add waitvsync() for atari and atari5200

doc/atari.sgml

@@ -332,6 +332,7 @@ See the <url url="funcref.html" name="function reference"> for declaration and u
 <item>_scroll
 <item>_setcolor
 <item>_setcolor_low
+<item>waitvsync
 </itemize>
 
 

doc/atari5200.sgml

@@ -77,7 +77,7 @@ Programs containing Atari 5200 specific code may use the <tt/atari5200.h/ header
 <sect1>Atari 5200 specific functions<p>
 
 <itemize>
-<item>TBD.
+<item>waitvsync
 </itemize>
 
 

include/atari.h

@@ -227,6 +227,7 @@ extern unsigned char __fastcall__ _getcolor (unsigned char color_reg);
 /* Other screen functions                                                    */
 /*****************************************************************************/
 
+extern void waitvsync (void);                            /* Wait for start of next frame */
 extern int  __fastcall__ _graphics (unsigned char mode); /* mode value same as in BASIC */
 extern void __fastcall__ _scroll (signed char numlines);
                                           /* numlines > 0  scrolls up */

include/atari5200.h

@@ -89,5 +89,8 @@ extern void atr5200std_joy[];        /* referred to by joy_static_stddrv[] */
 */
 #define _bordercolor(color) 0
 
+extern void waitvsync (void);
+/* Wait for start of next frame */
+
 /* End of atari5200.h */
 #endif

libsrc/atari/waitvsync.s

@@ -0,0 +1,15 @@
+;
+; Written by Christian Groessler <chris@groessler.org>
+;
+; void waitvsync (void);
+;
+
+        .include        "atari.inc"
+        .export         _waitvsync
+
+.proc   _waitvsync
+        lda     RTCLOK+2
+@lp:    cmp     RTCLOK+2
+        beq     @lp
+        rts
+.endproc

libsrc/atari5200/waitvsync.s

@@ -0,0 +1,15 @@
+;
+; Written by Christian Groessler <chris@groessler.org>
+;
+; void waitvsync (void);
+;
+
+        .include        "atari5200.inc"
+        .export         _waitvsync
+
+.proc   _waitvsync
+        lda     RTCLOK+1
+@lp:    cmp     RTCLOK+1
+        beq     @lp
+        rts
+.endproc