Compute 2bpp background framebuffer (#4)

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/ppu/registers.rs

@@ -111,7 +111,7 @@ pub enum BgSize {
     T32x32,
     T64x32, // V Mirror
     T32x64, // H Mirror
-    T64x64, // H Mirror
+    T64x64, // H/V Mirror
 }
 
 impl BgSize {
@@ -266,10 +266,10 @@ impl PPURegisters {
     pub fn get_bg_tile_size(&self, background: Background) -> TileSize {
         let byte = self._read(BGMODE);
         let bit = match background {
-            Background::Bg1 => byte >> 3 & 0b1 == 1, // Bit 4
+            Background::Bg1 => byte >> 4 & 0b1 == 1, // Bit 4
-            Background::Bg2 => byte >> 4 & 0b1 == 1, // Bit 5
+            Background::Bg2 => byte >> 5 & 0b1 == 1, // Bit 5
-            Background::Bg3 => byte >> 5 & 0b1 == 1, // Bit 6
+            Background::Bg3 => byte >> 6 & 0b1 == 1, // Bit 6
-            Background::Bg4 => byte >> 6 & 0b1 == 1, // Bit 7
+            Background::Bg4 => byte >> 7 & 0b1 == 1, // Bit 7
         };
         match bit {
             true => TileSize::P16x16,
@@ -393,9 +393,9 @@ mod ppu_registers_test {
     #[test]
     fn test_get_bg_tile_size() {
         let mut registers = PPURegisters::new();
-        registers.write(BGMODE, 0b00000100);
+        registers.write(BGMODE, 0b00000000);
         assert_eq!(registers.get_bg_tile_size(Background::Bg1), TileSize::P8x8);
-        registers.write(BGMODE, 0b00001100);
+        registers.write(BGMODE, 0b00010000);
         assert_eq!(registers.get_bg_tile_size(Background::Bg1), TileSize::P16x16);
     }
 

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/Cargo.toml

@@ -9,7 +9,11 @@ edition = "2021"
 snes-core = { path = "../snes-core" }
 
 # Frontend stuff
-eframe = "0.24.1"
+eframe = "0.25.0"
 env_logger = "0.10.1"
 rfd = "0.12.1"
 regex = "1.10.2"
+wgpu = "0.18.0"
+
+[features]
+wgpu = ["eframe/wgpu"]

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_state/emulation.rs

@@ -1,11 +1,13 @@
 pub struct EmulationState {
     pub is_paused: bool,
+    pub one_tick_per_frame: bool,
 }
 
 impl EmulationState {
     pub fn new() -> Self {
         Self {
             is_paused: true,
+            one_tick_per_frame: false,
         }
     }
 }

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

@@ -16,6 +16,12 @@ pub fn build_cpu_debug_controls(ctx: &egui::Context, cpu_debug_options: &mut CPU
         .show(ctx, |ui| {
             ui.monospace("Controls:");
             ui.horizontal(|ui| {
+                if ui.selectable_label(
+                    emulation_state.one_tick_per_frame,
+                    "Tick per frame"
+                ).clicked() {
+                    emulation_state.one_tick_per_frame = !emulation_state.one_tick_per_frame;
+                }
                 let pause_text = if emulation_state.is_paused {"Resume"} else {"Pause"};
                 if ui.button(pause_text).clicked() {
                     emulation_state.is_paused = !emulation_state.is_paused;

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

@@ -2,7 +2,7 @@ use eframe::epaint::{Vec2, TextureHandle};
 use eframe::{egui::Context, epaint::ColorImage};
 
 use eframe::egui::{self, TextureOptions, Ui};
-use snes_core::ppu::registers::{PPURegisters, Background};
+use snes_core::ppu::registers::{PPURegisters, Background, MAX_BG_WIDTH, MAX_BG_HEIGHT};
 use crate::emu_state::debug_options::BgDebug;
 
 
@@ -25,8 +25,9 @@ fn build_bg_preview_window(ctx: &Context, bgdebug: &mut BgDebug, registers: &PPU
                 ui.label("Charset");
                 compute_2bpp_bg_char_framebuffer(bgdebug.background, &mut bgdebug.char_framebuffer, registers);
                 paint_texture(ui, &mut bgdebug.char_texture, &bgdebug.char_framebuffer, 16 * 8, 8 * 8);
-                // ui.label("Background");
+                ui.label("Background");
-                // paint_texture(ui, &mut bgdebug.bg_texture, &mut bgdebug.bg_framebuffer, MAX_BG_WIDTH, MAX_BG_HEIGHT);
+                compute_2bpp_bg_background_framebuffer(bgdebug.background, &mut bgdebug.bg_framebuffer, registers);
+                paint_texture(ui, &mut bgdebug.bg_texture, &bgdebug.bg_framebuffer, MAX_BG_WIDTH, MAX_BG_HEIGHT);
             });
         });
 }
@@ -122,6 +123,102 @@ fn compute_2bpp_bg_char_framebuffer(background: Background, framebuffer: &mut [u
     }
 }
 
