Improve genesis emulation (#88)

* wip some tests

* reduce full frameskip back to 3 and fix sa

* fix genesis some

* working / good genesis audio

* update sdkconfig

* fix sa

* update readme

* minor update to patches

Author: finger563

README.md

@@ -20,7 +20,7 @@ ESP32-S3-BOX-3 which provides:
   - NES Emulator (nofrendo)
   - Gameboy / Gameboy Color emulator (gnuboy)
   - Sega Master System / Game Gear emulator (smsplus)
-  - Genesis emulator (gwenesis); NOTE: this is a WIP and does not support full-speed / sound / savestates yet.
+  - Genesis emulator (gwenesis) - full speed / buttery smooth when muted; unmuted it runs a little slower but has nice sound
   - LVGL main menu with rom select (including boxart display) and settings page
     (all generated from Squareline Studio)
   - LVGL emulation paused menu with save slot select, save slot image display,

components/genesis/CMakeLists.txt

@@ -5,5 +5,5 @@ idf_component_register(
   REQUIRES box-emu statistics
   )
 # target_compile_options(${COMPONENT_LIB} PRIVATE -Wno-char-subscripts -Wno-attributes -Wno-implicit-fallthrough -Wno-unused-function -Wno-unused-variable -Wno-discarded-qualifiers)
-target_compile_options(${COMPONENT_LIB} PRIVATE -Wno-unused-const-variable -Wno-unused-value -O3)
-# target_compile_definitions(${COMPONENT_LIB} PRIVATE GWENESIS_AUDIO_ACCURATE=0)
+target_compile_options(${COMPONENT_LIB} PRIVATE -Wno-unused-const-variable -Wno-unused-value -Ofast)
+target_compile_definitions(${COMPONENT_LIB} PRIVATE GWENESIS_AUDIO_ACCURATE=0)

components/genesis/gwenesis/src/bus/gwenesis_bus.h

@@ -43,8 +43,6 @@ __license__ = "GPLv3"
 #define GWENESIS_REFRESH_RATE_PAL 50
 #define GWENESIS_AUDIO_FREQ_PAL 52781
 
-#define GWENESIS_AUDIO_ACCURATE 0
-
 #define Z80_FREQ_DIVISOR 14     // Frequency divisor to Z80 clock
 #define VDP_CYCLES_PER_LINE 3420// VDP Cycles per Line
 #define SCREEN_WIDTH 320

components/genesis/src/genesis.cpp

@@ -36,7 +36,7 @@ static uint8_t *frame_buffer = nullptr;
 
 extern unsigned char* VRAM;
 extern int zclk;
-int system_clock;
+static int system_clock;
 int scan_line;
 
 int16_t *gwenesis_sn76489_buffer = nullptr;
@@ -46,7 +46,9 @@ int16_t *gwenesis_ym2612_buffer = nullptr;
 int ym2612_index;
 int ym2612_clock;
 
-static int frameskip = 3;
+static constexpr int full_frameskip = 3;
+static constexpr int muted_frameskip = 2;
+static int frameskip = full_frameskip;
 
 static FILE *savestate_fp = NULL;
 static int savestate_errors = 0;
@@ -185,8 +187,9 @@ void IRAM_ATTR run_genesis_rom() {
   static GamepadState previous_state = {};
   auto state = BoxEmu::get().gamepad_state();
 
-  // set frameskip to be 3 if muted, 60 otherwise
-  frameskip = 3; // hal::is_muted() ? 3 : 60;
+  bool sound_enabled = !espp::EspBox::get().is_muted();
+
+  frameskip = sound_enabled ? full_frameskip : muted_frameskip;
 
   if (previous_state != state) {
     // button mapping:
@@ -224,8 +227,6 @@ void IRAM_ATTR run_genesis_rom() {
 
   gwenesis_vdp_render_config();
 
-  bool sound_enabled = !espp::EspBox::get().is_muted();
-
   /* Reset the difference clocks and audio index */
   system_clock = 0;
   zclk = sound_enabled ? 0 : 0x1000000;
@@ -238,7 +239,7 @@ void IRAM_ATTR run_genesis_rom() {
 
   scan_line = 0;
 
-  int _vdp_cycles_per_line = VDP_CYCLES_PER_LINE / 2;
+  static constexpr int _vdp_cycles_per_line = VDP_CYCLES_PER_LINE;
 
   while (scan_line < lines_per_frame) {
     system_clock += _vdp_cycles_per_line;
@@ -251,7 +252,7 @@ void IRAM_ATTR run_genesis_rom() {
      *    =1 : cycle accurate mode. audio is refreshed when CPUs are performing a R/W access
      *    =0 : line  accurate mode. audio is refreshed every lines.
      */
-    if (GWENESIS_AUDIO_ACCURATE == 0) {
+    if (GWENESIS_AUDIO_ACCURATE == 0 && sound_enabled) {
       gwenesis_SN76489_run(system_clock);
       ym2612_run(system_clock);
     }
@@ -292,14 +293,13 @@ void IRAM_ATTR run_genesis_rom() {
     if (scan_line == (screen_height + 1)) {
       z80_irq_line(0);
     }
-
   } // end of scanline loop
 
