Align buffers to 8 bytes as per the PL111 datasheet, fix pointer cast

src/graphics.c

@@ -13,6 +13,7 @@ volatile unsigned *lcd_base = (unsigned *) (LCD_CONTROLLER + 0x10);
 
 #define BUFFER_SIZE 320 * 240 * 2
 unsigned short *buffer_front = NULL, *buffer_back = NULL, *buffer_os;
+unsigned buffer_front_offset, buffer_back_offset;
 
 /*
  * Buffer management
@@ -20,8 +21,8 @@ unsigned short *buffer_front = NULL, *buffer_back = NULL, *buffer_os;
 
 void buffer_allocate()
 {
-	buffer_front = (unsigned short *) malloc(BUFFER_SIZE);
-	buffer_back = (unsigned short *) malloc(BUFFER_SIZE);
+	buffer_front = (unsigned short *) malloc(BUFFER_SIZE + 8);
+	buffer_back = (unsigned short *) malloc(BUFFER_SIZE + 8);
 
 	if (buffer_front == NULL || buffer_back == NULL)
 	{
@@ -30,14 +31,19 @@ void buffer_allocate()
 		exit(0);
 	}
 
+	buffer_front_offset = 8 - ((unsigned) buffer_front & 0x7);
+	buffer_back_offset = 8 - ((unsigned) buffer_back & 0x7);
+	buffer_front = (unsigned short *) ((unsigned) buffer_front + buffer_front_offset);
+	buffer_back = (unsigned short *) ((unsigned) buffer_back + buffer_back_offset);
+
 	buffer_os = (unsigned short *) *lcd_base;
 	*lcd_base = (unsigned) buffer_front;
 }
 
 void buffer_free()
 {
-	free(buffer_front);
-	free(buffer_back);
+	free((unsigned short *) ((unsigned) buffer_front - buffer_front_offset));
+	free((unsigned short *) ((unsigned) buffer_back - buffer_back_offset));
 
 	*lcd_base = (unsigned) buffer_os;
 }
@@ -45,8 +51,11 @@ void buffer_free()
 void buffer_swap()
 {
 	unsigned short *buffer_front_tmp = buffer_front;
+	unsigned buffer_front_offset_tmp = buffer_front_offset;
 	buffer_front = buffer_back;
+	buffer_front_offset = buffer_back_offset;
 	buffer_back = buffer_front_tmp;
+	buffer_back_offset = buffer_front_offset_tmp;
 
 	*lcd_base = (unsigned) buffer_front;
 }
@@ -58,7 +67,7 @@ void buffer_copy()
 
 void buffer_fill(unsigned color)
 {
-	unsigned *buffer_back_32 = buffer_back;
+	unsigned *buffer_back_32 = (unsigned *) buffer_back;
 	int i;
 	color += color << 16;
 	for (i = 0; i < (BUFFER_SIZE / 4); i++)