[GG] add an option to render Game Gear software at SMS resolution (25…

…6x192)

backend/smsgg-core/src/api.rs

@@ -60,13 +60,13 @@ impl DerefMut for FrameBuffer {
     }
 }
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Encode, Decode)]
 pub enum SmsGgHardware {
     MasterSystem,
     GameGear,
 }
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Default, EnumDisplay, EnumFromStr)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default, Encode, Decode, EnumDisplay, EnumFromStr)]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub enum SmsModel {
     Sms1,
@@ -82,7 +82,7 @@ pub enum SmsRegion {
     Domestic,
 }
 
-#[derive(Debug, Clone, Copy)]
+#[derive(Debug, Clone, Copy, Encode, Decode)]
 pub struct SmsGgEmulatorConfig {
     pub hardware: SmsGgHardware,
     pub sms_timing_mode: TimingMode,
@@ -93,6 +93,7 @@ pub struct SmsGgEmulatorConfig {
     pub sms_region: SmsRegion,
     pub sms_crop_vertical_border: bool,
     pub sms_crop_left_border: bool,
+    pub gg_use_sms_resolution: bool,
     pub fm_sound_unit_enabled: bool,
     pub overclock_z80: bool,
 }
@@ -110,9 +111,7 @@ pub struct SmsGgEmulator {
     input: InputState,
     audio_resampler: AudioResampler,
     frame_buffer: FrameBuffer,
-    sms_crop_vertical_border: bool,
-    sms_crop_left_border: bool,
-    overclock_z80: bool,
+    config: SmsGgEmulatorConfig,
     z80_cycles_remainder: u32,
     vdp_cycles_remainder: u32,
     frame_count: u64,
@@ -137,7 +136,7 @@ impl SmsGgEmulator {
         log::info!("PSG version: {psg_version:?}");
 
         let memory = Memory::new(rom, cartridge_ram);
-        let vdp = Vdp::new(vdp_version, config.remove_sprite_limit);
+        let vdp = Vdp::new(vdp_version, &config);
         let psg = Psg::new(psg_version);
         let input = InputState::new(config.sms_region);
 
@@ -159,9 +158,7 @@ impl SmsGgEmulator {
             input,
             audio_resampler: AudioResampler::new(timing_mode),
             frame_buffer: FrameBuffer::new(),
-            sms_crop_vertical_border: config.sms_crop_vertical_border,
-            sms_crop_left_border: config.sms_crop_left_border,
-            overclock_z80: config.overclock_z80,
+            config,
             z80_cycles_remainder: 0,
             vdp_cycles_remainder: 0,
             frame_count: 0,
@@ -190,24 +187,21 @@ impl SmsGgEmulator {
     }
 
     fn render_frame<R: Renderer>(&mut self, renderer: &mut R) -> Result<(), R::Err> {
-        let crop_vertical_border =
-            self.vdp_version.is_master_system() && self.sms_crop_vertical_border;
-        let crop_left_border = self.vdp_version.is_master_system() && self.sms_crop_left_border;
         populate_frame_buffer(
             self.vdp.frame_buffer(),
             self.vdp_version,
-            crop_vertical_border,
-            crop_left_border,
+            self.config.sms_crop_vertical_border,
+            self.config.sms_crop_left_border,
             &mut self.frame_buffer,
         );
 
-        let viewport = self.vdp_version.viewport_size();
-        let frame_width = if crop_left_border {
+        let viewport = self.vdp.viewport();
+        let frame_width = if self.config.sms_crop_left_border {
             viewport.width_without_border().into()
         } else {
             viewport.width.into()
         };
-        let frame_height = if crop_vertical_border {
+        let frame_height = if self.config.sms_crop_vertical_border {
             viewport.height_without_border().into()
         } else {
             viewport.height.into()
@@ -295,7 +289,7 @@ impl EmulatorTrait for SmsGgEmulator {
             self.ym2413.as_mut(),
             &mut self.input,
         ));
-        let (t_cycles, remainder) = if self.overclock_z80 {
+        let (t_cycles, remainder) = if self.config.overclock_z80 {
             // Emulate a Z80 running at 2x speed by only ticking the rest of the components for
             // half as many cycles
             let t_cycles = t_cycles + self.z80_cycles_remainder;
@@ -364,17 +358,15 @@ impl EmulatorTrait for SmsGgEmulator {
     }
 
