variable support cleanup

src/basic/engine_variables/helper_strvarcpy_46K_50K.s

@@ -0,0 +1,46 @@
+// #LAYOUT# STD *       #TAKE-HIGH
+// #LAYOUT# *   BASIC_0 #TAKE-HIGH
+// #LAYOUT# *   *       #IGNORE
+
+// This has to go $E000 or above - routines below banks out the main BASIC ROM!
+
+//
+// Helper routine to copy string variable content
+//
+
+
+#if CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
+
+helper_strvarcpy:
+
+	// Unmap BASIC lower ROM
+
+	lda #$26
+	sta CPU_R6510
+
+	// Retrieve pointer to destination
+
+	ldy #$02
+	lda (VARPNT), y
+	sta DSCPNT+2
+	dey
+	lda (VARPNT), y
+	sta DSCPNT+1
+	dey
+
+	// Copy the string content
+!:
+	lda (__FAC1+1),y
+	sta (DSCPNT+1),y
+	iny
+	cpy __FAC1+0
+	bne !-
+
+	// Restore default memory mapping
+
+	lda #$27
+	sta CPU_R6510
+
+	rts
+
+#endif