improve printing of BASIC errors.

c64/basic/basic_do_error.s

@@ -1,39 +1,40 @@
 	;; Compute's Mapping the 64 p93
 
 basic_do_error:
+	;; Save error number
+	txa
+	pha
+
+	;; Print ? at start
+	lda #$0d
+	jsr $ffd2
+	lda #$3f
+	jsr $ffd2
+
+	;; Print main part of error message
+	pla
+	tax
+	jsr print_packed_message
+
+	;; Print ERROR at end
+	lda #$20
+	jsr $ffd2
+	ldx #33
+	jsr print_packed_message
+
+	;; XXX print IN if not in direct mode
+
+	;; XXX print line number if not in direct mode
+
+	lda #$0d
+	jsr $ffd2
+	lda #$0d
+	jsr $ffd2
+
+	;; Reset stack, and go back to main loop
+	ldx #$fe
+	txs
+	jmp basic_main_loop
 
 
 
-
-
-
-basic_error_messages:
-	.byte "TOO MANY FILES",0
-	.byte "FILE OPEN",0
-	.byte "FILE NOT OPEN",0
-	.byte "FILE NOT FOUND",0
-	.byte "DEVICE NOT PRESENT",0
-	.byte "NOT INPUT FILE",0
-	.byte "NOT OUTPUT FILE",0
-	.byte "MISSING FILENAME",0
-	.byte "ILLEGAL DEVICE NUMBER",0
-	.byte "NEXT WITHOUT FOR",0
-	.byte "SYNTAX",0
-	.byte "RETURN WITHOUT GOSUB",0
-	.byte "OUT OF DATA",0
-	.byte "ILLEGAL QUANTITY",0
-	.byte "OVERFLOW",0
-	.byte "OUT OF MEMORY",0
-	.byte "UNDEF'D STATEMENT",0
-	.byte "BAD SUBSCRIPT",0
-	.byte "REDIM'D ARRAY",0
-	.byte "DIVISION BY ZERO",0
-	.byte "ILLEGAL DIRECT",0
-	.byte "TYPE MISMATCH",0
-	.byte "STRING TOO LONG",0
-	.byte "FILE DATA",0
-	.byte "FORMULA TOO COMPLEX",0
-	.byte "CAN'T CONTINUE",0
-	.byte "UNDEF'D FUNCTION",0
-	.byte "VERIFY",0
-	.byte "LOAD",0