fixed screensize, timertick, revers mode

2015-07-16 16:00:32 +02:00
parent 1414411bba
commit 21ef6b8510
8 changed files with 86 additions and 27 deletions
--- a/libsrc/pce/revers.s
+++ b/libsrc/pce/revers.s
@@ -1,10 +1,24 @@

-; FIXME: actual revers output is not supported yet
+                .include "pce.inc"

-            .export _revers
-_revers:
-            lda #0
-            rts
+                .export _revers
+
+.proc   _revers
+
+                ldx     #$00                    ; Assume revers off
+                tay                                     ; Test onoff
+                beq     L1                      ; Jump if off
+                ldx     #$80                    ; Load on value
+                ldy     #$00                    ; Assume old value is zero
+L1:             lda     RVS                     ; Load old value
+                stx     RVS                     ; Set new value
+                beq     L2                      ; Jump if old value zero
+                iny                             ; Make old value = 1
+L2:             ldx     #$00                    ; Load high byte of result
+                tya                             ; Load low byte, set CC
+                rts
+
+.endproc

 ;-------------------------------------------------------------------------------
 ; force the init constructor to be imported