     fn reload_config(&mut self, config: &Self::Config) {
+        self.config = *config;
+
         self.vdp_version = determine_vdp_version(config);
-        self.vdp.set_version(self.vdp_version);
+        self.vdp.update_config(self.vdp_version, config);
 
         self.psg.set_version(determine_psg_version(config));
 
         self.pixel_aspect_ratio = config.pixel_aspect_ratio;
-        self.vdp.set_remove_sprite_limit(config.remove_sprite_limit);
         self.input.set_region(config.sms_region);
-        self.sms_crop_vertical_border = config.sms_crop_vertical_border;
-        self.sms_crop_left_border = config.sms_crop_left_border;
-        self.overclock_z80 = config.overclock_z80;
         self.audio_resampler.update_timing_mode(self.vdp.timing_mode());
     }
 
@@ -399,7 +391,7 @@ impl EmulatorTrait for SmsGgEmulator {
         self.z80 = Z80::new();
         init_z80(&mut self.z80);
 
-        self.vdp = Vdp::new(self.vdp_version, self.vdp.get_remove_sprite_limit());
+        self.vdp = Vdp::new(self.vdp_version, &self.config);
         self.psg = Psg::new(self.psg.version());
         self.input = InputState::new(self.input.region());
 
@@ -419,7 +411,7 @@ fn populate_frame_buffer(
     crop_left_border: bool,
     frame_buffer: &mut [Color],
 ) {
-    let viewport = vdp_version.viewport_size();
+    let viewport = vdp_buffer.viewport();
 
     let (row_skip, row_take) = if crop_vertical_border {
         (viewport.top_border_height as usize, viewport.height_without_border() as usize)

backend/smsgg-core/src/vdp.rs

@@ -7,6 +7,7 @@
 mod debug;
 mod tms9918;
 
+use crate::SmsGgEmulatorConfig;
 use bincode::de::{BorrowDecoder, Decoder};
 use bincode::enc::Encoder;
 use bincode::error::{DecodeError, EncodeError};
@@ -28,7 +29,7 @@ pub struct ViewportSize {
 }
 
 impl ViewportSize {
-    const NTSC_SMS2: Self = Self {
+    const NTSC_SMS: Self = Self {
         width: 256,
         height: 224,
         top: 0,
@@ -38,7 +39,7 @@ impl ViewportSize {
         left_border_width: 8,
     };
 
-    const PAL_SMS2: Self = Self {
+    const PAL_SMS: Self = Self {
         width: 256,
         height: 240,
         top: 0,
@@ -58,6 +59,16 @@ impl ViewportSize {
         left_border_width: 0,
     };
 
+    const GAME_GEAR_EXPANDED: Self = Self {
+        width: 256,
+        height: 192,
+        top: 0,
+        left: 0,
+        top_border_height: 0,
+        bottom_border_height: 0,
+        left_border_width: 8,
+    };
+
     pub fn height_without_border(self) -> u16 {
         self.height - self.top_border_height - self.bottom_border_height
     }
@@ -113,11 +124,17 @@ impl VdpVersion {
     }
 
     #[must_use]
-    pub const fn viewport_size(self) -> ViewportSize {
+    const fn viewport_size(self, gg_use_sms_resolution: bool) -> ViewportSize {
         match self {
-            Self::NtscMasterSystem1 | Self::NtscMasterSystem2 => ViewportSize::NTSC_SMS2,
-            Self::PalMasterSystem1 | Self::PalMasterSystem2 => ViewportSize::PAL_SMS2,
-            Self::GameGear => ViewportSize::GAME_GEAR,
+            Self::NtscMasterSystem1 | Self::NtscMasterSystem2 => ViewportSize::NTSC_SMS,
+            Self::PalMasterSystem1 | Self::PalMasterSystem2 => ViewportSize::PAL_SMS,
+            Self::GameGear => {
+                if gg_use_sms_resolution {
+                    ViewportSize::GAME_GEAR_EXPANDED
+                } else {
+                    ViewportSize::GAME_GEAR
+                }
+            }
         }
     }
 }
@@ -599,8 +616,11 @@ pub struct VdpBuffer {
 }
 
