Merge pull request #2508 from polluks/waitvsync

[ATMOS] waitvsync

doc/funcref.sgml

@@ -155,6 +155,7 @@ function.
 <item><ref id="atmos_tick" name="atmos_tick">
 <item><ref id="atmos_tock" name="atmos_tock">
 <item><ref id="atmos_zap" name="atmos_zap">
+<item><ref id="waitvsync" name="waitvsync">
 </itemize>
 
 
@@ -8358,6 +8359,7 @@ only in the presence of a prototype.
 <descrip>
 <tag/Function/Wait until the start of the next video frame.
 <tag/Header/<tt/
+<ref id="atmos.h" name="atmos.h">,
 <ref id="cbm.h" name="cbm.h">,
 <ref id="gamate.h" name="gamate.h">,
 <ref id="nes.h" name="nes.h">,
@@ -8365,6 +8367,7 @@ only in the presence of a prototype.
 <tag/Declaration/<tt/void waitvsync (void);/
 <tag/Description/Wait for vertical sync, to reduce flickering.
 <tag/Availability/Platforms served by the headers above
+(Atmos requires the VSync hack)
 <tag/Example/None.
 </descrip>
 </quote>

include/atmos.h

@@ -169,6 +169,9 @@ void atmos_tock (void);
 void atmos_zap (void);
 /* Raygun sound effect */
 
+void waitvsync (void);
+/* Wait for start of next frame */
+
 
 
 /* End of atmos.h */

libsrc/atmos/waitvsync.s

@@ -0,0 +1,18 @@
+;
+; Written by Stefan Haubenthal <polluks@sdf.org>, requires VSync hack
+;
+; void waitvsync (void);
+;
+
+        .export _waitvsync
+
+        .include "atmos.inc"
+
+.proc   _waitvsync
+
+        lda     #%00010000      ; CB1
+wait:   and     VIA::PRA2
+        bne     wait
+        rts
+
+.endproc