Add textcolor and bgcolor.s

libsrc/telestrat/bgcolor.s

@@ -0,0 +1,28 @@
+; 2019-07-02, Jede (jede@oric.org)
+;
+
+        .export         _bgcolor
+        .import         BGCOLOR
+        .import         BGCOLOR_CHANGE
+        .include        "telestrat.inc"
+
+.proc _bgcolor
+    cmp     BGCOLOR       ; Do we set the same color? if we don't detect it, we loose one char on the screen for each textcolor call with the same color
+    bne     out           ; Yes
+    lda     #$00
+    sta     BGCOLOR_CHANGE
+    
+    lda     BGCOLOR       ; Return last color
+
+    rts
+out:
+    ldx     BGCOLOR       ; Get last color in order to return it
+    sta     BGCOLOR
+
+    lda     #$01          ; Notify the change color  
+    sta     BGCOLOR_CHANGE  
+    txa                   ; Return previous color
+    rts
+.endproc
+
+