 impl VdpBuffer {
-    fn new(version: VdpVersion) -> Self {
-        Self { buffer: vec![0; FRAME_BUFFER_LEN], viewport: version.viewport_size() }
+    fn new(version: VdpVersion, gg_use_sms_resolution: bool) -> Self {
+        Self {
+            buffer: vec![0; FRAME_BUFFER_LEN],
+            viewport: version.viewport_size(gg_use_sms_resolution),
+        }
     }
 
     #[inline]
@@ -623,6 +643,10 @@ impl VdpBuffer {
     pub fn iter(&self) -> FrameBufferRowIter<'_> {
         FrameBufferRowIter { buffer: self, row: 0 }
     }
+
+    pub fn viewport(&self) -> ViewportSize {
+        self.viewport
+    }
 }
 
 impl Encode for VdpBuffer {
@@ -703,28 +727,20 @@ pub enum VdpTickEffect {
 }
 
 impl Vdp {
-    pub fn new(version: VdpVersion, remove_sprite_limit: bool) -> Self {
+    pub fn new(version: VdpVersion, config: &SmsGgEmulatorConfig) -> Self {
         Self {
-            frame_buffer: VdpBuffer::new(version),
+            frame_buffer: VdpBuffer::new(version, config.gg_use_sms_resolution),
             registers: Registers::new(version),
             vram: [0; VRAM_SIZE],
             color_ram: [0; COLOR_RAM_SIZE],
             scanline: 0,
             dot: 0,
             sprite_buffer: SpriteBuffer::new(),
-            remove_sprite_limit,
+            remove_sprite_limit: config.remove_sprite_limit,
             line_counter: 0xFF,
         }
     }
 
-    pub fn get_remove_sprite_limit(&self) -> bool {
-        self.remove_sprite_limit
-    }
-
-    pub fn set_remove_sprite_limit(&mut self, remove_sprite_limit: bool) {
-        self.remove_sprite_limit = remove_sprite_limit;
-    }
-
     fn read_color_ram_word(&self, address: u8) -> u16 {
         if self.registers.version.is_master_system() {
             self.color_ram[address as usize].into()
@@ -1025,6 +1041,10 @@ impl Vdp {
         &self.frame_buffer
     }
 
+    pub fn viewport(&self) -> ViewportSize {
+        self.frame_buffer.viewport
+    }
+
     pub fn read_control(&mut self) -> u8 {
         self.registers.read_control()
     }
@@ -1090,9 +1110,10 @@ impl Vdp {
         self.registers.version.timing_mode()
     }
 
-    pub fn set_version(&mut self, version: VdpVersion) {
+    pub fn update_config(&mut self, version: VdpVersion, config: &SmsGgEmulatorConfig) {
         self.registers.version = version;
-        self.frame_buffer.viewport = version.viewport_size();
+        self.frame_buffer.viewport = version.viewport_size(config.gg_use_sms_resolution);
+        self.remove_sprite_limit = config.remove_sprite_limit;
     }
 }
 

frontend/jgenesis-cli/src/main.rs

@@ -121,6 +121,10 @@ struct Args {
     #[arg(long, help_heading = SMSGG_OPTIONS_HEADING)]
     sms_crop_left_border: Option<bool>,
 