   /* Audio
    * synchronize YM2612 and SN76489 to system_clock
    * it completes the missing audio sample for accurate audio mode
    */
-  if (GWENESIS_AUDIO_ACCURATE == 1) {
+  if (GWENESIS_AUDIO_ACCURATE == 1 && sound_enabled) {
     gwenesis_SN76489_run(system_clock);
     ym2612_run(system_clock);
   }
@@ -324,8 +324,21 @@ void IRAM_ATTR run_genesis_rom() {
 
   if (sound_enabled) {
     // push the audio buffer to the audio task
-    int audio_len = REG1_PAL ? GWENESIS_AUDIO_BUFFER_LENGTH_PAL : GWENESIS_AUDIO_BUFFER_LENGTH_NTSC;
-    espp::EspBox::get().play_audio((uint8_t*)gwenesis_ym2612_buffer, audio_len);
+    int audio_len = std::max(sn76489_index, ym2612_index);
+    // Mix gwenesis_sn76489_buffer and gwenesis_ym2612_buffer together
+    const int16_t* sn76489_buffer = gwenesis_sn76489_buffer;
+    const int16_t* ym2612_buffer = gwenesis_ym2612_buffer;
+    for (int i = 0; i < audio_len; i++) {
+      int16_t sample = 0;
+      if (sn76489_index < audio_len) {
+        sample += sn76489_buffer[sn76489_index];
+      }
+      if (ym2612_index < audio_len) {
+        sample += ym2612_buffer[ym2612_index];
+      }
+      gwenesis_sn76489_buffer[i] = sample;
+    }
+    espp::EspBox::get().play_audio((uint8_t*)gwenesis_ym2612_buffer, audio_len * sizeof(int16_t));
   }
 
   // manage statistics
@@ -336,6 +349,8 @@ void IRAM_ATTR run_genesis_rom() {
   if (elapsed < max_frame_time) {
     auto sleep_time = (max_frame_time - elapsed) / 1e3;
     std::this_thread::sleep_for(sleep_time * std::chrono::milliseconds(1));
+  } else {
+    vTaskDelay(1);
   }
 }
 

main/main.cpp

@@ -24,9 +24,9 @@ extern "C" void app_main(void) {
   logger.info("Bootup");
 
   // initialize the hardware abstraction layer
-  BoxEmu &emu = BoxEmu::get();
   espp::EspBox &box = espp::EspBox::get();
   logger.info("Running on {}", box.box_type());
+  BoxEmu &emu = BoxEmu::get();
   logger.info("Box Emu version: {}", emu.version());
 
   // initialize
@@ -78,6 +78,10 @@ extern "C" void app_main(void) {
 
   print_heap_state();
 
+  // set the task priority (for main) to high
+  vTaskPrioritySet(nullptr, 20);
+
+  // main loop
   while (true) {
     // reset gui ready to play and user_quit
     gui.ready_to_play(false);

patches.sh

@@ -7,12 +7,12 @@ else
   echo "Applying patches to esp-idf in '${IDF_PATH}'"
 fi
 
-lodestone_dir=$(pwd)
+cur_dir=$(pwd)
 patches=($(find patches -type f))
 cd "${IDF_PATH}"
 for patch in "${patches[@]}"; do
     echo "Applying patch: ${patch}"
-    git apply ${lodestone_dir}/${patch}
+    git apply ${cur_dir}/${patch}
 done
 
-cd ${lodestone_dir}
+cd ${cur_dir}

sdkconfig.defaults

@@ -85,3 +85,14 @@ CONFIG_LV_USE_THEME_DEFAULT=y
 CONFIG_LV_THEME_DEFAULT_DARK=y
 CONFIG_LV_THEME_DEFAULT_GROW=y
 CONFIG_LV_THEME_DEFAULT_TRANSITION_TIME=30
+
+CONFIG_I2S_ISR_IRAM_SAFE=y
+CONFIG_I2C_ISR_IRAM_SAFE=y
+CONFIG_GDMA_CTRL_FUNC_IN_IRAM=y
+CONFIG_GDMA_ISR_IRAM_SAFE=y
+CONFIG_ESP_IPC_USES_CALLERS_PRIORITY=n
+
+CONFIG_FREERTOS_GENERATE_RUN_TIME_STATS=y
+CONFIG_FREERTOS_VTASKLIST_INCLUDE_COREID=y
+
+CONFIG_SPI_FLASH_ROM_IMPL=y