Add a setting to enable/disable the prefetch buffer.

hades-emu · Oct 12, 2024 · bdfd0c1 · bdfd0c1
1 parent 596b3b4
commit bdfd0c1
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Showing 9 changed files with 42 additions and 2 deletions.
diff --git a/accuracy/check.py b/accuracy/check.py
@@ -132,6 +132,7 @@ def main():
             "skip_bios": true,
             "speed": 1,
             "fast_forward": true,
+            "prefetch_buffer": true,
             "backup_storage": {{
               "autodetect": true,
               "type": 0

diff --git a/include/app/app.h b/include/app/app.h
@@ -190,6 +190,9 @@ struct settings {
         //   etc.
         float alt_speed;
 
+        // Enable the emulation of the prefetch buffer
+        bool prefetch_buffer;
+
         // Backup storage
         struct {
             bool autodetect;

diff --git a/include/gba/gba.h b/include/gba/gba.h
@@ -85,6 +85,9 @@ struct gba_settings {
     // Can't be <= 0.0 unless `fast_forward` is true.
     float speed;
 
+    // Enable the emulation of the prefetch buffer
+    bool prefetch_buffer;
+
     struct {
         bool enable_bg_layers[4];
         bool enable_oam;

diff --git a/source/app/config.c b/source/app/config.c
@@ -92,6 +92,10 @@ app_config_load(
             app->settings.emulation.alt_speed = d;
         }
 
+        if (mjson_get_bool(data, data_len, "$.emulation.prefetch_buffer", &b)) {
+            app->settings.emulation.prefetch_buffer = b;
+        }
+
         if (mjson_get_bool(data, data_len, "$.emulation.backup_storage.autodetect", &b)) {
             app->settings.emulation.backup_storage.autodetect = b;
         }
@@ -306,6 +310,7 @@ app_config_save(
                 "show_fps": %B,
                 "speed": %g,
                 "alt_speed": %g,
+                "prefetch_buffer": %B,
                 "backup_storage": {
                     "autodetect": %B,
                     "type": %d
@@ -356,6 +361,7 @@ app_config_save(
         (int)app->settings.emulation.show_fps,
         app->settings.emulation.speed,
         app->settings.emulation.alt_speed,
+        (int)app->settings.emulation.prefetch_buffer,
         (int)app->settings.emulation.backup_storage.autodetect,
         (int)app->settings.emulation.backup_storage.type,
         (int)app->settings.emulation.gpio_device.autodetect,

diff --git a/source/app/emulator.c b/source/app/emulator.c
@@ -196,6 +196,8 @@ app_emulator_fill_gba_settings(
         settings->speed = speed;
     }
 
+    settings->prefetch_buffer = app->settings.emulation.prefetch_buffer;
+
     settings->ppu.enable_oam = app->settings.video.enable_oam;
     memcpy(settings->ppu.enable_bg_layers, app->settings.video.enable_bg_layers, sizeof(settings->ppu.enable_bg_layers));
 

diff --git a/source/app/main.c b/source/app/main.c
@@ -52,8 +52,12 @@ app_settings_default(
 ) {
     free(settings->emulation.bios_path);
 
+    settings->emulation.bios_path = strdup("./bios.bin");
+    settings->emulation.skip_bios = false;
+    settings->emulation.show_fps = false;
     settings->emulation.speed = 1.0;
     settings->emulation.alt_speed = -1.0;
+    settings->emulation.prefetch_buffer = true;
     settings->emulation.backup_storage.autodetect = true;
     settings->emulation.backup_storage.type = BACKUP_NONE;
     settings->emulation.gpio_device.autodetect = true;
@@ -62,7 +66,6 @@ app_settings_default(
     memset(settings->video.enable_bg_layers, true, sizeof(settings->video.enable_bg_layers));
     memset(settings->audio.enable_psg_channels, true, sizeof(settings->audio.enable_psg_channels));
     memset(settings->audio.enable_fifo_channels, true, sizeof(settings->audio.enable_fifo_channels));
-    settings->emulation.bios_path = strdup("./bios.bin");
     settings->video.display_mode = DISPLAY_MODE_WINDOWED;
     settings->video.display_size = 3;
     settings->video.aspect_ratio = ASPECT_RATIO_BORDERS;

diff --git a/source/app/windows/settings.c b/source/app/windows/settings.c
@@ -343,6 +343,14 @@ app_win_settings_emulation(
         igTableSetupColumn("##EmulationSettingsMiscLabel", ImGuiTableColumnFlags_WidthFixed, vp->WorkSize.x / 5.f, 0);
         igTableSetupColumn("##EmulationSettingsMiscValue", ImGuiTableColumnFlags_WidthStretch, 0.f, 0);
 
+        // Emulate the Prefetch Buffer
+        igTableNextRow(ImGuiTableRowFlags_None, 0.f);
+        igTableNextColumn();
+        igTextWrapped("Emulate the Prefetch Buffer");
+
+        igTableNextColumn();
+        igCheckbox("##PrefetchBuffer", &app->settings.emulation.prefetch_buffer);
+
         // Show FPS
         igTableNextRow(ImGuiTableRowFlags_None, 0.f);
         igTableNextColumn();

diff --git a/source/gba/gba.c b/source/gba/gba.c
@@ -434,6 +434,11 @@ gba_process_message(
             memcpy(&gba->settings, &msg_settings->settings, sizeof(struct gba_settings));
 
             sched_update_speed(gba);
+
+            // If necessary, disable the prefetch buffer
+            if (!gba->settings.prefetch_buffer) {
+                memset(&gba->memory.pbuffer, 0, sizeof(struct prefetch_buffer));
+            }
             break;
         };
         case MESSAGE_QUICKSAVE: {

diff --git a/source/gba/memory/io.c b/source/gba/memory/io.c
@@ -791,8 +791,17 @@ mem_io_write8(
         };
         case IO_REG_WAITCNT:
         case IO_REG_WAITCNT + 1: {
+            bool old_pbuffer_enabled;
+
             io->waitcnt.bytes[addr - IO_REG_WAITCNT] = val;
-            gba->memory.pbuffer.enabled = io->waitcnt.gamepak_prefetch;
+            old_pbuffer_enabled = gba->memory.pbuffer.enabled;
+
+            if (old_pbuffer_enabled ^ io->waitcnt.gamepak_prefetch) {
+                memset(&gba->memory.pbuffer, 0, sizeof(struct prefetch_buffer));
+            }
+
+            gba->memory.pbuffer.enabled = gba->settings.prefetch_buffer && io->waitcnt.gamepak_prefetch;
+
             mem_update_waitstates(gba);
             break;
         };