Disable packed/double width palettes by default

Author: ccawley2011

examples/debug/peanut-debug.c

@@ -14,6 +14,7 @@
 
 #include "SDL.h"
 
+#define PEANUT_GB_USE_NIBBLE_FOR_PALETTE 1
 #define ENABLE_LCD 1
 #define ENABLE_SOUND 0
 

examples/sdl2/peanut_sdl.c

@@ -20,6 +20,8 @@
 uint8_t audio_read(uint16_t addr);
 void audio_write(uint16_t addr, uint8_t val);
 
+#define PEANUT_GB_USE_NIBBLE_FOR_PALETTE 1
+
 #include "../../peanut_gb.h"
 
 enum {

peanut_gb.h

@@ -95,6 +95,27 @@
 # define PEANUT_GB_12_COLOUR 1
 #endif
 
+/**
+ * If PEANUT_GB_USE_DOUBLE_WIDTH_PALETTE is enabled, the pixel colour data will be
+ * duplicated into both nibbles. This allows for faster scaling when rendering to
+ * a 4 bit per pixel destination.
+ *
+ * PEANUT_GB_USE_NIBBLE_FOR_PALETTE must also be defined for this to work.
+ */
+#ifndef PEANUT_GB_USE_DOUBLE_WIDTH_PALETTE
+# define PEANUT_GB_USE_DOUBLE_WIDTH_PALETTE 0
+#endif
+
+/**
+ * If PEANUT_GB_USE_NIBBLE_FOR_PALETTE is enabled, the pixel colour data will be
+ * packed into the four least significant bits of a byte (or nibble). This
+ * allows for a smaller look-up table (LUT) to be used directly, in comparison
+ * to performing bit shifts or using a larger LUT.
+ */
+#ifndef PEANUT_GB_USE_NIBBLE_FOR_PALETTE
+# define PEANUT_GB_USE_NIBBLE_FOR_PALETTE PEANUT_GB_USE_DOUBLE_WIDTH_PALETTE
+#endif
+
 /* Adds more code to improve LCD rendering accuracy. */
 #ifndef PEANUT_GB_HIGH_LCD_ACCURACY
 # define PEANUT_GB_HIGH_LCD_ACCURACY 1
@@ -501,20 +522,29 @@ struct count_s
 	#define LCD_COLOUR	0x03
 
 # if PEANUT_GB_12_COLOUR
-	/**
-	* Bit mask for whether a pixel is OBJ0, OBJ1, or BG. Each may have a different
-	* palette when playing a DMG game on CGB.
-	*/
-	#define LCD_PALETTE_OBJ	0x04
-	#define LCD_PALETTE_BG	0x08
-	/**
-	* Bit mask for the two bits listed above.
-	* LCD_PALETTE_ALL == 0b00 --> OBJ0
-	* LCD_PALETTE_ALL == 0b01 --> OBJ1
-	* LCD_PALETTE_ALL == 0b10 --> BG
-	* LCD_PALETTE_ALL == 0b11 --> NOT POSSIBLE
-	*/
-	#define LCD_PALETTE_ALL 0x0c
+#  if PEANUT_GB_USE_NIBBLE_FOR_PALETTE
+		/**
+		* Bit mask for whether a pixel is OBJ0, OBJ1, or BG. Each may have a different
+		* palette when playing a DMG game on CGB.
+		*/
+		#define LCD_PALETTE_OBJ	0x04
+		#define LCD_PALETTE_BG	0x08
+		/**
+		* Bit mask for the two bits listed above.
+		* LCD_PALETTE_ALL == 0b00 --> OBJ0
+		* LCD_PALETTE_ALL == 0b01 --> OBJ1
+		* LCD_PALETTE_ALL == 0b10 --> BG
+		* LCD_PALETTE_ALL == 0b11 --> NOT POSSIBLE
+		*/
+		#define LCD_PALETTE_ALL 0x0c
+#  else
+#   if PEANUT_GB_USE_DOUBLE_WIDTH_PALETTE
+#    error PEANUT_GB_USE_NIBBLE_FOR_PALETTE must be enabled for PEANUT_GB_USE_DOUBLE_WIDTH_PALETTE to work
+#   endif
+		#define LCD_PALETTE_OBJ	0x10
+		#define LCD_PALETTE_BG	0x20
+		#define LCD_PALETTE_ALL 0x30
+#  endif
 # else
 	#define LCD_PALETTE_OBJ	0
 	#define LCD_PALETTE_BG	0
@@ -1211,11 +1241,12 @@ void __gb_write(struct gb_s *gb, uint_fast16_t addr, uint8_t val)
 			gb->display.bg_palette[1] = ((gb->hram_io[IO_BGP] >> 2) & 0x03) | LCD_PALETTE_BG;
 			gb->display.bg_palette[2] = ((gb->hram_io[IO_BGP] >> 4) & 0x03) | LCD_PALETTE_BG;
 			gb->display.bg_palette[3] = ((gb->hram_io[IO_BGP] >> 6) & 0x03) | LCD_PALETTE_BG;
-
+#if PEANUT_GB_USE_DOUBLE_WIDTH_PALETTE
 			gb->display.bg_palette[0] |= gb->display.bg_palette[0] << 4;
 			gb->display.bg_palette[1] |= gb->display.bg_palette[1] << 4;
 			gb->display.bg_palette[2] |= gb->display.bg_palette[2] << 4;
 			gb->display.bg_palette[3] |= gb->display.bg_palette[3] << 4;
+#endif
 			return;
 
 		case 0x48:
@@ -1224,11 +1255,12 @@ void __gb_write(struct gb_s *gb, uint_fast16_t addr, uint8_t val)
 			gb->display.sp_palette[1] = ((gb->hram_io[IO_OBP0] >> 2) & 0x03);
 			gb->display.sp_palette[2] = ((gb->hram_io[IO_OBP0] >> 4) & 0x03);
 			gb->display.sp_palette[3] = ((gb->hram_io[IO_OBP0] >> 6) & 0x03);
-
+#if PEANUT_GB_USE_DOUBLE_WIDTH_PALETTE
 			gb->display.sp_palette[0] |= gb->display.sp_palette[0] << 4;
 			gb->display.sp_palette[1] |= gb->display.sp_palette[1] << 4;
 			gb->display.sp_palette[2] |= gb->display.sp_palette[2] << 4;
 			gb->display.sp_palette[3] |= gb->display.sp_palette[3] << 4;
+#endif
 			return;
 
 		case 0x49:
@@ -1237,11 +1269,12 @@ void __gb_write(struct gb_s *gb, uint_fast16_t addr, uint8_t val)
 			gb->display.sp_palette[5] = ((gb->hram_io[IO_OBP1] >> 2) & 0x03) | LCD_PALETTE_OBJ;
 			gb->display.sp_palette[6] = ((gb->hram_io[IO_OBP1] >> 4) & 0x03) | LCD_PALETTE_OBJ;
 			gb->display.sp_palette[7] = ((gb->hram_io[IO_OBP1] >> 6) & 0x03) | LCD_PALETTE_OBJ;
-
+#if PEANUT_GB_USE_DOUBLE_WIDTH_PALETTE
 			gb->display.sp_palette[4] |= gb->display.sp_palette[4] << 4;
 			gb->display.sp_palette[5] |= gb->display.sp_palette[5] << 4;
 			gb->display.sp_palette[6] |= gb->display.sp_palette[6] << 4;
 			gb->display.sp_palette[7] |= gb->display.sp_palette[7] << 4;
+#endif
 			return;
 
 		/* Window Position Registers */