+    /// For Game Gear, render at SMS resolution (256x192) instead of native resolution (160x144)
+    #[arg(long, help_heading = SMSGG_OPTIONS_HEADING)]
+    gg_use_sms_resolution: Option<bool>,
+
     /// Enable SMS FM sound unit
     #[arg(long, help_heading = SMSGG_OPTIONS_HEADING)]
     sms_fm_unit_enabled: Option<bool>,
@@ -464,6 +468,7 @@ impl Args {
             sms_region,
             sms_crop_vertical_border,
             sms_crop_left_border,
+            gg_use_sms_resolution,
             sms_fm_unit_enabled -> fm_sound_unit_enabled,
             smsgg_overclock_z80 -> overclock_z80,
         ]);

frontend/jgenesis-gui/src/app/smsgg.rs

@@ -177,6 +177,16 @@ impl App {
                 self.state.help_text.insert(WINDOW, helptext::SMS_CROP_LEFT_BORDER);
             }
 
+            let rect = ui
+                .checkbox(
+                    &mut self.config.smsgg.gg_use_sms_resolution,
+                    "(Game Gear) Display in SMS resolution",
+                )
+                .interact_rect;
+            if ui.rect_contains_pointer(rect) {
+                self.state.help_text.insert(WINDOW, helptext::GG_USE_SMS_RESOLUTION);
+            }
+
             self.render_help_text(ui, WINDOW);
         });
         if !open {

frontend/jgenesis-gui/src/app/smsgg/helptext.rs

@@ -73,6 +73,14 @@ pub const SMS_CROP_LEFT_BORDER: HelpText = HelpText {
     ],
 };
 
+pub const GG_USE_SMS_RESOLUTION: HelpText = HelpText {
+    heading: "Game Gear Expanded Resolution",
+    text: &[
+        "If enabled, display the full 256x192 frame rendered by the VDP rather than only the center 160x144 pixels.",
+        "Only the center pixels display on actual hardware, so the expanded parts of the frame may contain garbage.",
+    ],
+};
+
 pub const PSG_VERSION: HelpText = HelpText {
     heading: "PSG Version",
     text: &[

frontend/jgenesis-native-config/src/smsgg.rs

@@ -24,6 +24,8 @@ pub struct SmsGgAppConfig {
     pub sms_crop_vertical_border: bool,
     #[serde(default)]
     pub sms_crop_left_border: bool,
+    #[serde(default)]
+    pub gg_use_sms_resolution: bool,
     #[serde(default = "true_fn")]
     pub fm_sound_unit_enabled: bool,
     #[serde(default)]
@@ -58,6 +60,7 @@ impl AppConfig {
             sms_region: self.smsgg.sms_region,
             sms_crop_vertical_border: self.smsgg.sms_crop_vertical_border,
             sms_crop_left_border: self.smsgg.sms_crop_left_border,
+            gg_use_sms_resolution: self.smsgg.gg_use_sms_resolution,
             fm_sound_unit_enabled: self.smsgg.fm_sound_unit_enabled,
             overclock_z80: self.smsgg.overclock_z80,
         })

frontend/jgenesis-native-driver/src/config.rs

@@ -179,6 +179,7 @@ pub struct SmsGgConfig {
     pub sms_region: SmsRegion,
     pub sms_crop_vertical_border: bool,
     pub sms_crop_left_border: bool,
+    pub gg_use_sms_resolution: bool,
     pub fm_sound_unit_enabled: bool,
     pub overclock_z80: bool,
 }
@@ -199,6 +200,7 @@ impl SmsGgConfig {
             sms_region: self.sms_region,
             sms_crop_vertical_border: self.sms_crop_vertical_border,
             sms_crop_left_border: self.sms_crop_left_border,
+            gg_use_sms_resolution: self.gg_use_sms_resolution,
             fm_sound_unit_enabled: self.fm_sound_unit_enabled,
             overclock_z80: self.overclock_z80,
         }

frontend/jgenesis-web/src/config.rs

@@ -127,6 +127,7 @@ impl SmsGgWebConfig {
             remove_sprite_limit: self.remove_sprite_limit,
             sms_crop_left_border: self.sms_crop_left_border,
             sms_crop_vertical_border: self.sms_crop_vertical_border,
+            gg_use_sms_resolution: false,
             fm_sound_unit_enabled: self.fm_unit_enabled,
             overclock_z80: false,
         }