implemented BASIC command OLD

src/basic/basic_commands_CC/cmd__jumptable_CC.s

@@ -13,7 +13,9 @@
 
 	cmd_bload,
 	cmd_bsave,
-	cmd_bverify
+	cmd_bverify,
+
+	cmd_old
 )
 
 

src/basic/basic_commands_CC/cmd_old.s

@@ -0,0 +1,64 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+
+cmd_old:
+
+	// First make sure we are in direct mode
+
+	ldx CURLIN+1
+	inx
+	bne_16 do_DIRECT_MODE_ONLY_error
+
+	// Now try to restore program linkage
+
+	ldy #$01
+	tya
+	sta (TXTTAB),y
+
+	jsr LINKPRG
+
+	// Now we have to restore VARTAB    XXX deduplicate this with line editor
+
+	lda TXTTAB+0
+	sta OLDTXT+0
+	lda TXTTAB+1
+	sta OLDTXT+1
+!:
+	lda OLDTXT+0
+	sta VARTAB+0
+	lda OLDTXT+1
+	sta VARTAB+1
+
+	jsr basic_follow_link_to_next_line
+
+	lda OLDTXT+0
+	ora OLDTXT+1
+	bne !-                                       // branch if pointer not NULL
+
+	// Correct VARTAB by 2 bytes NULL pointer
+
+#if HAS_OPCODES_65CE02
+
+	inw VARTAB
+	inw VARTAB
+
+#else
+
+	clc
+	lda VARTAB+0
+	adc #$02
+	sta VARTAB+0
+	bcc !+
+	inc VARTAB+1
+!:
+#endif
+
+	// Call CLR to restore remaining variables
+
+	jsr do_clr
+
+	// Quit
+
+	jmp shell_main_loop