+fn compute_2bpp_bg_background_framebuffer(background: Background, framebuffer: &mut [u8], registers: &PPURegisters) {
+    let tileset_vram_base_address = registers.get_bg_tile_base_address(background) as usize;
+    let charset_vram_base_address = registers.get_bg_char_base_address(background) as usize;
+    let (bg_size_width, bg_size_height) = registers.get_bg_size(background).to_usize();
+    let (tile_size_width, tile_size_height) = registers.get_bg_tile_size(background).to_usize();
+    let vram = registers.vram();
+    let width: usize = bg_size_width * tile_size_width;
+    let height: usize = bg_size_height * tile_size_height;
+    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 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
+            // so 1 char is 8 bytes x 2
+            let effective_vram_address =
+                charset_vram_base_address +
+                ((char_index as usize) * tile_size_width) +
+                current_char_row;
+
+            let vram_word = vram[effective_vram_address];
+            let lsb_bitplane= vram_word as u8;
+            let msb_bitplane= (vram_word >> 8) as u8;
+            let pixels = [
+                (
+                    (lsb_bitplane >> 7) |
+                    ((msb_bitplane >> 7) << 1)
+                ),
+                (
+                    ((lsb_bitplane >> 6) & 1) |
+                    (((msb_bitplane >> 6) & 1) << 1)
+                ),
+                (
+                    ((lsb_bitplane >> 5) & 1) |
+                    (((msb_bitplane >> 5) & 1) << 1)
+                ),
+                (
+                    ((lsb_bitplane >> 4) & 1) |
+                    (((msb_bitplane >> 4) & 1) << 1)
+                ),
+                (
+                    ((lsb_bitplane >> 3) & 1) |
+                    (((msb_bitplane >> 3) & 1) << 1)
+                ),
+                (
+                    ((lsb_bitplane >> 2) & 1) |
+                    (((msb_bitplane >> 2) & 1) << 1)
+                ),
+                (
+                    ((lsb_bitplane >> 1) & 1) |
+                    (((msb_bitplane >> 1) & 1) << 1)
+                ),
+                (
+                    (lsb_bitplane & 1) |
+                    ((msb_bitplane & 1) << 1)
+                ),
+            ];
+            let effective_pixel = pixels[current_char_column];
+
+            let current_fb_pixel = x + (y * MAX_BG_WIDTH);
+            let fb_index = current_fb_pixel * 4;
+            let r = fb_index;
+            let g = fb_index + 1;
+            let b = fb_index + 2;
+            let a = fb_index + 3;
+
+            framebuffer[a] = 0xFF;
+            match effective_pixel {
+                0b00 => {
+                    framebuffer[r] = 0xFF;
+                    framebuffer[g] = 0xFF;
+                    framebuffer[b] = 0xFF;
+                },
+                0b01 => {
+                    framebuffer[r] = 0xAC;
+                    framebuffer[g] = 0xAC;
+                    framebuffer[b] = 0xAC;
+                },
+                0b10 => {
+                    framebuffer[r] = 0x56;
+                    framebuffer[g] = 0x56;
+                    framebuffer[b] = 0x56;
+                },
+                0b11 => {
+                    framebuffer[r] = 0x00;
+                    framebuffer[g] = 0x00;
+                    framebuffer[b] = 0x00;
+                },
+                _ => unreachable!(),
+            };
+        }
+    }
+}
+
 fn paint_texture(ui: &mut Ui, texture: &mut Option<TextureHandle>, framebuffer: &[u8], width: usize, height: usize) {
     if let Some(txt) = texture {
         txt.set(
@@ -129,7 +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(),

snes-frontend/src/main.rs

@@ -1,6 +1,7 @@
 use eframe::egui;
 use snes_core::emulator::Emulator;
 
+mod utils;
 mod emu_ui;
 mod emu_state;
 
@@ -9,6 +10,7 @@ mod emu_state;
 struct SnesEmulatorApp {
     emulator: Emulator,
     state: emu_state::AppState,
+    frame_limit: utils::frame_limiter::FrameLimiter,
 }
 
 impl SnesEmulatorApp {
@@ -25,14 +27,24 @@ impl eframe::App for SnesEmulatorApp {
             // ui::game::build_game_window(ctx);
         });
         if !self.state.emulation_state.is_paused {
-            self.emulator.loop_frame();
+            if self.state.emulation_state.one_tick_per_frame {
+                self.emulator.tick();
+            } else {
+                self.emulator.loop_frame();
+            }
         }
         emu_ui::debug::build_all_debug_options(ctx, &mut self.state.debug_options, &mut self.state.emulation_state, &mut self.emulator);
+        ctx.request_repaint();
+        self.frame_limit.limit();
+        self.frame_limit.reset_timer();
     }
 }
 
 fn main() -> eframe::Result<()> {
-    let native_options = eframe::NativeOptions::default();
+    let native_options = eframe::NativeOptions {
+        vsync: false,
+        ..eframe::NativeOptions::default()
+    };
     eframe::run_native(
         "SNES Emulator",
         native_options,

snes-frontend/src/utils/frame_limiter.rs

@@ -0,0 +1,35 @@
+use std::{thread, time};
+use std::time::Instant;
+
+pub struct FrameLimiter {
+    timer: Instant,
+    fps: u128,
+}
+
+impl FrameLimiter {
+    pub fn new() -> Self {
+        Self {
+            timer: Instant::now(),
+            fps: 16600,
+        }
+    }
+
+    pub fn reset_timer(&mut self) {
+        self.timer = Instant::now();
+    }
+
+    pub fn limit(&self) {
+        let elapsed = self.timer.elapsed().as_micros();
+        if elapsed > self.fps {
+            return;
+        }
+        let wait = (self.fps - elapsed).try_into().unwrap();
+        thread::sleep(time::Duration::from_micros(wait));
+    }
+}
+
+impl Default for FrameLimiter {
+    fn default() -> Self {
+        Self::new()
+    }
+}

snes-frontend/src/utils/mod.rs

@@ -0,0 +1 @@
+pub mod frame_limiter;