Enhancements for cursor calculation

Fix handling of newlines. Wrap around to top of screen when newline occurs in last line. Initialize screen width in crt0.s.
2014-11-23 15:32:48 +01:00
parent 12ca22c265
commit 0c62ddf123
2 changed files with 14 additions and 8 deletions
--- a/libsrc/c1p/cputc.s
+++ b/libsrc/c1p/cputc.s
@@ -44,14 +44,12 @@ L3:     iny
        rts

 newline:
-        lda     SCR_LINELEN     ; xsize-1
-        sec                     ; Account for -1 above
-        adc     SCREEN_PTR
-        sta     SCREEN_PTR
-        bcc     L4
-        inc     SCREEN_PTR+1
-L4:     inc     CURS_Y
-        rts
+        inc     CURS_Y
+        lda     CURS_Y
+        cmp     #24             ; screen height 25 lines hardcoded
+        bne     plot
+        lda     #0              ; wrap around to line 0
+        sta     CURS_Y

 plot:   ldy     CURS_Y
        lda     ScrLo,y