X} ", header, page);

snes-frontend/src/emu_ui/debug/ppu_graphics.rs

@@ -134,7 +134,8 @@ fn compute_2bpp_bg_background_framebuffer(background: Background, framebuffer: &
     for y in 0..height {
         for x in 0..width {
             let current_tile = (x / tile_size_width) + ((y / tile_size_height) * bg_size_width);
-            let char_index = vram[(tileset_vram_base_address + current_tile) & 0x7FFF] & 0b11_11111111;
+            let tile_byte = vram[tileset_vram_base_address + current_tile];
+            let char_index = tile_byte & 0b11_11111111;
             let current_char_column = x.rem_euclid(tile_size_width);
             let current_char_row = y.rem_euclid(tile_size_height);
             // 8x8 pixels, 2 bitplanes, each word (16bit) holds 8 pixels
@@ -225,7 +226,7 @@ fn paint_texture(ui: &mut Ui, texture: &mut Option<TextureHandle>, framebuffer:
             TextureOptions::default(),
         );
         let (whole_rect, _) =
-            ui.allocate_exact_size(Vec2::from([width as f32, height as f32]), egui::Sense::focusable_noninteractive());
+            ui.allocate_exact_size(Vec2::from([(width * 2) as f32, (height * 2) as f32]), egui::Sense::focusable_noninteractive());
         egui::Image::new((
             txt.id(),
             txt.size_vec2(),