add chline, cvline functions

libsrc/agat/cvline.s

@@ -0,0 +1,29 @@
+;
+; Ullrich von Bassewitz, 08.08.1998
+; Colin Leroy-Mira, 26.05.2025
+; Konstantin Fedorov, 12.06.2025
+;
+; void cvlinexy (unsigned char x, unsigned char y, unsigned char length);
+; void cvline (unsigned char length);
+;
+
+        .export         _cvlinexy, _cvline
+        .import         gotoxy, putchardirect, newline
+
+        .include        "zeropage.inc"
+
+_cvlinexy:
+        pha                     ; Save the length
+        jsr     gotoxy          ; Call this one, will pop params
+        pla                     ; Restore the length and run into _cvline
+
+_cvline:
+        cmp     #$00            ; Is the length zero?
+        beq     done            ; Jump if done
+        sta     tmp2
+:       lda     #$5C            ; vertical line character
+        jsr     putchardirect   ; Write, no cursor advance
+        jsr     newline         ; Advance cursor to next line
+        dec     tmp2
+        bne     :-
+done:   rts