Implement setting to force flash size

Adds libretro setting to toggle between automatic detection and fixed sizes for the cartidge flash. Allows for selection of "auto", "64kb",  and "128kb" options. This allows for compatibility with roms which need a specific amount of memory but do not appear in the list of known overrides.

gba_memory.c

@@ -2540,37 +2540,40 @@ static s32 load_gamepak_raw(const char *name)
 }
 
 u32 load_gamepak(const struct retro_game_info* info, const char *name,
-                 int force_rtc, int force_rumble, int force_serial)
+                 int force_rtc, int force_rumble, int force_serial,
+                 int force_flash_size)
 {
-   gamepak_info_t gpinfo;
-
-   if (load_gamepak_raw(name))
-      return -1;
-
-   // Buffer 0 always has the first 1MB chunk of the ROM
-   memset(&gpinfo, 0, sizeof(gpinfo));
-   memcpy(gpinfo.gamepak_title, &gamepak_buffers[0][0xA0], 12);
-   memcpy(gpinfo.gamepak_code,  &gamepak_buffers[0][0xAC],  4);
-   memcpy(gpinfo.gamepak_maker, &gamepak_buffers[0][0xB0],  2);
-
-   idle_loop_target_pc = 0xFFFFFFFF;
-   translation_gate_targets = 0;
-   flash_device_id = FLASH_DEVICE_MACRONIX_64KB;
-   flash_bank_cnt = FLASH_SIZE_64KB;
-   rtc_enabled = false;
-   rumble_enabled = false;
-   backup_type_reset = BACKUP_UNKN;
-   serial_mode = force_serial;
-
-   load_game_config_over(&gpinfo);
-
-   // Forced RTC / Rumble modes, override the autodetect logic.
-   if (force_rtc != FEAT_AUTODETECT)
-      rtc_enabled = (force_rtc == FEAT_ENABLE);
-   if (force_rumble != FEAT_AUTODETECT)
-      rumble_enabled = (force_rumble == FEAT_ENABLE);
-
-   return 0;
+  gamepak_info_t gpinfo;
+
+  if (load_gamepak_raw(name))
+    return -1;
+
+  // Buffer 0 always has the first 1MB chunk of the ROM
+  memset(&gpinfo, 0, sizeof(gpinfo));
+  memcpy(gpinfo.gamepak_title, &gamepak_buffers[0][0xA0], 12);
+  memcpy(gpinfo.gamepak_code,  &gamepak_buffers[0][0xAC],  4);
+  memcpy(gpinfo.gamepak_maker, &gamepak_buffers[0][0xB0],  2);
+
+  idle_loop_target_pc = 0xFFFFFFFF;
+  translation_gate_targets = 0;
+  flash_device_id = FLASH_DEVICE_MACRONIX_64KB;
+  flash_bank_cnt = FLASH_SIZE_64KB;
+  rtc_enabled = false;
+  rumble_enabled = false;
+  backup_type_reset = BACKUP_UNKN;
+  serial_mode = force_serial;
+
+  load_game_config_over(&gpinfo);
+
+  // Forced RTC / Rumble / Flash modes, override the autodetect logic.
+  if (force_rtc != FEAT_AUTODETECT)
+    rtc_enabled = (force_rtc == FEAT_ENABLE);
+  if (force_rumble != FEAT_AUTODETECT)
+    rumble_enabled = (force_rumble == FEAT_ENABLE);
+  if (force_flash_size != FEAT_AUTODETECT)
+    flash_bank_cnt = force_flash_size;
+
+  return 0;
 }
 
 s32 load_bios(char *name)

gba_memory.h

@@ -246,7 +246,8 @@ extern char gamepak_filename[512];
 cpu_alert_type dma_transfer(unsigned dma_chan, int *cycles);
 u8 *memory_region(u32 address, u32 *memory_limit);
 u32 load_gamepak(const struct retro_game_info* info, const char *name,
-                 int force_rtc, int force_rumble, int force_serial);
+                 int force_rtc, int force_rumble, int force_serial,
+                 int force_flash_size);
 s32 load_bios(char *name);
 void init_memory(void);
 void init_gamepak_buffer(void);

libretro/libretro.c

@@ -94,6 +94,7 @@ int sprite_limit = 1;
 
 static int rtc_mode = FEAT_AUTODETECT;
 static int rumble_mode = FEAT_AUTODETECT;
+static int flash_size_setting = FEAT_AUTODETECT;
 static int serial_setting = SERIAL_MODE_AUTO;
 
 u32 idle_loop_target_pc = 0xFFFFFFFF;
@@ -905,6 +906,18 @@ static void check_variables(bool started_from_load)
         else
            rumble_mode = FEAT_AUTODETECT;
      }
+
+     var.key                = "gpsp_flash_size";
+     var.value              = 0;
+     if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
+     {
+        if (!strcmp(var.value, "64kb"))
+           flash_size_setting = FLASH_SIZE_64KB;
+        else if (!strcmp(var.value, "128kb"))
+           flash_size_setting = FLASH_SIZE_128KB;
+        else
+           flash_size_setting = FEAT_AUTODETECT;
+     }
    }
 
    var.key                = "gpsp_sprlim";
@@ -1108,7 +1121,7 @@ bool retro_load_game(const struct retro_game_info* info)
    }
 
    memset(gamepak_backup, 0xff, sizeof(gamepak_backup));
-   if (load_gamepak(info, info->path, rtc_mode, rumble_mode, serial_setting) != 0)
+   if (load_gamepak(info, info->path, rtc_mode, rumble_mode, serial_setting, flash_size_setting) != 0)
    {
       error_msg("Could not load the game file.");
       return false;

libretro/libretro_core_options.h

@@ -136,6 +136,18 @@ struct retro_core_option_definition option_defs_us[] = {
       },
       "auto"
    },
+   {
+      "gpsp_flash_size",
+      "Save flash size",
+      "Sets the size of the flash memory for the emulated cartridge. Autodetect uses a ROM database that works with most commercial titles. You might want to force a particular size when using homebrew or ROM hacks that support or require it.",
+      {
+         { "auto", NULL },
+         { "64kb",  NULL },
+         { "128kb", NULL },
+         { NULL, NULL },
+      },
+      "auto"
+   },
    {
       "gpsp_frameskip",
       "Frameskip",