Introduce assembly for flipping text pages a bit faster

apple2048.c

@@ -14,6 +14,7 @@
 #include <string.h>
 
 #include "game.h"
+#include "textpage.h"
 
 
 #define TILE_WIDTH 10
@@ -185,21 +186,6 @@ void resetAnimations(void)
 }
 
 
-void switchToPage2(void)
-{
-    char *ptr = (char *)0xc055;
-    memcpy((char *)0x800, (char *)0x400, 0x400);
-    *ptr = 0;
-}
-
-
-void switchToPage1(void)
-{
-    char *ptr = (char *)0xc054;
-    *ptr = 0;
-}
-
-
 void performAnimationsLeft(void)
 {
     bool animInProgress;

textpage.h

@@ -0,0 +1,11 @@
+/*
+ * File: textpage.h
+ * Author: Jeremy Rand
+ * Date: July 23, 2014
+ *
+ * This file is a header file for the assembly routines in textpage.s.
+ */
+
+
+void switchToPage2(void);
+void switchToPage1(void);

textpage.s

@@ -0,0 +1,78 @@
+;
+; File: textpage.s
+; Author: Jeremy Rand
+; Date: July 23, 2014
+;
+; This file contains some assembly routines to more efficiently flip text pages.
+;
+
+    .export _switchToPage2, _switchToPage1
+
+    .include "apple2.inc"
+
+_switchToPage2:
+    ldx #0
+@L1:
+    lda $400,x      ; Line 0
+    sta $800,x
+    lda $480,x      ; Line 1
+    sta $880,x
+    lda $500,x      ; Line 2
+    sta $900,x
+    lda $580,x      ; Line 3
+    sta $980,x
+    lda $600,x      ; Line 4
+    sta $a00,x
+    lda $680,x      ; Line 5
+    sta $a80,x
+    lda $700,x      ; Line 6
+    sta $b00,x
+    lda $780,x      ; Line 7
+    sta $b80,x
+
+    lda $428,x      ; Line 8
+    sta $828,x
+    lda $4a8,x      ; Line 9
+    sta $8a8,x
+    lda $528,x      ; Line 10
+    sta $928,x
+    lda $5a8,x      ; Line 11
+    sta $9a8,x
+    lda $628,x      ; Line 12
+    sta $a28,x
+    lda $6a8,x      ; Line 13
+    sta $aa8,x
+    lda $728,x      ; Line 14
+    sta $b28,x
+    lda $7a8,x      ; Line 15
+    sta $ba8,x
+
+    lda $450,x      ; Line 16
+    sta $850,x
+    lda $4d0,x      ; Line 17
+    sta $8d0,x
+    lda $550,x      ; Line 18
+    sta $950,x
+    lda $5d0,x      ; Line 19
+    sta $9d0,x
+    lda $650,x      ; Line 20
+    sta $a50,x
+    lda $6d0,x      ; Line 21
+    sta $ad0,x
+    lda $750,x      ; Line 22
+    sta $b50,x
+    lda $7d0,x      ; Line 23
+    sta $bd0,x
+
+    inx
+    cpx #40
+    beq @L2
+    jmp @L1
+@L2:
+    stz HISCR
+    rts
+
+
+_switchToPage1:
+    stz LOWSCR
+    rts