Add LCD Color Filter core options

src/libretro/Makefile.common

@@ -59,3 +59,7 @@ SOURCES_CXX += \
 	$(CORE_DIR)/gb/gbMemory.cpp \
 	$(CORE_DIR)/gb/gbSGB.cpp \
 	$(CORE_DIR)/gb/gbSound.cpp
+
+# Filters
+SOURCES_CXX += \
+	$(CORE_DIR)/gba/gbafilter.cpp

src/libretro/UtilRetro.cpp

@@ -232,17 +232,25 @@ void utilUpdateSystemColorMaps(bool lcd)
 {
     int i = 0;
 
-    (void)lcd;
-
     switch (systemColorDepth) {
         case 16:
-        for (i = 0; i < 0x10000; i++)
+            for (i = 0; i < 0x10000; i++) {
-            systemColorMap16[i] = ((i & 0x1f) << systemRedShift) | (((i & 0x3e0) >> 5) << systemGreenShift) | (((i & 0x7c00) >> 10) << systemBlueShift);
+                systemColorMap16[i] = ((i & 0x1f) << systemRedShift) |
+                    (((i & 0x3e0) >> 5) << systemGreenShift) |
+                    (((i & 0x7c00) >> 10) << systemBlueShift);
+                }
+                if (lcd)
+                    gbafilter_pal(systemColorMap16, 0x10000);
             break;
         case 24:
         case 32:
-        for (i = 0; i < 0x10000; i++)
+            for (i = 0; i < 0x10000; i++) {
-            systemColorMap32[i] = ((i & 0x1f) << systemRedShift) | (((i & 0x3e0) >> 5) << systemGreenShift) | (((i & 0x7c00) >> 10) << systemBlueShift);
+                systemColorMap32[i] = ((i & 0x1f) << systemRedShift) |
+                    (((i & 0x3e0) >> 5) << systemGreenShift) |
+                    (((i & 0x7c00) >> 10) << systemBlueShift);
+                }
+                if (lcd)
+                    gbafilter_pal32(systemColorMap32, 0x10000);
             break;
     }
 }

src/libretro/libretro.cpp

@@ -56,6 +56,7 @@ static bool option_forceRTCenable = false;
 static bool option_showAdvancedOptions = false;
 static double option_sndFiltering = 0.5;
 static unsigned option_gbPalette = 0;
+static bool option_lcdfilter = false;
 
 static unsigned retropad_device[4] = {0};
 static unsigned systemWidth = gbaWidth;
@@ -1211,6 +1212,16 @@ static void update_variables(bool startup)
         gbColorOption = (!strcmp(var.value, "enabled")) ? 1 : 0;
     }
 
+    var.key = "vbam_lcdfilter";
+    var.value = NULL;
+
+    if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value) {
+        bool prev_lcdfilter = option_lcdfilter;
+        option_lcdfilter = (!strcmp(var.value, "enabled")) ? true : false;
+        if (prev_lcdfilter != option_lcdfilter)
+            utilUpdateSystemColorMaps(option_lcdfilter);
+    }
+
     var.key = "vbam_show_advanced_options";
     var.value = NULL;
 
@@ -1539,8 +1550,8 @@ bool retro_load_game(const struct retro_game_info *game)
       return false;
    }
 
+   utilUpdateSystemColorMaps(option_lcdfilter);
    update_variables(true);
-   utilUpdateSystemColorMaps(false);
    soundInit();
 
    if (type == IMAGE_GBA) {

src/libretro/libretro_core_options.h

@@ -189,6 +189,17 @@ struct retro_core_option_definition option_defs_us[] = {
         },
         "disabled"
     },
+    {
+        "vbam_lcdfilter",
+        "LCD Color Filter",
+        "TODO:",
+        {
+            { "disabled",  NULL },
+            { "enabled",   NULL },
+            { NULL, NULL },
+        },
+        "disabled"
+    },
     {
         "vbam_turboenable",
         "Enable Turbo Buttons",